SaabCentral Forums banner

li Arc's Cochenille 85' T16

135K views 514 replies 36 participants last post by  jamengual 
#1 · (Edited)


So after a lot of deliberation, I finally decided to start a project thread. This is mainly because it's a lot of work keeping the thread updated and listing a progress report, but at the same time, there are a lot of things I'm doing that I could use some advice on. To that end, a project thread seemed the most logical course of action, but I'll say right off the bat that this won't be as flashy as IJ's build, or as technically incredible as milos' restoration. If you're looking for fantastic reads, I point you there instead. I'm a poor engineer who decided to do his own car work because it's cheaper that way, and yep, this is my first car. My tools are minimal, my experience limited, and the junk yard is my holy grail.

First off, some history of the car. Originally, my dad owned a 1979 99 T8 3-dr, which had the louvre in the back, super inca rims, the rock guards on the headlight lenses, red interior, airplane-style clip seatbelts, and a turbo gauge that stuck out on the dashboard. It was a similar price to a Corvette at the time, but he got much more stares and compliments from the general public than any Corvette would have gotten. Sadly, with us kids growing up, the 3-dr wasn't as practical, and so he sold it around 1989. My dad bought the 900 in 1989 from the original owner, and we have kept it since. However, growing up I was always enthralled by Saabs, especially when we would make trips down to Seattle and visit the Saab dealerships around Kirkland. Around 2001, my dad cancelled insurance on it because downtown parking was skyrocketting and he decided taking the bus was more economical. The car sat for 4 years, until one day I decided I wanted to drive it. And so began the tale of the Saab obsession. It's my first car, so I knew nothing about vehicle repair before this. But slowly and surely, this car would force me to figure it out, luckily with the help and support of SC!



This car is a 4-door saloon, which seem to have less appeal than the 3- or 5-door hatchback counterparts. Its code colour is 127G I believe, "Cochenille Red", which my father mentioned was quite popular back in the day, but to date I believe I have only seen one other example in person (at the junkyard). I may have come across one or two other examples online, but just as rare, so I'm proud to keep it in its original colour. Being an 1985 T16, it's the first year of 16-valve production engines, which I have heard uses 8V pistons. It's currently sitting at 385,000km on the odo, with the original engine out for a rebuild and an 86' GM45610 gearbox fitted in unknown mileage. Its original turbo, basically a 0.48AR exhaust housing, 0.63AR compressor housing, stage 1 turbine 45 trim compressor T3 Garett turbo, was taken out around 340,000km's, with a crack in the exhaust housing, but that was all; it still spools strong.

Anyways, since I acquired it with 280,000km's on the clock, there have been some work done on it. In fact, I don't think there's anything I haven't yet touched (except for perhaps the headliner and transmission, but that will change soon). I'm sure some of you are familiar with some of the work that's gone into it.

Engine mods:
3.0bar FPR
-431 30# injectors (back to stock due to issues)
vacuum advance mod

Intake/Exhaust mods:
T3 Super 60 compressor, stage 1.5 turbine, 0.48AR turbine housing internally wastegated
3" turbo-back exhaust with widebend elbow and 3" v-band
ATP Ultimage Wastegate with 3" v-band
Forge FMAC900 adjustable wastegate actuator
2.5" intake aluminum piping
17"x12"x3" FMIC
open air intake filter
Forge FMDV004 BOV using yellow spring

Transmission mods:
SD carbon/kevlar clutch kit with uprated pressure plate

Suspension mods:
Koni red adjustable shocks all around
Brad's Adjustables spring/weightjack setup in rear
Squaab99's custom adjustable spring/weightjack setup in the front
Afco Racing 550lb/in springs in the front, 650lb/in springs in the back
Sportmax/XXR 006 17" mesh wheels in black
205/40/R17 Nexen 3000 tires
EBC green stuff pads in the front
PBR pads in the rear

Electricals:
APC mods as needed
H4-4 HID beams (4-ballast)
Jak's Stage 1/Stage 2 ECU (back to stock due to issues)
LED signal, reversing, and stop lights
Magnecor wires
battery moved to left side under air filter

Interior:
Grey carpets and knee bolster (changed from original beige)
Momo Champion steering wheel
Momo pedal covers
Momo shift knob
Momo leather shift boot
Autometer carbon fibre boost, voltage, and narrowband AFR
LED modified instrumentation lights

Exterior:
Clear corners (need replacing after the last accident)
pre-facelift SPG front and rear bumper extensions and front spoiler
hood (3 times), left fender, windshield wiper support bar, all 4 doors, trunk lid, roof, both rear quarter panels, have all been repainted

That's all I can think of for now!

li Arc
 
See less See more
2
#296 ·
Took the LHS axle out, cleaned the grease, and inspected the inner driver components. The tripod bearing was fine and still silky smooth, and no needle bearings were missing. The inner driver is smoother than ice, and didn't show any signs of damage or anything. Unfortunately, I didn't have any power-pressured brake cleaner, so I couldn't blast the stuff out...I wiped everything down and cleaned it with my lower-pressure brake cleaner, so I wasn't able to tell if there were any foreign contaminants in the grease, but it's clean now.

Originally when I spun the wheel on the spindle, that was smooth, and I didn't feel anything amiss. However, after I removed the axle and the rotor was free to spin on its own, it went "clunk, clunk, clunk". As one spun the rotor, it axially moved toward the car ever so slightly, until it did almost a 360 and fell back to its original position, producing the clunk. I removed the spindle assembly and it continued to do this, so I assume it can't be anything else but the wheel bearing. I didn't realize the wheel bearing was so large, so it's going to a shop to get done.

I'm not entirely convinced this is the entire problem, so we'll see what happens after it gets done. It just doesn't make sense for the wheel bearing to go at the same time I put the engine back in, and there's still that cyclical vibration I feel under acceleration only (wherein the inner driver is now ruled out). It would have had to be an awfully large piece of contaminant that I removed from the inner driver if that was it, and I would most likely have seen it...but whatever, if I scrub it down a last time, put in some new grease, change the wheel bearing, and it still does this, then we'll see where to go from there. Just don't blame me for being skeptical!

li Arc
 
#297 ·
I don't think there's any shame sending work out to be done. Sometimes after rebuilding engines, transmissions, and whatever the hell else, you want to just pay money and not mess with it. I have a local shop that does axles for a great price and guarantees their work for life. That beats the hell out of me messing with it any day.
 
#298 ·
So I had the wheel bearing replaced by Ray, and popped it back on with some new GKN grease, but no change, as I suspected. It's time for elimination now, but I'm almost wondering if it's something in the gearbox or diff, though I highly doubt it; I can't really see a gearbox problem translating into vibration only on one side, even if something is wrong with the diff. Ray says there's a slight chance it could be something along the other axle, but I think he was right in saying that it should be in the left, though all that's left is the outer CV which seems in good condition (I didn't feel anything out of the ordinary just twisting it by hand). It looks like the next logical course of action is to replace the entire axle, or perhaps borrow one. As I'm dirt poor now after the holidays, this'll just have to wait a while. Maybe I'll see if one of the other guys in town has an extra.

Anyways, hope you guys had a good holiday break! I'll probably take it easy for the next while and play things by ear.

li Arc
 
#299 ·
hey Li Arc

You used an oil catch can on your car didn't you?

Do you know how it's going any good?

My car is sucking a lot of oil, a bit from the turbo but most just because my car is an 8 valve (there's heaps pre turbo) after reading about how much oil and oil vapour can cause knock I've decided I wanna try a cheap catch can.

Any ideas?

Cheers


Ed
 
#300 ·
Sure, I put in an oil catch can to reduce the amount of gunk in the intercooler. It always pissed me off seeing oil coming out of the pipes when I need to take them off, when it's not near any fluids and should be clean has heck. But you'll want to make sure first that your turbo isn't leaking oil, because that indicates a problem with your turbo you should probably address.

Motor oil has a high specific heat capacity, >2.1 J/(g K) depending on the type, which is much higher than aluminum at 0.91 J/(g K) @ 25C, so it acts as a thermal insulator in comparison to aluminum. When it coats the inside of your intercooler, it creates a thermal barrier that, while it won't prevent the intercooler from cooling at all, will cause a higher intake temperature than if the oil weren't at all present. I'm also not a fan of burning oil: it's meant to be used as a lubricant, and doesn't burn cleanly at all. It can contain a lot of contaminants that shouldn't be released into the air.

What I did is to simply hook one end of the oil catch can to the PCV breather, and plug the other end (if it's got two ports), allowing the third port to filter the air. I've heard of others adding steel wool inside the can, to add obstacles to further filter the air before being exhausted, which is probably a good idea. Since I'm still awaiting good weather before re-starting work, I haven't had much of a chance to test the oil catch can: I'm slightly dubious as to how effective it will be (I haven't yet added steel wool to its interior), but I will certainly keep an eye on it. Before putting everything back together again, I also soaked the inside of the intercooler with gasoline, and though it may not be ideal as it too can leave a film, it should be much better than the oil it removes. I rinsed it with water reassembly.

li Arc
 
#301 ·
I haven't started looking at this vibration problem yet, but I had a chance to bounce some ideas around in the Saab rally forums, where many repairs carried out are not regular wear-and-tear induced, so that I can find some radical solutions to my unconventional problem. It appears as though most of the speculation here has been based on what would normally go wrong with c900's, but since we've been through all conventional solutions without seeing any results, I needed a different approach to this problem.

Thus from my travels, I have identified as the most likely culprit the inner drivers I installed. The problem is I received these inner drivers from mmoe, who although I trust, never guaranteed me their condition; as you may recall, the transmissions I received from Vince only contained one of four inner drivers. They appear to be in good condition, but unless one owned them since new, one can never truly know their history. So the consensus is that one of these inner drivers is slightly bent, from whatever cause it may be, enough that it only generates vibrations in a specific region inside the driver cup; in this case, the driver tripod rides across the boundary between where it's straight and where it's bent only when turning right. The surfaces are smooth and not at all marred, and they do not appear to be physically damaged in any way.

The current plan is once a warm day arrives (hopefully not this weekend but the next one), I should be able to pull the drivers from my '86 box, swap bearing housings, and reinstall them. It sounds simple enough, but from my estimate I'm going to need a good afternoon with 6 hours or more allocated (always plan for something to go wrong). I'm tempted to do it across two days so that I can utilize the press at work for the bearing housings, but it's not crucial (I can tap them out).

I guess we'll see where this cockamamie plan goes, but for now, that's what I'm sticking to!

Another thing is I started this thread to help pave the path for other people, and also for the enjoyment of casual readers, which I can't help but feel like I've failed in if the thread has no photos in it. Unfortunately, the first half of the photos in this thread were placed in the SC galleries, which for some reason has completely borked, so I will work on trying to recompile my image collection so that I can repost them elsewhere and update this thread. My apologies to those who have been missing out due to the lack of photos! ;oops:

li Arc
 
#302 ·
Hey yeah that sounds interesting about its insulating properties. I installed one with two ports and ran the hoses same as you. I used a plastic splitter down the centre to increase the distance the air has to travel and filled the inside with that plastic mesh that people use in those plastic shower scrubbers. I also just used nylon stockings over the ports to stop any stuff traveling through (the stuff I've added) ill pull it apart in a month and see how everything is fairing but should be ok as i followed instructions off another forum

I don't like steel wool its so abrasive. And the PCv on an 8 valve goes straight into the intake.

Hopefully I will be able tO check if I still have oil going through I'll know it's the turbo and I'll rebuild it. I can't tell ATM cos I have oil behind and in front of it.
 
#303 ·
It was 26C out on the weekend, so it made for a great day to finally start work again. Unfortunately, it's been so long since I did heavy work that most of it was light work just to ween myself back into the game. The driver swap won't be as heavy work as rebuilding the transmission, of course, but the thought of pulling the axles to get to the inner drivers and draining some of my precious Redline is making me sigh. However, Calgary being Calgary, the fantastic weather this "early" in the year only holds out in direct sunlight: as evening falls, the temps will drastically fall down near 5C, so I had limited time.

First thing to do was to prep the '86 transmission so that I can pull the inner drivers from it. This included draining the oil, cleaning the CV grease and gunk, and inspection.



The cleaning took a bit of time, and I wanted to prep the inner drivers clean so that I can re-apply a new pack of CV grease later. Once I cleaned the inners, I identified them to be two-ridged unit more like the RHS inner driver currently installed. The LHS unit currently installed has a more angled taper toward the box, and the stops for the tripod inserts were visible externally.



Unfortunately, once clean, I did my inspection on the RHS unit first, and found evidence of wear on the insert, on the regular driving side. This quite surprised me as I never encountered any vibration problems upon acceleration.



The wear is fairly even across all 3 surfaces, and is quite substantial (~0.5mm deep). Luckily, when I checked the reverse drive surface, they were all quite smooth.



Interestingly, however, when I cleaned out and inspected the LHS unit, all surfaces were smooth and looked quite good for wear.





Strangely enough, there seemed to be a tear in the housing of some sort, and although I'm not quite certain what caused it, it doesn't look like it can be of any harm. If I need to, I'll hammer it back in place, but it looks like it's been like that for quite some time. The reverse drive side surface is, of course, immaculate: the surface machining process can still be seen.

The oil was already drained, to my surprise; I must've done so when I first pulled it. Hopefully, there is enough residual oil inside that nothing will rust. The plan is now to pull the other two drivers and inspect, but I will most likely replace both with these two, reversed, since these two inner drivers are known good. Hopefully once they have been swapped sides there will be no vibration issue (either from the inner driver surface wear or my existing problem).

The next steps are to drain (and probably collect for reuse) the Redline MTL in my chillcast, pull the axles *sigh*, and pull and replace the inner drivers one at a time with the ones in this box; since the '86 box is known good, I don't want to do anything to it that will remove that certainty. Of course, once these unknown condition inner drivers are in, that'll be a known bad part if my vibration problems go away.

Stay tuned for more mayhem in the following weeks (hopefully)!

li Arc
 
#304 ·
Off Topic

Taking you back a couple years, what did you use to clean out the exhaust ports in your head? or did you have the machine chop do the work?

I am thinking wire brush on drill head; that shouldn't hurt anything right?

thanks
 
#305 ·
I'll need to fix my photos, but initially I had the machine shop clean the head. However, half-way through the job, I decided that while it was all clean, I may as well go ahead and port and polish the head, so I took a corded drill and a bullet-head rasp, and just enlarged the ports a bit; I used the paper gasket as a guide to the maximum port size. I'm sure if you went this route, you'll get it clean, however, using a wire brush is probably fine as well, just know that you'll be removing a little bit of material so try to remove only as much material as it takes to get it clean. Also make sure you don't knick anything else; part of the reason I took it home with me half way through the head rebuild from the shop is that it was completely gutted, so I didn't have any obstacles. That being said, enlarging the aluminum port with the rasp took much more effort than I expected.

A note on this: it is important to keep the surfaces of the ports in the head rough, as smooth surfaces will cause air to "stick" to the surface, creating drag and ultimately causing a back pressure buildup in the intake or combustion chamber. I assume that roughness perpendicular to the flow of air is more important than roughness parallel to the flow of air.

Other than that, there probably is some type of chemical you could use, I just wouldn't know what that is. Someone else can chime in if they know.

li Arc
 
#306 ·
I'll need to fix my photos, but initially I had the machine shop clean the head. However, half-way through the job, I decided that while it was all clean, I may as well go ahead and port and polish the head, so I took a corded drill and a bullet-head rasp, and just enlarged the ports a bit; I used the paper gasket as a guide to the maximum port size. I'm sure if you went this route, you'll get it clean, however, using a wire brush is probably fine as well, just know that you'll be removing a little bit of material so try to remove only as much material as it takes to get it clean. Also make sure you don't knick anything else; part of the reason I took it home with me half way through the head rebuild from the shop is that it was completely gutted, so I didn't have any obstacles. That being said, enlarging the aluminum port with the rasp took much more effort than I expected.

A note on this: it is important to keep the surfaces of the ports in the head rough, as smooth surfaces will cause air to "stick" to the surface, creating drag and ultimately causing a back pressure buildup in the intake or combustion chamber. I assume that roughness perpendicular to the flow of air is more important than roughness parallel to the flow of air.

Other than that, there probably is some type of chemical you could use, I just wouldn't know what that is. Someone else can chime in if they know.

li Arc
ok thanks; no I wont be making the ports any larger; I am still a stuck on stock kinda guy!


I have a potion to remove the carbon, I just cleaned the short block. I just wanted to be sure the wire brush wouldn't harm the aluminum head.


Thanks
 
#308 · (Edited)
Well, the going is slow, since I am trying to ease back into it, but this stuff takes surprisingly longer than I expected it to! I managed to prep everything for a single side swap, and just arbitrarily chose the left side. When I pulled the inner drivers out, I compared them, and I have to say they are not exactly the same.



Unfortunately, I wasn't prepared for doing the swap yesterday, so I didn't have my good camera on me. But as you'll see, the taper is different on the rear of the inner drivers. The one on the left is one of the suspect ones, the one on the right from my known good '86 transmission. I will also take some photos of the RHS when I pull those out. Replacing the inner drivers in situ is extremely time consuming, and including banging out the inner drivers from the bearing housings and banging them back in (with my 3lb hammer, I don't have a press handy), it took me 2.5 hours with the suspension parts already removed (ie. just banging the drivers and pulling and putting back in the 6 bolts on the transmission!)...for just the one side! I was glad it was done though, I will be handling the RHS next time.

It was then, after all that when I was driving back to my place from my parents' garage that I recalled what I mentioned in this thread: there is drive-face wear on the RHS inner driver and I was going to swap left-to-right! ;oops: Crap, there goes another 2.5 hours...

During all this, though, something occurred to me: the purpose of the plunger, I assume, is to keep the inner driver in its proper position pressed against the bearing. However, if I drove the inner driver into its bearing and left it instead of driving inner driver back outwards from the bearing housing to properly seat the bearing against the snap ring, would the plunger have enough force to do this during operation? If not, is it possible that the driver isn't properly seated against the bearing and as such will wobble, causing my vibration? It's only a remote suggestion, considering the inner driver is being held fast not just by the bearing but also by the diff so that it technically shouldn't be able to wobble, but it's a thought anyhow. Otherwise, I'm back to my bent driver theory (that must be bent between the diff and the bearing in order to cause a wobble).

li Arc
 
#309 ·
Hey mate, on an unrelated topic, would you be able to tell me how you attached the quarter (pre face lift SPG) side panels to the car (in front of the front wheel, and behind rear wheel) if you get what I'm saying.

If you had any pics or close up shots of how they attach to the car that would be great, I'm buying a kit so I can fit a t16 oil cooler to my 8v (the 16v oil cooler won't fit with the front airdam in the way) so going to change the side skirts too.

cheers

Ed
 
#310 ·
Sure, I'll snap some photos to show you how I did it. But basically, if you had rear mud flaps, the rear isn't too bad; you can just reuse those same holes (you will need to remove the mud flaps). The hardest part about mounting the rear extensions is the rear mounting hole, which goes behind the bumper into the body; I'm not certain it's the same for everyone, as mine looked slightly modified for this, but where it mounts into the body the hole is very difficult to reach from inside the car (for the nut and washer).

For the front, though, if I remember correctly, there are 3 holes needed in front of the front wheel, on each side, and I had to drill new holes for them; I'm always wary drilling holes as this creates a point where rust can easily seep in, so I try to seal the edges of the holes with some paint (preferably touch up of the same colour). Whereas the rear holes used sheet metal screws, I used nuts, bolts, and washers at the front (stainless). It probably doesn't matter either way too much, but I just want to be careful (rear holes have seen better days). Once it's on, it's on tight enough that the bumper extensions are on very solid, enough that if you hit or scraped it while driving, you'll feel it on the whole car. ;ol;

Anyways, I'll probably head up to the parent's place to try to finish the job this weekend, as I've been away on vacation, so I'll grab some photos then.

li Arc
 
#311 ·
Sorry for the late reply, I snapped this during the weekend but forgot to put it up. As you can see, there are two lower mounting points for the inner flap, and a single upper mounting point for a metal tab. I can't entirely recall if I needed to drill all 3 holes, but I remember having to drill a couple, at least. It appears I re-used the original lower mounting bolts, but if I were to do it again, I would have used stainless bolts/screws on all three locations.



In other news progress is slow, but hopefully almost complete. After replacing one of the inner drivers, it wasn't until I left the garage on my way home that I recalled I was going to swap the drivers from side to side due to surface roughness of my original drivers on the '86 box, doubling my work. This week, I went back, replaced that, and replaced the other side as well. All that I need now is to fill up on some CV joint grease, plug the axles back in, and put the front suspension back together again before testing. I'm still skeptical of whether or not this will fix the problem, but as the unknown origins of the existing inner drivers are the last suspension/drive train differences between my original working vehicle and my vibrating c900 (aside from the transmission itself), it is also logically the most likely culprit. Here's to hoping it'll all work out *fingers crossed*! :eek:

li Arc
 
#312 ·
I just had a chance to test drive the beast today after having replaced the inner drivers over the weekend only to find a dead battery, and found the exact same problem as before: absolutely no change! I was almost sure this was the problem, since it was the only "foreign" part in the drive train. So this means that whatever the problem is, it exists on a part that was previously on the car. I can't say it's impossible, but as this was very unlikely, I'm really stumped on how it wasn't present before I started the teardown.

Anyways, so moving ahead, my next plan is to contact Ray and discuss his idea of using a system of microphones he can borrow to place in the problem area to analyze the vibrations during cornering to narrow down and ultimately identify the offending part. If that proves to be too expensive, I will probably proceed by replacing the RHS wheel bearing (the LHS wheel bearing was replaced by Ray in December), while I attempt to source some axles (I may do the latter anyhow). Question: axle lengths, what do I need? Did they change some time in the mid-80's? My axles are the original for this car (as far as I know); is it possible that they aren't directly compatible with a chillcast transmission? If I source new axles, what are my options, or if I source old axles, which cars should they come from? I am also surprised that my tripod bearings are 37mm instead of the smaller ones, which doesn't fit the c900 knowledgebase (I think). This means I'll need to find axles that fit my car, but with tripod bearings from other years? I'd like to use my existing bearings, but I can't rule them out from being the problem neither...

This is getting so frustrating...:(

li Arc
 
#314 ·
It's certainly not wheel or tire problems, as I've tried two different sets of wheels with not even a deviation in the vibration. Hub thing sounds weird, where on the hub are we talking about? I had the front LHS bearing replaced already, and I'm sure any weirdness there would have been detected and fixed. It's possible it could be on the RHS instead, and getting the wheel bearing done on that side is one of the things I may try.

I keep meaning to lift it in the air and see if I can find anything strange with it. I might even do so with the tire removed (although that's bordering on dangerous in my mind).

The current plan is to check the yard; there is an '85 at the yard (I have seen other years, but never an '85) that I hope the axles are still there so I can yank the whole assembly on each side and test them out. I'm a little worried that the standard '85 tripod bearings are the smaller ones, as I have a suspicion mine are not stock to the year (37mm), and I'd really rather eliminate the tripods from the equation just to make sure I'm not double-trouble-shooting something. I guess we'll see what happens from here...I also got some suggestions from Saabrally, but it all still whittles down to axles or wheel bearings.

li Arc
 
#315 ·
I'd say your next move ought to be putting the car up on axle stands and trying it in all the gears to see if you can pick up what it is with the car running.

It won't be quite the same as driving it because there won't be any load on the suspension or drivetrain but it MIGHT show you the problem. Of course you can use the throttle to increase engine revs if at first you can't find the problem at idle speed.
 
#316 ·
I'll definitely do this, hopefully sometime this week. Maybe it'll give me new clues, which I could really use at this point. Or a confirmation would be good too.

I came into some new information, that the 37mm tripod bearings I have were introduced in 1985 on turbo models only, and then onto N/A models '86+. This means that there is a difference in tripod bearing sizes between turbo and non-turbo cars in '85, so this information makes a difference. When I went to the yard over the weekend, I was unable to remove the axle nuts on the '85 they had as the wheels were fairly free spinning and I did not have a cordless impact driver. However, given that the car there was an 8V N/A, this wouldn't have helped me anyhow. So I'm still awaiting a reply from another source to see if I can borrow some axles to test with, otherwise I'll probably order some in.

I found out that EMPI weren't the only suppliers of axles, though they seem to be the only ones supplying brand new axles. Given some of the testimony I have heard about them, I would rather not have to resort to their axles, but felt that if I had to pay $75 for a single tripod bearing to eliminate one variable vs. $100 for an entire axle eliminating 3 variables at once, I would have to choose the latter. Luckily, there is a supplier in Canada that offers A1 Cardone rebuilt axles, which I would prefer given the shaft itself is original vs. the weaker EMPI one. Although I don't know what components they use for their rebuild (I am quite certain not GKN), they do have a decent warranty on them, and are in fact cheaper than the EMPI ones (by a little). Also, shipping charges are nil over $75 within Canada vs. ripoff eeuro, so I am contemplating this move. However, I would still rather borrow some if possible, in case replacing the axles also does nothing. Axle lengths also worry me, in the event that axle lengths between a '78 or '79 99T (where this chillcast came from) is different from my '85 T16, which I would need to know before I dive into an axle purchase.

The work on this car has become almost tactical and strategic...I feel like I'm playing a game of chess that I can't win...:roll:

li Arc
 
#317 ·
Went to look in on the car yesterday, and put her up on jackstands and into gear, trying to figure out if it's possible to locate the vibration while stationary (albeit suspension unloaded). Interesting thing I found was absolutely no vibration in the usual scenario, all the way up to 4th gear 80km/hr (semi-proportional to speed). While it was up on the stands and going, I didn't hear anything unusual, or see anything unusual at the wheels neither, which means this only happens when the suspension is loaded.

I have a few theories about this, but I'm not sure how they will help. First thing is as Ray had mentioned to me before, when turning right, the suspension on the front left is loaded, so somehow the vibrations are somehow being transmitted to the frame. For example, if the springs are connecting with the wheels somehow or something. The easiest way to test this theory is to find a curb and load each front side (both stationary and in motion) and see if this changes anything. But I have a feeling it's not as simple: as I mentioned, the vibration is only semi-proportional to speed: even if the car is moving very slowly (hardly loading a corner), the vibrations exist at about the same amplitude as if the car was moving quickly.

Next theory is of course the axles or some component of the axles (most likely the inner tripods). At unloaded drive axle angles, you'd assume the vibrations would worsen if it were the outer CV joint, as they are more pronounced than if the car was resting on the wheels. However, in my mind's eye, the tripods are driven further out of the inner drivers when unloaded, somehow riding at different tripod angles (although the tripods are under much less pressure as they are only spinning the wheels, not driving the car). As changing the inner drivers still produced the exact same vibration, I am ruling them out as the problem (the physical characteristics of the inner drivers have to be almost exactly the same in order to reproduce the vibration exactly, and it is highly improbably that they're worn to the same degree, so most likely they are unworn [in other words they are good drivers]). To test this theory out, I will attempt to load each side by placing a spacer between the frame and the upper control arm while on jackstands, and see if I get the vibration.

I'm still trying to decide what each test means...I suppose for the curb test, it may mean I might have to look at the suspension and possible contact points, for the second test it may give me a chance to see the vibrations in person and try to locate its source, but it isn't a definitive test. If neither test gives me any vibrations, I'll most likely just get new axles...I'm still leaning on my feeling that the tripod bearings are problematic, but it seems like a bit of a long shot...

li Arc
 
#318 ·
Excerpt I posted on Saabrally:

I went back to check on a couple things that I were bugging me, and sure enough, they told me plenty. First thing, I noticed that the vibration was directly proportional to engine speed, regardless of road speed; it also didn't matter if the transmission was engaged or not (ie. clutch disengaged), and the intensity of the vibration is related both the g-force around a corner, and the steering angle (which are also related to each other, but I found that slow acceleration with a steep steering angle from stop produced the worst vibrations). It is also possible to get it into a "state" where even at idle there is a lot of vibration. Lastly, but still quite important, plunking it into reverse (in motion) produces very similar vibration, whether straight or turning (although turning left while reversing also attenuates the vibration). Loading either front corner on a curbside mostly appears to be irrelevant, although it could also be because the road surface is convex, so driving up on a curb simply levels the car off. Driving on the left side of the road (left side lower than the right side) seems to increase vibrations slightly, driving on the right side seems to decrease slightly.

My takeaways from this experiment: 1) I think somehow the engine vibrations are being transmitted to the frame somehow, like the engine shifts in the compartment (most likely culprit: engine mounts). My last set of engine mounts were all replaced in 2007 from the same source, and the front mount failed (was replaced with a NOS Geniune Saab mount in December); if one failed it's very possible they all failed or are on their way out. The fact that something can "shift" into a state where vibrations are present even at idle seems to support this. Caveat: no vibrations while on jack stands (placed under jack stand mounts under front doors). This makes no sense because if it were the rear mounts and the front of the car was lifted upwards, you would expect an increase of vibration, not a reduction. Unfortunately, I have yet to pinpoint any actual contact of the engine to the frame. A quick inspection of the mounts shows that the mount on the frame is not in contact with the bracket on the engine, and the rubber looks decent.

2) I don't think it's axle related now, because if it were, it would have to somehow be transmitting the engine vibrations to the chassis, such as if the inner tripod were too tight in the inner driver and were transmitting engine vibrations via the transmission to the wheel hub. I proved this wasn't the case before by pushing each axle in while steering left or right at least 2cm; admittedly, this was with the previous inner driver, but the feel of the vibration hasn't changed with the inner driver swap.

3) It's also possible it's suspension related, somehow the loaded suspension is in contact with something it shouldn't be. This will be difficult to prove, but I will attempt to use the spacer mechanism to artificially load each front suspension set. Caveat: it still doesn't explain why setting it to reverse would suddenly increase vibrations more than the forward equivalent.

Courses of action: I will attempt to locate any further points of contact with the engine outside of the shifter linkage and engine mount points. But I may yet revisit replacing the mounts.

li Arc
 
#319 ·
Well, caught the culprit today.

Photo from last year:



Photos today:







LHS mount: supported the LHS of the engine with a jack, loosened all mounts, relaxed axle (the majority of the work, but no more so than pulling an axle), undo mount frame bolts, removed mount bolt, raised engine until inner driver almost contacts drive tunnel, pull out mount.

I didn't realize what to look for in a collapsed mount until I started hypothetically looking at new mounts: there was no longer an air gap beneath the bulk of the rubber, and the mounting point should have been much higher. Parts arriving later in the week, replacing RHS as well. Should have seen it coming: if the front mount went, they all probably went at roughly the same time. Just surprised Ray didn't spot it. Look at the smarmy thing grinning at me. Let's hope this is the end of it.

li Arc
 
#320 ·
I don't think you should expect to see an air-gap in the lower part of the mount. The weight of the engine pressing down would be enough to close that up. Nevertheless, that engine mount does look goosed and would explain the symptoms so I think you're doing the right thing. Must have been such a relief when you found this problem.... although I can understand if you are waiting until the mounts are fitted before breathing out. :cheesy:
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top