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Discussion Starter #1
Hi,

My 1993 900 NA brakes are poor.

I've tried New disks + pads + hoses on front + new rear hose from body to axle.

The brakes have never been brilliant in my ownership ( 4 years ), so I'm now thinking its a problem with the ABS master Cylinder.

Pedal has very long travel and feels spongy. I have bleed the brakes again and again to no avail.

I've spoken with a SAAB mechanic, he tells me that the ABS set up does lead to a spongy ish pedal but the brakes should be good.

As a latch ditch attempt I may take it to SAAB and have them bleed the brakes, but I think this is possibly a waste of my money.

Is there anybody in North West UK ( Liverpool ) who could drive my 900 and confirm that the brakes really are as bad as I think ?


Thanks.

Barry.
 

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I don't know if this helps, but my '82 T8 brakes will stop the car well and good with a firm foot. But we usually rent cars for our longer (300 mile+) trips to take some wear off the old beast. I tend to spend the first hour locking the rental's brakes up every time I brake. They don't work any better at stopping, but they are crazy senstive to the lightest touch.
 

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barry

im local to liverpool - so if you want to hook up, drop me a PM nd we cn sort something out im sure

Graham
 

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My guess is that the master cylinder seals have gone bad, so are not holding pressure.

This is not an expensive fix (new seals and honing of the cyl. bore), but if the bore is too pitted to hone, I'd try another one from a salvage yard.
 

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I changed the whole (ABS) master cyl. 12 months ago.......

and can honestly say the difference was minimal. I always had a 'firmish' pedal but the position of resistance in the pedal height seemed to be vague or inconsistant. The biggest change came about when I dismantled the rear bearing hubs and repacked the bearings with fresh grease and re torqued them. I'm guessing the bearings are 'not as tight' as there were new but re-torqueing them seems to have reduced the any float or play that would translate to the disc changing axial position (end float). I believe the fronts could be a little worn as well....... A light 'double jab' at the pedal always brings the resistance point up higher in the stroke.



Can you buy the seals separate for the ABS mas. cyl.? Here in OZ, it's very price prohibative.

Good luck!
 

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hmm my loaner SPG that i'm driving right now (1990) has antilock brakes. the pedal is extremely firm and has no spongyness whatsoever. it requires more foot force to stop the car than my 89' turbo w/o ABS does. the ABS works well, and the car stops well, so yeah-i would say they are great brakes, perhaps yours have a fault.
 

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Discussion Starter #7
Thanks for the feedback so far.

I had considered the bearings.

Has anybody else had naff braking due to bearing runout on ABS equipped cars ?

Is the rear bearing removable ? I've just took a look on www.partsforsaabs.com and its appears to come already attached to a hub.

Rodentmaster, can you give me some more details on tightening the rear bearing. Is it a concical bearing ?, I assume it must be if tightening removes play.

Barry.
 

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do you know that you have to bleed a ABS-car differently than a non-ABS car?Could be there's still old brake fluid inside your system due to inproper bleeding...

and the rear bearing is one piece with the hub on almost all C900's. only the 1979-1982 have a seperate rear wheel bearing and hub.
 

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Discussion Starter #9
Hi,

Thanks for the bearing details.

Yes, I've bled the system as per the ABS method. i.e. you need to have pump / stored pressure to bleed the rear. Whereas the front can be bled with or without pump / stored pressure.

This leads me to an interesting point.

If you depressurise the system ( push pedal over 20 times with ignition off) you have no stored pressure and hence nothing going to the rear circuit. Therefore if the pedal is no longer spongy ( which mine isn't ) then the front circuit is fine. this narrows the problem down to the rear system or the booster part of the ABS unit.

I'm going to try the brakes with the ABS disabled, to see how effective just pure leg pressure on the front works.

If this seems better than the spongy / vague / unpredictable brakes I have presently then I will definately swap the ABS master cylinder.


Barry.
 

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..........(sigh) o.k ..... :cry:

I will post some pictures on the weekend as I'm going to do the left hand rear hub again as I did not have enough grease to complete the task.

I am aware that the hub comes complete and is not 'supposedly' dismantleable but it can be done. Repacking some new grease and reassembling is not to difficult and when the hub is reinstalled on the car the lock nut will compress the bearing again.
ANY bearing will become 'looser' with time and wear without necessarily being classified as 'worn out' or 'shot'.
I beleive it will, and for my car it has, made a difference.
I have the attitude that, most things that have been 'assembled' can, with a little care and time, be disassembled.

Still, ......if it's not 'turbo'..............
 

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Discussion Starter #11
I guees your right, if it goes together it must come apart.

I tried checking for play in the rear bearing last night. Grabbing the wheel an attempting to move it. I couldn't feel any play.

Spinning the wheels didn't cause any odd noises, i.e no rumbles or cyclic rubbing as the disc hit the pad.

here's a question, after some spirited driving / braking I checked to see is the discs were warm, both fronts were very hot, the rears were almost cold.

Should the rear discs be getting warm ? this to me sounds like I'm getting little to no braking on the rear.

I had my wife press the brake with the rear jacked up and they seem to be applying but my arm strength compared to the energy of a moving car is nothing.

any ideas ?
 

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Did you adjust the rear brakes?

  1. Jack up the car and remove wheels.
  2. Undo the cover at the back of the caliper (14mm hex)
  3. Use a 4mm(?) allen key to wind in the pads until the wheel locks
  4. Back off 1/4 turn and check that the wheel turns relatively easily (a little drag is ok)
  5. Replace the cover
  6. rinse and repeat for the other side
After that, if the brakes are still spongy/weak, flush and replace the brake fluid 'cos that's the next cheapest option. After that, there are faulty components...
 

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Here we go.......


Will post more later.
 

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What do the rear bearing hubs and.....

SKF bearing, 6306-2Z have in common?
They use the exact same diameter balls as I was lucky enough to discover.
I thought the noise I was hearing was a suspect tyre but on closer inspection of the wheel hub bearing again I discovered this.............



Luckily, there is no sign of damage in the hub race.
I was not going to put it back into the hub and since this is an everyday car, I was desparate to get it back on the road. So I started to rumage some of my old toolboxs and discovered an old 6306-2Z SKF bearing that I bought by mistake years ago. It seemed unlikely but I went and dismantled the bearing and removed the balls........... and incredibly they were the same.

I'll be buying more of the bearings to stock up the ball supply for future overhauls.

Certainly cheaper than a whole new hub assy.
 
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