Overboost?

[Rogozhin]

I just started having a strange problem with my Viggen. Under acceleration the rpms jump quickly but then drop. I thought it was the smbc that I had put on but I took it off and it still does it. Any ideas?


Rogo

[fromero]

Sounds like a slipping clutch..I've seen it in a couple of 500Nm of torque Viggen's.
The stock clutch is not so good, valid for normal driving, but...

[Rogozhin]

fromero

I'm thinking it may not be the clutch. It doesn't do it all the time. I think it may be either an air filter or plugs.

It's really a strange thing.

Rogo

[liketheword]

Here is a quick check to see if it's the clutch.

STEP 1: Find a stretch of open road, or a long street with no traffic. STEP 2: Bring your car up to about 20-25 miles per hour

STEP 3: Shift into 5th gear. Yes, it's too soon to shift into high gear, but that's the point of the test--to stress the clutch.

STEP 4: Press the gas firmly, as if you were accelerating onto a freeway.

STEP 5: Observe! If the engine starts to rev free, as if it were in neutral, and/or your tach spins toward redline very quickly, your clutch is slipping.

STEP 6: Observe! But if the car slowly accelerates, even if it staggers, bucks and strains, then the clutch is okay!


If your car passes this test that is not your issue. Try it and report back.

[Shirozina]

Clutch slip will occur at peak load and torque so it won't be linear at all and is highly unlikely to happen at low speed initialy. It's easy to tell if you clutch slips - rpms climb rapidly but you remain at the same speed - anything else and it's not the clutch.

[fromero]

That's why I said clutch slipping from the begining.

The symptons he describes are that. Of course, it is difficult to explain the feelings and symptoms of a problem.

Maybe check what you can, and try to explain the conditions of the failure..

[Corn Cob]

I had somebody tell me a good way to test a clutch was to take off from a dead stop in third. If you can do that the clutch is slipping. Don't really know how good of a test that is, but you could try it easily.

[99Saabnut]

Careful footwork will allow you to take off from a dead stop in pretty much any gear. Definitely 1-4 at least, as I have done it in many cars, so I wouldn't think that is a very good test.

[t_buck09]

yea thats not a good test cuz my friend n i tried this in my car but in 5, i could do it, and he could do it in his 6 spd audi in 6th, all about foot work, and distance before letting off the cluch

[Corn Cob]

LIke I said I didn't know if it was bunkem or not, just something I heard once. Now I know

[Rogozhin]

Well, I do accelerate but the rpms surge and then fall back a little to catch up with the acceleration. I'll try the 5th gear experiement tommorow. This is the original clutch and my Viggen has 130000 miles now.

Rogo

[t_buck09]

thats when the cluch went out in my car, sounds like you have a slipping cluch

[Rogozhin]

I just ordered the Viggen replacement clutch from eeuroparts. It was actually $20 cheaper than from genuine saab and they say that gs was their source. Strange.

Should I replace the slave?

Rogo

[SPATL]

Originally Posted by Rogozhin

Should I replace the slave?

Rogo

Wihout a doubt YES!
The slave cylindar is inside the tranny case so if that goes, the labor involved is just like replacing the clutch. For a litle over $100, it is a MUST do when you replace the clutch.

[Ribz80]

Originally Posted by fromero

Sounds like a slipping clutch..I've seen it in a couple of 500Nm of torque Viggen's.
The stock clutch is not so good, valid for normal driving, but...

I do not agree. I have 54k miles on my stock original clutch and have had stage 4(approx 310-320lbs of tq to the wheels) for 25k miles and it has not slipped once. I dont do smokey launches but the car sees plenty of wheelspin.

[fromero]

That's low mileage, when you get into higher mileage with high torque..... That's why we use stage 3 or higher clutches, specially with Viggens with high torque.
My own 93 has a stock (not even Viggen) clutch and 390Nm of torque. But I am careful with my clutch, if you tend to like "takeoffs", then your clutch will degrade very fast, and slip...

[Rogozhin]

Today it isn't overboosting/slipping, just very quick acceleration. I tried the 5th gear pull from 30mph and it just acclerated slowly.

I'm confused now.

Rogo

[Shirozina]

You need to shift at peak load and peak torque to induce slip.

[G96nt]

When they say genuine Saab, they mean actual saab part.
Not nick T.
In either case, It seems you ruled clutch out before considering TB, and DBW.

Does the car act the same with traction-control off?

[John Z Williams]

Originally Posted by 99Saabnut

Careful footwork will allow you to take off from a dead stop in pretty much any gear. Definitely 1-4 at least, as I have done it in many cars, so I wouldn't think that is a very good test.

No, this is a very good test and the test we used at the repair shop all the time, but the way you do it is put the e-brake on and put it in third gear and give it a little gas and let the clutch out and if it does not kill the car, the clutch is slipping!!!

A very good clutch test and its fool-proof!!!

John