Brief "KNOCK" in rear end or tranny when clutch clamps...only when accelerating

[SchmeelDeal]

I gotta '92 Laser RS AWD Turbo 5spd and over the past six months I have noticed a "THUMP" or "KNOCK" when the clutch takes hold. This only occurs when accelerating. The car goes into gear like butter; I can pretyt much shift with one finger if I wanted to. Also when accelearting, there is a small grind like noise (like sticking a pencil into a fan) when shifting into and up through the gears. It is louder going to 1-2, then gets less and less through 2-3, 3-4 and is not present from 4-5. I think that the grinding when shifting is probably because there is a lot of play in my shifter and it needs adjusted, but I other then the universal joint, I don't know what the thump could be. (universal joint has just been replaced).

Could anyone give me some insight on what could cause this thumping noise.?

I am currently getting the engine rebuilt along with installing an 2600 ACT clutch kit, SS clutch line, and ACT Exact Flywheel. Do you think this will fix the THUMP?

 

[Enigma_Man]

Welcome to the 92 Laser AWD club (is it black?)

A few things to check:

As far as the constant noise (my car does also, it's just part of the car, I've stopped worrying after 20k miles): check the level of your transfer case, they can start to make some noise when they are low on fluid. Also, check the level in your trans. while you're at it. Make sure nothing is rubbing up against your wheels. I've hardly heard of any problems like this, but you might want to look at the rear diff, see if anything is leaking out. Make sure your CV boots are all in place, and clean.

For the click, my car does it too, and always has (again, I've stopped worrying), check your suspension, make sure nothing's loose or hanging. Check for any play in the driveshaft to the rear / rear axles. Also... This sounds silly, but make sure your wheels are all on well. Mine come loose after I put them on, and I have to torque them down a couple times. They make a clunk when accelerating or braking (it sucks that I know exactly what that sound is, but it's saved me a few times).

Hope that helps!

-Jesse

 

[SchmeelDeal]

First, my Laser is white, but it looks kinda black at the moment because of the ash on the road due to the bad weather here. However, it's gonna be black in about six months. Gonna put on a Dragon Z body kit also.

Now this is just to clear up my problem maybe a bit more:

Secondly, the noise is not constant. It is a one time thing that happens each time shift gears when accelerating. As soon as the let the clutch out fully, there is knock in the rear end/drive shaft (possibly the back of the transfer case). It can be felt more than it can be heard. It is just like a dead blow. I don't necessarily have to be giving it the gas for it to make the THUMP. For instance, if the RPMs were high and I just upshifted without giving it any more gas, the THUMP would still occur. But if is give it some gas just before the clutch is fully released, the bump does not occur. If I try to shift fast (sorta power shift) the THUMP is extremely bad and the whole vehicle jerks. I don't think this is something that is normal.

On the other hand, the clicking/grinding when shifting is obviously coming from inside the vehicle. It sounds like it's right there below the shifter. I think this will go away with some adjustments.

But as far as the THUMP goes, is it possible that it is the transmission, even though it shifts so effortlessly? Could it be something in the differentional where the driveshaft connects?...The fluid levels are

--James

 

[DSMRevolution]

I wouldn't be surprised if the thump you hear is from the driveshaft. Look on http://www.plymouthlaser.com/ They have a tech article about filling the bushings with black silicone.

 

[SchmeelDeal]

Originally posted by DSMRevolution
I wouldn't be surprised if the thump you hear is from the driveshaft. Look on http://www.plymouthlaser.com/ They have a tech article about filling the bushings with black silicone.

Thanks alot. Will do. I looked over that site thoroughly but I guess I missed that one somehow. I will try it out after I get the engine rebuilt in a couple of weeks because I won't have a spare vehicle until then. Guess I will see what happens.

-James

 

[SchmeelDeal]

Finally after 5 months, I did the driveshaft thump fix. Also found two of my exhaust hangers were broken. Yet, I still have the thump in the rear end. It is especially bad during quick shifts under accelearation, but not always. I mean sometimes I can shift hard and I get nothing, just smoothness. While other times, I go to shift and ...boom, I get a knock in the rear end. Maybe its my rear differential, I dunno. I don't know anyone else with an AWD 1g to compare it to.

 

[Jimi91iststi]

I have the same problem 91 tsi the hard thump between shifts in the rear end, i ignore it haha, but the cb silicone fix thing is great! did that to the rear completly fixed it, then about 4 months later im on my way home from a 4 hour drive and i hear a vibration again on the highway then with in 30 miles i had to drive 30 mph the whole way home and it sounded like someone was under my car hitting it with a hammer! then for about 2 miles i could only go 15 mph because i felt like my ds was going to come through the floor, whent on some snow coverd dirt roads then it went away.... drove it 15 miles after that at 65mph on pavement all fine. what would cause this extreme thumping for about 45 miles then nothing? My only thoughts are transfer case low or dry, or the front cb bushing.