Hi guys,

We've just fitted a ZZ4 Crate Engine into my 1989 TransAm GTA and need some advice. This problem was there before the new engine so is definitely not related to it.

There is a pulsing rhythmic vibration which begins quitely from 3000rpm, building with increasing revs and speed. After 4000rpm it becomes much more violent and loud. It sounds as though it is coming up through the centre/front of the transmission tunnel.

It is rev related rather than speed so I don't think wheel/tyre balancing is an issue. I can easily check
this though, even though it was only done a few thousand miles ago.

I think the same vibration might be there to a tiny extent when revs are applied in neutral, but am not
certain. When you change into neutral on the highway when the vibration is happenning it goes away, but I think that is due to the revs dropping down.

Could this be driveshaft imbalance? Worn UJ's? Wheel imbalance? Automatic transmission problem? Torque convertor problem? Are there shafts/bearings related to the box that could wear or become loose to cause this symptom? Torque arm pinion angle incorrect? Rear end issue? What do you guys think seems the most likely cause for the problem?

We are planning to get the car up on axle stands next week and get a look around.

I've bought new front and rear UJ's to fit and also plan to send the driveshaft off for dynamic balancing. The driveshaft is a stock aluminum one.

Any comments or suggestions would be welcome.

Dr G / JamFitz

Any ideas guys?

My first guess would be drive shaft. You can pull it and have it checked for balance and straightness. If its not it, you just ruled out one possibility. Check the next item till you find it.

Tom, what other items would you suggest? Any particular order?

Well, you can crawl underneath it and look for the obvious. Broken or torn mounts, loose bolts etc.... If you dont have one you can get a magnetic base angle finder and start checking angles. Are you running a stick or auto tranny? There could be different items in either tranny to cause you problems.

Will get a look under tomorrow Tom and post what I find. The transmission is an automatic TH700R4. I've got the Spohn magnetic angle finder so I'll start checking things out and post what I find.

Took off the torque convertor cover and checked the external balance weights are all there, which they were.

Will check the other things and keep the thread updated. All ideas and suggestions are welcomed.

How about spinning the torque convertor a 1/3 of a turn.
Or revving the engine in park and see if the vibe is still there

I had the same problem and it turned out to be the lock-up torque converter.

Auggie

Auggie, funny you should mention that, we were discussing wither or not the TC is locking up when we were last out and it doesnt seem to be. Do you mean the problem was with the TC not locking up properly? Or a malfunctioning convertor which was a lock-up type?

Oh and we think the vibe is there in neutral, though we havent tested it with the car stationary.

JAmes.

Well, I had this problem for a couple of years and it got worse and worse. I bought a Peterson drive shaft, rotated the torque conv. twice without any luck, checked driveshaft angles changed trans mounts ect, ect. I have a B&M shift kit so when I was at the Sema show I went by their booth and explained the symtoms (kind of a rumbling viberation) to this guy there and he said change the torque conv. Being a man of limited funds I wasn't about to run out and by a new torque conv. so I suffered with the vib. and noise for a couple of more years. Well because I am additiced to the button my trans started to go south so I decided to have it overhauled. I called Art Carr about tq. conv's. and he suggested I get rid of the lock-up conv. so I bought a kit to rerout the oil from him and use a diesel rebuilt tq. conv. that cost $150. This cured all of my viberation problems. This conv. had a stall speed of 1500 rpm which I liked because my car is a dailey driver during the summer and the low stall speed helped reduce wheel spin. Without that lock-up B.S. this car is smooth and the driveabilty is just great. I, of course don't know if this is your problem but I sure hope it doesn't take as long it took me!!! Good luck.

Auggie

Okay, heres the update!

The vibration does NOT occur at all in neutral or park.

I removed the driveshaft, checked the balance weights were still there. Fitted new properly lubricated U-joints.

I reset the pinion angle to -1 degrees. I did this correctly by the proper instructions. I also tightened up my adjustable LCA's, one nut was slightly loose.

Went for a drive and the vibration is still there but has changed slightly as regards when it occurs. Now under full throttle the vibration doesn't really appear until AFTER 4000rpm and by 5000rpm gets as violent and loud as it used to be at 4000rpm. It seems more prominent on part throttle loads and on part throttle is noticeable after 3000rpm.

Could I be dealing with more than one cause here? I'm encouraged that changing the pinion angle has changed/improved it. Perhaps I've set the pinion angle better than before but still not correctly so I'll check that again in a few days. I haven't had the driveshaft balanced yet, so I can still do that. I may be able to source a loan of a stock torque convertor to try, but it's a lot of work to swap it in and out and it might not help.

Any ideas or comments are much appreciated.

It's been suggested to me that the automatic transmission or the torque convertor could be faulty and causing this vibration. What do you guys think?

Bump!

Hello again,

Here's the update.

I've checked the pinion angle again, adjusted it with the appropriate instructions. Went for a drive. No change.

Checked the adjustable panhard rod location, properly centered. Went for a drive. No change.

Turned the driveshaft 180 degrees in terms of location at the rear end. Went for a drive. No change.

Checked the tranny fluid level. Found it to be a little high. Drained it down to the max level. Went for a drive. No change.

I ran the engine up to 4500 revs with the driveshaft disconnected and there was no vibration. However, I don't think that helps at all as the engine is not under load, neither are the driveline angles etc.

The driveshaft is now off and being delivered to the engineering shop tomorrow. That allows me to rule it out 100%.

After that I'm looking at going to a local Auto Transmission specialist to see what they say. Pay them for the (suggested) diagnosis, then order the parts from the States myself. I'm now pessimistically thinking that it's definitely the torque convertor or transmission that's gone.

I'll keep the thread updated as to how I get on. As always, any comments, suggestions or ideas are very welcome.

while its vibrating ease down on the brake pedal. When your brake lights come on, your lock up in the converter also unlocks. If you ease down on the brake and the vibe stops, its the lockup and you need a new converter. If your running any power at all, you can kill the clutch in the converter. I did mine in with only a 50 shot of nitrous.

Easing on the brakes doesn't affect it unfortunately. The TC doesn't seem to lock up at all. The car was previously featured in a magazine in the early 90's - and the then owner said it had a higher stall convertor but it didn't specify whether it was a lockup one or not. I presume that it was a non lockup as it the 5 years I've owned the car - it's never locked for me.

I'm tempted to buy a new TC to try to see if it solves this issue, the problem is that if I'm buying a new TC then I'd want a multidisc Vigilante at nearly $1000 as opposed to a cheap stock replacement.
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I took the driveshaft to a local engineering shop last week for balancing, complete with the trans output shaft and both UJ's. They said they couldn't balance it as there was 'no yoke at the rear'. I explained that the other end is bolted onto the rear end and to give them anything else would mean taking the rear end apart or giving that to them as well. They said all they could do was check the shaft for trueness - so they did that and said it was only 0.001" out at the rear and 0.002" off at the front. They felt this was within tolerance levels and unlikely to be causing the vibration.

I went to the best auto transmission rebuilders in my area yesterday to get their advice/help regaring the problem. They went for a drive with me and then put the car up on their ramps and say they feel that it is unlikely to be related to the transmission or convertor.

They pointed out 2 points where my true dual exhaust system is too close to the body. Also, they noted the Spohn crossmember sits virtually against the transmission oil pan.

The next thing for me is to address these areas and take things from there.

Have you determined if it is speed related or RPM related?
Can you create the vibration in all the gears at the same RPM?
Can you create the vibration on jack stands?
If it is speed related RBob has a good check list in this thread.
https://www.thirdgen.org/forums/tran...bration-2.html

If it is RPM related I would think has to be motor or tranny.

Ahusted, as above it is not speed related, not solely load related. Mostly RPM only related in all gears. you can't create it when the car is on jack stands and the driveshaft out. haven't tried with it in.
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Well I've modifed the passenger side exhaust system now. Several areas have been massaged with a ball peen hammer and the whole thing has been mounted more sercurely and isn't touching the body/chassis now. But.... the vibration is entirely unchanged.

Heres the latest.

I loosened the Spohn transmission crossmember and the torque arm, and was able to adjust it so that there is no interference between the transmission oil pan and the crossmember - it's all been straightened up. I then checked and reset the pinion angle.

I took the car out and the problem is still there, but I now think I can feel/hear it in neutral when I rev the engine up.

I think I will try to find a different set of engine pulleys to 100% rull them out, and then go back to the transmission shop.

As always, all comments and suggestions are welcome.

Dr. G, I feel your pain. I've had 4 3rd gens over the last 13 years (I'm on my 4th and last now). The first 3 at one point or another always had some sort of driveline vibration....used to annoy the sh*t out of me. For some reason I'm super sensitive to vibration in the car. My first car was because the tranny mount made the tranny end housing point to far up (towards the tranny tunnel). This is the same effect as the pinion angle being outta wack with an adjustable torque arm. IF you have poly mounts anywhere (engine,tranny,rear control arms), spherical rod ends on any suspension components you are going to be more susecptable to vibration, that just comes with using those type of parts. Stupid Q, but your transmission isn't off center? I mean is the tail shaft pointing down the center of the tunnel or is it cocked left/right? My second car was like that becasue of the passenger side engine mount took a dirt nap and the guy who owned it before me actually had shifted the entire drive angle towards the pass side when mounting the tranny xmember. Just a couple of thoughts / experiences I've had over the years with vibration. The other big thing, this is drive line vibration not bent wheel vibration right?

AC, he stated that it was RPM induced not speed induced. if it were a bad wheel it would be speed induced, this also tells me that you need to look at every thing in front of the driveshaft.

Dr. G, I read your post and all of the reply's. I just swapped my whole drivetrain, (moser 12 bolt, new driveshaft, new 2004r, new 350) and I got 200 miles on it and I have the EXACT same problem. unfortunatly I don't have an answer yet, But if you do find out let me know vise versa. I've thought of everything you mentioned, tq conv. tires, driveshaft ect. I've had my brand new driveshaft double checked with no help, tires balanced (I knew it wasn't that but did it anyway). but it's weird it's a total rythmic pulsing the higher the rpm the stronger it gets. the only post that I read that I want to double check was AC who mentioned one of his 3rd gens tranny pointing UP too much, I thought about this when I put in my mount (spohn crossmember/torque arm) so I need to double check. long and short I'm in the same boat.

so correct me if im wrong. there is vibration problem when you raise r.p.m.s
i would check the engines timing and other things. this may have something with the engine.
but if you only feel it while driving then check these
1. out put shaft on the rear of trans with shaft off see if you can move the output shaft
2 the tires may have a broken belt causing the problem but would rather be driving related
3 worn u joints in the shaft try to shake the shaft at each endwhile holding the rear or trans. since the shop couldnt test the shaft rotation then no way of telling the u jonts are bad.
4 problem could be in the rear gears badly worn out pull the cover check any metal shavings or broken parts or loose parts.
and the torque converter may be the cause.

thats the problem with drive line vibration so many things to check and rule out. Ive worked on cars that had problems missing during driving and wouldnt do while in parked revving the engine. had to put it under a load to find it.

My problem (which seems just like MR. G's) I can feel very very little while in park and revving, however when on the road the vibrations are amplified (due to load?) so as revs higher the vibration gets stronger and quicker. if I leave it in first gear (auto) and do about 3000 it is very strong. My u-joints are brand new, rear end is new tranny new. I think i'm going to try and disconnect the converter and try it in park and see if it stops, but it is so light in park it's difficult to tell. I double checked timing and that is fine as well. I will try and move my slip today to see if there is any movement. thanks

Good point on the bent wheel tip. One other occurence of vibration was when I originally put my blower setup in. Procharger gave me a secondary crank pulley to run for the blower. SO, I had the crank pulley, 3" OD aluminum spacer and an 8" blower crank pulley all coming off my crank snout. Try having conectricity between 3 different objects. Needless to say I had a vibration from about 2500 to 5000 RPMS. This was ALL due to my 3 pieces at the end of my crank being non-conenctric. After a dial indicator and some time under my car I was able to tightent the pieces where they were only .001" of each other being true. Vibration went away. Morale of the story is the comments previoulsy may be leading you to look at something within your engines rotating assembly (pulleys and everything else related). Just trying to spark a thought that leads you to a solution.

AC, Duckman and Shmeck:- Thanks for the input and suggestions. In answer to a few of your queries -

All mounts are poly, engine, trans, LCA's, TA, panhard, A-Arms, ARB's etc. Tranny output is in the centre.

I think a wheel tyre imbalance would be speed related rather than rpm and load, would it not? If I get the vibration/harmonic in 2nd and then shift the auto box into 3rd, but stay at the same speed then the noise reduces with the reduced revs. Would a wheel issue not stay constant with the speed?

Engine timing is spot on. All electrics new and in good condition.

Driveshaft U-joints have been replaced and vibration is unchanged.

AC:- I've found my old pulleys and am going to try them on the engine, in case the underdrive pulleys are causing a problem. Many thanks once again. I keep things updated.

ok so its doing it park and everything else is ok or dead on then i would look at the engine rotating ***., like the 1 person just mentioned then.
because with all that said now its the only thing left that can cause a vibration. harmonic balencer or crank pulley last the torque converter.
its not the trans at all. your getting it from your rotating ***., on your engine
sorry i couldnt be more help.

sounds like a prob my friend had. turned out to be his harmonic balancer. hope you find the prob soon. good luck

Engine is new, harmonic balancer is new. Problem was there before that.

Many thanks for your point about the trans. I take it a trans issue would cause slipping or shifting issues but not vibrations/harmonics? I'm becoming inclined to buy another TC to try as that's what things seem to be pointing towards.

As always any comments, suggestions or advice are very welcome.

Dr G, please read post #11.

Auggie

Thanks Auggie. Did they say that the TC was simply broken? Or is it something related to, or involving lock up convertors only. I'd like to keep the TC as a lock up one preferably.

If I end up changing it in the near future, which is looking increasingly likely now, then I plan to go for a multidisk full throttle lockup Vigilante convertor with whatever stall Dana at Probuilt recommends - I'd imagine 2600-2800rpm.

You changed the TC and the trans at the same time when the trans went south. When the trans went south, did it start to slip or give other problems with shifting? Did the noise/vibration/harmonic get worse in this time period? What I'm asking is was there a transmission issue all along, or was it two problems - the convertor for years, and then only the transmission at the end. I hope you don't mind all the questions! Many thanks for your input!

Didnt read all the post but from your 1st discription, I recognized an exact problem I had. Couldnt figure it our for years. Yeah...years. Turned out to be my driveshaft. I had done new u-joints and tranny slip yoke. It was profesionally done too. I moved on to other things. In that time I had GTA wheels with 2 different sets of tires and then the Ronals with new tires. Balabced them a few times perfect. Tried drums and brakes. Checked pinion angles. Started B4 I had the 355 motor and the rebuilt tranny and continued after thosse were installed. Completely different trans. The moror mounts and trans mount were replaced at the time of those installs. Suspension upgrade and springs/shocks were all done. Those were upgrades already planned but they didnt cure it. I tried the driveshaft off my sisters 86 Camaro for shi*s n giggles. Better but didnt cure it. Tried the worm clamp on the tube balancing method, impacting the u-joints and turning the shaft 180*. Nada! Finally I got back around to it and decided to re-visit the driveshaft. Went to a salvage yard and picked up one off a donor car. BINGO! No more vibrations. My sisters shaft is appartently not perfect either. The only time I had NO vibration was with the driveshaft removed. If you try that, keep in mind that you must put the tranny in neutral and shut off the motor to let it stop by itself B4 putting it in park. =)

Why, do you want to keep the lock-up torque converter? Any how the rummbling/viberation came on slowly. The shift kit was installed before the R/Vib started. The trans worked perfectly during the R/Vib period (two years) and I just learned to live with it after I ran out of things to try (read all these posts). I started to do a lot of drag racing (NOS) and the trans started to slip some (did not change the R/Vib) so I talked to this trans guy who informed me that I had the weakest (82 to 84) 700R4 built and he could upgrade it with later stuff. When he removed the trans he called me and said that the torque converter was shot. I asked him if that could be the cause of the R/Vib I had and I told him what the B&M guy had told me at the SEMA show. He said "could be". CYA I guess. Anyhow I called Art Car and he suggested to use a non-lockup converter (NOS) and he had a kit to rerout the oil in the trans. so it would not over heat. Dr G, that is probely one of the best decisions I ever made. I drove that car for two years with that R/Vib and you cannot imagine the great feeling of driving that car now and flying down the hwy. with out all that R/Vib. Smooth as slik and to be rid of all that lock, un-lock, lock, un-lock BS in town was just awesome. I thought I had bought a new car. Like I said in post #11, I don't know if this is your problem but it sure sounds like it. Keep in touch and good luck.


Auggie

Dr G, any luck?

Well guys I replaced the torque convertor and the major vibration/harmonic is now CURED. Their are still numerous trim rattles but they will be dealt with in due course.

The problem now is the lack of traction and the car kicking sideways at highway speeds when you go past half throttle. The increase in low down torque with the higher multiplication/higher stall convertor is phenomenal. God it feels good to be driving a healthy V8 again.

Thanks to all of you for your help, suggestions and encouragement!

Dr G, I know just how you feel and all you other guy's reread posts #9, #11, #31, and #34.

Auggie