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vibration after tranny swap


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18 replies to this topic

#1 greggbrat

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Posted 19 April 2004 - 05:27 PM

I should have listened to Jerry (Bratsrus) when he said using an EA82 flywheel during this tranny swap would cause highway vibration. When I hit about 60 MPH the resonance of the flywheel seems to vibrate the entire vehicle........I dont think its affecting the driveability but it is very very annoying. Oh well, back to the drawing board.

#2 carfreak85

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Posted 19 April 2004 - 06:10 PM

No good flywheel will vibrate, unless you cut a chunk out or welded something on. Not even in the EA82, they are designed to spin, vibration and spinning are not good friends. I have an EA82 flywheel on my turbo wagon and during my test drives, it never vibrated (I used a lengthened 1-pc driveshaft). My bet is that the driveshaft is not stright (If you used a 2-pc shaft) or that its not balanced (If its a 1-pc). or a wheel whight fell off or mud on the rim or something silly like that.

#3 Qman

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Posted 19 April 2004 - 06:42 PM

I would have to concur with 'freak on this. I have run EA82 flywheels with a number of 5sp swaps and have not experienced a vibration due to engine speed. I would be willing to bet that the pressure plate may not be set on the flywheel right though. There are marks on the flywheel and the pressure plate. They have to be at least 100 degrees away from eachother. The mark is on the ring gear and the plate. It looks like a circle imprinted into the metal. These are used for referencing the two parts. Unfortunately, the only way to check that would be to seperate the engine and trans.

#4 greggbrat

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Posted 19 April 2004 - 08:16 PM

Its a one piece driveshaft.....I had it lengthened and balanced.

I thought the pressure plate was keyed by two small metal nubs sticking out of the flywheel and they fit into the pressure plate?

#5 edrach

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Posted 19 April 2004 - 08:40 PM

You might have a totally different issue. If you run the car up to 60mph and then let off on the gas, does the vibration stop? Then if you step on the gas again, does it come back and increase with speed? If that's the case, you have a bad DOJ on one (or both axles). Vibration on acceleration that goes away on trailing throttle is a classic symptom of a bad DOJ. I can't tell you which one, but if you have a torn boot on one side that's most likely the bad one. Good luck.

The other possibility is that you actually have a bad transmission; I had that mis-fortune with the first 5 speed that was installed on my Brat. 2nd tranny cleaned that right up.

I also forgot to add, I did use a EA82 flywheel and an '88 d/r tranny for my swap.

#6 greggbrat

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Posted 19 April 2004 - 08:44 PM

Edrach, the problem goes away when I let off the gas as the RPM's decrease.

I have read "DOJ" on many threads.......what does it stand for?

The problem didnt exist before the tranny swap......but it does exist now. Given that it would seem likely its either a flywheel/clutch issue or a bad tranny.

What is DOJ??????

#7 edrach

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Posted 19 April 2004 - 08:59 PM

DOJ is double offset joint. This is the inner joint (transmission end) on your front axle; as opposed to the CVJ (constant velocity joint) which is the outboard joint (wheel end). CVJs start to click under hard lock when failing, DOJs tend to vibrate during acceleration and stop when you let off on the gas. Trust me, very classic symptoms. Sometimes the vibration is so bad you think the transmission is about to fall out of the car; sometimes it's so minor, an experienced mechanic won't notice it. If you pulled too hard on the axle during removal and/or it was difficult to get off your old tranny, you could have damaged the DOJ which might be causing your vibration--it doesn't take much.

#8 greggbrat

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Posted 19 April 2004 - 08:59 PM

I almost forgot.......I changed out the front rotors and brake pads (with new parts) during this whole tranny swap. Could I have missed something there?

#9 greggbrat

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Posted 19 April 2004 - 09:05 PM

More information.......I get the vibration (although it feels a bit different) just revving the engine while sitting still. (sorry, I forgot to give this vital information earlier)

#10 edrach

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Posted 20 April 2004 - 01:05 AM

Boy, that certainly changes things. Just for laughs, does the vibration still occur when stopped AND the clutch depressed--that would eliminate anything in the tranny as well as the drivetrain which seems to have been eliminated. Perhaps a resonance resulting from a flakey tranny mount or engine mount.

#11 GeneralDisorder

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Posted 20 April 2004 - 03:41 AM

I think I'm going to cast my vote with Qman - I think your PP is not properly aligned on the flywheel. There is NO WAY that the flywheel itself could cause a vibration. It is centered on the crank, and no amount of play in the bolt holes would result in any vibration. If you could find a way to glue the flywheel on instead of bolt it, you still wouldn't get any vibration since the bolts are NOT what align the flywheel to the crank in the first place. Also the bolt holes are too close to the center of the flywheel to cause an out-of-balance condition. For something to vibrate enough for you to feel, it would have to be out near the edge of the flywheel - like the surface of the PP for example..... There are marks on the flywheel and the PP that should be aligned properly per the manual as Qman sugested above. I must say that I wasn't aware of them till he pointed them out to me a while back.

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#12 greggbrat

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Posted 20 April 2004 - 07:57 AM

I will do a bit more diagnostics today. Right now I am in the process of cutting/grinding/beating fenders to fit my 27" tires. That should also check to see if a tire weight fell off. More to follow later. Thanks

#13 greggbrat

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Posted 21 April 2004 - 09:31 AM

I put a junkyard 5sp D/R into my 82 brat and also replaced the front rotors/brake pads, repacked the front bearings at the same time.

On test driving the vehicle I am getting a vibration while accelerating or under load.......when I let off the gas the virbration goes away (it also goes away by pushing in the clutch......even I rev the motor). Prior to the tranny swap there were no vibration issues at all.

I just put on new wheels and tires but that didnt change the vibration. And the vibration is not felt just in the steering wheel but rather through the entire vehicle. And the vibration can best be described as if the stereo bass was really booming.

I have heard that a bad DOJ will cause this problem. Like I mentioned earlier I didnt have this problem prior to the tranny swap......and all the boots are intact on the axles. If it were a bad DOJ how could I find out for sure which axle and if it is really bad (without having to replace them to find out.....thats an expensive and time consuming fix)

I imagine it could also be the junkyard tranny causing the issue.......but again its a time consuming and expensive test to replace the tranny again.

And ideas on how to isolate where the problem is located?

#14 GeneralDisorder

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Posted 21 April 2004 - 03:50 PM

I can confim that a bad DOJ *can* cause serious vibration. It happened to me one time on my wagon. The car was completely stock at the time.... in the space of about 3 or 4 miles, the joint went, and I thought the car was going to fall apart from the vibration. I pulled over about 4 or 5 times to make sure I still had all four wheels. It was REALLY BAD. So bad that I was scared to drive it after this, and changed the axle immediately.

The other possiblity is a bad front differential in the tranny you installed.... check for play in the stub's with the axles disconnected.....

GD

#15 greggbrat

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Posted 21 April 2004 - 03:57 PM

How would I figure out which DOJ is bad?

#16 GeneralDisorder

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Posted 21 April 2004 - 04:05 PM

If the vibration is worse turning right, then it's your left axle, and visa-versa. At least that's the way it's always worked for me. You can also dissasemble the axle's inner joint and look for wear - spalling on the bearing surfaces and what not. Likely you won't be able to tell tho, and you'll just end up guessing. Check that diff too....

GD

#17 greggbrat

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Posted 21 April 2004 - 04:10 PM

The vibration doesnt change when I turn left or right......its just constant.

#18 GeneralDisorder

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Posted 21 April 2004 - 04:21 PM

I think it's your tranny - especially since you didn't have this problem prior to the swap. Inspect that diff closely.

GD

#19 greggbrat

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Posted 21 April 2004 - 08:02 PM

Will the fun never end.......one of these days I might actually get to actually get to drive the brat someplace besides the junkyard. :-) It would be more fun to work on it if there was not snow in the forecast.




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