tshort

I think I may have figured out my vibration problem with the new AR 383. As I was crating it up tonight, yes, it's already out of the car, my friend that was helping me noticed I forgot to install a pilot bushing. DOHHH!!!!!!!!
Would that have caused my bad vibrations? I'm talking fast, butt numbing vibrations that when you rev the car high it feels the like the engine wants to come off the motor mounts.
Also, let's assume that is the root of my problems. Does anyone think this could have caused engine damage or would things be good if I just put the bearing in and put it all back together?

burners

Yes, I think a missing pilot bushing would cause a serious vibration. It also has the potential of damaging your transmission, particularly the input shaft. I would suggest inspecting the transmission (maybe magnafluxing the input shaft gears) and perhaps even replacing the front bearing. Consider the fact that without a bushing it will allow the clutch plate to move off center. Once you engage the clutch it will be locked off center and cause an imbalance. It will be just like a driveline imbalance but much more intense. I would say that you found the problem. You probably didn't hurt the engine but I would pull the pan and look at the rear main bearing (including the thrust surface). If it looks fine then I would say you are ok.

OkeeGuy

:iagree: EXACTLY WHAT HE SAID... :yesnod:

tshort

So what's magnafluxing and how much does it cost? It would be so nice if the problems were solved with the pilot bushing. I'm thinking it's very possible. :banghead: :banghead: :banghead:

GrandSportC3

Looks like you found your problem.. I hope that it didn't cause any damage....

Fevre

Personaly I would put a pilot bearing/bushing in it and re-install to check for any problems. No sense tearing the trans apart if you are uncertain as to whether or not there is a problem with it and it might be the eng is still not right and the lack of the pilot bearing is not the problem.

lars

tshort -
Pop a pilot bearing in it and slap it back together. The missing bearing would definitely cause the vibe problem, and - no - it won't cause any permanent damage to either the tranny or the engine: The input shaft with the clutch disc on it will only wobble around within the confines of the input shaft housing: that's enough to cause a vibration, but not enough to really damage anything. When you put a bearing in it, I recommend use of the actual bearing instead of the pilot bushing.

69Rat

:iagree:

What he said!

yellow 72

Just imagine how much the clutch disc could move around :eek: ....
I was just wondering how did you align the clutch when you assembled it with the pressure plate :confused:

tshort

Lars,
Why do you suggest the bearing over the bushing? I did a search and just about everyone that replaced the bushing with a bearing had problems in a short time. They said the bearing was totally destroyed while the bushing wasn't bad at all. Is there a correct procedure you have to follow that maybe some of the others missed out on? Certain type of lube that work correctly? Or maybe no lube :confused:

I'm planning on not shipping it back for now and seeing if the pilot bearing/bushing fixes my troubles. But before I put it in, I want to check the rest of the engine. I was planning on popping off the oil pan and checking things in there. Could you please send me a list of things you would check? You can email me if you prefer.
Thanks!


[Modified by tshort, 9:44 AM 10/2/2003]

Fevre

My take on the bushing/bearing is the bushing cannot fail while the bearing can. The General put millions and millions of bushings in cars over the years, may still be putting them in all their cars for all I know. The bearing offers less friction but the risk in my opinion is not worth the benefit.

tshort

Fevre, I believe that they switched to bearings either late in c3's or in the c4's. Not sure if they did this across the board or just on the vette. Heck, I don't know if they stuck with it but that's what I've heard.

Fevre

Forgot to mention that I speak from experience, the 2 times I put bearings in they where trashed when I removed the eng again. Might have been user error on my part but I just feel better known the bearing isn't in a million pieces grinding away inside the crank end.

norvalwilhelm

Fevre do you check the bellhousing for run out? It must be within .005 maximum. Maybe the bearing will not tolerate runout as well as a bushing.

burners

From my experience the bearings fail if the transmission is improperly installed or the transmission comes loose. I run bearings on all my cars and have only had one fail on me (for the above reason). My tip for installing a transmission is to buy 4 or 5" long bolts that you can thread into the bellhousing and use as guide pins to slide the transmission into place. Never, ever pull the transmission tight to the bellhousing face by tightening the bolts. You should always be able to push the transmission by hand until it mates with the housing face. If the input shaft is misaligned and you tighten the bolts down it will push the bearings out and crush the bearing cage and then you won't have a bearing once again. I have done that and it tweaked the input shaft enough to crack several teeth which eventually departed the gear. THAT made a loud noise!

I agree that you should slap a bearing/bushing in the engine and give it a shot. If that fixes the problem then just plan for a time in the future to overhaul the transmission. Mangafluxing the input shaft is no big deal. Most engine machine shops have the tool. It just checks for cracks. It would probably cost $10 or $20 to have it checked.

BeaterShark

I tried searching on topics you created to see if you posted the details of the vibration, but could not find anything.

Did it vibrate with the clutch in? If so, I seriously doubt it was due to lack of pilot bushing/bearing.

I could understand that it would cause a vibration with clutch enganged, but after reading your website, you state "I'm also having a vibration problem that seems to be engine related because it is unaffected whether or not the car is moving or in gear".

I ran my car for 20k miles without a pilot bushing. I pulled the tranny due to a bad T/O bearing and tore it down to the flywheel. It was then that I noticed that I had forgot the pilot bushing upon install. I have since installed the bushing and I noticed NO difference, other than smoother TO bearing operation.

Fevre

No I did not.

I just like the idea of using parts that less prone to failure. Can anyone tell me what advantage the roller bearing offers over the bushing? I know it reduces friction but I bet most who are recomending using a roller bearing for the input shaft do not use roller cam bearings, or roller cams, or elec fans, or EFI, or .... so many things can bed made better but each person has to choose what they feel is best for their application. I like the comfort of knowing that the pilot bushing is not going to be in pieces if the input shaft is off .00000005" when I mate up the eng to the trans.




[Modified by Fevre, 2:03 PM 10/1/2003]

Fevre

Tshort

I have a ? for ya, did the eng come with a fly wheel and/or balancer? You probably got a ext balance eng so you can't use the stock vette balancer or fly wheel. Just one more thing to check if you haven't already.

69schemers

Is your 383 internal or externally balanced? Having the wrong combination will create a bad vibration. I also believe that the pilot bushing could also be the problem.

Ryan77

Tshort bought the motor from AR racing, and I believe almost all of their engines come assembled from balancer to flywheel, so he shouldn't have anything from the original vette motor that would cause the vibration


[Modified by Ryan77, 3:44 PM 10/1/2003]