New wheels and New Problem

[Jr. Corvette]

Another update. I phoned my transmission guy to see if he had any ideas. He told me nothing in the transmission will vibrate. I highly doubt it is engine related. What I'll may try and do is go somewhere private and try and rev the engine in park to make sure it's not related.

 

[Black 03 Z06]

Jr. did you have the motor out of the car? Is it possible that something is no longer in proper alignment? Different motor/transmission mounts??

Frustrating I am sure. You will figure it out.

 

[Jr. Corvette]

Jr. did you have the motor out of the car? Is it possible that something is no longer in proper alignment? Different motor/transmission mounts??

Frustrating I am sure. You will figure it out.

Thanks man! Hopefully soon. So thankful for these forums and for the help.

I just built a new motor 600 miles ago. New poly bushing all around. Every single bushing has been changed to poly. I think everything should be aligned as it all fit back together very nicely.

The problem is I changed so much. New U-joints, new bushings, new torque convertor

I did just have a thought though. With my fuel injection setup it's still learning a bit and a bit of tweeking is still required. I'm just curious if under fast acceleration, if the fuel injection system is having a hard time keeping up causing a lean condition causing surging. The vibration is more prominent because of the poly bushings so what I'm feeling is a pulsing/surging vibration?

It would make sense and I could corect it by trying to adjust my fast accel pump. I could also test it inducing the surge and thenback offthe throttle to maintain speed and see if it goes away. I will also try to slowly increase my revs in first gear to see if it happens. I'll update once I do more testing

 

[Riley P]

Interesting that the vibration appears to be engine speed related and not driveline related. I guess with changing averything to poly, it's possible the vibration was always there but it's more pronounced? I would suggest putting all your old bushing back in to check.......
To check if it's engine related, would you be able to accelerate in first up to the point where you feel the vibration, then put it in neutral and see if the vibration goes away?

 

[henkz06]

Take the driveshaft in somewhere to check whether it is properly balanced, or try a different driveshaft. Make sure that you have the proper motor and transmission mounts. I hope you get it figured out, vibrations are very annoying.

 

[nascar03]

That Riley guy is pretty smart..
I would start with his idea to see what/where/how that vibration happens.
Or just turn the radio up and sit on a pillow!!
LOL
Good luck pal.
Graham

 

[turbozig]

Once again, I would check the driveshaft for correct balance at a reputable driveline shop. I have had 2 vehicles that had that issue and both times were the driveshaft. Changing the u joints is a good thing, but balancing is just as critical. That shaft has alot of mass and spins at a high rate of speed. If it is not perfect, things happen.

 

[Jr. Corvette]

Thanks for the suggestions. I just finished testing. Engine does not make the vibration in neutral and the vibration appears at 4000 - 4200 and just keeps getting worse. I'm going to try the driveshaft as many of you have recommended. I have a good driveshaft guy at Driveline Specialities. I will update once I have it balanced.

As a side note, I've been having heating issues. I just upgraded to a 3 row aluminum radiator and I got up to about 208 on the highway and 228 quickly pulling in my garage after the drive! I know, I know. 228 is very hot and worry some but my research tells me 230 seems to be the cut off point. I was pushing it.

I'm going to completely remove the thermostat as this is the third time I've replaced it and it runs so hot I figure it should at least help. If that fails I will upgrade my water pump and switch to maybe electric fans as my fuel system can control them.

It might be a bit until I post an update but I will.

 

[Black 03 Z06]

Why do I recall something about a driveshaft being in "phase". Something to do with the position of the yokes on each end. Just trowing stuff out now but you just never know.

 

[turbozig]

Thanks for the suggestions. I just finished testing. Engine does not make the vibration in neutral and the vibration appears at 4000 - 4200 and just keeps getting worse. I'm going to try the driveshaft as many of you have recommended. I have a good driveshaft guy at Driveline Specialities. I will update once I have it balanced.

As a side note, I've been having heating issues. I just upgraded to a 3 row aluminum radiator and I got up to about 208 on the highway and 228 quickly pulling in my garage after the drive! I know, I know. 228 is very hot and worry some but my research tells me 230 seems to be the cut off point. I was pushing it.

I'm going to completely remove the thermostat as this is the third time I've replaced it and it runs so hot I figure it should at least help. If that fails I will upgrade my water pump and switch to maybe electric fans as my fuel system can control them.

It might be a bit until I post an update but I will.

My big block would get up to 220 regularly before the restoration. I changed to a Dewits radiator, Mezerie bilit aluminum high flow water pump and Robert shaw thermostat. I spent many hours replacing all the shroud seals correctly, and made sure all was air tight in all the recommended locations, before the entire assembly was installing into the car. Now it never gets above 180 degrees, averages 160-170. I am extremely happy with the results and it was worth all the hard efforts.

 

[Jeremiad]

Jr, sorry I didn't click into this thread earlier. I'm a bit late to the party, but I'd like to add a couple of opinions here, and perhaps I can follow up with some help.

Does that vibration occur in every gear, or just at speeds above 140?

You mentioned that your transmission guy said that there is nothing that can cause a vibration there, but that is not true. Anything with moving parts can cause a vibration, and Ken (BabyRay) can attest that he had a vibration that was caused by the torque converter.

I can offer you some help, perhaps. I have a few cameras that we could set up on your car to monitor the back wheels through a few pulls to see if they vibrate. I can also set up the cameras underneath your car to watch both ends of the driveshaft, but I don't know if we'll be able to see anything because of the torque tube. Won't cost you anything but time (and gas), and as Spence mentioned, there is some lovely smooth pavement just north of Airdrie so that won't interfere with the camera footage.

Also, as Riley mentioned, can you see if the vibration goes away by putting the trans in neutral (on the fly at speed as it happens)? If the vibration goes away immediately, it is likely the torque converter.

If it happens above a specific speed whether it is in gear or not, I would suspect a balance issue somewhere between the driveshaft and the wheels.

If it happens at a certain rpm in each gear, I would look first to the torque converter as it is the biggest mass, but it could be the flexplate (doubtful), a bearing, or the input shaft.

 

[Jr. Corvette]

Jr, sorry I didn't click into this thread earlier. I'm a bit late to the party, but I'd like to add a couple of opinions here, and perhaps I can follow up with some help.

Does that vibration occur in every gear, or just at speeds above 140?

You mentioned that your transmission guy said that there is nothing that can cause a vibration there, but that is not true. Anything with moving parts can cause a vibration, and Ken (BabyRay) can attest that he had a vibration that was caused by the torque converter.

I can offer you some help, perhaps. I have a few cameras that we could set up on your car to monitor the back wheels through a few pulls to see if they vibrate. I can also set up the cameras underneath your car to watch both ends of the driveshaft, but I don't know if we'll be able to see anything because of the torque tube. Won't cost you anything but time (and gas), and as Spence mentioned, there is some lovely smooth pavement just north of Airdrie so that won't interfere with the camera footage.

Also, as Riley mentioned, can you see if the vibration goes away by putting the trans in neutral (on the fly at speed as it happens)? If the vibration goes away immediately, it is likely the torque converter.

If it happens above a specific speed whether it is in gear or not, I would suspect a balance issue somewhere between the driveshaft and the wheels.

If it happens at a certain rpm in each gear, I would look first to the torque converter as it is the biggest mass, but it could be the flexplate (doubtful), a bearing, or the input shaft.

Thank you so much Jeremiad for offering to help me. I really appreciate that. However I have good and surprising news for everyone!

I HAVE FINALLY FIXED IT! I bet no body could have guessed this and in all honesty, I probably should have thought about this more.

During my engine build and ordering parts, it became time to balance the engine. I was at the parts store and wasn't sure if my engine was internal or external. I phoned up GM while I was there and they told me it was external. Now, yes my 350 is technically external because it is a late model first gen. Both the 400 and the late 350's are however the 350 uses the same neutral balancer as all other 350's but the flexplate is weighted. The 400's use a external balancer (that is weighted) and a weighted flexplate. My parts guy tells me he is all out of 350 balancers but that the 400's would work just fine seen as how they are both externally balanced..... He didn't know that the balancers were completely different and couldn't be swapped. I phoned up my tranny guy and he did some research for me and made me aware of this. I now know to never trust what any guy in a part store says. What an idiot I was to not double check what he said.

Anyway, the guy who sold me all my parts moved to Newfoundland but the store agree to warrenty the part and gave me a new balancer at cost netting me $26 back for an issue that could have wrecked my $10,000+ engine.

Moving on. It didn't cause any damage. The vibration is gone and boy, it is smooth as glass literally feels like driving on glass compared to before. Major difference.

I have also fixed the cooling issue by installing some Derale 4000 CFM fans. I was a bit busy fixing some rust on my parents suv and in my raste and excitement to get my car running and install electric fans, I failed to accurately measure the fan depth. I went with the close enough approach. I ended up having to drop my left suspension and clearance the fan so the A-arm actually sits inside the fan (but has room for suspension travel and room between the fan blades). It barely clears elsewhere. We are talking 1/8" here and a 1/16" there! I don't believe anyone else has installed these fans before on there C3 and I can see why. Nobody's just as stupi... special as me. Just to top of how.. special I am, I also forgot to check how much these fans draw. 50Amps! I had the factory 63 and actually calaculated my amp usuage before the fans and I was overpowering the alternator. I had to buy a new 150A alternator. Everything runs fantasti now. No engine bogging rolling up and down the windows. I even found a new light on my dash. I never knew we have a 'brights' light. I always thought it was for cruise control or something because it never worked. That's how bad my alternator situation was. Haha.

I love how it turned out though. Keeps the new engine farely cool at 192-195 at idle and no more than 203-206 elsewhere. Might have to consider an electric water pump if I want it cooler, or just wait until my engine breaks in a bit more.

Thanks for all the help and suggestions!!! I greatly appreciate this forum and you guys, the Corvette community.

 

[Rruuff Day]

Damn Jr... she looks great under the hood.... nothing quite as sweet as a happy ending.... Congrats on finding the shake... Enjoy and if you find yourself heading north and wanna meet for coffee sometime, drop a note...

 

[turbozig]

Great job troubleshooting jr.

 

[Black 03 Z06]

Trophy for 'NeverGiveUPNess".

Congrats. Hope you enjoy all the efforts you have put into your Corvette.

 

[ddgermann]

So glad you got it all figured out and that new mill is rotating smooth and cool now. That is one clean and tidy looking engine bay. Great job.

 

[Riley P]

Very, very good job! That is fantastic news that you got this resolved!