Jcpstrat

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Happy Easter everyone.

In the process of doing shake down runs when it hasn’t been raining, I been hearing noises from what I though was the rear of the car that I didn't like. I think I've got them all taken care of finally but I thought I'd list them out in case it might help someone else.

Initially it sounded like something rubbing and I did find things:
  • One of the mag wheels was barely scraping on a brake caliper. The vendor I bought them from sent me some 3/8” spacers that took care of that.
  • A piece of the tunnel insulation (underside), was rubbing on the front drive shaft U-joint. Re-attaching the insulation to the body clip solved that.
  • Both rear tires started slightly rubbing on the inside lip of rear fenders once suspension started moving as I began driving at speeds to make the suspension work. I hated to do this part but I very carefully sanded off probably less than a 1/16” from the inside fender lips. Nothing anyone can see and I can’t even feel the difference but that solved that rubbing noise.
Each time the noise(s) seemed to get better but there was still a rubbing sound that had a frequency the same as the wheel rotation but I could not see anything obviously wrong. I know these vintage years had a know issue with the clutch packs in the differential that usually could be cured by adding a special GM differential additive so I ordered (2) 4Oz bottles of the AC Delco differential additive.

The day before I got the additive, the noise turned into a clicking sound, about twice the frequency of the wheels and the car felt weird (like shuttered), when I tried to make a turn, at a slow speed or from a stop.

I drained some fluid out of the differential and added the 2 bottles of additive and then took the car out to a parking lot where I did about 6 figure 8’s, which is recommended to work the additive into the clutch packs. On the way home the noise got worse, the clicking was replaced by a heavier sounding "clunk clunk clunk”, even when going in straight line. It was loud enough that when I pulled in the driveway, my wife was outside and she could hear it. I was sick about it but asked her to stand on the other side of driveway and listen again. She did and said it was louder on the passenger side.

I pulled the car into the garage and put the back end up on jack stands. I took the wheels off, the brake calipers off, the rotors off and both of the half-shafts (axle’s) out. At this point nothing was connected to the differential so I started the car, put it in gear and everything was quiet as could be from the rear of the car. With engine off and transmission in neutral I turned the differential side yokes by hand and everything was smooth as could be but without simulating a turn neither of those things I did would probably work the clutch packs.

The noise is all gone now after putting it back together so I don’t know which these following things solved the noise issue but the car drives great.
  • I replaced the passenger side half-shaft (including U-joints and flange). The flange was warped (0.032") when checked with a straight edge and there was 0.030" of end play in the U-joint cross, that fits into the flange. Also one of the caps of that U-joint was freely rotating in the journal of the half-shaft ... I guess just worn out.
  • I fixed the driver side parking brake shoe where the front shoe was engaged (could tell due to brake dust and polished inside of rotor where it presses against), and fixed the star wheel adjuster which was frozen solid in the collapsed position.
  • Car sat for 7 days with 2 bottles of the 4Oz special additive for the differential clutch packs after I had done a some figure 8's with it while waiting for me to figure out I needed to replace that half-shaft assembly. Maybe the additive really needed to soak into those clutch packs even thought the noise was present when going in a straight line.
Actually I didn’t feel like I had found anything serious enough to cause the loud “Clunk clunk clunking” but without doing anything, else the problem is gone.

I hope this info. will help someone else.
 

turbozig

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Wow, talk about a ghost in the machine. Glad to hear it all worked out well for you, but it makes one wonder what it actually was. I understand all too well strange noises after reassembling a restoration. There are so many variables when you have rebuilt everything and take it out for that first drive. I am still trying to locate a very slight strange tin sounding grinding noise on my 70 when turning left slowly. It does appear to be coming from the back of the car and at approximate frequency of the wheel rotation. I am thinking maybe something with the ebrake pads on the inner part of the rear rotors. I have looked at everything and can't see any rub marks on anything. The rear trailing arms were ordered as complete new assemblies from a reputable Vette shop in the US. Once it warms up and the streets are cleaned I will continue troubleshooting the noise. Thanks for sharing @Jcpstrat.
 

Rruuff Day

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Hopefully It's fixed John. Keep us informed... :thumbs:
 
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Black 03 Z06

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John, I know mine is a later model but when I changed the rear end gear lube mine made a odd noise for the first couple of miles, went away and never returned. Really thing the gear lube/additive needs to work in.

Good luck with it. You will solve any issue with it. :thumbs:
 

Jcpstrat

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turbozig ... I also had '70 and really liked it, another nice ride to keep. I believe the suspension & drive train is basically the same as my '67. It could be something in your ebrake assemblies but so hard to work in that area with the spindle installed. You might also check the yokes on both sides of differential ... they are held in the diff. by snap rings ... if a snap ring broke or popped out it could allow yoke and trailing arm to move outward when turning. If its a small block check to make sure the ends of the U-bolts that hold the half-shaft in the yokes of diff. aren't hitting on diff. case ... not much clearence at that spot. I found the wheel rubbing by putting Painters Tape on the fender lip and the peeling it off after driving. If I think of anything else I'll let you know.

Rruuff Day ... thanks ... will do🤞

Black 03 Z06 ... this diff. had been sitting for 40+ years. During rebuild I opened it up, cleaned it out, checked the ring & pinion gears and they looked beautiful so I just changed the yoke seals and refilled it with new fluid. You could be right that it may just have needed time to work back in to those clutch packs.
 

Kyle78

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Jcpstrat, I had the same noises on my 66 Vette when I got it last year. It was the Rear Diff oil issue. I would of have sucked out all the oil and added fresh fluid and the 2 bottles of Gm Additive. Then you know everything is clean and new. Once I did that she's been quite as a kitten in the rear end. Even after a good run on the 400 series highways. My next project is the factory power steering( Leaking as usual). :)
 
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Jcpstrat

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Thanks Kyle ... mine is quiet now too. :) That's a nice ride you have with your '66. I reason I didn't change all the fluid is that it was all new fluid before I started driving it. Even had some of the additive in it and the initial noise wasn't enough to make me even think about the differential. Anyway I do believe the differential did need more additive and I did find some other things that needed to be addressed so I feel good about that. Don't forget to put some pics up your album as you don't see may of these C2's on the road anymore.
 
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Kyle78

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Drive mine as much as possible. My old man has a beautiful Red 65 and we found this one word of mouth. My next big things are transmission needs attention most likely a rebuild as she very winey and leaks in the usual places and as I said in the last post the power steering. I put new fluid in everything so it leaks a clean. :) My car is originally from Texas a Lawyer here bought it in 2018 and thought you can just turn the key and drive it but after he was taking for a lot of repairs that I think the car really didn't need but now everything is new from most of the rear suspension, half shafts, brakes, springs front and back, rebuilt the factory 327. He complained about overheating issues and that he was done with the car and bought a new Boxter. Going through this thing, too many mechanics had their hands on it that just wanted to make buck. Changed the thermostat to a 180 degrees fix the overheating issue plus fix all under the dash after the car almost burnt due to someone rewired the curiosity lights wrong. So when I put in all new wiring I found the AC/Switch would not engage the off position fix that fix the vacuum switch for the heat, the vacuum lines were backwards. Then cleaned instrument panel up so every looked a lot newer and did the clock mod. So I have put in a few hours since I got it last August. I will post some pictures she is a very nice car but a good highway car as someone put a 1969 2.73 rear end from a 427 car in it so cruising at 100km/h is really nice even the 400 series are nice as it does not over-rev to much.
 

Rruuff Day

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Drive mine as much as possible. My old man has a beautiful Red 65 and we found this one word of mouth. My next big things are transmission needs attention most likely a rebuild as she very winey and leaks in the usual places and as I said in the last post the power steering. I put new fluid in everything so it leaks a clean. :) My car is originally from Texas a Lawyer here bought it in 2018 and thought you can just turn the key and drive it but after he was taking for a lot of repairs that I think the car really didn't need but now everything is new from most of the rear suspension, half shafts, brakes, springs front and back, rebuilt the factory 327. He complained about overheating issues and that he was done with the car and bought a new Boxter. Going through this thing, too many mechanics had their hands on it that just wanted to make buck. Changed the thermostat to a 180 degrees fix the overheating issue plus fix all under the dash after the car almost burnt due to someone rewired the curiosity lights wrong. So when I put in all new wiring I found the AC/Switch would not engage the off position fix that fix the vacuum switch for the heat, the vacuum lines were backwards. Then cleaned instrument panel up so every looked a lot newer and did the clock mod. So I have put in a few hours since I got it last August. I will post some pictures she is a very nice car but a good highway car as someone put a 1969 2.73 rear end from a 427 car in it so cruising at 100km/h is really nice even the 400 series are nice as it does not over-rev to much.

Great pictures. Beauty cars Kyle. Thanks for posting. :thumbs:

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Kyle78

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Thanks Rruuff Day. Good forum you guys have here. Did a lot of research on C2's if people have questions.
 
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Jcpstrat

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Yes thanks Kyle for posting all the pics ... both really great looking C2's and it looks like whoever took the pics might also be into photography. You have put some definite work into yours and in areas that aren't a lot of fun to get to and put back together but all those things will payoff. Nice to see others who really enjoy driving theirs. John
 

Luke 1967

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Drive mine as much as possible. My old man has a beautiful Red 65 and we found this one word of mouth. My next big things are transmission needs attention most likely a rebuild as she very winey and leaks in the usual places and as I said in the last post the power steering. I put new fluid in everything so it leaks a clean. :) My car is originally from Texas a Lawyer here bought it in 2018 and thought you can just turn the key and drive it but after he was taking for a lot of repairs that I think the car really didn't need but now everything is new from most of the rear suspension, half shafts, brakes, springs front and back, rebuilt the factory 327. He complained about overheating issues and that he was done with the car and bought a new Boxter. Going through this thing, too many mechanics had their hands on it that just wanted to make buck. Changed the thermostat to a 180 degrees fix the overheating issue plus fix all under the dash after the car almost burnt due to someone rewired the curiosity lights wrong. So when I put in all new wiring I found the AC/Switch would not engage the off position fix that fix the vacuum switch for the heat, the vacuum lines were backwards. Then cleaned instrument panel up so every looked a lot newer and did the clock mod. So I have put in a few hours since I got it last August. I will post some pictures she is a very nice car but a good highway car as someone put a 1969 2.73 rear end from a 427 car in it so cruising at 100km/h is really nice even the 400 series are nice as it does not over-rev to much.

Hey Kyle, Nice to see another C2 has fallen into the hands of someone who's main goal is to drive and enjoy. Cruising with your old man must be special! Its also great that you have knowledge and skills to work on these cars, that's a big part of the fun. That wiring meltdown looked pretty nasty, you were lucky to catch it in time.
Luke
 

2KforeverC5

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Happy Easter everyone.

In the process of doing shake down runs when it hasn’t been raining, I been hearing noises from what I though was the rear of the car that I didn't like. I think I've got them all taken care of finally but I thought I'd list them out in case it might help someone else.

Initially it sounded like something rubbing and I did find things:
  • One of the mag wheels was barely scraping on a brake caliper. The vendor I bought them from sent me some 3/8” spacers that took care of that.
  • A piece of the tunnel insulation (underside), was rubbing on the front drive shaft U-joint. Re-attaching the insulation to the body clip solved that.
  • Both rear tires started slightly rubbing on the inside lip of rear fenders once suspension started moving as I began driving at speeds to make the suspension work. I hated to do this part but I very carefully sanded off probably less than a 1/16” from the inside fender lips. Nothing anyone can see and I can’t even feel the difference but that solved that rubbing noise.
Each time the noise(s) seemed to get better but there was still a rubbing sound that had a frequency the same as the wheel rotation but I could not see anything obviously wrong. I know these vintage years had a know issue with the clutch packs in the differential that usually could be cured by adding a special GM differential additive so I ordered (2) 4Oz bottles of the AC Delco differential additive.

The day before I got the additive, the noise turned into a clicking sound, about twice the frequency of the wheels and the car felt weird (like shuttered), when I tried to make a turn, at a slow speed or from a stop.

I drained some fluid out of the differential and added the 2 bottles of additive and then took the car out to a parking lot where I did about 6 figure 8’s, which is recommended to work the additive into the clutch packs. On the way home the noise got worse, the clicking was replaced by a heavier sounding "clunk clunk clunk”, even when going in straight line. It was loud enough that when I pulled in the driveway, my wife was outside and she could hear it. I was sick about it but asked her to stand on the other side of driveway and listen again. She did and said it was louder on the passenger side.

I pulled the car into the garage and put the back end up on jack stands. I took the wheels off, the brake calipers off, the rotors off and both of the half-shafts (axle’s) out. At this point nothing was connected to the differential so I started the car, put it in gear and everything was quiet as could be from the rear of the car. With engine off and transmission in neutral I turned the differential side yokes by hand and everything was smooth as could be but without simulating a turn neither of those things I did would probably work the clutch packs.

The noise is all gone now after putting it back together so I don’t know which these following things solved the noise issue but the car drives great.
  • I replaced the passenger side half-shaft (including U-joints and flange). The flange was warped (0.032") when checked with a straight edge and there was 0.030" of end play in the U-joint cross, that fits into the flange. Also one of the caps of that U-joint was freely rotating in the journal of the half-shaft ... I guess just worn out.
  • I fixed the driver side parking brake shoe where the front shoe was engaged (could tell due to brake dust and polished inside of rotor where it presses against), and fixed the star wheel adjuster which was frozen solid in the collapsed position.
  • Car sat for 7 days with 2 bottles of the 4Oz special additive for the differential clutch packs after I had done a some figure 8's with it while waiting for me to figure out I needed to replace that half-shaft assembly. Maybe the additive really needed to soak into those clutch packs even thought the noise was present when going in a straight line.
Actually I didn’t feel like I had found anything serious enough to cause the loud “Clunk clunk clunking” but without doing anything, else the problem is gone.

I hope this info. will help someone else.
Yes it did too. Had the same issues with passenger side. Upon investigation after removing tires I was able to turn the Axle nut by hand. Torque to specifications (118 ft/lbs) decided to drain and fill differential (Red Line 75w 90 with stabilizer). While the car is at level I decided to drain and fill the transmission fluid (manual transmission) note ensure the filler plugs are available before draining. Be patient even with few unwanting words. It’s now ready for a road test 🤞 (few T Times it can wait) Cheers 🥂
 

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