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Finally took it for a really short spin. Had to garage it prematurely because when the drive gets off of load I’m getting a moderately loud clunk that sounds like it’s coming from the transmission tail shaft area. When the car is under load, no noises. Only when coasting without any load. Never got over 8 mph. Any thoughts? New TKX with custom drive shaft. Could the yoke be slide out?
Sloppy/loose fit between yoke and the tail housing brass internal bushing?
good call, doorgunner. I spent the whole day on it today. Lubricated the splines in the slip yoke, not the problem. Reinstalled the driveshaft, not the problem. The TKX from American Powertrain came with a custom driveshaft to fit the 5 speed. That drive shaft is 2.5” diameter. The stock is 2”. Not much clearance to the floor board. Also noticed the driveshaft isn’t perfectly centered to the floor board. Not sure if that’s stock or an issue. The Ridetech suspension package is also brand new so I raised the rear ride height about an inch and that actually reduced the amount of clunking noises. It’s like it gave the driveshaft more clearance? I’m thinking maybe get lower profile tranny mount bushings? Still can’t ride so I bummed. I did get it up to 20 mph though......so some progress.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
I would check your rear bushings to make sure the bushing are all good and the nuts are all tight. It shouldnt be moving that much. I had a cracked snubber that was allowing the differential to rotate causing all sorts of issues. Look where all the u joint knuckles come close to the body for wear on the fiberglass. I wore a hole through the center compartment in the rear before I found the issue.
I would check your rear bushings to make sure the bushing are all good and the nuts are all tight. It shouldnt be moving that much. I had a cracked snubber that was allowing the differential to rotate causing all sorts of issues. Look where all the u joint knuckles come close to the body for wear on the fiberglass. I wore a hole through the center compartment in the rear before I found the issue.
Thanks, RR. I’m going to take a look at this today. I’m not exactly sure what the rear bushing would look like. Is their a diagram I can look up to see the breakdown? Never had the rear taken apart before so I’m guessing their is a slip yoke for that end of the driveshaft like the from to the tranny? Is that bushing there?
It's one of those problems where you need the car safely lifted on heavy duty (truck) jack stands so you can watch the drivetrain flex while someone engages the parking brake...then puts the car in 1st and reverse....then release the clutch JUST ENOUGH that the wheels will try to rotate.
OR....position-clamp a video / GoPro ccamera under the car so it records each drivetrain area individually while the car sits on the driveway and you make the shifts listed above as the car moves at 2-3 mph along the driveway in 1st and then Reverse...maybe even 2nd gear also.
Snubber can be loose or rotten
Example only
Also...is the differential TIGHTLY bolted to the crossmember...sometimes techs forget to torque bolts.
Last edited by doorgunner; Jun 13, 2021 at 12:43 PM.
It's one of those problems where you need the car safely lifted on heavy duty (truck) jack stands so you can watch the drivetrain flex while someone engages the parking brake...then puts the car in 1st and reverse....then release the clutch JUST ENOUGH that the wheels will try to rotate.
OR....position-clamp a video / GoPro ccamera under the car so it records each drivetrain area individually while the car sits on the driveway and you make the shifts listed above as the car moves at 2-3 mph along the driveway in 1st and then Reverse...maybe even 2nd gear also.
Snubber can be loose or rotten
Example only
Also...is the differential TIGHTLY bolted to the crossmember...sometimes techs forget to torque bolts.
REALLY appreciate that, DG! I’m at the car now and it’s jack up. I think that snubber but is a little loose. Should I torque it down? Also was already scheming how I could record under car while driving it to see what’s going on. Big thanks!
It's one of those problems where you need the car safely lifted on heavy duty (truck) jack stands so you can watch the drivetrain flex while someone engages the parking brake...then puts the car in 1st and reverse....then release the clutch JUST ENOUGH that the wheels will try to rotate.
OR....position-clamp a video / GoPro ccamera under the car so it records each drivetrain area individually while the car sits on the driveway and you make the shifts listed above as the car moves at 2-3 mph along the driveway in 1st and then Reverse...maybe even 2nd gear also.
Snubber can be loose or rotten
Example only
Also...is the differential TIGHTLY bolted to the crossmember...sometimes techs forget to torque bolts.
just checked the snubber bushing. It’s pretty damn tight. Check out these pictures. Not much clearance to the tunnel but NO evidence of scratching in the fiberglass. Side view of mount. Doesn’t look like the prothane bushing is flat on the bracket. Could be because I have the rear jacked up? Underside of the tranny mount. Maybe the two bolts are sliding back and forth when driving? That bracket is new with the kit. That worn part of the holes could be from me when installing the tranny and having to go at it a few times.
Last edited by Bluesting70; Jun 13, 2021 at 12:57 PM.
It's looking like Video-time...you'll see any abnormal movement and Hear abnormal sounds better...that will help you alot.
exactly. Of course it’s raining now so we wait. But I notice while under one of the two screw studs that go through the mount was loose. It was the one in the picture that showed paint scrape around the hole. Hoping it was that all along sliding back and forth. We will see.
Last edited by Bluesting70; Jun 13, 2021 at 01:49 PM.
FYI.......STUFF happens....
I bought a highly-rated new truck about a month ago...
a slight thump became a loud clunk.....
visual checks din't show a problem...
I finally checked stuff with wrenches.....
the driver-side U-bolts that hold the rear axle tube to the spring-pack were less than finger tight FROM the Manufacturer...
which allowed the tube to jerk up/down on the spring-pack centering pad.
Last edited by doorgunner; Jun 13, 2021 at 01:56 PM.
FYI.......STUFF happens....
I bought a new truck about a month ago..a slight thump became a loud clunk.....
the driver-side U-bolts that hold the rear axle tube to the spring-pack were less than finger tight FROM the Manufacturer.
yikes. That sucks. Imagine if you didn’t know about cars. You would’ve been chasing that issue for months. You would have been at the hands of how good the dealers “tech” would have been. What truck did you get?
Last edited by Bluesting70; Jun 13, 2021 at 01:53 PM.
say it ain’t so!! Just kidding. As long as you like it, man. I’ve been considering a Silverado or Sierra lately. I currently have a 2018 Infiniti Q50 Sport as my driver on lease. Gotta decide if I’m going to buy it by January or go another direction.
So a big thanks to those that recommended the snubber!! Me and my 13 year old changed it out today in about an hour. Pretty easy job. Took it on first real drive and it was awesome after no driving for 9 months. I’m thrilled. On to alignment and tuning some minor tweaks.
I think my snubber might have been the worst one out there!
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Tranny Question
