Bruce Nunnally

Mailbag: Chevette drivetrain?

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Dwight wrote:

Hi - this thread is great for me... I have a kit car using a 79 Chevette drive line and it has a vibration problem. i can't find anyone to work on it directly. How ever I did find 2 guys that tried to "beef up" the rear suspension. The assembly manual said to replace the drive line parts with a single longer drive shaft. But to that I have to find a "conversion" part for the rear end to attach the new shaft.
So my questions are
1. where do you think I can get that adapter yoke since it is required to install a universal joint?
2. Did your machinist keep notes on the part he made and could he make one for me? 3. would fixing the center bearing like you did be cheaper than converting to a longer drive shaft?
FYI - I read about another kit like mine where the drive line was not in a straight line so they just shifted the bearing support to get it in a straight line - it seemed to work but I fear that years of misalignment probably damaged the bearing. Thanks

Bruce

2016 Cadillac ATS-V gray/black; 2013 Cadillac ATS 2L Turbo Premium (Wife's)

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The Chevette driveline and rear axle is pretty unique from what I have found.There is a long extension housing bolted to the rear center member which is attached to a frame cross member ahead of the axle. The purpose of the extension housing is to keep the axle from twisting due to torque. I don't know of any way to extend the drive shaft and eliminate the extension unit without major re-engineering and parts fabrication, because there are no replacement parts or mods available. If you research the web, there are a couple of Chevette forums that have helpful information. There is also a Facebook Chevette user's group.

Apparently, the popular conversion is to use an older Chevy S10 pickup rear axle. However, that also requires some modifications like removing the spring mounts from the stock axle and welding them to the S10 axle, and then rigging up some kind of trailing arms to control the torque. This is a necessary mod if you increase the engine output or put in a bigger engine, because the stock axle is barely adequate to handle the measly torque of the stock 1.6 Chevette engine.

I had a grinding noise from the bearing section of my extension housing and some vibration. That turned out to be due to (1) a worn out rubber support bushing that allowed the bearing to float out of alignment, and (2) the forward extension mount being about an inch out of alignment from the transmission to the rear axle, causing side pressure. I sourced a replacement support bushing from one of the forums. The bearing turned out to be OK despite the years and miles of abuse. Go through my posts on the thread on my Jaguar Duke replica to see some pictures and a better description of what I am talking about.

(edit) Upon re-reading your post, I think you had got some ideas from Bruce's description of the work he did on his replica. That has a Ford Pinto/Mustang chassis with leaf rear springs and a more conventional driveline configuration. Totally different animal from the Chevette in the driveline setup. If you have the Chevette chassis, you will have to deal with its unique quirks like I said above.

Edited by two2go

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