69427

Just a simple question here. I've heard reports elsewhere on this site that the ZR-1 halfshafts are specific to the ZR-1. Is this true, or just rumor? If true, what's the specific difference?

As the title says, I'm just curious from an engineering standpoint. I put a C4 suspension under my '69 years ago, and had custom halfshafts made to provide some extra durability during track days.

WVZR-1

They're NOT different specification wise. There's conflicting reports of the first few hundred having 'steel' vs aluminum but that's been argued for years,

69427

Thank you for this clarification. I was always under the impression that the C4 halfshafts were common amongst the production models, but I was also open to my being mistaken in that.

WVZR-1

There were 'steel' for restricted RPO - an '84 thru '86 A4 with no power seats was likely a 'steel' by build at BGR.

phrogs

I have owned 90 #354 and #266 both had steel half shafts, its like the first 600 90 ZR-1s had steel then switched to the normal aluminum ones..

I have a pair of the steel ones in my parts stash.

fxkenny

My '90 #0442 has the steel shafts. I have also heard that the first approx 600 had the steel shafts, but have not heard exactly what the number is.

WVZR-1

On your Build Sheet what do you have in I believe Block #14.

phrogs

Here's some photos

Steel from 90 #266 and aluminum from 90 #854 Both made by spicer

fxkenny

I will check on that next time I'm in the shop.

pappy.72

#839 confirmed aluminum half shafts. Fun observation on mine. It has ZR1 written in marker on each half shaft.

69427

I'm curious why they were marked. Is there something different there than L98/LT1/LT4 cars?

phrogs

They liked to write on things I have seen spare tires with ZR-1 or K O H written on them maybe they were excited and we get to find random stuff written on some cars.

Here's #266 buildsheet

Crabs

The halfshafts on mine #792 are aluminum and are marked in the same fashion.
I will post a pic later.

Crabs

69427

I understand the random written stuff. Under the rear deck of my '69, some gal named Lilly Belle wrote her name in very large script.

DEAN A NELSON

i have # 418, bought new and it has the steel and.......manual air.

Dean Nelson

69427

Just a quick post to say thanks for all the input here. I was not aware of the temporary steel shafts. The mix of steel and aluminum shafts at the same time (if I am understanding things correctly) is a head scratcher for me. Given that the ZR-1 production eventually went to strictly aluminum does impress me on the strength of the standard halfshaft parts.

FWIW, when I was fitting the C4 suspension under my '69 I needed to shorten the halfshafts by 1.5" each to retain the stock C3 trackwidth to enable the use of stock wheels. The driveshaft shop manager told me that these stock halfshafts were IIRC .091" wall tubing. He suggested that if I wished to go to thicker wall tubing that this would be the most convenient time to do it. I agreed, and he put .138" tubing in the parts. I don't drag race, and so far these shafts have held up well in my application.

fxkenny

Finally remembered to check my build sheet.
On my '90 #0442 buildsheet block 14 shows "8YZ" just like the one pictured in this thread.