Hi all, I had the GS out yesterday, found a nice abandon road. Hit the line-loc and lit the tires, I noticed that the right tire was turning like crazy, but the left barley spun. Does this mean the clutches in the posi unit are weak ? Thanks, Harry
John, I've looked a Jegs website but can't find the rebuild kit. Any ideas on where to get it? Also will I have to remove the carrier and put a new crush collar in to do this or just the pin and spider gears? Thanks, Harry
For Buick rear?? theres no clutch packs or rebuild kits . You need to machine the cone ends the fix is here http://www.buickperformance.com/82posirepair.htm
Before going through all the trouble, go to NAPA or Pep Boys and get a tube of Equa-Touque (or go to a GM store and get a tube of posi rear additive). I've seen it fix many sloppy rears, and it only costs 4 bucks and takes 10 minutes to put in.
The Buick Performance link provided above is really irrelevant, in that a '72 GS posi rear should have an 8.5 "S" spring clutch type posi. Cone type Warner-Motives were typically used by GM in '71 8.5's. Replacing clutchs...Too many folks think that just throwing a new set of GM clutchs in a 20-30 year old used 8.5 clutch carrier is going to make it perform "like new". As a result, often both tires are not going to grab equally. GM intended for the used "S" spring type 8.5 posi carriers to be shimmed up when the carrier was rebuilt & clutchs replaced. This is part of a TRUE 8.5 posi carrier rebuild. Detailed directions are listed in most '72-79 GM service manuals. GM parts even offered a wide range of clutch shims for this task depending on which 8.5 clutch type carrier one had. Problem is, the majority of these clutch shims have since been disco'ed. Today there are shim kits from Ratech, or rebuild kits from Supercar Unlimited, which can help with tightening up the spider gear to side gear clearance. Unfortunately the limited amt of shims do not always allow for the exact stack thickness needed to get the correct clearance. After buying up all disco'ed GM clutch shims I could find, over the last 6 years I've been forced to make many of my own clutch shims. For those interested in kits... below is a link to the Supercar Unlimited posi rebuild/shim kit. It also includes a 300lb preload spring, the $80 GM clutch pack, & a tube of GM posi additive. http://www.supercarsunlimited.com/Items.cfm?CategoryID=282 :3gears: Roger
If your going to spend the trouble and cash to rebuild maybe replace posi unit with an Eaton Carrier. Worth the trouble and expense and never worry about it again. 30+ year old stock units are pretty beat up by now.
Do you think it could be "dangerous" if not repair ASAP ? Or it won't damage it more if you wait couple of months ?
Smart to take it easy until you can upgrade to HD 30 spline Eaton posi & axles. Over the years, I've rebuilt several heavily used S-spring posis that were subjected to line lock use with wide slicks. One was in a high 11 sec '73 Camaro, that owner, just had to spray to get into the low 11's. With stock 28 spline axles, what was he thinking o No: Still have a side gear out of the Camaro's S spring posi. The teeth on the side gear are chewed down pretty bad. Ground up metal made its way to the pinion bearings on the Camaro rear. All bearings had to be replaced. Got Posi? :3gears: Roger
Or you could buy a complete Dana for a GM . I have on in a 70 thats soon to hit the road . Lots of parts for that one but its heavy . I probably will not break it even with the Doug Nash 5 spd . Oh yeah there are a few places you can up grade to Ford 9" unit . My opinion is the 9" is thye best unit out there and if you have a few extra bucks you can have a track set of gears and a street set . John
