Posi Rear End For GS, Optional?

jaredyocum

Hi guys glad to be a new member. I have a 65 skylark GS and it didn't come standard with a posi rear i understand from some lititure that I read in the past that none of the 65 GS's did and they all had 3:36 gears ,weather or not some were orderd with diffrent ratios and or posi Im not sure.I inhearited my brothers 64 GTO rear when he tubbed his car and it bolted right in and had 3:90 gears and a GM cone style posi ,but his brakes were all togeather diffrent than mine narower shoes and non finned drums. I thought I wanted 3:90 gears turns out they wer'nt so cherry after all too low for my 26 inch tires so I coverted back to the 3:36 with the same posi.Cone style posi isnt really too log lived either I found .But thats the price you pay for jerkin gears and goin fast. thanks Jared

 

Well in my 72 I dont have a factory posi unit, but when I first bought my car years ago I decided to get rid of that single tire fire and put a posi unit in it. So I went with the Eaton 3:42 posi unit, and still to this day I love every bit of it. Of course if you were to drive it in the rain you need to be carefull especially when taking corners, but in the dry weather which is all my car see's it is so much fun and worth all $1000 I put into it.

If I could only find someone to buy this 10 bolt 3:42 rear end complete from me, then I could move on to getting a 12 bolt. And it only has about 6,000 miles on it since the change over, anyone interested?

 

Well when you start a thread and ask a question I don't think anyone would quite expect to hear from someone who was on the assembly line in Flint putting together rear ends for Buicks. I find that extremely ironic and also really cool to have been able to post this and still run into someone like this. Another reason why this board is so helpfull.

And who knows now maybe someone who is responsible for spraying on the undercoating on my inner fenders from the factory can answer up to why the heck this stuff is such a pain to get off. :TU:

 

that is not correct. in 65 the standard ratio for an automatic transmission equipped car was 3.08 non posi. posi was an option. the standard ratio for a manual transmission equipped car was 3.36 non posi. there were other ratios available as an option but those were the standard ratios.

 

Here is a page from some '65 documentation that I have.

:beer

 

I already have taken the undercoating off of the inner fenders. I sprayed on some Mr. Muscle Oven Cleaner, let it sit for 20 min. and then used a scraper to take it off, worked great, but still needed to give it some good elbow grease.

 

Jaredyocum

Yea Bob My 65 GS is a 4 speed so that is consistant with what your saying I was uder the impression that they all had 3:36 gears like mine but I never really knew It to be fact. Mine did have a nonposi 3:36 from the factorythough.

 

So what do you guys think about how this 10 bolt will react and run with an M-22? Will the rearend be able to hold up to the built 455 and the M-22? I don't think I would be sidestepping the clutch at 4,000 rpm's or higher more than once in a great while. And no I would not be running slicks the majority of the time this car is running, but mostly on street radials, only slicks once or twice maybe to pull a few ET's. Just don't want to get down the street and have to watch the tow truck driver tow my car home, if you know what I mean.

 

This is a old post yes but I just toasted my differential.
It was a 70 gs auto 455 car with A/C has the springs clutches I think.
Another 70 stage 1 auto rear without A/C has the cone brake set up
Last 70 stage 1 with A/C auto has the clutch also
Which is prefered

 

Here's an oddball - My '70 GS 350 4-sp (would've come std. w/3.23 open) was ordered w/ Trailer Tow (H1) which according to the assy. manual & shop manual got it an unannounced/no-charge upgrade to a (SCO) 3.64 ratio however since there was no 3.64 open rear, the posi option (G4) did have to be ordered/paid for in conjunction w/H1. In my case, G1 (performance axle w/posi) was ordered which w/o the H1 option would've resulted in a 3.42 posi. I suppose nobody (even the zone office) was sure but w/either G1 or G4 the car would've come through w/the 3.64 posi because of the H1 option. I assume (@Mike Trom) that G1 was a tad bit more expensive than G4? If so, Buick needed the extra $ on this car as they apparently forgot (clerical error) to invoice the dealer for the painted top as it didn't show up on the Wayne Roberts report but is on the trim tag & there's physical evidence.

A '70 Skylark (as well as '68-9 GS 350) w/manual transmission & trailer tow would've come w/a 3.91 (also posi would've been required option) so you never know what you might find under a MT car. I assume there was also some similar provision in '71-up. In my case, I suspect someone knew what they were ordering (hence the G1 just to be sure) to get the 3.64 (stripper car w/gauges/tach) but imagine the customer's surprise when their 2BBl Skylark w/3.91's that they weren't expecting won't go over 55 mph. The hot ticket/insurance beater in '70 would've been the HC engine option and trailer tow in a post sedan w/3 on the tree. Probably could've done a SCO & gotten a 4-sp. & gauges/tach.

 

Wow Dano,
thats alot of info to take in!! I still need to re read it a few more times

 

From my perspective, they serve different functions. The cone type (Auburn style) is light duty, drives great, works well for snow, traction issues and an OCCASIONAL burnout. The clutch type (Eaton style) is heavy duty, will occasionally bind and chatter around corners, is less pleasant to drive with every day but will last through 4-5 seasons of hard racing before it needs to be serviced. I've burned out Auburns in two seasons, and wont use them for the way I use my cars..

 

Both My 70 stage 1 is all origanal rear end is OO one is cone type the other has clutch like the 70 455 rear end

 

Did the gs 455 have cone ? I hear someone was rebuilding cones some place