2.93 posi in a 8.2 diff?

Who knows if a 2.93 posi comes in a 1970 GS 455 Base engine with 8.2 difirential.

I bought a 70 Buick GS 455 that started life as a Base, 350 Hp car.
The build sheet says the diff is a 2.93, ID'ed as the letter K stamped on the axle.

However, I've been told on a base car, the diff is a open unit.

The build sheet does not state if it's an open or posi unit.

While I had the car in the shop, I had the diff pulled and sent out for rebuild. The diff mechanic called me and say the diff was in excellent condition and is a posi.

I thought it was a cone unit, but it turns out to be a clutch unit.

My GS is a early build, December 1969, out of KC.

Anybody heard of a factory installed 2.93 posi differential in. Base GS 455???

 

I wouldn't go by build sheet. Could be anything in there now....
Stock GS455 in 70 was 2.93 with cone posi.

 

I had JD Race check out the differential casting numbers and he said, it's original to my car.

 

I agree, I also thought the cone diff was standard for the base 455.

 

I could not find that LW code anywhere. I could only find the K letter stamped into the axle tube that was done in the KC plant (Leeds). Plus the diff casting numbers UD the diff as a 2.93 diff by JD Race.

I wonder if I will ever know if this differential came with my Buick GS 455?

 

Monzaz (JD Race) knows his stuff. But just because the case is correct casting number doesn't mean the internals are. or the rear for that matter, original to the that car. If it works well - be happy!

 

Correction, ID the diff by JFRace as a 2.93 posi.

 

It works well now. You'll love this story.
When I received the car, I did a couple of burn outs but noticed quickly, only the passenger rear tire burned rubber. I had the shop check to see if the diff was an open model. The shop said it was a posi but couldn't explain why only one tire would burn rubber.
Thinking the clutched were worn, I had the diff removed and sent out to one of our forum members. He inspected the diff and said it was one of the tightest diffs he's ever seen plus it's a clutch model and not a cone model he was expecting.

So he shipped it back to my shop. Now you'll love this part.
Shop installs the diff, adds the friction modifier and diff oil.

I test drive the car and all of a sudden both tires are now burning rubber.
My conclusion is, someone forgot to add in the friction modifier.
My next conclusion is, this posi with clutch discs is most likely not what came in this car.
It might be right for say a 70 Stage 1 car, but not my Base 455.
I just happy the posi works again.
Does seem strange to find a posi in a 2.93 highway diff!

 

Hi, I am a little confused here. I always thought a stock 1970 GS455 got an open 2.93 rear end and posi was an add on option?

 

I agree, everything I have read says a stock/base Buick 455 comes with a open diff & a 2.93.

I have to assume someone added a posi.
That said, the classic dealership advertised my car having a 3.42 diff.
I found that ad from two different classic car dealerships.
In 2015 and the other dealership when I bought the Buick in 2021.
It appears, the dealership when I bought the Buick just copied the dealership and of 2015.

No one bothered to check the diff gearing.

 

I had an original 1970 GS455 with factory 2.93 8.2 rear end purchased from the original owner. I also have the original window sticker for it and it shows the G80 posi was a $42.13 option. So, the 2.93 standard rear was non-posi unless posi option was ordered.

 

Vet, I thought we had this discussion awhile back when you contacted about the cars history.Any how the car had an open 2:93 in it.That was pulled and in it place was installed a 2:93 factory limited slip.Hope this helps.Joe

 

Hi Joe, great to hear from you.
We did have a discussion.
However, I don't remember you telling me you installed a limited slip diff. You restored this car a long time ago and you do a huge amount of restorations, I thought you couldn't remember exactly what was done. I know when I had problems with only having one tire burn outs, you told me it did both tire burn outs when you finished the car build. You told me maybe the clutch discs were worn, so I had it removed and inspected, only to find it is in great condition.
Thank you for clearing this up for me. This is one of the last questions/mysteries that I had on this car. I have put together a book on this car. I appreciate you sending the history on my car. Just so you know, my car has been in the shop for over 33 months now and just got finished with a new Griffin radiator to cure the high water temperatures I was having. VET

 

Correction, over 22 months.

 

Joe, just so you know, the previous owner of my Buick changed out the pistions that John installed and put in Kenne Belle high compression pistons.

This really screwed up the engine, caused detonations to occured at all rpm's. I found out he was using race gas and octane booster to calm down this problem.
I assume, because of this issue and he didn't want to spend more money to fix this issue, he put the car up on consignment for sale.
I could not get him to call and talk to me.
I'am not going to tell you how much money it took to get this Buick up and running a gain, but it turned out to be a lot more than I expected.
Let me put it this way, I should have taken you up on your offer to build me a Stage 2 car.
That will get you close to what I have onto this Buick GS. VET

 

Correction Stage 1 car.

 

If compression too high would have been good candidate for aluminum heads.

 

I agree.
That said, my pockets are only do deep.
It was cost effective to install an MSD ignition system with an adjustable vacuum advance canister. Tuned the engine total advance tweaked the carb and all seems to have done a great job. That also includes a aluminum radiator, TA Performance high volume water pump, fan clutch and Evan coolant.
Dedonation is gone, high water temperature is gone. I'am ready to rock and roll now.
And a lot happier now.