I have a relatively simple question for the experts.

I ahve an 86 TA with disc brakes all around. What kind of rear end do I have stock? Tomorrow its coming off and I'm hoping its a 10-bolt posi with 3.42 or something close? Was that an option in 86?

Thanks for the help.

-Max

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86 Trans Am LB9/700R4
-Flowmaster 3inch exhaust, K&N, Ported Plenum, Redone Ignition system

 

I'm just going to take a stab in the dark and say its a Borg Warner 9 bolt with 2.7? gears or so... maybe 3.27's or 3.45's, but probably 2.7?'s...

Check your RPO sheet if you have one, it'll tell you.

 

I'd guess 9-bolt with either 2.77 or 3.08 gears.

 

Can you count to 10? First off get underneath and count the number of bolts in the cover 9 or 10? Common rear end ratios: 10-bolt auto; 2.73 or 3.23. 10-bolt 5 speed; 3.08 or 3.42. 9-bolt auto; 2.77 or 3.27. 9-bolt 5-speed; 3.45. With one wheel jacked up and the car in neutral, count the number of revolutions of the driveshaft relative to one revolution of the wheel. Match it up with the ratios common to either a 9 or 10 bolt. Good luck, Lon.

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90 RS Convertible
Owner: Top-Down Solutions
http://www.sc3gfb.org/members/lonsal.html
http://www.taskerinc.com/gs3/profiles/Lon_profile.htm

 

My answer will be 2:73, possi and be a ten
bolt. Borg-Warner 9 bolts not used in 1986.

 

Since I don't have a jack at the moment (left it in my friends car) I will find out the answer tomorrow, the whole rear is getting taken out so I'm going to take a look at the rear while I'm at it.

 

9 bolts were definitely used in the 86's. My T/A has one and another guy on the board has a 9 bolt in his 86 T/A. mine has the 3.27's and his has the 2.77's-both cars have 4 wheel discs.

 

"Borg-Warner 9 bolts not used in 1986."

Uh... wrong. 1985 was the first year for the 9 bolt in the Firebird, 1987 was the first year for the 9 bolt in the Camaro.

 

Well I guess that this site and others will have to up date there tech data on when the Borg-Warner 9 bolt was available. I also
find it interesting that no 2:77 & 3:27 ratios were offered in 85 & 86. You may have
them but not from the factory. Quote from the tech data from this site.

 

Don't believe everything you read in the tech data. The charts are chock full of errors. The history info is much more accurate but not 100%. I wrote almost all of the Firebird history, and added quite a bit to the Camaro history, but there are typos and a few wrong years, etc.

 

Both my friends have 86 TA's, both have 9 bolts, one has 2.77s, and the other 3.27s. Don't believe everything you read.