Good afternoon,
I've got a few quick questions I was hoping you guys could answer for me. I'm swapping my 2.73 open drum axle for a 3.42 posi disc axle from a 1983 Trans Am Pacecar. What things will I need to make the car function as it did before? I'm making sure to grab the proportioning valve and the ebrake cable and mechanisim but do I need anything else?

Also, what gear will I need to get for my trans so that my speedometer gives me the correct speed?

My car is a 1989 Firebird Formula with a 700R4 and 2.73's..

Thanks for the help!

Derek

 

The 83's combination valve will be the old-style cast iron version with SAE fittings and line connections that are different from your 89. If your 89 is an early production run, you should be able to use a newer alum style metric combination valve, about 85 through 88. If your 89 is a late production run, the 85-88 won't fit either as the tube nut sizes are different. In that case, your best bet might be an after market adjustable.

Check the sticky at the top of the page for speedo gear info.

JamesC

 

Thanks for the info James!
I think my 89 is an early production car, the sticker says it was actually made in 88. According to the sticky I need 15:40 speedo gear (drive:driven) for my 3.42's, does that sound right?

Derek

 

Well now the bigger question is where can I get these gears? I found the drive gear on ebay with no problem but can't seem to find the correct type of driven gear for my bird which of course has the electronic speedo. Where did you guys get your gears?

 

Also, is this the correct part number for the 40 tooth driven gear I need? #25513047

 

i bought mine at the chevy dealer about five years ago.no idea if they still have them.

 

Thanks, I'll call them in a few minutes here. Can anyone tell me the GM part number for the proportioning valve I need?

 

One last question. The e-brake stuff from the donor rear end is rusty and nasty. Will my ebrake cables work or will I need to buy new ones?

 

New. The drum cables won't fit the disc system.

JamesC

 

Thanks James.
I went to buy the rubber lines for both calipers and the center line as well. Guy at the parts counter tried telling me that my 89 doesn't have one, that's its got a two metal lines instead. What a moron. The 83 has the center line and I just checked, sure as doo so does my 89, also with the brake tee. If I order a center line for a drum equipped car will it fit the tee for my 83's rear end? I was planning on keeping all of the 83's hardware except for the e brake cables. Also, does anybody know where I can get the 40 tooth (part # 25513047) driven gear for cheaper than 40 bucks shipped?
Those are my last questions, thanks for your help James!

Derek