Hey everyone I am fairly new here and never played around with rear ends before so I have a few questions. Iv tried searching it but couldnt get a straight answer.

I have a 92 rs open rear drum.

I found a 373 posi disk brake rear from a 89 firebird with 88k on it all for $250. From what I understand they do fit in a 92 rs. But what I am not sure is would have to change anything with my transmission?

Also how hard is it actually to do with the disc setup, how much is involved?

Thanks in advance

-Joe

 

Swaps right in - you just need to get the brake line on the driver side connected to the axle at the T-block - given it's 89 - 92, it might not need anything exept doing it - worst case scenerio, you have to cut a brake like with a small pipe-cutter and flare on end with a flare tool - those might cost $20 for both tools.

 

Some folks swap in the proportioning valve at the master brake cyclinder for one from a car with rear disc, but others leave it alone and say it works fine. Overall, a simple 3 hour driveway swap.

Consider though - since you are dropping the rear axle for the swap, might as well make a day of it, and drop the gas tank and install a new fuel pump if it's never been done - it's time for one, your 1/2 way there anyway. New sway bar end links, sway bar bushings and shocks would complete the deal, and you'd have the rear all wrapped up!

 

First, if the rear is a disc brake rear from an 89 (11.7" rotors and alum PBR calipers), it should be a 9-bolt, and IIRC, 3.73's aren't a 9-bolt gear (I don't believe they wouldn't have been found in an 89). Double-check before you purchase. If the rotors are 10.5" and the calipers are iron, the rear end is 88-

You'll need to consider the speedo drive and/or driven gears, combination valve (the bias is different between drum and disc) and so on. Check the brake info in the following link:

https://www.thirdgen.org/forums/tran...-10-bolts.html

JamesC

 

Thanks for the info guys.
James C i def will check on the year before I buy it, the guy prob just made a mistake.
Some people have told me that since the gears are diff then mine it will mess things up with my tranny, is this true? or will everything work out fine without me touching it?

Joe

 

itll mess up your spedometer but not the tranny persay, you can swap the gear in the tranny so it will output the right speed but it wont actully hurt the tranny

 

Well my speedometer isnt working right now anyway so im all good then

 

Depending on the gear ratio of the new rear vs. your current ratio, you may have to swap only the drive gear, but it's possible you'll have to swap both the drive and driven gears in the trans. If the speedo isn't functioning and everything is in place as it should be, your problem probably goes beyond the gears themselves.

JamesC

 

Where would you be able to pick up speeds gears then after a swap such as that? And not to steal a post but if I were to put a 1le rear from a 89 into my 88 trans, with the appropriate combination valve, I would just pick up a parking break cable for a 89 trans correct?

 

Your 88 has an electronic speedo with the VSS on the tail shaft of the trans. Finding gears might prove somewhat difficult. If you can't savage them from the donor car, try the following company who may be able to help or direct:

http://www.transmissioncenter.net/sp...n_______va.htm

You'll need the 1st design 1LE valve.

Correct. You'll need the 1st design parking brake, 1434 mm.

JamesC

 

Sometimes the governor needs to be recalibrated when changing rear end gears. This isn't a big deal. Most of the time it's not improtant. You might notice that the transmission changes gears too soon or too late. If this happens you might want to recalibrate it.

 

So how will I know if I need to swap the gears?

-Joe

 

Hey, big gear,

I've never heard of this issue before.

JamesC

 

Check the stickies at the top of the page for more info.

JamesC

 

The governor runs off of the main shaft in the transmission. When you change the gear ratio in the rear end the shaft speed changes for whatever MPH you are running. Sometimes changing the gear in the rear end will cause the transmission to change gears at the wrong time. It's usually not a problem, but sometimes a huge change in the gear ratio will cause the transmission to shift too soon or too late. It's usually only noticable at WOT.