I have a 90 formula with a horrible grinding noise from the rear axle. I lifted it up today and checked out the yoke and it seemed pretty tight. However I can take the rear tires and move them in and out towards the pumpkin. Is that normal or is there something that should be tightened or maybe just replaced with another axle.

 

the axles will move in and out a little.

you should jack up the car and pop off the diff cover, see what going on. maybe you blew it up, or it leaked out all the oil, and its about to blow up

 

Thanks I will check it out this weekend.

 

Which differential do you have? If it's an Auburn then the axle end play will increase as the Auburn wears. Replacing it is the only way to reduce the axle end play. If you have a standard differential and you have been doing a lot of one wheel burnouts then you might have worn the differential case and thrust washers, which will cause increased axle end play.

The noise could be from a bad bearing.

 

It is a standard 2:73 axle..and that sounds like it might be it. I bought the car from a kid that must have beat the sh*% out of it. Well the price was right so I guess I can now shop for an axle with 3:73's.

 

There is 2 89 Firebirds V6 at my local pick n pull. They should have 3:42 ratio in them. Is that something I can just swap into my car? Thanks

 

Yes, but there are some other considerations:

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

JamesC

 

What do you mean about other considerations? Camaros and Firebirds are very hard to find in MD that are not already picked apart of the good stuff. I think the 3:42 V6 rear end for $69 is a steal.

Edit: This car is just a stock Formula that is used for commuting to work and not beat on or run hard.

 

buy it !!!!!!

you cant go wrong for that money

just swapped one into my friends v8 car. (had a 2:73)

big improvement,grab the speedo gear too.

 

Where is the speedo gear located? I have never done an axle swap on a third gen so I have no idea! The pick n pull near me charges $69 for ANY axle you can find, but the 89 IROC Posi is gone lol.

 

drivers side rear at the tail of the trans.

you will see the cable or plug (depending on the year) at the tail of the trans.should be one 10mm with a hold down pull that out and grab the gear,it will slide off the speed sensor.

a good cordless sawzall should be all you need to get the rear out of the car at the yard

 

Thanks hopefully I will have this done next weekend.

 

As the link I provide mentions, you may have problems with the drive and/or driven gears depending on what ratio your current rear end is (and there may or may not be a VSS, again depending on year); there is also the possibility of combination valve and parking brake issues. Good luck.

JamesC

 

Thanks james.. I read that page a few days ago and I am hoping that everything will be the same on the axle since it is an 89 and my car is a 90. I will grab the drive gear in the tranny to go with it.

 

Going to the yard in the morning to grab an axle.. Ill let you know what I get.

 

Picked up some injectors for my jeep and got a 3:42 rear for the firebird out of a 91. Direct bolt in and I grabbed the speedo gear to.

 

Ok so I have a 90 and I got a 91 rear... rear end went in no problem and pulls great. I grabbed the speedo gear out of the same car and it looks the same as mine but a diff. color. Well now my speedo reads about 12 mph faster than I am going.. Any suggestions?

 

If you went from 2.xx's to 3.42's you need to swap both drive and driven gears. Check the stickies above.

JamesC

 

I changed the gear on the tail or my trans. 700R4 Where would the other one be?

 

Remove the driven gear from the tail shaft and take a peek in the hole. You'll see it.

JamesC