I'm getting this to put in my 89 to replace drums

question is this has 2.77 gears and would like 3.73's
I can't seem to find gears for a gm 9in

what do I need to look for and how many splines is this
I have not seen it yet.

as always your help is appreciated

I gotta tell ya and any newbie's...this forum is just fricken
awesome

 

I assume you mean 9 bolt, which would have 3.70's (series three carrier). 28 spline axles. You'll need a disc combination valve (if your 89 is equipped with the 1st design valve, one from a 85-88 should work) and perhaps drive and/or driven gears to make the speedo read correctly.

https://www.thirdgen.org/forums/faq-...now-about.html

JamesC

 

well the listing said 9in with 2.77..I have bought many parts from this guy in the past....

but I have not heard of a 2.77 gearing.....I'm asking for pic's though

 

A 9-bolt can be equipped with 2.77's, but not 3.73's (3.70's instead). A 9-inch and a 9-bolt are two different dogs altogether.

JamesC

 

the 9 bolt is a borg is it not

 

"A 9-inch and a 9-bolt are two different dogs altogether."

You said it brother... but the two sure get confused a lot on here... or ppl know what they mean they just dont say it

 

Yes.

JamesC

 

okay ...one more thought

all I really need is the disc set-up, would I be able to just swap those over to my axle which is a 10 bolt with drums as stated?

 

Yes. But if the calipers are the old style iron Delco-Moraines, you might consider an upgrade at this point and go with, say, PBR's. The following link, toward the end, should answer most of your questions:

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

JamesC

 

Ummmmm....If you are saying the 9-bolt disc setups can just be swapped over to a 10-bolt, I'm 99% sure you are incorrect.

If you know otherwise, please share. My Delco Moraine calipers function perfectly, but I would like to put LS1 rotors & calipers on, since I still have the smaller pre-89 discs under my 17" wheels.

 

All Delco-Moraine set-ups are the same, regardless of rear end. All PBR set-ups are the same, regardless of rear end. All that differentiates the two braking systems is the backing plates, which have a different bolt pattern. For example, I installed parts from an 89 9-bolt with PBR's on my 85 10-bolt, using 10-bolt backing plates. Here's a link to the install:

https://www.thirdgen.org/forums/faq-...iscs-89-a.html

JamesC

 

James...thanks for the link btw all good info

I read about grinding the flange to bolt the disc onto the existing axle about 10mm

is there any pic's that show where to grind at...or will it be pretty obvious

copied from the link

"Just reconiced that axle flange diameter at 28 splines axle is bigger than 26 splines axle.Both were GM axles.26 spline axle flange dia. is 147mm and 28 splines axle dia is 156mm.
So if you have old delco moraine disc rear brakes,you must grind down some millimeters from flange that you can put disc rotors to axle.Ask how I noticed that...

 

The problem lies with drum vs. disc axles (and not splines). Apparently the rotors will fit some drum axles and not others, in which case the flange needs to be turned down.

Since the axles will need to be removed--and providing they're good--I'd take them to a machinist if fitment is a problem (Count the splines). If bad, perhaps new Moser disc axles, along with new bearings/seals would be an option.

https://www.thirdgen.org/forums/tran...ing-axles.html

JamesC