[OVERULD]

Now I'm afraid to buy a set of 3.08s from Randy's R&P to put in the Firebird to replace the 3.73 R&P. Anyone have a set of original GM 3.08 R&P they want to sell?

BJ

[unruhjonny]

don't be afraid...

it's more a matter of, if you can find original stuff in good useable shape, there's no compelling reason to go new

[77 Canamman]

Randy's is a reputable company, and is your best choice for a new R&P.

[SD455DJ]

BJ, I had a new 3.08 R&P installed in an A-body 12-bolt a few years ago and have no noise issues at all. Randy's is a good shop and as 77 Canamman mentioned, they know what they are doing.

Dennis

[OVERULD]

I've been told that going from a 3.73 ring and pinion to a 3.08 will require a change in the carrier as well. Steve, are you having to do that on yours? I want to keep the posi in mine, and was hoping all I would need to do is change the R&P. I've been quoted $1,350 by a local shop with a longtime excellent reputation for new R&P, posi carrier, bearings and labor. They say they can do the work with the car on a lift without removing the axle.

BJ

[njsteve]

3.42 to 3.08 uses the same carrier. Don't know about taller gears but sometimes they need a spacer between the ring gear and the carrier on 4.10s and taller. The race shop swapping my gears quoted me $250 for the swap and changing all bearings etc. I supplied the parts and the rear of course.

If you have the original transverse muffler they will have to drop the exhaust and maybe even the gas tank too if they are doing it in the car.

[OVERULD]

Thanks Steve.

[unruhjonny]

i believe that the carrier is classified as a "three sereies" which is to suggest that it's for 3.xx:1 gear sets;
I also believe that with factory gears, the three series was for 2.73 through 3.90 gears.
I believe I have seen four series gear sets made for three series differentials too...

So I'm inclined to call BS on needing to swap differentials when going from 3.73 to 3.08.

[OVERULD]

Originally Posted by unruhjonny

So I'm inclined to call BS on needing to swap differentials when going from 3.73 to 3.08.

Makes sense to me. I had a pal say essentially the same thing.

Sorry for the rabbit chase Steve....now back to your thread!

Thanks,
BJ

[74 SD455 Formula]

Originally Posted by OVERULD

Makes sense to me. I had a pal say essentially the same thing.

Sorry for the rabbit chase Steve....now back to your thread!

Thanks,
BJ

BJ,
Did you check the Dif. to see what the code is. I dont think Tom purcased a new rear end,he just added the Posi carrier and gears to the original one. I had the original 308's,but got rid of them. Little did I know someone would need them.

[njsteve]

I stopped in at the chassis shop today and they already had the rear all finished. That was quick - dropped it off Monday, picked it up Wednesday.

Ended up costing $250 to set up the gears and an additional $100 to replace the axle bearings. He found that the small retainer bolt that holds the center pin into the carrier, was sheared off. The portion of the bolt head with threads was holding the remaining portion of the retaining pin in place. He said the broken piece came out with a thin magnetic probe. He indicated that this was a common problem he has encountered over the years. Whew!

The rear is back home now in the garage. That gives me something to start cleaning and painting now.

[yahooskidoo]

No issues with the gears then?

[njsteve]

Other than his initial grumbling about reusing old gears, the chassis guy said they set up without a problem. I am now waiting for my new springs to arrive to get the car back on the road. I'll try to package up the gears for you and get them out this weekend.

[njsteve]

Getting ready to paint and reassemble the rear. I had the chassis guy who set up the rear, sandblast the backing plates and rear cover. Looks like the tubes and backing plates were originally painted black but the center section was natural cast. There is a remnant of the orange "E" on the top. Not much on the bottom. There are orange paint daubs on the bearing caps, where the tubes join the center section and underneath the mating surface of the spring perches.

[njsteve]

The new leaf springs arrived today. Dayton Spring 80-335 was on back order all over the country (this is the 1970-81 Trans Am specific leaf spring with 4 leaves). I was able to order them through Stengel Brothers Spring in Pennsylvania. They had them on sale for $104 per side. Rock Auto just got some in and they show $145.79 each plus shipping. I was able to pick up my springs directly at Stengel Brothers and save the shipping costs. I bought this same set five years ago for my 1972 black Formula and the car sat nicely with them.

http://www.stengelbros.net/80-335-Po...y-_p_2927.html

Now I can replace the old, worn out 5-leaf set up in the car that had too tall of a stack for the perches on the 1980 T/A rear. The lower shock mounting plate got all bent out of shape from being tightened around the 5 leaves. Luckily I was able to use my hydraulic press and get them flat again.

[Formulabruce]

Originally Posted by njsteve

The new leaf springs arrived today. Dayton Spring 80-335 was on back order all over the country (this is the 1970-81 Trans Am specific leaf spring with 4 leaves). I was able to order them through Stengel Brothers Spring in Pennsylvania. They had them on sale for $104 per side. Rock Auto just got some in and they show $145.79 each plus shipping. I was able to pick up my springs directly at Stengel Brothers and save the shipping costs. I bought this same set five years ago for my 1972 black Formula and the car sat nicely with them.

http://www.stengelbros.net/80-335-Po...y-_p_2927.html

Now I can replace the old, worn out 5-leaf set up in the car that had too tall of a stack for the perches on the 1980 T/A rear. The lower shock mounting plate got all bent out of shape from being tightened around the 5 leaves. Luckily I was able to use my hydraulic press and get them flat again.

Whats the rate on those springs? 126?
Why did that 1980 rear have 5 leafs in it?
I have seen that plate bent many times due to the generic 5 leafs stuffed in and Impact gun bends a 'U" in the plate. aftermarket rubbers can cause that same u as well. I always end up grinding them to get the right fit. Thanks, Bruce

[njsteve]

The original 5 leaf, springs were from the 1975, 2.56 rear that the car came with originally. The 1980 rear came from an 80 T/A. I was thinking that the spring perches were taller on the 2.56 rear to accommodate the taller spring pack?

[njsteve]

Yes the new springs are 126 lb rated with a much lower arch than the five leaf setup.

[Formulabruce]

Originally Posted by njsteve

The original 5 leaf, springs were from the 1975, 2.56 rear that the car came with originally. The 1980 rear came from an 80 T/A. I was thinking that the spring perches were taller on the 2.56 rear to accommodate the taller spring pack?

I have never seen a 75 bird with 5 leafs, BUT ALL the Camaros except the Z had 5 leafs. thats the big difference between the rears, as you said taller perches.
I have a 1980 WS-6 rear in one of my cars, and its a 4 leaf perch. Just checked a '79 I have, 4 leaf.
2.56 with 5 leafs in '75. I would have never guessed Interesting!

[njsteve]

Remember it was a 350 Esprit with base suspension, not a Formula.