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Author Topic:   rear-end dilemma
doubletrouble
Dirt Full Roller

Total posts: 37
posted January 11, 2003 02:08 PM
We have a 79 pontiac grand prix with a 10 bolt 7.5 rearend.The gear is a high one like 2.80 something.I was planning to leave it all stock except put in a mini spool.When placing a order from our local distrubtor who is also the owner of the new track being built and a so called racing legend,he told me I need to find out the manufacorer of the rear end because there was diffrent thickness on the gears.He did suggest replacing gears also which I could agree.Reading the post here on the forum it's my understanding a metric 10 bolt 7.5 is all the same.I just counted and recounted the splines on the axle and come up with a 26(??)spine.I thought there were only 28 or 31 splines.Can someone out there help me understand(in dummy terms) what is really going on here!

doubletrouble
Dirt Full Roller

Total posts: 37
posted January 11, 2003 03:33 PM
More to add,which has really caused more confussion.The gears are 2.29 (21pinion&48 ring).Just got off the phone with the pontiac dealer he says the book shows 6 diffrent gears that came in this car...2.29,2.41,2.56,2.73,2.93,3.23. There were two diffrent manufactors 'corporation'&'eaton'.He had no record of the spline count on the axle yet the book shows all being the same.Is it possible I am miss counting the splines??I am still comming up with 26???

loojack
Dirt Maniac

Total posts: 133
posted January 11, 2003 03:46 PM
On the front right side(passenger side) of the axel, about 3 inches from the center section casting is a code stamped in to the tube. I think it'll have 2 letters a space another letter (this 3rd letter is the Mfg's code) and then two numbers. Give the dealer this code and he should be able to help you. There are two thicknesses of carriers, one for 3.08 down, called a series 2, and one for 3.23 and up a series 3 carrier. If you have a series 2 carrier, and want to put a 3.73 gear you need a spacer or a thicker ring gear set. I hope this helps and I explained this clearly. Good luck loojack..

racer17j
Dirt Forum Champ
Total posts: 1565
posted January 11, 2003 05:14 PM UIN: 54865418
here i'll save you $100 and alot of frusteration find the gear ratio you want on ebay for a 7.5 rear end like lo said they made two cariers so you will be better off finding one that comes complete or you can get new ones for what ever carrier you have from speedway or jegs or summit for like 150, then don't worry about the splines and a spool just weld your spider gears together. what gear are you looking for i have a 3.23 i want to get rid or will sell carrier and all for $100 plus shipping. or another way if you want a lower gear go to a junk yard and look for a s-10 or blazer or astro van they all have the same size rear ends and most have 3.42,3.73,4.10 gears in it i believe your right on the splines at 26 ford 9 inch are what come with 28 or 31 splines but realy like i said you don't need to know how many there thats kinda one of those fyi deals

[This message has been edited by racer17j (edited January 11, 2003).]

[This message has been edited by racer17j (edited January 11, 2003).]

rfb320
Dirt Full Roller

Total posts: 43
posted January 11, 2003 08:55 PM
I have an "81" grand prix with the 7.5 rear end in it and it has 26 splines on the axels.
mine also had a 2.29 gear in it and i needed the thick gear set.

racer17j
Dirt Forum Champ
Total posts: 1565
posted January 12, 2003 12:24 AM UIN: 54865418
3.08 is thre point that starts the different carriers any stock gear from 3.08-4.10 will use that carrier

loojack
Dirt Maniac

Total posts: 133
posted January 12, 2003 08:01 AM
Double, try e-bay, I picked up a set of 3.42 gears and carrier for $42.50 plus shipping. 3.73s tend to go a little higher. I figure a 3.42 with a powerglide in low will yeild about a 6.00 final drive. loojack..

------------------
Middle aged wannabe racer!

wrenchjockey
Dirt Full Roller

Total posts: 31
posted January 13, 2003 08:28 PM
I think the 28 or 31 spline you're referring to are common 9-inch Ford spline counts. Your 26 splines are correct for your GM 7.5 rearend.

66jj
Dirt Freak

Total posts: 352
posted January 14, 2003 03:11 PM
loojack

my understanding is most glides are 1.71 which would yield you a 5.84

another glide gear is 1.82 i or so which would put you at 6.22

thats both sides of the 600 you wanted!!

jeff

outlawstock17
Dirt Forum Champ
Total posts: 620
posted January 14, 2003 04:45 PM
actually, most powerglides have a 1.76 1st gear with a 3.42 rear gear would make a 6.02 final.

zoomy#74
Dirt Roller

Total posts: 19
posted January 24, 2003 06:53 PM
Double,

I have a complete metric rear end with 4.11 Richmond gears(new), mini spool(new), brake shoes and cylinders(new). The rest of the components are in excellent shape. The unit was pro-built, but has never been raced because I changed my mind and got a 9-inch ford setup. I'm looking for $225.00 or best offer. Good deal considering the gears are $180.00, mini spool $80.00, brakes $40.00, and the labor for assembly was $100.00. If interested e-mail me at lizard@chipshot.net

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