Hi, I have a 10 bolt rear end in my car, is there any way of knowing the size and how many splines without opening it up? I've been looking online, because I want to put a posi and change the ratio, but I don't know if it is 8.5", or 32 spline or what.
There is a code on the passenger side axle tube extending from the main differential center unit over to the brakes. The code will be stamped on the front of the tube, a few inches away from the main diff unit. If you get me the code I'll see what I can figure out. Usually the easiest way to get the code is to take a wire brush to that area, and rub chalk into the stamping to get the digits.
If you don't have the codes on hand to identify if a 10 bolt rear end is an 8.5" or not, you can measure the distance between the very bottom bolt for the cover and the next adjacent bolt (either right of left), it will be 3-3/4" for a 8.5" and 3-1/4" for a 7.5". Note: Some installation kits for the 8.5" and 7.5" use ring gear bolts with a 5/8" head, so if someone has rebuilt the rearend with one of these kits the bolts will have smaller heads than the original bolts.
Another tip is to check the size of the pinion nut. The 8.2" uses a 1-1/8 inch socket on the nut and the 7.5" and 8.5" use a 1-1/4 inch socket. That is as long as they have a OEM type nut on them.
There are usually two distinctive lugs cast into the bottom of the 10 bolt rear end housing. These lugs are arrowed in the image above.
The ring gear of the corporate 10 bolt is secured by 7/16-20 left hand thread bolts having a 3/4" hex head on them; there will be ten bolts holding the ring gear to the differential. The ring gear is (as mentioned) 8.5" diameter and the pinion shaft diameter is the same as the 12 bolt at 1.625". The 8.5" pinion has 30 splines.
The 8.2" diff will have 10 bolts holding the ring gear on the diff, the bolts will have a 9/16" hex head and be right hand threaded. The 8.2" uses ten 3/8-24 right hand thread bolts to hold the ring gear on the diff. The pinion diameter is 1.438", having 25 splines.
Hi, I have a 10 bolt rear end in my car, is there any way of knowing the size and how many splines without opening it up? I've been looking online, because I want to put a posi and change the ratio, but I don't know if it is 8.5", or 32 spline or what.
Thanks
If it's the original it would be an 8.2".
Does it have the protruding upside down "V" on the outside of the cover?
Thanks for all the responses. I can't look closely right now because my Pontiac is up on a lift, with my truck under. I am changing the coolant on my truck. When I am finished I will have a closer look, but the cover definately has the upside down V. on the cover.
whats the difference between a standard and positraction axle?
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cutting a roof off a four door is NOT a convertible.....
65 Parisienne convertible.one of 49 built for RHD export market,402BBC, T400, 2500 stally, posi rear, upgraded brakes with front discs, FUEL FAST efi custom built by me.
Thanks, nice licorice whip!! Sorry, may not have been clear there....I know that difference! Just put a posi centre in mine....I thought it referred to the axles as being different in some way....odd thought ai know...
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cutting a roof off a four door is NOT a convertible.....
65 Parisienne convertible.one of 49 built for RHD export market,402BBC, T400, 2500 stally, posi rear, upgraded brakes with front discs, FUEL FAST efi custom built by me.
Fortunately, they're not like flies here, I lole all available grunt to get to the road, we also have drag strips...had to reco my diff and found a good posi. very hard to come by here in Oz so has good poser value too....
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cutting a roof off a four door is NOT a convertible.....
65 Parisienne convertible.one of 49 built for RHD export market,402BBC, T400, 2500 stally, posi rear, upgraded brakes with front discs, FUEL FAST efi custom built by me.
Removed the cover on my diff, 15 41 so I have the factory ratio of 2:73. I want to lower the ratio and put a tranny with overdrive. Thinking of 3:73 with either a 700R4 or 4L60E, Would love to put a 5 or 6 spd manual, but putting another AT would be easier, but probably more $$, especially for the 4L60E.
I might do the gearing this winter, and maybe a posi unit, and tranny winter.
I'm not sure why they say the bottom. Vince, haven't you found that most of them you can stare at the tube with the car on a hoist and the code is almost staring right back at you?
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars
I'm not sure why they say the bottom. Vince, haven't you found that most of them you can stare at the tube with the car on a hoist and the code is almost staring right back at you?
I should have said disregard the location too.... Yea... Always on the front side facing the front of the car....
-- Edited by 67Poncho on Tuesday 13th of January 2015 11:41:54 AM
Try going a little higher, the numbers on my 69 housing are towards the top. You've certainly cleaned a large area, I've always just been able to used a wire brush to clear away the surface rust.
