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what years had 8.5 rears?

Old 10-13-2018, 11:13 AM
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bigfish_Oh
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Default what years had 8.5 rears?

externally can i tell what i have in my 1976, or do all from a certain year up have 8.5 rears? I want to order gears before taking anything apart, In don't see any tag other than use posi additive tag.
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Old 10-13-2018, 01:52 PM
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C3 Stroker
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1963-1979 had the same rear ends (Eatons). 1980 and up had Danas I believe.
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Old 10-13-2018, 04:10 PM
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but, where they 8.2 or 8.5?
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Old 10-13-2018, 04:25 PM
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They are Corvette specific, other gears won't fit. I've never heard the size listed, but there's lots I don't know!
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Old 10-13-2018, 05:32 PM
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Originally Posted by bigfish_Oh View Post
but, where they 8.2 or 8.5?
The gears are Corvette specific, 8.2 The 8.5's are for other GM vehicles.

Last edited by C3 Stroker; 10-13-2018 at 05:33 PM.
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Old 10-13-2018, 08:56 PM
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Strange list this
GM 8.4 Corvette 4.11 Gear – Thick US/Strange Gear

Part Number: RS01884411CXApplication
1963-1979 8.4 Corvette
Special design for 3.90 & numerically lower carrierStandard Gears are the perfect choice for replacement of OEM gear sets
Providing long service life in Street, Street / Track, & Oval track vehiclesThese gears can also be used in some Drag Race cars depending on weight & power
If tooth breakage occurs, a larger rear end will become necessaryMachined From 8620 Forged Steel
Heat Treated to Maximize Gear Life
Matched Ring & Pinion SetRing Gear
– 8.32″ OD
– Tooth count 37
– 10 bolt holes
– 3/8″-24 RH threadsPinion
– 30 spline shaft
– Tooth count 9 When I called them, he said I had to know if it was 8.2 or 8.5
can anyone confirm this is correct part to order?
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Old 10-13-2018, 09:25 PM
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Originally Posted by bigfish_Oh View Post

Strange list this
GM 8.4 Corvette 4.11 Gear Thick US/Strange Gear

Part Number: RS01884411CXApplication
1963-1979 8.4 Corvette
Special design for 3.90 & numerically lower carrierStandard Gears are the perfect choice for replacement of OEM gear sets
Providing long service life in Street, Street / Track, & Oval track vehiclesThese gears can also be used in some Drag Race cars depending on weight & power
If tooth breakage occurs, a larger rear end will become necessaryMachined From 8620 Forged Steel
Heat Treated to Maximize Gear Life
Matched Ring & Pinion SetRing Gear
8.32″ OD
Tooth count 37
10 bolt holes
3/8″-24 RH threadsPinion
30 spline shaft
Tooth count 9 When I called them, he said I had to know if it was 8.2 or 8.5
can anyone confirm this is correct part to order?
If you have a stock 3 series gear ratio, then that is the gear for you. It is thick and made to fit in the carrier. That is the very gear I have in my '69. There is only one rear end for the 63-79 Corvette. That is the 8.2 Corvette specific rear. Period. There is no 8.5, or any other. Why "he" is asking that question is beyond me. It is made by U.S. Strange, and sold also by Zip Corvette where I bought mine from. Here...https://www.zip-corvette.com/63-79-4...s-carrier.html
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Old 10-13-2018, 09:30 PM
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If you are using the stock 3 series carrier you want the thick gears. I would check the gear ratio you have now before
ordering just to be safe. Most automatic cars came with 3.08 ring and pinion gears and I do not believe they offered a 4:11
from the factory in 1976.
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Old 10-14-2018, 09:11 AM
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I have a 3.70 or 3.73 which ever was offered for the vette.

thanks for the clarity.
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Old 10-14-2018, 11:28 AM
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3:70 was the stock ratio, 3:73 was/is offered by Tom's. There are more teeth on the gears that is the difference. You can still buy new 3:70 gears but they are all imported. Tom's are still USA made and there is no difference in driving feel or speedo gearing.

As mentioned the vette gears are specific to corvette.

If you are new to corvettes and have an original 76 diff you have questions on then you should know some things
1- the stock axles are soft faced and should be replaced
2- clutches are what I refer to as SnowFlake type and are weak. Solid Steels should be installed, forget about fiber coated clutches.
3- Some 76's got the flange head ring gear bolts, which backed out many times Check your LH housing wall for gouging to know if this happened. Use ARP RG bolts over the weaker kit RG bolts a rebuilder uses to save time and increase profit. The $35 or so for the ARP's is worth it.
4 - GM gears have the date and tooth count( ratio) stamped on the side of the ring gear so you know what is in there.
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