Joined: Sat Dec 10 2005, 04:28PM
Location: United States
Posts: 4954
You know? The Sure Grip Rear find brings up a question in my mind. I don't have that kind of info here.
What was the typical ratio of the 8 3/4. So far, all I've seen discussed here is 3.23. For that matter, what were the ratios available for the 8 1/4's?
This project I am working on is interesting with a slight miscalculation on my part. The D150 Donor for the engine and trans had a 3.51 Rear. The Polara, which is getting a 8 3/4 Sure Grip, is an 8 1/4 2.71. (Talking about cruisers. .Lock Up & over Drive Trans on a Magnum?)
Having not done any rear work in years, I never bothered to collect a catalog of the data. Can anyone post the ratios available from 68 to 73?
Unfortunately, us poor small block guys get blessed with 8 1/4. They're still heavy. . .
Joined: Mon Oct 10 2005, 01:49PM
Location: Grand Rapids, MI
Posts: 421
Man bringing back memories, used to hit every junkyard in southern Alberta looking for SG pigs.
In 8.75's, I've found 2.76, 2.94, 3.23, 3.55, 3.91. I've seen all those in factory cbods.
Prolly the most common were 3.23, usually BB cars. 318 polys seemed to come with 2.94's alot. Found a bunch of 3.55 geared ones behind /6's with one and only in 6-7 years of looking 3.91's in a 383 SC '68 Polara 500.
Bunch of other aftermarket ratios are available now tho
Other ratios available for the 8.25 include 2.45 (special carrier required), 3.21, 3.55, 3.92 (I think), and 4.10. Maybe even higher in the aftermarket. I've got a 3.21, 3.55, and 4.10 out in the garage. They're pretty good rears, all things considered.
Joined: Mon Oct 31 2005, 12:48PM
Location: Bakersfield, California
Posts: 1755
Stevo, that 3.51 sounds like a common number for light duty trucks. I had the same ratio in my RamCharger and in my Van, but they had two different rears.
On the 8 1/4, I've seen 2.2's on some M body cop cars (talk about dog gears!) 2.45's, 2.71, 3.21, 3.55, and 3.9. I had a Dart that I converted from 7 1/4 w/2.94's to 8 1/4 w/3.21. It certainly woke that slant 6 up!
How can you ID a 7.25 vs 8.25. I have a 70 slant 6 Dart w/small lug pattern and a 74 318 Dart w/the larger bolt pattern.The 74 is my parts car for the 70.Front and rear suspention will be swapped for the larger bolt pattern and the disc brakes.Are the ratio s stamped on the 3rd member as on the 8 3/4 ?