Rear end Gear Ratios

[340_6pak]

Mancini has some deals on 3:23s for 489 rear
http://chucker54.stores.yahoo.net/choem8489car.html

Thanks Bullitt - I will put these on my Christmas list. Now I just need to figure out how to install them without screwing anything up!

[tommyg29]

the tire size calculator is generic, and isnt accurate for every tire. There are too many variables, including tread depth and wear, etc. but I agree I must have a VERY high gear!

[Bullitt-]

Thanks Bullitt - I will put these on my Christmas list. Now I just need to figure out how to install them without screwing anything up!

Notice they are on clearance, when their gone  ...Hope Christmas is early this year.

[73Chally]

the tire size calculator is generic, and isnt accurate for every tire. There are too many variables, including tread depth and wear, etc. but I agree I must have a VERY high gear!

Not sure on the generic thing but it was dead on for mine.  It was close enough that I couldn't tell any difference on the gauge vs. the calculation.

[MEK-Dangerfield]

wow...seems to me then that I dont have the dana 3.54 I was told I had. I just took a 130 mile road trip and at 70mph was running about 4200 rpm.
Have 275-60-15 radial TAs in back, so I must have something over 4.00.
And my tires are about 26-3/4" tall. Probably 27 or a little more at speed

I'm curious if you are using the stock Rally gauge tach, or an afer-market tach?  It seems as the Rally gauge tach gets older, it reads way too high. Another member had this problem and I sent him my after-market tach that totally agrees with my rebuilt Rally tach. I'm willing to do the same offer for you, and I will provide instructions too.


  Mike

[tommyg29]

rally gauges and they were refaced and I think "rebuilt" about 7 years ago. Honestly, it sure sounded like it was running that high, and I know the dana 60 was originally from a b-body, and it had to be shortened, so it could be one of the 4.xx gears. I cant see any numbers on the right axle...maybe because of the customizing?
As for the tire size calculator, I'm assuming it is calculating that the sidewalls are 60% of the 275mm, which would be 165mm, times 2, plus 15" for the wheel...thats 27.99"....which is exactly what their calculator says. Theoretically its accurate, but real world numbers are not exact between manufacturers and brands, etc. Close enough for most purposes though.

[tommyg29]

Dont want to hijack this thread but after much sanding and...flashlights...and glasses... I have a b-body 3.54 powr-lok (603109-1), manufactured 12-69 (with 2 different date stamps, 12/3 and 12/16), or at least thats what the decode says.
So...guess I've gotta check the tach for accuracy.