Rear axle gear ratio

[Steve-Avanti]

Hi All,

Any idea what the standard rear axle ratio is on the 87 Avanti?  Were there any optional ratios? Thx in advance!!

Steve

[wildfelr]

RQB3263/81 .... This is the orig. tag on my 81 ...it reads 2.72 ... I hope this does not add to the confusion .. BILL

[Steve-Avanti]

I'll crawl underneath & see if I can find anything.  Thx!

Edited November 4, 2022 by Steve-Avanti
Misspelled

[silverstude]

Here's  what Dr. Google says:                

The Automatic overdrive transmissions were designed for axles like this..

 

 

Edited November 4, 2022 by silverstude
more info

[Stacey]

Didn't the 87 build on a Monte Carlo? I thought 89,90 and 91 were Caprice? 

[silverstude]

Regardless of the type, the transmissions dictated the axle ratio

[Steve-Avanti]

Trans is 200r4

[silverstude]

The Caprice had a 700-R4, made for good gas mileage.  It has a 3.06 first gear ratio.   Axle ratios for them started at 2.73 which gave higher highway speeds with low engine rpm.    The downside of using them with a higher geared axle is that 1st gear is 0-15mph, then an abrupt (to say the least) shift to 2nd.  You cannot start out in 2nd gear...

 The 200-4R, developed later,  has more normal ratios, something like a 2.56 first gear  and is much more comfortable to use, so your axle would likely be around 3.31 - 3:54    

[IndyJimW]

Mine is a 7.5" Posi-Trac. Forgot the original gear ratio, but there are lots of options. The one thing you have to look out for is that at about 3.42 gear ratio and higher it takes a different carrier to fit in the housing.

Good luck all,

Jim Wood