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Rear axle ratios, what's got what

If it has fins on the bottom, it's usually it's a 1030, but not always. If it's smooth on the bottom, it's probably a 1031, but not always. I think '84 is the latest cars I've seen the finned-bottom diff housing, but that doesn't mean it was a 1030 for sure. Just my assumption that it was.

The pinion flange on my '79 1030 matched the flange on my '88 1031, so you can't tell by the flange.

Best bet is to pop the cover and measure the diameter of the ring gear.

Here's my 1030 that's finned:

110986156.jpg
 
It turns out the 85 740 manual trans (M47) has a 3.31.. The gears out of the 242t automatic we have are 3.91 In doing the math we've realized that we need a 3.73 set... But now we have only 3 day left.
 
My 87 745ti w' M46 has 4.10 but may have been swapped.

91 940 16v has 4.10 stock

The auto 740's I've had were shorter, but never checked what.
 
EvilGenius said:
It turns out the 85 740 manual trans (M47) has a 3.31.. The gears out of the 242t automatic we have are 3.91 In doing the math we've realized that we need a 3.73 set... But now we have only 3 day left.
Click to expand...

3.73's are all over the place.. basically all turbo 7xx/9xx with AW autos have em.
 
My 88 765 converse engineering 5.0l has a stock 4.10 and gets about 11mpgs... Lol wish i had the 3.31 or 3.54 gear that would up the mpgs and stop go driveability...
 
3.31s can come from 960s and 940s (according to car part). That's what I swapped into the v8 car.
 
I got a 240 1031 3:15 rear end and I know of at least another one. No idea where it came from.

edit: some proof. 41:13

1py001.jpg


2lw126v.jpg
 
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Id guess from a diesel. Dont think that R&P ratio made it to the states.

Based on the 48 tooth speedo ring, its definitely a 90+ car. Probably a 1031, but maybe not. Measuring the pinion and bearings would easily tell.
 
Part #1216159 is a 240 rear axle with 3.15 gears. It's only listed in the '79-'84 parts catalog and it's definitely a 1031.

The tone ring is shown in the '79-'84 240 parts catalog with a note that says it's for vehicles with a shift indicator. 240's didn't get electronic speedos until '86.
 
hiperfauto said:
Part #1216159 is a 240 rear axle with 3.15 gears. It's only listed in the '79-'84 parts catalog and it's definitely a 1031.

The tone ring is shown in the '79-'84 240 parts catalog with a note that says it's for vehicles with a shift indicator. 240's didn't get electronic speedos until '86.
Click to expand...

They used the a tone ring in the diff just to drive a shift light while still having a mechanical speedo? :wtf::rofl:
 
blkaplan said:
Id guess from a diesel. Dont think that R&P ratio made it to the states.

Based on the 48 tooth speedo ring, its definitely a 90+ car. Probably a 1031, but maybe not. Measuring the pinion and bearings would easily tell.
Click to expand...

The carrier is from a later car, hence the speedo ring. The original was without one but welded, so I had to swap it.
 
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