Final Drive Ratios

[TurboZed]

ON the rear axels of these cars are the final drive ratios different for different models? I'm hopeing that 760/960 diesel auto is much higher than a basic 740/940 manual diesel (UK/European market)
Cheers
Jim

[piper109]

If the D24T is coupled to a ZF auto the standard rear axle ratio is high. The ZF overdrive ratio is tall. Consequently, if you put a manual transmission in place of the automatic, the engine will rev very high on the highway. The rear axle would need to be replaced to compensate for this unless you get addicted to the extra zip:-).

Steve

[Jason]

In the US market, the auto cars (zf22) came with a 3.73 rear end, while the M46 equiped cars came with a 3.55 ratio.

Not sure about the 9 series cars or later stuff sold in Europe or other markets.

Jason

[piper109]

I believe you will find that the US market ZF automatics came with a higher axle ratio than that, 3.93 I believe. My 86 is that way. My 92 converted from gas came with a 3.73 Detroit locker and it is geared a bit higher than its supposed to be for the zf but it seems to run fine.

Steve

[Jason]

I should have clarified, the zf auto behind the diesel came with 3.73. It may have changed later, and I wouldn't be suprised if they shortened the ratio some for the 4cyl powered cars. The rear end I blew up that was original for my car was a 3.73 (or maybe its was 3.74 but real close).

Jason

[hvguy]

since were sort of on topic with differentials, would a 940 wagon diff fit in my 740 wagon? or... would lets say would a 760 sedan diff fit in my 740 wagon? and does it matter if the 760 is a gasser? would it be a different ratio? even though it seems that both engine rev in about the same RPM scale...

and by 'fit' I mean, everything bolts up perfectly, no cutting, bending, welding etc

[Jason]

760 into 740 will work, gas or diesel. As for the 940, thats a later car and I'm not sure about that. Ratio may be different depending on if its a manual or auto, and as steve was saying the ratios changed slightly over the years. May want to check over on turbobricks... There's a huge knowledge base over there and a few threads dedicated just to rear end ratios/swaps etc...


Jason

[hvguy]

how about this: would I be able to just swap out the gears and bearings? does anybody have a picture of what the inside looks like? Im in fear that my diff is about to meet its maker... its sort of whining.

[hvguy]

not sure if anyone did any googleing but i saw on youtube some guy has a 945 diesel and was showing off his locker he installed "had it high centered on a rock, with one wheel on traction and it rolled off the rock like nothing' any way, he installed a locker and mentioned the volvo diff's came with dana 30 axles in which case this kind of opens up the market for lockers and LSD rebuilds.

here is the video: http://www.youtube.com/watch?v=9rx-nvyEV8E&feature=related
and ehre is the writeup i found mentioning a TON of info on 240 and 740 series differentials: http://www.davebarton.com/volvorearends.html

I will copy and save this website because god knows good information is put on cheap websites and it tends to disappear. Email me if you need the specs or w/e

[piper109]

I may be wrong but I believe that any of the solid rear axles on the 700/900 series can be fitted. The later 900 series tend to have IRS so those axles wont fit without a lot of work. The tone ring on some earlier cars is different from the later cars so the speedo wont work.
My 92 745 Turbo (now converted to Diesel) came with the Detroit locker 3.73 as standard. A little research may turn up which models had that feature.

Steve