Rear Axle, 1988 765 TIC

[lummert]

Did Volvo install 3.91:1 rear axle with Anti-Lock Brakes in US Spec 88 Volvo 765 TIC ?

My trans is AW-71.
My rpm at 60 mph is 2500.
My tire size is 195/60R15 91H.

Any comments on this would be appreciated.

[luketrash]

Look on the driver's side of the rear axle and see if there's a tag down there.

I had to clear away the factory undercoating material with my fingernail, but this is what mine looks like:



In my case, my 93 Volvo 240 is a 3.31:1 ratio.

I don't know anything about 700 Volvos, but I thought this info might help.

[lummert]

Thanks for the reply. I will have to have that checked out.

I looked it up at Volvo Parts Online and there is a 3.91 ring & pinion listed for 85-90 740,760 & 780. Also a 3.91 differential w/ABS listed for 84-90 740,760, & 780. But all the specifications list a 3.73 for an 88 760 Turbo Wagon. It can't be 3.73 because the speeds don't match the RPM's.
For 3.91 rear axle:
In O.D. at 40 MPH = 1700 RPM
In O.D. at 45 MPH = 1900 RPM
In O.D. at 50 MPH = 2100 RPM
In O.D. at 55 MPH = 2300 RPM
In O.D. at 60 MPH = 2500 RPM
For 3.73 rear axle:
In O.D. at 40 MPH = 1600 RPM
In O.D. at 45 MPH = 1800 RPM
In O.D. at 50 MPH = 2000 RPM
In O.D. at 55 MPH = 2200 RPM
In O.D. at 60 MPH = 2400 RPM

By these estimates there is a difference of 100 RPM at each speed.

Any corrections are welcome.

[lummert]

I had the gear lube level in the rear axle and there wasn't enough of the tag there to read anything. I contacted Volvo and they said that the 1988 Volvo 760 came with 3.73 rear axle and that I should contact a Volvo dealer to check it out. I still think it is 3.91.

They used 3.91 rear axles with abs on 740's from 89-92.