Which car has which diff?

[RealEstate]

'Roger',

Many thanks for your spreadsheet.

One puzzle: According to your spread sheet, for my ZF HP22 with 3.91 diff, engine rpm@70 is 1000x2.688559=2688rpm.

However @70mph my tacho says eng speed=3000rpm. Your tyre circ is correct for my 195/65R15 and my speedo is spot on according to my satnav.

[Laney760]

Originally Posted by rogerthechorister

Staring at the owners handbooks I have here, it would seem that as far as 9 series cars go, only the B230FK ones had 3.31s and that all other 3.31s are ONLY in 7s (and maybe some 2s) - but which 7s is harder.

In my book 700 series:

740 GL estate manual gearbox 2.3i cat version introduced in 1982 and restricted to US and Canada is 3:31

200 series:

240 DL estate 2.3i cat manual gearbox version introduced in 1974 and restricted to US and Canada is 3:31

[rogerthechorister]

Yes, I agree that the empirical data may raise questions.

Are you sure that you have a 3.91, not a 4.10?

Are you sure your rev counter is accurate?

How new are your tyres (wear reduces diameter)?

Am I right that the HP22 is the lockup box? Is it locking up?

In short, I don't know! Some of my spreadsheet data seems to reflect the owenrs manuals, some not.

[Steve940estate]

There are many variables involved with tyre sizes, not all cars came with 195/65x15" tyres. My Estate had 185/65x15" on it but could have had either. The small difference in diameter will affect things.
Out of interest I will check what revs my car is doing in the gears before and after I swap the axle and I might find out what M90 gearbox I now have.

[RealEstate]

Originally Posted by rogerthechorister

Yes, I agree that the empirical data may raise questions.

Are you sure that you have a 3.91, not a 4.1? : Yes I physically checked the label - it's 3.91

Are you sure your rev counter is accurate? : I imagine it's one of the more accuate instruments, but no I've not checked it so it could be out.

How new are your tyres (wear reduces diameter)? : Yes my 195/65R15 tyres are half worn, so dia could be less by say 10mm, which would increase engine revs by (10xPI/1993)x2689=42rpm, which is still ~270rpm less than my tacho reading.

Am I right that the HP22 is the lockup box? Is it locking up? : Yes pretty sure it's locking up - I feel a slight jerk at 50mph.

In short, I don't know! Some of my spreadsheet data seems to reflect the owners manuals, some not.


Perhaps some other owners can check engine revs @70mph to verify your tables?

[ian2000t]

Originally Posted by RealEstate

Perhaps some other owners can check engine revs @70mph to verify your tables?

I have a D24TIC with 3.73 and ZF HP22 - I can check if it's any help to you?

[RealEstate]

Originally Posted by ian2000t

I have a D24TIC with 3.73 and ZF HP22 - I can check if it's any help to you?

Hi,

Yes that would be interesting.

If you have 195/65R15 tyres, according to Roger's tables, your engine should be doing 2565rpm@70mph.

If you have different size tyres, we can make the necessary correction, which will prob be fairly small.

Many thanks,

[Mikeymo]

OK, drove the car up on a ramp, crawled under it. What sticker? Blowed if I can see it.

I've got a late 940 CD. Previous owner said it was LSD. But can't tell. Apparently the raising-on-jacks-turning-one-wheel-while-seeing-what-the-other-wheel-does test isn't reliable.

I'm assuming locker. Any other way of identifying diff apart from the sticker that I can't see?

[Steve940estate]

Good of you to have a look at least. It sounds like Volvo wern't too careful about putting the stickers on and then sprayed underbody wax on the top to make sure they can't be found. I took me a while to find the ones on my car as the wax was quite thick.

Short of removing the rear cover I don't think there is any way of identifying what axles is what by looking. Various ways of spinning the wheel to activate the lock but i haven't tried it. I did find a way to test the locking diffs were working on Vadis using a torque wrench. It said to jack up one side so one wheel was on the floor the other not and the handbrake off and it out of gear. The torque would then have to be in a specified range.

If your car is a B230FT I would think it's got a 3.54 diff. Vadis doesn't show any Proper LSD's in the listings for any 940's as far as I can see, only the low speed locking type.
Thats not to say that they weren't a special order option or I just haven't found them though.

[gpl1968]

When I found my axle sticker it was under a layer of underseal and needed careful cleaning with white spirit to make it readable.