engine and drivetrain Which Diff Ratio?

[gaius]

No. is not the answer i wanted. 

[crumble]

Thanks for the help guys.

As for location, I am in South Australia, Adelaide, to be exact.

I have the old diff in the shed, and will see if I can find any markings on it for ratio.

I do have a spare speedo, but it is an mph speedo. Not sure if I can legally run one of those these days.

I am currently at work on a oil rig (drilling for more fuel to run '02's .. so will check when I am back home on Tuesday.

[ray_]

Thanks for the help guys.

As for location, I am in South Australia, Adelaide, to be exact.

I have the old diff in the shed, and will see if I can find any markings on it for ratio.

.. or you can turn the input flange and count ;-)

 

Cheers,

[crumble]

.. or you can turn the input flange and count ;-)

 

Cheers,

 

The diff failed and was replaced.

Turning the input flange doesn't turn the 'axle stubs' (whatever their proper name is?)

[TobyB]

 

so the 318i E36 case, is the same/interchangeable with a 02 ????

Not in the least.

But the ring and pinion will fit into an E21 case, or with a bit of grinding, (says Andrew)

a 2002 case.  Then you get a 3.45.

 

It's not that different from the 3.64, really...

 

And you can always pull the back cover and count the teeth on the ring gear and divide that

number by the number on the pinion gear,  That'll give you the ratio, too, if the diff's failed.

 

I'll bet it's a 3.64...

 

t

[kbmb02]

FYI: There's a series of letters/numbers stamped on the ring gear, which usually starts with the letter H.

 

"H41" is the code for a 168mm 3.45 ratio ring gear.

(in my experience, the H codes are unique to each ratio and also unique to 168 vs 188mm gears).

[Conserv]

And some differentials -- or does this just begin in the e21 era? -- have the number of pinion and ring teeth stamped on the housing, left front side. The photo below is of a 1978 e21 LSD; it's stamped "11 S 40," indicating a 3.64 (40/11 = 3.64) LSD (the "S" represents limited slip).

Steve

Edited November 16, 2014 by Conserv

[kbmb02]

And some differentials -- or does this just begin in the e21 era? -- have the number of ring and pinion teeth stamped on the housing, left front side.

Steve

 

That's true - and I believe I've seen that on at least some of the 2002 diffs, Steve. (Though around here, we often swap gears, parts, etc. That's why I use the H code to be absolutely sure.) -KB

[Conserv]

That's true - and I believe I've seen that on at least some of the 2002 diffs, Steve. (Though around here, we often swap gears, parts, etc. That's why I use the H code to be absolutely sure.) -KB

Thanks, KB,

And I wonder how many were originally stamped in this manner but have had the stamp deteriorate with time, grease, and rust!

Best,

Steve

[peterschop]

My '74 has the 11/40 stamped in large letters on left side of case but is hard to see if there's any dirt or grease is on it. 

Edited November 16, 2014 by peterschop

[M3M3]

The diff failed and was replaced.

Turning the input flange doesn't turn the 'axle stubs' (whatever their proper name is?)

you can still pull the back cover, turn the input flange and count revs for one turn of the ring gear.  if the diff really has "failed" this should also be entertaining to see what loose bits are rattling around in there....

[AlanM]

 

As for location, I am in South Australia, Adelaide, to be exact.

I have the old diff in the shed, and will see if I can find any markings on it for ratio.

I do have a spare speedo, but it is an mph speedo. Not sure if I can legally run one of those these days.

 

I live near Brisbane in Australia.  No problems with running an MPH speedo in a pre '76 car.  Given most 2002s were produced before 1976 you will have no dramas. Just put some small bits of tape showing 60, 80, 100Kph set up via a GPS, and not worry what the numbers the speedo says.

I run a 4.1 diff in a "73 Tii with a 235/5 5speed with 1:1 5th, 205/50/15 tyres, showing about 50MPH when it is doing 38. (80Kph is 60 approx.) I don't know which speedo I have nowadays. 

 

[gracer]

As has been stated in this thread, the 3:45 was in early TII. The 3:36 was a turbo ratio. The ratio is stamped on the drivers side as shown in the pic.

All this is out the window if the PO changed the ring and pinion. G

[Preyupy]

Gordon is right. Some of the early Tii's had 3.45:1 diffs. The standard ratio for the Turbo was 3.36:1, a number of them had 3.45:1 on special order.

Edited November 22, 2014 by Preyupy

[jgerock]

It's not too hard to pull the rear cover and look at the markings or count the number of teeth. BMW used either Klingelnberg or Gleason ring and pinion patterns.

 

 

K is Klingelnberg    K9 = 3.64:1    K41 3.45:1   K1 = 4.11:1  More footnotes describe the applications.

 

H marking is Gleason pattern   H1 or F1: 4.10:1    H9 or F9: 3.64:1

 

Other special versions are listed on page 33-0/3

 

Edited November 22, 2014 by jgerock