Final Drive Ratios

[Mick01]

I've just replaced the very noisy final drive unit on my 325i Touring with a unit from a 'C' reg cabrio from the breakers yard. The small tag on the replacement unit is rusty so I can't make out the ratio from it. I feel the car is slightly slower. Does anyone know if the ratio of the 'c' reg cabrio is different to my 'F' reg Touring?

Cheers, Mick

[cliffybabe]

what lump was in the cab???

Have u tried taking th etag off and leaving it in coke for a while to get rid of the rust??? Thats the trick i was shown

[Mick01]

[quote="cliffybabe"]what lump was in the cab???

It was a 325i also.

Cheers for the tip with the coke, I'll give it a try

[stuartgallafant]

different engines used different 'boxes and diffs, meaning different ratios.

the early 325i engine was faster then the later, and i think they used different boxes too, which would mean different diffs too

like neil said, clean the tag up and tell us what you find

[jmc330i]

The cab would of had either a 3.64 or 3.91 diff and the touring would of had a 3.91. Sounds like youve probably fitted the 3.64.

Was the Cab an auto?

[Ziggy]

My (manual) D-reg 325i cab came with a 3.64, so I reckon there's a fair chance that's what you've just fitted...

[BMW_YARD]

Why dont you do a search this has already been covered!

http://www.e30zone.co.uk/modules.php?na ... highlight=

[Mick01]

I don't know if the cab was an auto or not as that was all that was left on the shelf.

Thanks all for your help. I'll get the rust off the tag on the unit with coke and know for sure.

I'll let you know how I get on.

Cheers

[jmc330i]

It does sound like youve fitted the 3.64 as Ziggy said.

I only asked if the Cab was an auto because the early autos had either a 3.46 or 3.64 diff - your 325i would be slower again with a 3.46 diff, but if its only slightly slower then 3.64 would be the best guess, and probably a good trade off between performance and MPG.