What's the diff?

[fat richie]

Esteemed readers...

Can anyone tell me what the final drive ratios are for an '88 Mayfair (998) and an 87 MG Metro (1275 non-turbo)? Ive been told that the Metro is 3.44:1. Also what tyre size was used on the Metro?

Many thanks.
Rich

[fwdracer]

87 MG Metros had Metric wheels (315mm?). Closest equivalent is 155/70/12 which the original 1984 MG Metro had as standard.

If you have an engine number for the 998cc unit you can run a check to see if it is a high or low compression unit. They had different final drives. High Compression used 3.1 final drives, low comps on 3.44.

Edited by fwdracer on Tuesday 15th August 15:22

[fat richie]

Thanks for that Gareth. The 998 lump's number was 99HD800106362. Can you confirm what the Metro diff would have been? Currently rnning the 145/70R12s that came off the Mayfair, sounds like it needs taller gearing (or tyres) as by my calculations it's turning 4000rpm at 70mph - that's a guesstimate as the speedo is out (just a bit, indicates 55mph at 4000rpm!).

[fwdracer]

99HD appears to be a 998cc Metro unit. It would have had a 3.65 diff as standard. Pulling 4000rpm at 70mph would be about right on 145/70/12.

Edited by fwdracer on Thursday 17th August 08:37

[Guessworks]

Most metro's run 3.44 diff's, with only the commercials running higher, the turbo's run 3.2, and "E" models running a 3.1... also consider that minis have run diff ratio's from 2.7 through to 3.77 and higher on special order.

If you're goin 70@4krpm, then that would tie up with a 3.44 diff

You'll find this very useful page a very useful tool for determining the diff/tyre combination which suits your driving style..

http://rcmoc.org/bitsnbobs/coolstuff/