Diff ratio

[tjk]

Can someone tell me if the following means I have the correct diff, at 60mph my rpm reads 3000 in 4^th no overdrive.

Great weather here for driving the stag to work, all my male work mates are jealous and the girls love it. Wish I was allot younger.

tjk

[73stagman]

depends on your tyres really but according to the handbook on standard fitted diff wheels and tyres your engine will be doing 3084RPM at 60mph

OR 58mph at 3000RPM

[GDPR]

Get a ZF 4 speed auto, and a 3.45:1 diff and 60mph = 2000rpm.....

[tjk]

Thanks for the replies, guess I have correct diff. PS any spare money you have for the conversion to 4 speed auto will be greatly appreciated.

tjk

[jamcarr2]

Will it say on the diff what ratio it is I looked on mine but could only find this diff.jpg

[73stagman]

NO.
The ser/no is hand stamped into the front end of the diff at the input end shaft on the underside. It only has an LD type number which then has to be deciphered using a data base similar to Club Triumph's list

Stag

Commission: LD
Body: LD
Engine: LF
Gearbox: LD
Diff: LD

Stag USA

Commission: LD/LE
Body: LE
Engine: LF
Gearbox: LD / LE
Diff: LD

This info is from CLUB TRIUMPH which is available on their internet site

[redstag]

You need to look on the underside of the diff casing and you will see a number stamped rather crudely into the metal. Can be hard to make out sometimes though due to rust and abrasions.

If it starts LD followed by numbers it is a Stag 3.7 diff. Any other prefix and it is from a different Triumph with a ratio ranging somewhere between 3.45 and 4.11. Assuming the internals haven't been changed at some point of course.

Pete

[73stagman]

All Stags had "LD" diffs with a 3.7:1 drive ratio.

Triumph 2500's had a similar diff (not exactly the same) which can be mounted into the Stag but had a 3.45:1 drive ratio. Some people have done this to their stags on purpose others like me have done it by accident. Some say its worth it others say it isnt! I have to wait and see!

[ChasR]

One thing to bear in mind is that an MOD car may be worth more than a ZF car, although I think the ZF suits the cars I have been in very well .

[Westfaling]

Guys
This website is quite useful in calculating RPM to speed.

http://www.mintylamb.co.uk/gearspeed/

Nick