3.89 Diff

[david painter]

Hi looking for a good 3.89:1 diff as fitted to the late Ital 1.3 or 1500 Dolomite
Thanks
Dave

[wfb]

Full Dolomite 1500 axle on ebay
https://www.ebay.co.uk/itm/Triumph-Dolo ... 1438.l2649

[david painter]

Thank you for the link but as collection only a bit far away for me Hopefully I have a recon 3.89 one coming next week from a local Triumph Specialist he has agreed to take a 3.63 in exchange
Dave

[timspencer]

Would this make for higher gearing?

[david painter]

The lower the number the higher the ratio my car is currently running a 4.11 diff it is still a 1.3 at present so a 3.63 would be too high the ie at 3500rpm with the 195/55r15 tyres I run equates to
4.11 = 59.27mph
3.89= 62.62 mph
3.63= 67.10 mph
Short term I plan to do the Cowley Convoy. Long term I an going to fit a 2.0TC O series engine with a lt77 box I feel this will be best overall gearing mixed for running in the lanes and reasonable motorway cruising.
Dave

[timspencer]

I would like a higher ratio for my 1.7, which runs 165/70 R 13 tyres, at 70mph its doing 4000!

[MarinaCoupe]

Tim you have a 3.63:1 rear axle in the 1700, the next one up is the 3.29:1 talk to David Balme about the performance. Good top speed and cruising but sluggish off the line with a standard engine its a 9.3% increase in gearing.

I would look at some wider tyres with the same ratio so 185/70 R13 - that would take 5% off the revs (200 rpm). But then you’ll need some wide wheels as wider tyres won’t fit on 4.5” rims - so maybe banded wheels with standard rims.

[david painter]

I would not be looking at a 3.29 diff as it will take far to much edge off the performance. My reasoning for going for the 3.89 is I intend to fit a LT77 gearbox with a 5th gear ratio of 0.83 gives the equivalent of 3.23 diff ratio so you get the best of both worlds
Dave

[timspencer]

Tim you have a 3.63:1 rear axle in the 1700, the next one up is the 3.29:1 talk to David Balme about the performance. Good top speed and cruising but sluggish off the line with a standard engine its a 9.3% increase in gearing.

I would look at some wider tyres with the same ratio so 185/70 R13 - that would take 5% off the revs (200 rpm). But then you’ll need some wide wheels as wider tyres won’t fit on 4.5” rims - so maybe banded wheels with standard rims.

Thanks Chris

I bought some TR7 wheels for that reason, which turned out to have a different location of the valve so couldn't fit my correct hubcaps, which is one of the things i like about the HL.

I will need to get my current ones banded slightly