The 'E' Type Forum

My query is what is the diff ration needed to obtain minimum engine revs to maximum speed.
I have read somewhere that 2.88:1 is what I need .
Would somebody educate me please?!
Thanks
Phil

Basically, the lower the number the higher the speed for any given revs.
Standard series 2 diff. uk spec was 3.07:1
USA spec had a higher ratio, so more revs needed for same speed.

What car do you have, and is it manual or auto?

If you search this forum you’ll find lots of comments that 2.88 diff doesn’t really work for an E, though some will beg to diff(er).
Why do you want this? What is the present diff ratio? If you plan to change from the UK norm of 3.07 for a manual 6 cylinder car then factor in the cost of doing the work against any so call benefits.
In normal UK driving 3.07 gives very nice torque curve without unnecessary gear changing in town, up hills, etc.

Geoff

2.88 was only used IIRC on the automatic 2+2 cars . It is frankly too high for comfort on any manual car, because it makes 1st too high and restarting on any significant hill starts to punish the clutch in a big way particularly if repeated hill starts are needed

I did put a 2.88 in my E-type OTS and I am happy with the results. I changed from a 3.54 diff, but I am limited in choices here in the US. I do agree that if you live in a hilly area with a lot of uphill starts the 2.88 might be too tall, but overall I am pleased with the spread between the gears, and relaxed 70mph highway revs.
We in the states are limited in our options for ratios, with most cars delivered with the too low 3.54. You can’t get through an intersection after a stop without shifting up, all the gears are quite close together, and the car is very busy at speeds above 60. The 3.30 would have been a better choice, and I would certainly accept and be satisfied with a 3.07 if it were available to me.
I am currently wanting to replace my coupe diff and so far have only found a 3.30, so that might be what I end up with.

Mark

TheMadBadger wrote: ↑

Fri Aug 12, 2022 2:25 pm

I am currently wanting to replace my coupe diff and so far have only found a 3.30, so that might be what I end up with.

Mark

The 2.88 was used in the XJS and XJ12 although you may need to use the Girling rear calipers.

You can buy a Dana 3.07 crown and pinion and have them installed in your existing diff by someone who knows what they're doing.

IIRC Coventry West supply diffs in various different ratios.

I changed to 2:88 some years ago and very happy with the result, can only recommend to do so.
Mine came from XJS, I also took the calipers from XJS, also an improvement. Kept the originals with the car.
At 130 kmh now ca. 2800 rpm, very comfortable.

The only issue I had was with the alternator, cruising at 80 - 90 kmh at low rpm did not always charge the battery. Finally I changed to a dynamo in an old Lucas (C45?) housing, now charging very well. My car is positive earth, these dynamo's are now available with regulator as a set, also for + earth

I just drove in the Belgian Ardennes, quite hilly but no issue whatsoever

Thank you all for your comments.
Perhaps on balance, and living in a fairly hilly area of North Yorkshire, I should stick with a 3.07 diff.

Can anyone recommend where in Yorkshire I might get my diff reconditioned?

Cheers
Phil

malcolm wrote: ↑

Thu Aug 11, 2022 4:00 pm

Basically, the lower the number the higher the speed for any given revs.
Standard series 2 diff. uk spec was 3.07:1
USA spec had a higher ratio, so more revs needed for same speed.

What car do you have, and is it manual or auto?

Thanks for the info Malcolm.
I drive a 1970 series 2 convertible.
cheers
Phil

Phil, you’ll probably be on a waiting list wherever you find to overhaul your diff. If you’re happy to wait until winter and do without the car then why not contact Alan Slawson? Yes, he’s in Essex but he is regarded as about the best.
You could try Ken Jenkins or Ken Verity who are closer to you. A search on here will give you their contact details.

Geoff

abowie wrote: ↑

Fri Aug 12, 2022 11:52 pm

IIRC Coventry West supply diffs in various different ratios.

Sorry for some reason I thought you were in the USA.