Differential needed

[Painterdave]

So I got under the car today 4 terns of the prop =just under 2 tern of the wheel approx 4"short at the risk of sounding silly I think it is 3.9 ratio ,advice welcome

[MetBlue]

I'm assuming you only have one wheel in the air, so the ration will appear to half.
My understanding though is that 4.1 relates to prop shaft and 1 to the wheel in a 4.1:1 ratio. So you have just over 2 turns of prop for one full wheel turn, hence a 4.1 ratio (as would be original on an 84 car).

[Painterdave]

Yes I'm up on one wheel ,it a pain but marked prop lot of slack in differential your old differential is getting more attractive, where are you approximately to me I'm billericay essex

[Painterdave]

Early cars were 4.1:1, later cars changed to 3.9:1. An 84 car will be 4.1.
Auto's were 3.7:1.

If you have a provenance certificate, it will tell you the serial no for the diff. Suffix A is 4.1, Suffix B is 3.9. Must be marked on the diff somewhere, but no idea were and doubtful still legible after 40 years.

So Tony i think it may be your differential that is the best choice as it is tested ,have you a price in mind ,in the meantime I will fill mine with some gear aid products any suggestions welcome thanks in advance Dave

[MetBlue]

So Tony i think it may be your differential that is the best choice

I'll PM you my phone number Dave. It's complicated as the 4.1 diff I have is waiting to be fitted to my car after LITP this weekend ( isolation bushes and repairing the crack in the diff carrier the driver).
Then I want to redo the seals in my OE diff, then swop 'em back as my car uses the 3.9 diff as standard, and although I like the idea of a little more surge off the line, I think I prefer the idea of lower revs at motorway speeds.
If I have a reason to do quickish though, no reason why I can't have a spare diff within a month or so from now. It might actually motivate me to complete the job quickly

Tony

[Painterdave]

I will phone you Tuesday evening and we can go from there .thanks Dave

[Schrowi]

Where can I request a provenance certificate? Many thanks!

[Alan_M]

Where can I request a provenance certificate? Many thanks!

Contact Andy Graham at Lotus. You can get the full blown one via TLF - https://shop.thelotusforums.com/product ... provenance

Not sure if available, but used to be able to get just the certificate without all the parafinalia for a sensible price.

[Zag]

Just the stuff you need, none of the balls.

https://shop.thelotusforums.com/product ... provenance