Diff ratio's

[Mervyn]

Hi, This is my first post as the newbie

Is there a way to tell each diff ratio by the amount of pinion teeth, I have three cwp sets available, each pinion has the following;

First has 8 teeth, 2nd has 10 teeth & third has 11 teeth.

Can anyone help with the specific ratio of each please?

Are they ok to set up, do I need any specialist tools etc?

I would like to finish up with a 3-9 or possibly a 3-7

Many thanks. Mervyn.

[billwill]

Isn't the ratio just the number of teeth on the crown wheel divided by the number of teeth on the pinion?

[gerrym]

Bill, you're bang on the money. The CWP set is exactly what determines the diff ratio.

Eg for Plus 2s, either 34/9 or 32/9 (3.777 or 3.555 respectively)

Regards

Gerry

[Bruce Crowthorne]

What is the "tallest" diff easily available for an Elan?
And what are the likely sources - eg escorts, capris etc
Thanks
Bruce

[gerrym]

Tallest ratio apart from any specials is the 3.54 from the RS2000 Escort.

Regards

Gerry

[elans3]

Just to qualify this, a smaller number of both Elan's and Elan +2's were specified (by the original owners), and delivered with a 3.55:1 diff ratio. These are extremely rare now, and can be substituted with the later 3.54:1 from the sporting escort.
My first Elan S3 DHC was originally specified with this 3.55:1 diff, and the closest ratio gearbox, which combined gave a relaxed motorway cruising speed, and phenomenal max speeds in gears.
elans3

[Elanintheforest]

The S3 S/E came with a 3.55 as standard for a long time, but it was phased out and only supplied as an option towards the end of S3 production.

Mark

[Mervyn]

As my post has been rather hi-jacked.

To reiterate,

Do I need any special tools etc, to set up a diff ?

Thanks for your help.

Mervyn.

[gerrym]

Mervyn, the most important special tool you will need is knowledge. If you have setup a diff before, this one will not be any harder. It's just an "english" setup with a Lotus rear alloy cover.

Do you have the workshop manual, its all laid out in there, section R final drive. The main things are setting the mesh correctly so that you don't wear out the CWP or cause it to whine. Also, the pinion bearings have to be correctly pre-loaded.

Alternatively if you don't have the skills, there is a line of reasoning that says it's not worth damaging hard to get components for the sake of the few pounds required to entrust the job to a specialist. An old school gearbox specialist used to working on rear wheel drive vehicles will have the special tools or his own equivalents to those listed in the manual. For a well used CWP, its generally important to re-establish the existing mating pattern. Ultimately, this is where the skill and experience comes in.

Regards

Gerry

[bcmc33]

As my post has been rather hi-jacked.

To reiterate,

Do I need any special tools etc, to set up a diff ?

Thanks for your help.

Mervyn.

From the way you ask the question I guess you already have the main tool - a car to take you to an 'expert' who can do it for you.

But as you have not bothered to tell us where you're located, it is difficult for anyone to give you the best advice.

[bill308]

I just purchased a 3.54:1 cwp on ebay from Burton Power. I plan to drop it off at Quantum Mechanics (USA) and have John Esposito do the setup. I'll pare it with an alloy nose and a 26R carrier.

If I were going to do it myself, and I never have, I'd be sure to have the Lotus Workshop manual, a dial caliper, a dial indicator with a mounting bracket, and a good torque wrench for starters. In addition, I'd also have some Dykum Blue or other marking paint to visualize the contact patch.

Bill

[Mervyn]

"gerrym" & "bill 308" Many thanks for your help, all much appreciated, I have completed the job. The L/C is now running well on a 3.7.

"bcmc33" I assume you know nothing about diff assembly either! Therefor, there is no point in bothering you with my address!!

Mervyn

[512BB]

Mervyn,

I feel you have rather got off on the wrong foot on the forum, which is a shame. As I am sure you are aware, this really is a great place to learn, share your knowledge, and be entertained, and I would think, that is why you joined.

Brian was simply making the point, that you have not entered any info on where you are, or what car you have, not that that makes any difference with the question you posed on diff rebuilding.

I myself have answered questions asked by members, only to find out later that the advice given was a complete waste of time, because the member was not even in the same country as the company where they were told they could get a job carried out, if you see what I mean. You might like to chip in here Gary, with a link to your post, WHAT, WHEN, WHERE, HOW, so that Mervyn can see what I am talking about. I dont know how to do that. Trust you are well by the way, you havent posted recently.

And just a heads up to other members who might read my ramblings, I can assure you, you will get more replys to your questions if, at the very least, you say where you are in the world, as I find it so infuriating to find I have been wasting my time. I am sure others will agree.

Oh, and welcome to the forum Mervyn.

Leslie

[Mervyn]

Hi Leslie,
Thanks for your note. I don't feel to have got off on the wrong foot on the forum at all really, rather more that one contributor was attempting for whatever reason, rather in my opinion, sarcasm at it's finest, the implication being, I am far to daft to attempt such work on a diff, so I should best go off in my 'tool' & see an 'expert'

Actually, that kind of terminology smacks of how a chauvinist may speak to his wife,
"The helpless little lady who is best just left at the kitchen sink"
A very poor & pointless reply to someone who has just joined a most interesting forum, & clearly indicating newbie.

I have been involved with Ford mechanics for over fifty years. The only reason I asked re the diff is. In the good old days, much of this kind of kit was basically tuppence a ton with no particular need to re-build, so I never did restore a diff. However, things have changed these days with limited availability, hence my original question.

You mention, maybe I should have indicated what my car is etc. I figured correctly as it turned out, that there was no need judging by other replies folks here know & understand their stuff & that; 3.9 3.7 3.5 indicate Ford products.

It probably comes down to the fact I see no reason to ramble on & on like this post!! what my car is, how long I have had it, where I live & so on, is a thing I don't normally do !!

Anyway,
Thanks for your kind welcome Leslie, I hope we will chat again.

Best Regards,
Mervyn.

[types26/36]

Hi Mervyn,
First welcome to the forum, as an old time member I am not attempting to take sides here and I tend to agree with you that it is not necessary to give your life story on as public forum..... others seem to think it a good idea but that is their choice......I do think though that a members location is important as it can make a difference to replies to specific topics so the best advice can be given, it is also of lesser importance but it is of interest to most members where our Lotus cars are spread throughout the world......after all we would not be on the forum if we did not share a common interest in them.
Of course there will always be disagreements on the "how and why" of topics (I have had my share) but I hope you stick around (you may well have the answer to someone's question) fortunately or unfortunately we often get "thread drift" and "thread hijacking" but that is just the nature of things (and it is not always bad) it just has to be accepted as a reality of a public forum.