Differential gear ratios

[promotor]

If you speak to Gordon Strachan at NTG company in Arbroath he will do a 3:1 CWP for you. A very helpful chap indeed. https://www.ntgear.co.uk/ Good luck.

Did you ask him if he was one and the same Gordon Strachan? I bet he's been asked a thousand times, at least over the phone anyway!

Nice job persevering with this and finding an alternative to a 5 speed 'box!

Serious head on now! Did you use the backlash and depth of mesh settings recommended by NTG, or use the original English diff settings?
Did I read in your post somewhere that you deviated from the recommended settings?

The reason that I ask is that his first production run of 3.3 CWP's recommended 0.004" only whereas Ford specs are 0.005-0.007".
Also, are the depth of mesh settings (ie pinion shim adjustment) the same, or slightly offset against original Ford tooling?
Tighter backlash settings than factory spec bring the contact patch down towards the toe in a Ford diff (and should do in all hypoid gear sets). I wonder if this is how all his CWP's are, or whether the contact patch is still in the correct place with a tighter backlash?

[TBG]

Promotor - I did not do the actual work as I am not competent to deal with differential internals. I can take it out and put it back but the innards I leave to the more experienced!

When the CWP was delivered it came with instructions from Gordon and a photo of it showing how it should mesh when set up correctly. I assume my chum who did the work used these instructions.

Anyway I am thrilled to bits with the result and cannot wait for this blasted virus to bugger off and I can get back to chasing motorcycles in the Alps!

[TBG]

I have just spoken to Gordon at NTG and he has a dozen 3:1 cwps in stock as we speak. Be prepared for a slight whine on the over run. D

[gjz30075]

[quote="TBG"n stoc] Be prepared for a slight whine on the over run. D[/quote]

Is this Gordon's disclaimer, and expected?

[promotor]

Promotor - I did not do the actual work as I am not competent to deal with differential internals. I can take it out and put it back but the innards I leave to the more experienced!

When the CWP was delivered it came with instructions from Gordon and a photo of it showing how it should mesh when set up correctly. I assume my chum who did the work used these instructions.

Anyway I am thrilled to bits with the result and cannot wait for this blasted virus to bugger off and I can get back to chasing motorcycles in the Alps!

Thanks for the info! You might just slip past a few motorbikes on the twisties!

I have just spoken to Gordon at NTG and he has a dozen 3:1 cwps in stock as we speak. Be prepared for a slight whine on the over run. D

I had heard this was the case previously on the 3.3 diffs unfortunately as I know someone who built a couple. As I understand it they were originally destined for race cars and not meant for quiet road cars.

Perhaps the option is to not let off the throttle/allow any overrun in the Alps!

[TBG]

gizz375 - Well yes in away. I am not totally sure that my pinion shaft has been correctly tightened. The other thing is that Gordon makes these to a design and does not have failures as he uses amazing steel. Some he has seen he describes as made from chocolate. BUT he does not have the time and effort to do development work like the massive Ford lot had years ago. He has supplied a Lotus Cortina racer who got 60 racing miles from cwps made by the usual suspects - you know who they are! This chap has now done 600 racing miles without a problem.

The whine I get on the over run is hardly there and I cannot hear it unless I am going very slowly - so not often then! The noise is not damaging to the gears in any way. I am a very happy chappie as the drive is fantastic.

[Davidb]

I had a whine on the overrun so I decided not take take the wife in the Elan any more...

[SENC]

I had a whine on the overrun so I decided not take take the wife in the Elan any more...

[1owner69Elan]

Just noticed that TTR is offering a 3.0 CWP on their website under “new products” for 350 pounds. Also a 3.3

So, perhaps TBG’s “experiment” is now an accepted, readily available, mod.

[TBG]

Somerset is the Silicon Valley of CWPs!!

[Brock]

I'm bringing this thread up. I know that TBG is out now that his car is gone...

So, what are the teeth numbers of this mythical 3:1 CWP (ring and pinion)? I have seen reference to 3.1:1 -- and reference to 3:1.... so I'm confused.

Does anyone else have a review?

[billmoore42]

Yes, I have a 3.1 Diff from Gordon at ATG and there is a noticeable whine on overrun. It bugs me quite a bit, and the gears were installed by noted local Lotus Specialist Kampena Motors in Sonoma.

I believe the overrun whine is a result of the gears and not the skill of the installer (Kampena Motors is excellent). I wish there were a way to quite the overrrun whine, but the wonderful thing is how the new taller gears work with my 4 speed and my 1700 CC motor. Although i hate the whine, it only happens when coasting, and the tradeoff of going down the freeway at 3000 rpm at 70 miles per hour is worth it. I live in Northern California and you often need to go 75 to 80 mph to keep up with freeway traffic.

I wish there were a gearset that was more refined, and did not have the whine. I may try 140 weight diff oil, but I feel this will probably not quite it much.

Bill Moore

[h20hamelan]

would a synthetic fluid like redline be worth a shot Bill?

[rgh0]

Redline shockproof gear oil would be worth a try.

cheers
Rohan

[elancoupe]

Yes, I have a 3.1 Diff from Gordon at ATG and there is a noticeable whine on overrun. It bugs me quite a bit, and the gears were installed by noted local Lotus Specialist Kampena Motors in Sonoma.

I believe the overrun whine is a result of the gears and not the skill of the installer (Kampena Motors is excellent). I wish there were a way to quite the overrrun whine, but the wonderful thing is how the new taller gears work with my 4 speed and my 1700 CC motor. Although i hate the whine, it only happens when coasting, and the tradeoff of going down the freeway at 3000 rpm at 70 miles per hour is worth it. I live in Northern California and you often need to go 75 to 80 mph to keep up with freeway traffic.

I wish there were a gearset that was more refined, and did not have the whine. I may try 140 weight diff oil, but I feel this will probably not quite it much.

Bill Moore

I have an NTG CWP, professionally set up to their prescribed specs, and it whines like crazy on overrun. The fact that my car is a coupe probably exacerbates the noise. I put 75/140 in it, no difference. One of my biggest mistakes was buying this, but I now have the fix - a brand new, genuine Ford CWP.