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MG TD TF 1500 - Mg TD ring and pinion conversion

Good day to all, I am in the U.S. looking for who is still doing ring and pinion conversions for the MG TD. I would like to convert to 4.1 or 4.3. Any help you can give would be appreciated.

Jim
JV Smith

Ditto.
Kevin McLemore

I suggest you both FIRST locate a 4.3 CWP. Forget the 4.1. They're rare as hen's teeth! Finding someone to fit it is the easy part.

Gord Clark
Rockburn, Qué.
Gord Clark

Check out Virgin Rear End Conversion and Carl Cederstrand's document for the technical stuff. Agree about using the 4.3. What isn't that well known is that the early B also used the 4.3. Cheers
Peter TD 5801
P Hehir

Butch Taras in California will probably do the conversion for you.
Regards
Declan
Declan Burns

First of all, as Gord suggests, forget the 4.1. It's FAR too high, unless you have a supercharged 1500 with a hot cam.

The response of a stock 1250 engine is changed considerably with a 4.3; it is slower off the line, and generally slower to respond in every gear. On flat terrain it works great; on hilly terrain, you end up shifting more. MGA pumpkins are getting harder to find, but are still out there.

To make up for the higher ratio I boost the power of my cars a bit; higher CR, hotter cam, etc., that more than makes up for the 4.3 axle ratio.

4.55 is a nice compromise, but hard to find in a quality gearset; it was a factory optioned ratio, but little-sold.

Butch Taras is the very best guy I recommend to do the conversions; I did NOT take over that part of Dave Clark's axle business.

When doing a diff conversion is the best time to install my Dave Clark axle shafts, which put the very-real fear of sudden MOWOG axle-shaft breakage completely out of the picture. To paraphrase Packard's slogan, ask the man who has broken one!

Tom Lange
MGT Repair
t lange

Peter, the Virgin Rear End Conversion is copyrighted by the SEMGTR. Carl Cederstrand's document is sold through Moss. Where do you propose that Jim obtains these documents? Bud
Bud Krueger

Jim, I might be able to help. Contact me via email at the address above. Bud
Bud Krueger

Same place I did Bud. The original Virgin Rear End Conversion article was actually published in the North American Classic MG Magazine Issue 3, Summer 2001, a sports car magazine; so I would assume the copyright rests with them and/or with the author of the article. The Cederstrand document is distributed by Moss, just as you said - which is where I obtained my copy...
Peter TD 5801
P Hehir

> Ring and Pinion Interchanges - Carl Cederstrand
http://www.ttalk.info/RingAndPinion.pdf

> T-Talk
http://www.ttalk.info/RearEndConversion.htm

> T-Talk
http://www.ttalk.info/RearEndConversion3.pdf

> Dave Clark 4.3
http://www.ttalk.info/ClarkConversion.html

Lonnie
TF7211
LM Cook

Hello Jim and Kevin. I'm still doing the conversions. Contact me off site at mgyowner@yahoo.com for more information.

Butch Taras
R Taras

I have a 4.1 in the TD, I have an .80 over xpag and the 4.1 is fine. I ran on the freeways with no problem, sometimes you have to drop down a gear but overall I think I made a good decision. JMHO
TRM Maine

Good day to all. Thanks so much for the feedback. Thanks Lonnie for the feedback from the Florida group.
On the Carl Cederstrand instructions, I found both it and the Virgin Rear End Conversion on the internet. I read Carl's excellent material and decided that this was not a job for the faint of heart.
To address one of the concerns about low-end and hill climbing power, the engine is currently bored at.080" over and I had planned to do some enhanced tuning.

Tom, I found Dave Clark on the internet and sent an e-mail, but did not get a response. Is it possible that I found an old address? I was also considering the axle shafts that you mentioned.

Since several of you brought it up, what does everyone think the modestly enhanced rebuild of the engine should include? Tom mentioned a hotter cam and higher CR. What is advisable and what is just plain fun?

Jim
JV Smith

The Atlanta chapter’s version is pretty straight forward and a nice weekend project, the tough part is finding a donor MGA pumpkin to scavenge.

Regards, Tom
tm peterson

Dave Clarke quit supplying axle shafts. The good news is that Tom Lange of MGT Repair now sells the same items.
Dave H
Dave Hill

Dave Clark built me a 4.1 rear for my TF 1500, it was the last set of 4.1 gears he had, I hardly ever have to downshift on normal highway driving. PJ
PJ Jennings

I run a 3.9 in my TF,stock thickness head which I ported myself and a fast road cam with original gearbox. I do have to change down a bit more often than I did, it has been in for more than 20 years. It is a lot nicer than the original stump puller.
Mind you, I live in a country that considers a hill over 1000 feet as a mountain :-}
Ray TF 2884
Ray Lee

Ray, I have a set of 3.9 gears from an early MGB banjo rear and thought of putting them in the TF, but went with the 4.1 instead. My rebuilt XPEG is quite snappy and I often wondered how it would preform with the 3.9 in it. If I had another T series rear housing, I'd build it. PJ
PJ Jennings

IMHO, from first hand experience (from living in Minnesota and Colorado) if you have any kind of significant hills, let alone mountains, would highly advise NOT going to anything less than 4:3 in a stock TD! Otherwise you'll be spending a LOT of time in 2&3 gear running 4500+ rpms.

And then with 4:3 you'll need a properly tuned 1250. Maybe if you have supercharger a 4:1. A supercharger TD with 4:3- IDEAL!
Randy
R Biallas

MG SERVICES www.mgrepairs.com
Jim Pesta in Ohio also does this conversion.
Dave Clark no longer does them.
As Tom Lange states "To make up for the higher ratio I boost the power of my cars a bit; higher CR, hotter cam, etc., that more than makes up for the 4.3 axle ratio"
My Abingdon Performance Ltd. Street performance roller cams, normally aspirated or supercharged profiles work very well.
CSI igniton distributors for T types ( Lucas 23 D / 25 D housings) in stock with special curves for XPAG XPEG engines
Len Fanelli
Len Fanelli

Jim - please see mgtrepair.net for information on the Dave Clark/MGT Repair axle shafts. They are well worth doing, for peace of mind if noting else.

Tom Lange
t lange

Jim and Kevin:

Ken Silvia did my 4.3 conversion and also did one for a friend...machined his own single spacers...nice work.

Jim
James Auer

Hi all
The other solution to this problem is a 5-speed gearbox. I had a Volvo 5-speed laying around in my workshop and put it in the car. The result is great; I have the usual first 4 gears for the mountain roads here in the pre-alps and the fifth for the flat roads in the valley.
Just my suggestion
marcel
Marcel Schaepman

Marcel - I have not heard of a Volvo conversion. Can you give us details of which transmission, and what you had to do to make it fit? Was it a 5-speed, or a 4-speed with the Laycock-de Normanville overdrive?

Thanks. Tom Lange
MGT Repair
t lange

Hi Tom
I have no idea if others have done it. I just had this gearbox ready. It is a real 5-speed, I think it comes from a 760. In those days the overdrive of my 244 broke and I replaced it with this box. Some time later the whole car died (at 545000 km) and the box came to rest under my workbench.
I made an adapter plate between the MG clutch housing and the volvo box. The box is a little shorter than the original 4-speed so I made a little adapter for the transmission also. The clutch is a mix of the 2.
All this without making any hole in the car; if someone later wants to put the car back in its original state, it must be possible. So I made a new cover for the box.
Marcel Schaepman

Here are a number of directly installable CWPs available for our TD/TF axle housings. Yes, its a mix of banjo and split axle housings, but that doesn't really matter as its really only the CWP that you need:

A LIST OF INTERCHANGABLE CROWN-WHEEL AND PINIONS, FOR ALL MGs, FROM THE TD TO THE MGB

CW-P Ratio Teeth P to CW Application MPH/1000 RPM

5.455 9 : 49 Opt TD

5.125 8 : 41 Std TD 14.80 67.530

4.875 8 : 39 Std TF & ZA/ZB 15.57 64.236

4.556 9 : 41 Tunung Opt for TF 16.66 60.027

4.300 10 : 43 Std MGA 17.65 56.659

4.100 10 : 41 MGA MK II 18.51 54.024

3.909 11 : 43 Std. MGB 19.41 51.509

3.727 11 : 41 Opt MGB 20.36 49.113

Sorry its so jumbled. Took it from an Excel file.

Gord Clark
Rockburn, Qué.
Gord Clark

Hi Gordon. I thought that the 4.55 was std for the ZA/ZB. That's where I got the gear sets from

Butch
R Taras

The 4:55 was also available as a option for the TD MK II. Regarding the MGB CW&Ps. Does that encompass all MGBs or only certain years?
W A Chasser

Butch: I got that info from a ZA owner who had changed to a 4.3, a 5-speed, and installed a seriously modified MGB engine.

Bill:- MGBs had several axles but all used the same CWP and of course, are interchangeable up and down the MG range. But the MGC is an entirely different axle.

Gord Clark
Rockburn, Qué.
Gord Clark

Gordon thank you for your response. I didn’t realize the MGB CW&P were interchangeable. I always thought the MGA 4:30 and 4.10 were the only options.
W A Chasser

All Mark II TDs and TFs came standard with the 4.875.

Tom Lange
MGT Repair
t lange

Hi Marcel, I have one of these Volvo 5-speed gearboxes sitting on the end of my spare engine. In this case the doner was a Volvo 240. I don't suppose you have any pictures of the adaptor plate?
Cheers, Hugh
H.D. Pite

Hi again to all,
Ok, my rear end is out from under the TD. Starting to clean the frame. Ready to send out rear end for 4.3:1 conversion. Since we have moved on to engines, I would appreciate advice on enhanced engine rebuilding. My engine is already at .080" over. I will be doing a complete overhaul, but I do not expect any damage or change to the cylinder bore. Where is the most "bang for the buck" in enhanced engine work? What about higher CR, larger valves, better guides, and head work for unleaded fuel?

Ray, what about the porting? I have seen it described somewhere, but I cant find it. Did you do the porting yourself, or should I let a shop do this? I have the stock S.U 1.25" carburetors.

All advice is appreciated.

Jim
JV Smith

Jim try contacting the local chapter of the M.G. Car Club. There is bound to be someone there who can assist you. Thankfully there are still one or two M.G. clubs around the world whose focus is on the cars rather than administration or the social aspects. I'm not in the least interested in wasting a day on fish and chip runs or spending a couple of hundred bucks on fuel and a meal to view kangaroos; but am ever willing to engage with knowledgeable owners on the technical aspects of these cars. There are a more than a few on this forum who could assist, but nothing beats the face to face/hands on approach. Contact me offline and I can provide you with a couple of options. pjbm at bigpond dot com. Cheers
Peter TD 5801
P Hehir

Refer to "MG - the XPAG engine by WKF Wood". It includes much information on tuning and can be found on the net quite easily. This can be supplemented with information from elsewhere. I did almost everything that Woods recommended for Stage 2 and looked at lots of pics of work done to cylinder head porting before tackling it myself.
Dave H
Dave Hill

Jim,

When I was contemplating the engine rebuild, I contacted a vintage racer for advice. I pretty much did what he said:

New internals (crankshaft, rods, custom pistons)
Derrington style exhaust header;
Lightened flywheel (w/diaphragm clutch, roller t/o);
Head porting, light skimming (CR about 9:1),MGB springs with spacer;
Hi-Gear 5-speed;

I did not take his advice for a sports camshaft and stuck with the Crane std cam 340-002. There are quite a few cam choices out there now, but the Crane seems to work well.

I think the emphasis on breathing combined with the flywheel lightening made a big difference. I have had no negative issues due to the lighter flywheel.

This is one way to go, and it gives a good engine.

https://www.freewebs.com/manley776/
J Barry

Jim,
I matched the manifold to the head to remove steps and then thinned off the leading edge of the inlet divider,dont go mad there as the head bolt goes through it.Equally to both edges to ensure one tract is not getting preference.Port shape is important,we used to make tapered inserts to get equal mixture on single carb twin m/cycles in the 1950's. Not too shiney a surface as you need some turbulence in the mixture.
Ray TF 2884
Ray Lee

not head bolt, I meant stud
Ray
Ray Lee

Thanks for all the good information
JV Smith

I have an early MGB Banjo rear on the shelf and I think it's a 3.9. PJ
PJ Jennings

All MGBs had 3.9
There is some confusion as a list I've seen lists MGB diffs as B series diffs through to 3.07 but doesn't note the change at 3.9 from pumkin(banjo) to Salisbury which continued through MGC and MGBv8
I had always believed MGBs with auto trans were 3.7 but having had one out it was 3.9 and a Salisbury as autos didn't come out till MK2s were released
William Revit

We've danced all about the conversion issue, but I haven't heard of any available 4.3 or 4.1 CWPs. They're getting impossible to find.

Autogears ran a batch about 15 years ago and they were asking £500 for a set. I contacted them a few years ago, without response.

I'll bet if someone underwrote a run of say, 25 sets, they'd be gone in a few days, if the price was under $500 US. About 5 years ago, I contacted Aisan and it took me a month to get an answer. They would do it for a run of several thousand, but not 25 or even 50 sets.

There are several companies who make small runs, one of the best is TANDLER Zahnrad- und Getriebefabrik in Germany, but they make Ferrari and Porsche special runs, and I'm afraid we'd end up facing Ferrari and Porcshe prices!! Quaife might be worth a try.

Gord Clark
Rockburn, Qué.
Gord Clark

Gord
Found this, might be of interest-

https://www.mgcarclubsydney.com.au/fitting-mga-mgb-crown-wheel-pinion-t-final-drive/

and this --325 UK pounds--------$406 USD

https://www.ukmgparts.com/product/mga-midcat-1-submga42-rear-axle-assembly-differential-wire-wheel-conversion-kits/4-3-crown-wheel-pinion-10-43-banjo-88g283
William Revit

Gord,

Both Moss US and Moss Europe have the 4.3 set available for the MGA. These are interchangeable with the TD as long as you use the correct pinion spacer and the MGA drive flange.

https://mossmotors.com/gear-set-standard-4-300-1-10-43

John
J Scragg

JV "For the best bang for your buck" ask Tom Lange @ https://mgtrepair.net/ phone # 207-288-0978.
I am a Crane Cams dealer & will match any advertised Crane Cams price! When only the best will do my Street Roller Cams, a roller cam will always outperform a flat lifter cam of the same duration, with no cam or lifter wear, and a much wider power band! I also supply state of the art swirl polished valves instead of using a 85 year old design. Avoid porting work, I know of only a few that can properly do porting! Ray Lee above info on porting is correct. A proper 3 or more angle valve job is a must, use the later 36/34 MM valves & throat size.Have the valves unshrouded in the combustion chamber, use an old head gasket as a template.
I have been building engines for 55 years.
Land Rover / ASE Master Technician
Abingdon Performance Ltd. since 2006
Recommended by MG engine builders world wide!
http://www.ttalk.info/Fanelli.htm
Len Fanelli
914 420 8699












Len Fanelli

John,
Gord
There is a cheaper source for MGA gearsets. The CWP costs 282.56€ incl VAT.
https://shop.bastuck2.de/index.php?&cat=40000&hg=41000&lang=en
Bastuck commissions gearsets and that is probably where Moss sources them. This info I got from a local gearbox and axle specialist. I purchased a midget 3.9 CWP set from them for my Morris Minor but had issues with the tolerances although that was a few years ago and it could have been my mistake. On the wrapping it stated "Made in Turkey".

Regards
Declan
Declan Burns

John,

You are spot-on. Yes in Moss' catalogue 267-180 at $600 US. Pretty dear for we Canuks!

Many thanks for your astute observance.

Gord Clark
Rockburn, Qué.
Gord Clark

This thread was discussed between 10/06/2020 and 09/07/2020

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.