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MG TD TF 1500 - 4.3 rear end?

At the moment I have a 4.5 diff. With 165/80R15 tyres I get just shy of 16 mph for 1000rpm. The car is very comfortable cruising at 3000rpm but I feel a bit under geared and would like to be doing at least 50mph at those revs. I am thinking of changing to a 4.3 diff ratio.
I generally tend to pull away in second gear. Will I still be able to do this with
the 4.3 diff or will I have to use 1st gear more. Many thanks. Lionel.TD3490
L.F. Thorne

Hi Lionel,
I have the 4.3 ratio. Yes first gear is necessary. I have a stage 2 engine but I think this doesn't change anything for low rev. At high rev this is definitely the ratio suited for cruising with this stage 2. Also suited for mountain driving shifting to third or second with very good overall performance.
Knowing this I'm not sure that the 4.3 is the right choice for a standard engine.

Laurent.
LC Laurent31

You will slip the clutch more if you get started in 2nd with a 4.3, so will probably use 1st more. I just start rolling in 1st, then shift right into 2nd and accelerate briskly.

I don't generally recommend a 4.3 diff on a standard engine, unless it is a 1500 - a stock XPAG will need to be somehow power-enhanced. With a stock engine I recommend a 4.3 ONLY if you live and drive on dead flat roads.

Tom Lange
MGT Repair

t lange

I converted to a 4.3 15 yrs ago with a standard engine tune. No issues in drives from Illinois to Vermont and Texas.
Highly recommend the change. You will use 1st.. but that is why we have it.

Regards, Tom
tm peterson

I can confirm this. 10 years with 4.3 on a standard engine. It has 1 1/2 carbs, but Idon’t think that makes much difference. I live in a hilly area, and have no issues going uphill. The car has great torque as long as you stay above 2000 rpm, then it is time to shift down to 3rd…
Perfect cruising speed off highway is when the tacho needle points straight up (3000) ;-).
Rgds Mike
Mike Fritsch

Thank you all for your thoughts and experiences. If I go ahead and fit the 4.3 I will report back. Thanks again. Lionel TD3490
L.F. Thorne

This thread was discussed between 11/06/2025 and 16/06/2025

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