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MG MGF Technical - Tyre pressure mis-print?

Sorry, two posts in one day...

Reading through the owners handbook and it states the rear tyre pressure for my new (to me) 2002 TF should be 36 psi. My old 1997 VVC was 28 psi for the same 205/50 R15 tyres. Is this correct?

Also the same book states the gearbox oil capacity is 2.2 ltr. I've always thought that the engine and gearbox used the same oil, with one filler and dipstick.
Where would the gearbox filler and level check be found?

Mike
M King

Confucious say "man who fail to ask questions pay large repair bills" ;-)

The 36psi rear tyre pressure is specific to the factory-fitted 215/40 16 Goodyear Eagle F1 GSD2 tyre, reflecting its softer sidewall. If that's the tyre you have fitted, that's the correct pressure. Manufacturing has dwindled to occasional batches so supply is intermittent, many owners have opted for alternative tyres and almost without exception they'll not require such high pressure. If you give the corner or axle weight to the tyre manufacturer they'll be able to confirm the appropriate pressure for their tyre, but if the fitted tyre has a load rating of 86W (the more common for 215/40 16" tyres) that's usually in the 30-32psi range.

The gearbox oil is separate to the engine oil, on the side of the gearbox casing there is a plug with a 3/8" square drive socket in it and that's the drain out point. A few inches above it is a 17mm plug, that's the level check & filling point #2. On the top of the casing, almost hidden by the starter motor, is a filling point, which I regard to be #1. Workshop manual method is to remove the level check plug, and add oil until it overflows out again, based on MGR regarding the MTF-94 gearbox oil as being 'For Life'. My preferred method is to drain completely, whereupon you'll likely discover nowhere near 2.2 litres comes out (underfilling at the factory was a well-known issue) and then re-fit the drain plug, fill with 2 litres of fresh MTF-94 oil through the top filling point, undo the level check plug, and slowly add the remaining 0.2 litres or until oil flows out of the level-check hole. Dieter's site has a good page on this - http://www.mgfcar.de/gearbox/refill.html
bandit

Thanks Bandit,

Well, I had a VVC for 11 years and never ever checked the gear box oil level, let alone renewed it! Always thought the engine 'shared' the oil like the old Minis. I'll check out Dieter's site as suggested.
As for the tyres, this car is 9 years old, so I expect they have been replaced several times.
Mike.
M King

i have just fitted four of these bf goodrich profiler tyres to my MGF freestyle
http://www.bfgoodrich.co.uk/bfgoodrichuk/en/tyres/sizes/20071217163749.html

215/40 ZR 16 86 W

since that is the size that was fitted , though they were very shoddy korean cheapies, fitted before i got the car.. and one had developed splits all around the inside rear wall on the drivers side.. and all had flat spots and were really irritatingly noisy.. like a faulty wheel bearing noise.. so much like a wheel bearing noise i began to think it might be faulty bearings.. of course it wasnt.. it was the crap tyres.

the Goodrich tyres transformed the ride, tyre noise and steering instantly.. so far, worth every penny..

the pressure ive found by perusing this site.. and ive set all four to - is 28 psi.. and that works for me.. but they are XL tyres.

N.J. Simon

I must admit I've never realised that the recommended high rear tyre pressures of 36psi were specific to the Goodyears. What is the recommended rear tyre pressures on the TF for Toyo Proxes?

John, Surrey
J Rudofsky

Techspeed Motorsport routinely service my TF. Some time ago they recommended 28 PSI all round. They said that this was the pressure they specified on their MGF Cup cars. Techspeed are well regarded on this forum. I've run on 28PSI all round(on Goodyears) for about five years with no problems and the lower PSI doesn't seem to have had any adverse effect on either MPG or tyre wear.

Also gives a more comfortable ride on a car fitted with sports pack suspension.

HTH
R Thompson

I'd trust Gavin from Tech-Speed more than any other if I was to entrust an MGF or TF to someone else's spannering, but bear in mind that the Cup cars didn't run on GSD2 tyres, and used the Cup alloys not the 11 spoke. If your Goodyear tyres are the 'replacement' GSD3, these have a stiffer sidewall so the 36psi rear setting isn't appropriate. If yours are the original GSD2 and you prefer the 28psi-all-round option over the 36r/24f MGR specified, I'm surprised. I tried 1 lap of Donington at 28 all round on GSD2s and once through the Craner Curves was enough to have me stopping mid-session to go straight back to 36r/24f
bandit

This thread was discussed between 01/01/2012 and 19/02/2012

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