Gearbox
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3000M
Ford 4 Speed Gearbox as standard. Pretty strong reliable gearbox, cast iron casing & bellhousing. Layshaft wear evident after year of use but generally last well.
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A 5 Speed gearbox conversion is a favourite for the 3000M (Ford Sierra), as are overdrive options. The Reliant Scimitar GTE had an overdrive gearbox fitted & so many second hand boxes complete or for spares are still available. As the Ford Gearboxes generally had the same gear casing bolt pattern, adapting other (better) Ford gearboxes has been possible, including the Cosworth Gearbox. For the 5 speed mod you'll need to shorten the propshaft nose by a small amount. More details to follow on this.
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4 Speed fitted to Essex 3 Litre V6 in the M series & Taimar
Pictures to follow shortly.
The four speed Ford Capri gearbox is the most common one found on the 3 litre cars. It is a little long in the tooth as far as performance is concerned, but a straight cut gear kit is available to make it more suitable for the "tuned" Essex engine. Many people opt for a 5 speed 'box, but this requires a bellhousing adaptor, and some go as far as fitting a Cosworth type gearbox..... Not much goes wrong with the 4 speed gearbox, main problem areas that do exist are:
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Oil seal leaks inside the bellhousing, but more common is the seal leaking at the propshaft end.
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Jumping out of second gear on deceleration (can be worn synchro hub/ring, or loose gearbox mount)
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Rear (and only) gearbox mount can disintegrate due to oil leaks getting onto the rubber coupling.
It is a bit of a myth that gearboxes are a nightmare to work on - in fact as long as you're a methodical person and have a bit of patience, there is no reason why you can't strip & rebuild it yourself. Parts for this gearbox are becoming scarce now, but keep an eye out for the online parts pages appearing soon - I intend to eventually keep a stock of the usual items which are required to keep your cogs spinning, or perhaps even stock exchange gearboxes which may be a more useful option...
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5 Speed (Scimitar) with overdrive
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5 Speed Sierra
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2500M
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1600M
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Propshaft
3000M
TVR made their own propshaft to allow the Ford Gearbox to mate with the Jaguar or Triumph Diff.
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Differential & Half Shafts
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Salisbury
The 4HU diff was fitted, with optional Limited Slip
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TR6
Triumph Type Differential
Overview
1. The Triumph TR6 differential was fitted to many of the M Series Cars, generally being used for the smaller 1600M and 2500M models, but also used on the earlier 3000M cars. Parts are generally easy to source, Rimmer Brothers (see links page) being a popular place to find new parts.
The main problem with servicing the differential is its location. Access
is really only available with the unit removed, and that can be done either by
removing the bodyshell, or fabricating an access panel inside the car.
Draining & Filling
Drain the diff using the bottom drain plug. You'll need a suitable open ended spanner unless you have the correct female square drive socket handy. The thread is a taper fit so the plug needs to be tightened well when refitting to prevent leaks. If this still leaks (not very common) use some plumber's PTFE tape to seal the thread.
To fill the diff, use a suitable gear oil pump to fill using the filling/level hole (2) until the diff oil can be seen to drip from this hole (car must be on level ground). Again use the correct sized spanner to remove the filler/level plug. There is a vent tube with a dirt cap (1) in the rear cover plate to allow venting of the diff casing for changes in oil temperature and therefore air expansion/contraction.
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​Half Shafts
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