Tr4a gearbox

[DMRL]

Hi all - I am doing a complete rewrite build of my 67 tr4a - have just started the chassis and drivetrain - looking at gearbox it has an "MB" serial number. Have searched the web and it suggests this is from a 2000 saloon - can any one tell me what is the difference between this and the correct gearbox ie ratios etc plus if I trade in for reconditioned correct unit from say rimmers will they accept it?

[John Morrison]

No diference with ratios whatsoever,

Back in teh day Moss stated that for G/B rebuilds they may

take your TR box and return a rebuilt saloon Box,

don't worry about it,

 

Input shaft may be different diameter if it has not been changed in which case you run a Saloon Driven Plate with a

TR Pressure Housing, again without any issues.

John.

[Lebro]

An unmodified saloon box will have a different input shaft, different overdrive inhibit switches (3rd, & top only) a reversing light switch, the speedo drive will be at a different speed ( 2.5:1 for TR box, 3.5:1 for saloon), & if overdrive fitted the overdrive will not be as strong internally as TR, & will have the wrong rear casing to match your mountings.

 

Other than that they are exactly the same !!

 

Bob.

[The_Doc]

I have recently rebuilt a TR4A gearbox (non-overdrive) and added on a J-type overdrive onto it. I bought an old Dolomite Sprint gearbox that had the J-type over drive on it, that I could then swap over. The things I found were that the gear ratios were different, you can do your own snaity check by counting the teeth on the cogs on the lay shaft and doing a couple of sums. The input shaft for the salon cars also seem to be different as Bob has pointed out above, and there was problems with the gauges used, i.e. the main shaft was metric, which meant I have to have a sleeve made and pressed onto the main shaft to get it to fit.

 

Like John and Bob have said things should fit, but it's worth just doing a quick checks first to make sure you know where you stand.

 

Adam