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Gearbox Reconditioning

I've just picked up 2 used 'boxes for my 75, and plan to have one reconditioned before it's put in the car.... don't fancy taking a chance on just sticking one in, as there's a risk it will be as bad as the one I've already got.

AFAIK, the weaknesses in this box are synchro rings and differential bearings.

Any idea how much I'm likely to have to shell out for this work to be done? - or is it something that isn't too hard to do at home? (Never touched a 'box before)

A recommendation for somewhere to take it within reasonable distance of Cardiff would be handy, too.

Cheers,

Reply to
SteveH
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["Followup-To:" header set to uk.rec.cars.classic.] SteveH was seen penning the following ode to ... whatever:

AFAIR the repair bill for the overhaul of my 3l's box was in the order of 300-400 quid, and that was a couple of years back.

As to doing it yourself - check the BoL if it mentions the use of hydraulic presses somewhere in the gearbox overhaul section, that might be a clue...

Actually I wouldn't do it myself, but that's got more to do with the hassle factor than the complexity of the job. The question is more like - are you confident that you can do a job that'll last a reasonable amount of time/miles compared to a pro job for a lot less?

Reply to
Timo Geusch

Ouch. Lets hope it's cheaper in Wales.

Still - most places wanted £250 for a used box, and I got 2 for a hell of a lot less :-)

Ahhh, that's not a good sign. A proper '5 spanner' job, then :-(

I'll fork out for it, I reckon. Should be able to save on parts as I have 2 lots of bits to pick from.

Reply to
SteveH

Just avoid the temptation to mix gears - it'll end up noisy. Keep the sets together and choose the best one. Should be ok to mix other bits, though.

Reply to
Dave Plowman

But Sod's Law says that both boxes will have the same grotty bits :-(

Ron Robinson

Reply to
R.N. Robinson

But it's exactly how the re-con trade work. Chap doing rebuilds in Derby has a yard full of donor gearboxes, he buys them from local breakers which puts a high price on second hand gearboxes. Gets expensive if all boxes need new input or main shafts.

-- Peter Hill Spamtrap reply domain as per NNTP-Posting-Host in header Can of worms - what every fisherman wants. Can of worms - what every PC owner gets!

Reply to
Peter Hill

And that's exactly why a cheap re-con isn't as good as new - gears 'lap' themselves into one another, and mating secondhand ones results in a noisy box. Even mating a new gear to old will be noisy.

Reply to
Dave Plowman

Totally agree. Mixing and matching mated gear pairs is bad news. On most boxes some gear pairs can be split form the set and safely used in a different box like 5th and reverse which are keyed on the end of the layshaft and run free on the main shaft. All gears which are fixed on a shaft have to stay as a full set with the free running pairs. Things like syncho rings, clutches (as a cup/cone set - they bed in too) and selector forks/rods can be swapped. Output shaft on rwd boxes usually don't have fixed gears (or only reverse which is free on the layshaft) and can be swapped. Layshaft drive gear usually detaches so input shaft and layshaft drive gear can be swapped as a pair. On FWD all sorts of arrangements exist, all fixed on output like a normal RWD layshaft, 2 gears fixed on input with 2 fixed on output, 5th and rev keyed is used on some Citroen boxes. So you could mix and match an output with a different input so long as all the free running gears are kept as pairs with the fixed ones.

-- Peter Hill Spamtrap reply domain as per NNTP-Posting-Host in header Can of worms - what every fisherman wants. Can of worms - what every PC owner gets!

Reply to
Peter Hill

I'm not planning on new cogs - just synchro rings and diff. bearings really.

As for output shaft..... I don't have one ;-)

Reply to
SteveH

ALL gearboxes have input and output shafts. What you are missing if you have a step over box (normal FWD) is a layshaft.

-- Peter Hill Spamtrap reply domain as per NNTP-Posting-Host in header Can of worms - what every fisherman wants. Can of worms - what every PC owner gets!

Reply to
Peter Hill

Hmmmm. Not sure of the full mechanics of it, but the gearbox and diff. are one unit mounted under the boot floor.

Reply to
SteveH

SteveH ( snipped-for-privacy@italiancar.co.uk) gurgled happily, sounding much like they were saying :

The 'box output shaft is the short one carrying the pinion for the diff.

Reply to
Adrian

Care to explain more fully? The only FWD boxes I've had apart were BMC ones, so basically the same as RWD.

Reply to
Dave Plowman

It's bit hard without pictures.

Conventional RWD standing box up on tail shaft. Ascii art use fixed pitch font to view, set tabs to 8. V is the needle roller bearing that the output shaft runs in spigoted into the end of the input shaft. When 4th is selected the input and output are directly joined by the 4th gear selector. ---> indicates direction of power flow though meshed gears. Except for 4th the power is transmitted from the input shaft though a gear mesh to the layshaft and then though a second gear mesh to the output shaft. Reverse, 5th and input/layshaft drive gears can all be replaced as pairs. 1st, 2nd and 3rd must be replaced as a set with the layshaft. Output shaft can be replaced without replacing any gears.

Clutch spline on input shaft ] [ bearing bearing input gear fixed---> layshaft drive gear splined on V ] [

3/4 selector ] [ ] [ ] [ 3rd gear free
Reply to
Peter Hill

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