scary new gearbox/clutch noise

[mogatron]

hi team. i've just put a recon gearbox on the mogatron and a new clutch set. was very happy with my self. then stared her and when driving there's a slight grinding noise. it worse in second. is that normal?

[alex_holden]

Not really; a newly reconditioned box should whirr slightly in first and reverse but be virtually silent in the other gears. Did it come with a warranty?

I think Mogatron is a great name for your car, BTW.

[bmcecosse]

First - check you have some free play in the clutch pedal, and a return spring attached - to make sure the release bearing is not rubbing on the clutch cover all the time. If that's not the problem - then straight on to whoever 'reconditioned' your gearbox and ask them what they are going to do about it! It should be virtually silent. Of course I assume you have filled the box with engine oil ok ??

[mogatron]

cool i think theres about 1"1/4 1"1/2ish play in pleddle but shall cheack tomorrow. got gearbox on a sertain bidding website that a guy had spare so cann't really shout at anyone. not that i'm much of a shouter. yeah there slite whirr in first and reverse just second sounds like its rubbing on something but only when coasting in gear and not when accellerating. is that bad?

[bmcecosse]

Well - if it's ok in 3rd and 4th, and not jumping out of gear on the over-run - it may just need some Running In.

[rayofleamington]

only when coasting in gear and not when accellerating. is that bad?

The fact the noise changes under load is interesting as it rules out some faults, but hard to say if it's 'good or bad' until the root cause is known.

Did you change the bush in the end of the cankshaft?

[mogatron]

yeah changed the bush on crankshaft as old one disintergrated. shes got a small oil leak fron the propshaft oil seal, i don't know if that makes any difference. oil level ok still.

[MoggyTech]

A slight grinding noise that is worse in second, would suggest the noise is there all the time, but more noticeable in second?

If it does it in neutral it's either front or rear main bearings in the box
If it only does it in gear, it's the layshaft bearings.
If it only does it in second, it's likely to be syncro unit or selector fork bedding in.

Might just need running in, but rebuilt boxes are usually fairly quiet if rebuilt correctly using quality parts.

[MarkyB]

a small oil leak from the propshaft oil seal

Do you mean where the propshaft goes into the gearbox?
I believe there is a brass bush in there as well as the external seal.
A leak there would suggest the bush may need replacing
Anyone know if this would normally be replaced when reconditioning a gearbox?

[MoggyTech]

Usually easy to tell if the rear bush has been replaced as the propshaft is a pig to get back into the gearbox, as most companies don't ream the bush once fitted in case the old prop nose is worn.

Very slight oil leak from the rear bush ( a drip or two over night ) is fairly common, nothing to be worried about.

[mogatron]

propshaft wasn't that hard to fit back in. i think the guy that the guy i got it from bought a moggy with it on and changed it or something like that. so might need new seal i think cos more like 9 or 10 drips a night. is it worth changing the bush at same time?

[bmcecosse]

It's a job to change the bush! And it needs reaming to size once installed. Try a new seal first - but really - I would wait and see if the box is going to be any good before worrying about a few drops from the tailshaft!

[les]

most companies don't ream the bush once fitted in case the old prop nose is worn.

If they don't you will not get even a very worn prop spigot into the bush, me and these bushes have had many encounters!