transmission failure - pics included!
Turbo Mini Forums

i have been running a gt close ratio gearset in my cooper, ususal mods, cam, head, overbore etc etc.

git it mot'd last week (thursday). drove out of the test station, the gearbox started to whine and rumble. i have had minis like this before and the gearbox has worked fine for a long time afterwards. i drove to work the day after, the noise worsened. then i lost drivwe when i arrived at work.

got a tow home, pulled the engine out friday night, dropped a tempory replacement in satuday and got it running again.

i pulled the diff housing off and saw some needle rollers/tops of teeth in there. initially i thought my gearset had gone. had a spare hour earlier, split the engine from the gearbox, this is what i found.

drop gear totally stripped. looks like the gearbox side needle roller had failed. also a need roller had collapsed on the layshaft, otherwise it all looks to be good. a lucky escape i think - it would have cost a fortune to replace the gearset

dan

Nasty ! But like you say, it could have been worse.

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You didnt have a mix of A and A+ drops did you?

I seriously doubt it!

Common failure on the pre A+ idler gears as the shafts are smaller iirc.

Ive done this and drove home on it

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

yes drive totally went, i did have a tow so does that count

the gearbox is a funny one - its a very late 1275 gt, with an early a+ casing. i even bought the idler conversion bearing to allow you to use the a series drops with the a+ flywheel housing, only to find that the original drops were a+. i did not mix and match - i think i used the drops that came with the gearbox.

i think that this might also be the cause of my reccent intermittent starting problem - sometimes it would only turn over very slowly, not enough for it to fire,. the next day it would be fine. i think it might be because the idler bearing was completely shot.

dan

spirited driving seen this many times, wind it up & drop the clutch ..... it could have been much worse! dan.

Mine lost 60% of the teeth so was still driving

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

That's bost that is.

and its still got more teeth than half the donny birds!!

Yes i moved to the darkside

Instagram @jdm_brett

On 4th Apr, 2013 BENROSS said:

On 4th Apr, 2013 Brett said:
and its still got more teeth than half the donny birds!!

been there bret in the 80s ...nothings alterd then ?

Yes i moved to the darkside

Instagram @jdm_brett

that sux hopefully the shrapnel didn't do to much damage to journals ect has anyone heard of the med fixed pin roller straight cuts drops doing this?

Try a night out in the valleys...now thats an eye opener!

The oil pressure has been gradually dropping over the last month, i presume now that it was related to this.

It was very low when this happened, hopefully the bearings took the damage and not the crank. I will whip the caps off this coming week to investigate.

The engine was getting tired, head and rockers needed an overhaul, as well as the cam being knackered, so will have a look and see whats what

Edited by welshdan on 6th Apr, 2013.

Yummy

Confessed addiction to everything mini

dan as you know what happens the gearbox starts to disintigrate and then the debris builds up and blocks the oil filter opens the bypass on the filter housing .......... hey presto! fooks the engine bearing etc ......like you have mentioned,

regular filter and oil changes bring to mind.

benross i changed my filter and oil almost weekly on my daily mini it never ever had even slightly dirty oil always like honey it still craped out the crank and bearings form abrasive wear i believe the bypass function needs to be fooked off and a far larger filter put in place cape able of passing the full flow of oil at high rpms i have got the spin on housing with out a bypass i just need to find i massive filter with no by pass if not i have an idear of setting two up in parallel

Was the crank heat treated?

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

i don't think so? like ni tried

yep I was just thinking you would have more chance the bearings taking all of the hammer and not the crank?

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

i agree the softer material takes the abuse my point was i keeped golden oil in my mini and it only lasted 3 years or there abouts i think its more inportent to have the oil compleatly filted not just a fraction on it

I also did frequent oil and filter changes on this. I think that once the idler bearing started to go that was it.. the gearbox casing is also scrap as the idler thrust face has worn at a funny angle as you could imagine. Going to build completely fresh engine and gearbox, hopefully will give me another few years and good mileage. Only problem is that its put getting my turbo running with its new engine back a few weeks