14 replies to this topic

[valve bounce]

1275 with 276 cam, big valve head, exhaust inlets stuff etc on a serise gear box with standard a serise drop gears.

the problem is when driving along at 30ish it makes a noise like it has striaght cuts, the gearbox was rebuilt 10,000miles ago and the drop gears and bearings are only 1700miles old, now my dad reckons that the idle bearings are shot at and thats whats making the noise and the upratedness of the engine has caused them to wear quickly. i will admit i do drive it quite hard but surly the bearings should last longer that that?

to the clever folk of tmf please help

[MRA]

Good old dad knows his Minis

If you are hard on the clutch then the idler bearings will fail quicker 1700 miles is a little low, but it really depends on how hard you drive

[bmcecosse]

Dad is right - as always ! Stop driving it NOW before you do serious damage.

[Twisty]

how would you go about changing the idler bearing? as im sure i may need to do this myself soon.

[valve bounce]

dam, probably doesn't help that its got a orange diaphragm clutch and come to think of it the other weeks i discovered that it'll spin the wheels in 3rd gear in the wet.

whats the best way to fix it and prevent it happening again?

[Guess-Works.com]

Well it's an engine out job for a start...

An orange diaphragm on it's own will not harm the idler bearings, it's more likely to be the initial set up and shimming, and or driving style...

The engine spec' would give me no cause for concern relating to longevity of idler bearings ( or gears ), oh and as you're wheel spinning in third, I'd check your diff pin while you have the engine out.

Edited by Guess-Works.com, 20 May 2011 - 06:26 PM.

[valve bounce]

i put a new diff pin, planet gears and them washer things in the diff when i rebuilt the engine, im wondering if i've shimmed the idler gear up wrong when i built it up, so over the bank holiday weekend i will lift the engine out strip the end case off and replace the bearings, correctly shim the idler gear and check the diff.

couple of other quick ones, is it possible to reshim the idler gear without splitting the engine from the gearbox?
is it worth upgrading to a 4 pin diff if so which one?

[bmcecosse]

Yes - you can shim with box on engine - but the gears may be dmaged if they have been running in loose bearings - so be sure to have a new/another set handy. I certainly wouldn't refit these ones..... Better hope the casings aren't damaged.

Edited by bmcecosse, 20 May 2011 - 07:35 PM.

[valve bounce]

i have a spare set in the shed just in case, how would i go about measuring the the float of the gear without splitting the engine/box? remove the primary gear then refit the housing and poke the feeler blades through the crank/gear hole?

[valve bounce]

just been out to do some investigating, with the engine idling there's a rumbeling/wuring/bearing noise, when you press the clutch it disappears so im confident that its the idler bearings now. thanks everyone but

how do i measure the clearances with the engine still on the box?

[valve bounce]

well today i removed the clutch and transfer housing with the engine still in the car and had a look, the bearings appear fine and spin very nicely (will still be replacing them) but the bits of the gear that the bearings run on are ruined i measured them with my verniers and they got some big dips and bumps on, then i went to get the spare gear out of the shed just to find its A+ therefore doesn't fit.

also does anybody know were i could buy the special tool for removing the idler bearings?

[MiniLandy]

Afraid i can't be of any help to you, but cheers for the info!

This sounds like it's probably what's gone on mine. It sounds horrendously loud, gearbox-wise, a kind of rattling/whining noise. Luckily, i've got a spare gearbox and transfer case in the shape of a spare 998 engine and box.

Good luck chap

[valve bounce]

any ideas how to remove the idler gear bearing from the gearbox with the engine still fitted?

[bmcecosse]

Just lift the engine off the box to get access. And sorry - I was thinking earlier of primary gear end float - not idler gear.

[valve bounce]

i was hoping you weren't going to say that, i was hoping some one would know a way to remove the bearing but it looks as though i will be removing the engine