14 replies to this topic

[Danuneek]

Hi.

I've recently (Feb I think) replaced my gearbox with a reconditioned one I bought off a guy on here (the reason I replaced it was because 2nd gear was popping out)

Fast forward a few months (May) I had my car MOT'd and the mechanic said that my 2nd gear synchro was going and this was with the new box. He said the gears were crunching when dropping down from 3rd to 2nd above 3000 revs.

Now, at the time I didn't take much notice of him, particularly as I dont drop down at that high revs. Also my mechanic friend said that all standard boxes will crunch dropping down gears at high revs.

Fast forward to the present and 2nd gear has started crunching a lot more. To change down to 2nd I have to let it drop to 2000 revs. Other than this the gears feel fine. The strange thing is I didn't have this problem at all with the old box, I could change down at really high revs and no crunching, but it did pop out.

Is this a common characteristic of mini's? I've done a bit of research on here and a lot of people have said that most standard boxes crunch.

Also, how much damage is happening everytime it crunches?


Any experience/help would be welcome. I've spent so much money on my car and its getting to the point where its going to have to go! There's always something that needs sorting and I would love to have the know how and equipment to do it myself. I've replaced the whole dash, switch pannel, wired it all up, resprayed parts of the car, overhauled the engine bay but theres so much more that needs doing.

[java gt]

Yes this is a common problem on Mini gearboxes.The baulk ring has worn between 2nd and 3rd but depending on your driving style you can get away with this for a while.Try not to change gear too fast when going from 3rd into 2nd and it will not crunch.This will give you time to save up to get the engine and box back out and get your box reconditioned.

[Cooperman]

Just double de-clutch like we used to have to do on all the early Minis where the synros used to go after about 2000 miles if driven hard. It really was not a problem. I guess the younger drivers may not even know what double de-clutching is.

[monster_mini]

Cooper man explain:)? from the sounds of it you bring you clutch up and put it back down between changes? can i ask why you should do this? also im trying to learn to heal and toe at the moment aswell, but im finding it harder to do in my mini compared to my dads austin healy frogeyed sprite where the pedals are all vertical and level?

thanks(sorry for stealing the thread:P hope you sort your gearbox out soon:))

[Cooperman]

To double de-clutch on the downchange, you push the clutch down, move the lever into neutral, let the clutch pedal up, give the engine a few revs to bring the engine speed up and, as the gearbox is in neutral with the clutch engaged it speeds up the gearbox to match the higher revs, push the clutch down and move the lever into the lower gear. It should then always go in without any crunch when you have got the hang of it. If you want to down-shift whilst braking, you rock the side of your right foot onto the accelerator whilst braking and double-de-clutching. That's called 'heeling & toeing'.
To double de-clutch on the upshift, just de-clutch, move the lever into neutral, let up the clutch pedal, push it down again and move the lever into the next gear.
Obviously you do all this very quickly and it just takes a bit of practice.
It's the way we all used to have to drive Minis back in the early '60's as the gearboxes were very poor on the early cars.
I hope this makes sense.

[minidaves]

should not be a comman problem especially with a rebuilt box, if it crunches at 2000 rpm on a down change then there is a problem in that either you cant drive or the box is faulty.

dave

[bmcecosse]

Or perhaps the clutch is dragging..... But yes - double de clutching is the answer for any Mini driver!

[monster_mini]

well i doo that( give the engine some revs on the down change so its smoothe and straight into the power) but i dont bring the clutch up to do it? should i :/?

thanks:)

[Danuneek]

It crunches at about 2500 revs and you can almost feel a reluctance before you select down to second. Anyhow I took Coopermans advice and went for a long drive today to practice my double declutching and I'm pleased to say it didn't crunch once, even when I was dropping it down to 2nd at really high revs. So that's the way its going to be driven from now on. Thanks Cooperman for your constructive advice.

Dan

[monster_mini]

even tho my gearbox doesnt crunch, im giving it ago tomoz:P

[Danuneek]

even tho my gearbox doesnt crunch, im giving it ago tomoz:P

Type double clutching into youtube and it gives you loads of video demonstrations.

[monster_mini]

cheers:) i still dont understand why you have to release the clutch and put it back down again? you can achieve the same thing without.

[Guess-Works.com]

No, because the release of the clutch means the gearbox is 'spun' by the engine while in nuetral, this has the effect of changing the speed of the gears and makes it easer on the synchronisers to engage,

[Cerberus]

cheers:) i still dont understand why you have to release the clutch and put it back down again? you can achieve the same thing without.

I do it your way too, just rev the engine with clutch down to bring the engine revs into the correct area.

As stated, this doesn't spin up the gearbox so double de clutching is probably better, but its obviously harder to do it if you've never done it before.


Also, with heel and toeing, I do it in our TVR on the race tracks, but I've never done it on the road, because I find that to heel+toe effectively, you need to be braking quite hard, which when on the road in normal driving, is too hard for most situations. I would guess the better you get at it, you can do with lighter braking, but I never really find that I need to do it anyway. I have heard it a number of times that heel+toeing isn't the best thing to do on the road, i.e. it can be dangerous.

[monster_mini]

ohh i seeeeeeee:) thankyouuuuuu:) sorry for being a complete novice:P