Gearbox rebuild problems update 20/04
Turbo Mini Forums

Ive decided to have a go at rebuilding my box, but ive already reached a sticking point. lol

I can't seem to get the gears to lock, so I can undo the mainshaft nut? Ive pulled the selector rod out as far as it goes and it is completely disengaged from the selector forks, but still no joy.

I can just about get them to lock, but then as soon as I get a socket on the nut and twist it, the syncro hubs spring apart and the gears rotate? Has anyone had this problems before? Is it down to worn components or something else?

Is there another way of locking the gears?

Cheers
Matt

Edited by matty on 20th Apr, 2010.

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1/4mile in 13.2sec @ 111 terminal on 15psi

where the ball and spring goes there is a steel collar thet goes around it( right side diff plate looking from the back) that has to come out too there is an o-ring around it,
i made the same mistake too

Yes i moved to the darkside

Instagram @jdm_brett

im sure your making a school boy error here and will be quite embarrassed when you find out

ive re read that, and maybe you have a different problem if you have already got the selector bit out

Yes i moved to the darkside

Instagram @jdm_brett

have you tried manually engaging reverse as well? Should slide in and help lock it

With the interlock mechanism disengaged in the diff housing you just tap the two synchro hubs away from each other (giving 1st and 4th together) and it's locked. Make sure you "tap" them with a soft drift, ie, brass.

It's easy to see from the gaps whether the two gears have engaged properly.

Schrödinger's cat - so which one am I ???

I found while it was easy to fully engage first gear by hand, fourth did need the assistance of a tap in the right direction.

sometimes they do jump back. you have to tap the hubs over so they stay there.

I lever gently with a long screw driver against the synchro hub

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1/4mile in 13.2sec @ 111 terminal on 15psi

they will go together too, but i have heard its better to use 1st and 4th as your less likely to break a tooth off.

sometimes they just seem to be reluctant on some box's.

Done!

Its all apart, ive founs some worn parts already which is encouraging as it means its less likely to be the cones that are worn! So far the baulk ring in 1st looks worn, which I guess explains the grinding 1s gear, and the selector fork also look very worn on the other syncro. Reverse gear has seen better days too!

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1/4mile in 13.2sec @ 111 terminal on 15psi

Ive just finished stripping my spare box, and I was hoping to use the reverse gear out of it. After comparing it to the old one its appears to be missing a washer? Are they compatible with each other?

The one that came out, didn't have the washer.

Edited by matty on 15th Apr, 2010.

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1/4mile in 13.2sec @ 111 terminal on 15psi

Matty whats the difference between each box they came from? Age ect?

Mike

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

Not a clue tbh Mike? I can have a look at the casting numbers when I get home if that would help identify them?

Could it be one is A+ and one is an A?

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1/4mile in 13.2sec @ 111 terminal on 15psi

I think one is single bushed and the other double, so long as it has the same amount of teeth and is the same width i cant see any problem. One appears to be A+ and the A, Ive never seen the one on the right before.

Edited by MikeRace on 15th Apr, 2010.

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

If they are both out of rod change boxes they should be compatible but, beware of the double bushed reverse idler.....

Although I've never seen it myself, they have a reputation for one of the bushes working its way out and stopping reverse from engaging.

Schrödinger's cat - so which one am I ???

Thats good if they are compatible, I don't think the reverse gear moves far enough to the clutch side for the washer to contact anything?

I'll have a look at the bushes before fitting.

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1/4mile in 13.2sec @ 111 terminal on 15psi

Washer????

When I say "washer" I mean the boss on the side of gear. The one I took out didn't have one, and the one I want to fit does? See the gear on the left, it has an extra boss about 3/4mm thick.

Edited by matty on 15th Apr, 2010.

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1/4mile in 13.2sec @ 111 terminal on 15psi

I've had experience of the double bushed idlers where one of the bushes has started to work its way out. Its easy enough to replace the two bushes with the older single bush, and infact, Rover did this themselfs towards the back end of production. One fix to the bush thats worked its way out with the gearbos still in the car, is to smack the reverse gear backwards and forawrds sharply, and it does infact work.

However, do some straight cut gear sets come with a different reverse gear idler? if so, a standard A or A+ idler wont work

The one on the right, with the flat face, looks like every straight cut idler I've played with.

Hmm maybe I should just re-dress the edges of the burred teeth on the gear that came out then.

Is the the profile of the gear that differs?

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1/4mile in 13.2sec @ 111 terminal on 15psi

I think its more to do with the gear ratio