reverse gear problems
Turbo Mini Forums

hi all

A couple of years back I built up a straight cut close ratio gearbox (a+) using the tran-x clubman gearset. When doing this I replaced one of the bearings (broken race), plus a few other minor items that were showing wear.

I got my turbo mini on the road this year and it has gone well, all forward gears select easily, there is no jumping out of gears really, apart from once in 4th – I am not sure it was properly selected to be honest.

The issue is with reverse – reverse is very difficult to select. When it goes in it crunches in, the car jerks. Also under any load ie when reversing it pops out of reverse.

I plan on building a higher spec replacement engine this winter. I plan on using my current gearbox, but want to get this problem sorted prior to dropping it back in. does anyone have any ideas what the culprit for these reverse gear problems might be?

Im thinking it cold be something like me putting the reverse gear in backwards, something worn, maybe selectors, or even a clutch problem?

I hope that someone can help, cheers, dan

I would look at worn selector arm, the gear in back to front and the brass bush in the gear starting to come out of the gear.

cheers, i will take a close look at these points when i pull the engine and inspect the gearbox

Could also be worn 1st/2nd synchro hub not engaging reverse correctly.

what do you look for on a worn synchro hub? if it was worn would it have an effect on 1st/second gear? cheers, dan

When you engage reverse the teeth on reverse mesh onto teeth cut into the outer ring of the synchro hub and rotate it the other way against first gear.

Reverse gear only fits one way. The bush can and does move as Andy said.

You did install the detent ball bearing and spring behind the driver side diff side cover, when you built it back up?

The reverse gear relies on this detent ball and spring to keep it where it is, while it increases the retention of the synchro hubs own detent balls and springs, but with out it, that might explain why it jumps out of fourth.

For the cost of them, new springs and balls all round on a gearbox rebuild, is peace of mind

As above, as Andy says, check!

Colin is correct, that where you need to be heading. Detent spring and ball bearing

mine had a massive problem jumping out of second on overrun, reverse was very hard to get, to cure mine i bought 2 new roll pins and 2 new rubber bushes for the selector housing,
-for what it cost its worth a try, i tryed it on the off chance because there was a little slop in the linkage

1380rich can verify, the transformation is nothing less than epic..it made him re-design his whole selector settup

Edited by Brett on 5th Oct, 2012.

Yes i moved to the darkside

Instagram @jdm_brett

thanks for the input, i will check all of these things when i get it apart. i am sure the big ball bearing and spring went in, il have to renew them when i take it apart to see whats what

hi, bit of a post resurection here. i have pulled the engine and split the gearbox.

i have inspected the gearbox and the gearset looks to be good. the 1st/second selector/synchro hub has 2 of the dog teeth missing so i will replace this.

the reverse retainer ball bearing and spring were correctly inserted into the rear of the box. i stripped the gearset out last night. the reverse gear looks to be good, no movement of the bush etc.

i plan on checking the selectors later today and comparing them to some that i have in other spare casings for wear. i think that i will also replace the detent springs and balls as these may have become weak? i also have a new bush for the linkage that fits onto the rear of the box. i will crack on and look at these areas, anyone have any other ideas?

a thought might be that the clutch adjustment might have been slightly out making this more of a problem. sometimes reverse would select ok, but mostly not. also the clutch system might have had a leak, possibly allowing air into the system. it would need a slight top up of fluid every now and then. i will check the pipes etc, also have another cylinder to go on.

if anyone has any ideas of anything else to check whilst its apart i would very much apreciate it. cheers, dan

Edited by welshdan on 3rd Mar, 2013.

Was it difficult to get 1st as well, if so it could have been clutch drag, just a thought.. Alan

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sounds like the clutch system is part falt. as above i think the dent ball n spring in the diff caseing is worth replaseing also the selector arm along with roll pins
i had badly worn hubs it always dropped out of gear with out any load on the box this was caused by shifting with the power still partly on my dumb lesson...

cheers for the input. i stripped the gearbox this afternoon. everything looked in good order apart from the missing dog teeth on the 1st/2nd synchro hub everything else seemed to be in order. if felt good on the hub. the selectors had slight wear to them, i changed them for a set with no evident wear. reverse gear etc looked good, no movement of the bush etc. its all back together now, i have a feeling that the clutch may have been the main problem. the resevoir was half empty, i have refilled the system and will see where is leaking to over the next few days. i have a new slave to try on there. i hope that its sorted now - will report back in a couple of weeks when i have it running again. cheers, dan