Gearbox rebuild problems/questions (1st motion shaft)?baulk rings
Turbo Mini Forums

Hi, a few months ago I fitted my mpi mini with a fast road engine and a late 1275 gt close ratio gearbox. At the time I also fitted a centre oil pickp pipe, changed the final drive and fitted an uprated diff pin

The gearbox was bought as good working order, so not tested prior to use. It was found to crunch down from 3rd to second, and crunch up into 4th.

This week I have pulled the engine to try and sort this problem out.

I was led to believe that worn baulk rings were the likely cause. On stripping the box to change these I have found a couple of things, of which I’m not sure about

Firstly, where do the baulk rings wear? I was always under the impression the grooved inner being smooth would constitute wear. However, when comparing this surface to the new genuine rover baulk rings I have bought there doesn’t seem to be a huge difference. There are some ‘polished’ areas to the outer of the baulk rings, especially on two just before the triangular parts (highlighted in red). Is this just general wear?






Also, on inspecting the 1st motion shaft I have found a raised area (on the area where the baulk ring sits, highlighted in yellow). Is this supposed to be there? My guess would be no. I have tried to photograph it the best I can. Could this be a problem with wear or manufacture?










If the baulk rings aren’t the problem, what might be? I was thinking maybe a problem with worn selectors?

Any help/input would be greatly appreciated. Many thanks

also, iv not had chance to look, but are a and a+ selectors interchangerble? thanks

Can we have some decent pictures that show the parts you are talking about in full focus Please. All I can see is the floor.

Sorry to be a twat, but its not difficult to see that those pics are of no use, and it is also not difficult to take a picture in focus. How can you expect a decent answer with blurry pictures like those. Again, sorry, rant over. No offence :)

All in the best possible way :)

il try to get a few tomorrow. it was the oil on the parts messing the reflection/focus up

If you have a macro setting on your camera this will help for close up's. usually a little flower on one of the arrow buttons. Also have a neutral/plane background. not trying to be patronizing if you know this already.

good luck

no, im crap with phones/computers etc. my phone doesnt work half the time!

does anyone know if a series selector forks can be changed with A+. may change them for some known good ones whilst its apart if they are compatable? as i said baulk rings seemed to look ok, so trying to rule out the cause. thanks

Fit the syncro ring on the cone. If there is less then 0.8mm clearance between the ring and the face where the dog teeth sit, the ring or gear is junk.
As Sprocket says, your pictures as useless, but the lack of coating on the cone is almost visible. The gear is junk.

thanks for the input. will measure up later and hopefully get something sorted. only problem is that the 1st motion is the close ratio gt type, therefore nla?

thanks, was thinking along those lines. hopefully have things sorted for now.

managed to get most of it back together this evening. changed the baulk rings, mainshaft and 1st motion bearings, as well as 1st gear needle roller. also fitted a set of selectors from an mpi box, they are much tighter, the old ones were well worn. you didnt have to measure, the wear could be seen by eye. also fitted the syncro hub and base from the mpi box. prior to this they all had the .8mm clearance, appart from the 1st motion gear. however after fitting the mpi cone and hub there is now just over the .8mm gap. will see how it goes anyway when in the car. the gearbox is slighty tighter turning over than it was, im putting this down to new baulk rings, the new selectors, and ner main bearings (not fully oiled). it still turns over easily by hand.

Raised areas on the baulk surface is probably what's left of the coating - new rings won't help much (if at all) and certainly not for long.

well looks like you have covered most areas, how ever i would check on the clutch set as well as lack of clutch thorw will cause all the stated probs to, but hopefully the new rings will sort it out.

always looking for them bigger bunches of bannanas

you will still have a non syncro fourth gear that is for sure...

These are not NLA either BTW.

dan, im out of action at the mo with a bad back, but i have an 's' close ratio box in stores that needs a rebuild (bought off ebay as spares) ive never had a close look at it as bought a straight cut gearbox off turbotim instead, so dont know off the top of my head the condition its in

i cant guarantee when ill get chance to dismantle it, but ill let you know if the parts are in ok nic, if so ill wing them your way

"Turbo's make torque, and torque makes fun"

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