10 replies to this topic

[amsgw]

Hi all, I'm at the end of my rod change box rebuild, ready to torque down the pinion gear and am beginning to worry as the gears are not spinning at all. They spin maybe 1cm in either direction without resistance before stopping as if they're up against something. They're the same with or without the layshaft installed. I don't want to torque up the box for fear that I'll crunch something / whatever is stopping them from moving - is this illogical? As I know this can help to seat the gears... Should I just pull the main shaft out again? It's in neutral, no gears engaged. Any advice welcomed, this is the first time I've done anything like this!

[Steve220]

can you spin 1-3 on their own individually?

[Spider]

It'll most likely be binding up on the Baulk Rings. Torque up the 1st Motion Shaft and Mainshaft Nuts. That pulls these shafts away from each other and lets the Baulk Rings float and not bind.

[amsgw]

I've just tried to move them individually and they're not moving at all - also just realised that when I engage reverse it locks up entirely, and I can only get the selector over to 4th, no 3rd 2nd or 1st
I've been very slow going on this project as it's dragged out over my pregnancy and then having such little time with an 8 month old... Could it just be that it's seized slightly..?
Any ideas how to either free up the selectors (provided that isn't the cause of the issue perhaps?) or to engage the gears differently in order to be able to torque the nuts ?!

Edited by amsgw, 21 January 2025 - 06:43 PM.

[Spider]

I've just tried to move them individually and they're not moving at all - also just realised that when I engage reverse it locks up entirely,

 

I'm not surprised.

Check the Interlock Spool is disengaged completely and with it rotated about 180⁰ from it's normal position, pull it as far out of the gearbox as it will come, that should stop it fouling on the bellcrank forks, something like this;-

 

 

Then use a soft drift and knock the Syncho Hubs over to engage 1st and 4th gears. That will lock it up so you can Torque up the Nuts.

 

 

[amsgw]

Update - managed to beat it into submission and have finally torqued down the bolts. True to form Spider was absolutely right it's all come free and is spinning well. Thank you!

Two questions - I couldn't get 4th to stay in gear properly at all. I ended up having to lock up the box in reverse and 1st. Any movement at all and it popped halfway out and spun freely even if another gear was engaged. Is this cause for concern?

Second - I've rebuilt the diff, but before putting the new bearings on the shafts, it is completely locked up as well. I haven't seen anything that suggests this is common. I have replaced the spider gears, uprated the pin to the minispares moly type and obviously the fibre washers, but I found it really difficult to get the block that fits over the diff pin seated it was so tight. I've had several issues with parts being machined incorrectly from mini sport, these replaced parts are also from them. Any ideas if this is normal or whether I should just reuse the original spider gears?

Thanks again 🙏

[Spider]

Good work - so far !

I'd suggest finding why you couldn't fully engage 4th gear before going too far. One reason for this could be the bell cranks having disengaged from the selector fork and fouling on it. You'll probably need a torch to see in there. Of try and engage 4th again, then check if the bell cranks are still free, I'd have a guess here that the middle one will have locked up. You can get them back where it should be, just need a bit of patience.

If it's not that, then perhaps the 3rd / 4th Syncho Hub has been assembled wrong way around ? The outer track might be OK, but the inner hub might be back to front.

 

In regards to the Diff, there's 2 thicknesses in the Thrust Washers on the outputs - 0.035 and 0.044", you may have the thicker one in there ? to be honest, I don't like these thrusts and haven't used them in a very long time. They disintegrate in short time I found (when I was running stock diffs and also on those I serviced). For a while in our local production, they fitted bronze ones. While these are NLA I make my own.

But coming back to yours, if you find the thrusts are the thin ones, then it maybe that the thrusts on the planet gears are thick. While there was only one thickness used in production, I have found there seems to be at least 2 thicknesses in the replacement items. Check too that they are seating completely.

If you find all these are OK, then it's likely the Output Shafts are binding on the Centre Pin Thrust Block (which really is a misnomer). You can check for this by removing it and re-assembling the Diff, if it all spins over nice, that's likely the issue. You can go one of two ways here. The early Metros were assembled without that Block and really, there's no proper need to have it in there as when in use, because the gears are all bevel types, no matter what, they only ever thrust out, so that Block is never thrust upon (hence why it's a misnomer), or you can grind small amounts from the 'pip' in the centre of the Outputs until you get about 5 thou clearance here.

[amsgw]

Stupid rookie error - I'd taken the sleeve for the detent out and so the interlock spool sleeve was incorrectly positioned, I think this is what you meant for me to check Spider but either way solved it! Massive relief as I remembered the orientations of the synchros being tricky.

Re the diff, the output fibre thrusts are the thin ones and I get the planet gear copper thrusts to be 0.0412 - is this correct? Assembled without the thrust block it spins like a charm though with a lot of play on the output shafts - more than 20 thou. The block has wear marks from the previous output shafts contacting the sides but it was the planet gear ends that seem to be binding, I even tried gently drifting it and it truly was stuck. Based on your experience I'll likely go ahead without the thrust block, unless that amount of play seems to be too much?!

Credit to this forum, I'm amazed I've been able to get this far. When I bought my mini I could only change a tire and a ball joint at best. Thank you all 🫡

[Spider]

Glad you found and sorted the issue with 4th.

 

With the Diff, when you say it has around 20 thou play on the output shafts is that just in and out play (pushing the shaft in our out) or side to side play ?

If that's in and out, that's fine, if it's side to side, then your Centre and Crown Wheel need re-bushing. There's another thread presently running on that.

[amsgw]

I should say, having read the other similar thread by babs about rebushing the crown wheel and cage, their video looks similar to the amount of play in mine though I reckon I don't have as much side to side play - it's more the in-out movement that caused me concern.

[amsgw]

Haha, great minds! I'll see if I can get a better idea of the side to side play tomorrow - I'm already rebushing the diff covers so may as well go whole hog. At this stage the money pit is exponential.......