20 replies to this topic

[ThermalEvent]

Hi all,

After a bit of advice with some gearbox problems I am experiencing.

I've cover 600 miles since the rebuild and always had a problem selecting 1st and 2nd with the engine running. Not impossible but by no means easy. Engine off its absolutely fine finding 1st and 2nd.

Changing from 1st to 2nd anything other than very very slowly whilst driving will cause it to crunch. Its not as bad when warm but still there. First is difficult to get into gear and made easier by selecting 2nd first.

3rd/4th absolutely fine and no problems with them.

It was a full gearbox rebuild which I did myself including new baulk rings, all bearings as well as a new 1/2nd synchro and selector fork. New MED verto clutch/flywheel assembly, new plunger, new arm, new slave and master, braided line + linkage pins. Gear linkage gearbox bush and socket in the gear linkage body also replaced.

Clutch travel set to 6.5mm as per haines manual.

Clutch bled twice and plunger travelling full 6.5mm (I videoed it to confirm).

It feels to me like the Clutch isn't fully disengaging but wouldn't it be the same for 3rd/4th?

I was thinking of increasing the stop nut distance but don't want to damage the thrust bearings.

Has anyone got any ideas or any pointers as to what could cause this?

Cheers,

[Spider]

Sorry to hear of your problems here.

 

Firstly, a litmus test for the Clutch - does it grind going in to Reverse ? Even a small amount ? If it does, then look to the Clutch, if not, then it's in the Gearbox. If it does grind, then the issue is likely the Clutch (but I doubt this).

Given the issue seems common to 1st and 2nd, I suspect the issue here is with the Synchro Hub. The Hub itself maybe worn, but when you did your overhaul, there's 3 spring and ball dentents in these hubs. These Springs do get weak with time and are normally replaced at the time of overhaul. They play a very important part in Synchronising the Gear Speed to the Mainshaft Speed. There's 3 of the springs in each of the Synchro Hubs.  So, were these also replaced ?

 

Item 23 in the sketch below;-

 

 

[ThermalEvent]

Hi Spider,

Thanks for the reply. When rebuilding the gearbox, I found the 1st/2nd synchro was completely knackered, so I replaced it with a brand new item from Minispares (DAM7455) which came fully assembled.

Also, looking at my minispares order, I forgot that I had also replaced 2nd gear with a new item (DAM4932) due to damage.

Reverse is spot on and no issues with it.

I should add maybe its better to describe the change from 1st to 2nd as a crunch more than it grinding which does get slightly better when up to temp.

Edit: Just been thinking about this some more and if 1st/2nd is more difficult to engage with the engine running then is something dragging in the gearbox? Could too tight a clearance on the primary gear bushes/crankshaft cause this?

Cheers,

Edited by ThermalEvent, 24 January 2022 - 09:00 PM.

[D 'n A]

I experience nearly the same issue regarding shifting from 1st to 2nd. When the engine was cold is did not really want to engage 2nd gear, the other gears are fine. When the engine warms up it shifts into 2nd no problem.

 

After replacing the oil seal at the shiftrod in the gearbox the problem got worse, it now did not want to go into 2nd or 4th, reverse was ok-ish.. During this work I saw my gearstabilizer bushing that connects the gearbox to the shifting mechanism was completely gone, no rubber what so ever was left. So when you pull the shift lever back for 2nd or 4th you push against the gearbox and because of the lack of bushing the shifting mechanism was pushed even more back. I also have a QAD shortshifter I might add.

 

I found it was impossible to get the outer bush out of the gearbox housing, the housing is aluminium and the bushing steel. I think its welded into place after all these years. I happen to have some really strong rubber lying around, pushed it into the bush and pushed the inner bush in the rubber with force. It has no movement now what so ever. I changed the 2 rubbers that hold the shifting mechanism and cleaned that part completely and added new grease. It now seems to shift perfect, but that's standing still. I currently replacing my headgasket and will be fitting a new exhaust, so will have to wait for the real challenge; the drive.

 

Long story short, hows your stabilizer bushing holding up?

[cal844]

I fit a brand new anti leak kit to my cars whenever I have the engines out... I've never had one seal as advertised out of 6 times I've fitted them! And that's on DAM5626 gear cases with matched diff housings (standard rod change mechanism)

Edited by cal844, 24 January 2022 - 10:10 PM.

[Spider]

Hi Spider,

Thanks for the reply. When rebuilding the gearbox, I found the 1st/2nd synchro was completely knackered, so I replaced it with a brand new item from Minispares (DAM7455) which came fully assembled.

Also, looking at my minispares order, I forgot that I had also replaced 2nd gear with a new item (DAM4932) due to damage.

Reverse is spot on and no issues with it.

I should add maybe its better to describe the change from 1st to 2nd as a crunch more than it grinding which does get slightly better when up to temp.

Edit: Just been thinking about this some more and if 1st/2nd is more difficult to engage with the engine running then is something dragging in the gearbox? Could too tight a clearance on the primary gear bushes/crankshaft cause this?

Cheers,

 

OK, thanks for the added background info.

If Reverse can be selected OK with no grinding, then I can't see it being the Primary Gear being tight on the crank. There is a very small possibility of the 1st / 2nd gear (and 3rd & 4th) occurring if the Idler Gear is too tight.

As D'n A mentioned, oil temp plays a part here. When it's cold, it's viscosity is usually too thick for even the best Baulk Ring to cope with, but when the oil warms up & thins out, then this aspect isn't usually a problem.

Just on Oils, what Oil are you running in it ?

[ThermalEvent]

@DnA I replaced the gear selector bush when rebuilding the engine/gearbox and it was a pig to remove, but we got there eventually. Had to pick the rubber out and chisel the steel part in on itself. The shift mechanism bushes were replaced with poly bushes and I think this is all OK.

I have also used the Minispares anti leak kit so whether this isn't helping the problem I don't know?

@Spider Idler gear end float was OK when I built up the casings with a gasket and measured using a DTI (0.004').

Oil wise I have been using Millers CTV 20W50 apart from Halfords 20w50 when running in for the first 100 miles.

Happy to try a different oil if you can recommend one?

Cheers,

[Spider]

Oil wise I have been using Millers CTV 20W50 apart from Halfords 20w50 when running in for the first 100 miles.

Happy to try a different oil if you can recommend one?

Cheers,

 

We don't have Millers Oils available to us here, so I can't speak from any experience on that particular Oil. I do note though that it's a Semi-synthetic that aimed more at Racing Minis, that use LSDs and more than likely, Dog type Gearboxes. While I wouldn't say it's likely unsuited to a road Mini, I feel there's better suited oils available. Just off hand, I'm not sure what a popular oil is in the UK, but I know there's many here on the forum who would likely recommend something. My choice in Oil is available in the UK, but it's a bit on the obscure side there I think (Penrite HPR30). If the issue is the Oil, it may take a while or even a few changes to remove the Semi-synthetic from the gearbox.

Are you running an oil cooler ?

I did note you mentioned you've fitted a new Synchro Hub for 1st / 2nd gear. All the same, you you give it a feel for it's break-away pressure / action ? They do need to be a firm 'snap-snap'.

Given what we've covered, I feel it is likely to come down to Oil here.
 

[GraemeC]

The CTV is popular in the U.K. and is (supposedly) specifically designed for the Mini.

[ThermalEvent]

Oil wise I have been using Millers CTV 20W50 apart from Halfords 20w50 when running in for the first 100 miles.

Happy to try a different oil if you can recommend one?

Cheers,

We don't have Millers Oils available to us here, so I can't speak from any experience on that particular Oil. I do note though that it's a Semi-synthetic that aimed more at Racing Minis, that use LSDs and more than likely, Dog type Gearboxes. While I wouldn't say it's likely unsuited to a road Mini, I feel there's better suited oils available. Just off hand, I'm not sure what a popular oil is in the UK, but I know there's many here on the forum who would likely recommend something. My choice in Oil is available in the UK, but it's a bit on the obscure side there I think (Penrite HPR30). If the issue is the Oil, it may take a while or even a few changes to remove the Semi-synthetic from the gearbox.

Are you running an oil cooler ?

I did note you mentioned you've fitted a new Synchro Hub for 1st / 2nd gear. All the same, you you give it a feel for it's break-away pressure / action ? They do need to be a firm 'snap-snap'.

Given what we've covered, I feel it is likely to come down to Oil here.

I've found you can buy that oil here in the UK but it's called 'Penrite Classic Light 20w60' and I believe this to be a rename of the HPR30?

Running no oil cooler, from what I've read they are not really warranted on a lightly tuned engine.

When assembling I did move the synchro by hand, it did feel firm/tight and went with a solid/precise click. It felt good to me but I've nothing to compare to.

I'm at a bit of a loss with it, I haven't lost anything trying a different oil execpt a bit of cash, but beyond that I suppose its a strip down and inspection? Maybe I didn't assembly something correctly or a part is out of spec.

I'm trying to get my head round what changes in the gearbox with the engine running and why this would then make getting into 1st/2nd difficult?

You can live with it but it takes the fun out of driving, especially stop/start traffic and in built up areas.

Cheers,

[ThermalEvent]

The CTV is popular in the U.K. and is (supposedly) specifically designed for the Mini.

I chose this oil after reading up on it as it seems popular and as you say, supposedly developed for Minis. The other oil I hear good things about is Valvoline VR1 but have yet to try it.

Cheers,

[alex-95]

I had the same issue of crunching from 1st to 2nd after I built my gearbox, I assembled the synchro hub the wrong way around. One side has a smaller step than the other. Worth checking if you have photos of the build or strip the box.

[Steam]

 

 

Oil wise I have been using Millers CTV 20W50 apart from Halfords 20w50 when running in for the first 100 miles.

Happy to try a different oil if you can recommend one?

Cheers,

We don't have Millers Oils available to us here, so I can't speak from any experience on that particular Oil. I do note though that it's a Semi-synthetic that aimed more at Racing Minis, that use LSDs and more than likely, Dog type Gearboxes. While I wouldn't say it's likely unsuited to a road Mini, I feel there's better suited oils available. Just off hand, I'm not sure what a popular oil is in the UK, but I know there's many here on the forum who would likely recommend something. My choice in Oil is available in the UK, but it's a bit on the obscure side there I think (Penrite HPR30). If the issue is the Oil, it may take a while or even a few changes to remove the Semi-synthetic from the gearbox.

Are you running an oil cooler ?

I did note you mentioned you've fitted a new Synchro Hub for 1st / 2nd gear. All the same, you you give it a feel for it's break-away pressure / action ? They do need to be a firm 'snap-snap'.

Given what we've covered, I feel it is likely to come down to Oil here.

I've found you can buy that oil here in the UK but it's called 'Penrite Classic Light 20w60' and I believe this to be a rename of the HPR30?

 

Penrite Classic Light is a different product to HPR 30 so not a rename.

Penrite also make Classic Mini oil. 

Either of the classic oils will be fine and work well in a Mini.

[D 'n A]

Did you solve the problem?

[ThermalEvent]

Brought some Valvoline VR1 20w50 in the end and plan to change the oil this weekend. Providing the weather is dry I'll take it for a spin and report back.

Cheers,