MK3 engine with a single rail gearbox issue

[aknight123456]

MK3 engine with single rail gearbox and O/D issue

 

Has anyone got any experience using a mk3 small journal engine with a single rail gearbox? I bought a donor car which had an old MK3 engine and single rail gearbox already mated together. Car was a non runner. I've had the engine and gearbox refurbed but we can't get the clutch to engage properly. It's got a 20 spline shaft and the flywheel is the MK3 style with a triumph dolomite clutch plate so it's the right diameter.

 

Any help appreciated. Cheers!

[Clive]

I had the same combination in my Herald (it was a GE engine, so small journal crank, not that it makes any difference)

The only issues I can think of would be if the plate and cover ar from different manufacturer. Of course, if the plate was fitted teh wrong wat round that would also be an issue.

Can you better describe the problem. Does the clutch feel solid? Or slipping? Or not disengaging?

[aknight123456]

So the pedal is depressing about half the travel of how it used to and then it goes rock solid. We released the nipple for the clutch and confirmed there's no restriction on the pedal end. So we're thinking it must be something in the clutch but can't work out what. We've measured all the clutch pack and flywheel compared to the old engine and we can't find any noticeable difference.

[aknight123456]

So from lots of experimentation it appears that the problem is lying with the clutch actuation mechanism. When we took the original gearbox apart the gearbox push rod was inside the bell housing and a bodged bracket and bolt welded together was being used to push the arm. We assumed this was when the put the gearbox together that they forgot to move the pushrod out of the hole in the casing and instead of taking it apart when they realised they made this bracket. Turns out though that the pushrod doesn't give enough travel. It looks standard and is exactly the same as on the other gearbox. 

 

We could extend the rod but we shouldn't have to, something must be not right. We've measured and compared the components and unless they're both worn etc in the same way everything looks good. We've checked the bore of both the master and slave cylinder and both are good. The extended rod is about 10mm longer.

 

Anyone experienced this before?

[RobPearce]

Can you get some photos and upload them, please? It's a lot easier to follow with pictures.

The slave cylinder is held in place by a clamp that should be bolted through a recess. It allows some adjustment but not much. However, it's still possible to assemble it completely wrongly such that the cylinder is in the wrong place and doesn't have enough throw.

[sparky_spit]

I've been following this thread as I have a Mk3 FD engine and a single rail OD gearbox which I fitted years ago. Your last post about the bodged extended clutch pushrod jogged my memory and I remembered that I had to extend my pushrod too, so that I got proper clutch release action. I was using the fine spline friction plate intended for the Toledo and Morris Marina I think. Apologies for not remembering sooner.....

Somewhere there is a forum thread about this issue with dimensions etc, although it was many years ago, and might even have been on the TSSC or Sideways forum.

Edited July 10, 2021 by sparky_spit

[aknight123456]

Hi sparky, thanks for your reply. That is essentially what we have concluded and gone with. We couldn't figure out why but it just seems like it's a common fault with these. We found an old slave cylinder which upon inspection had a 10mm spacer in it which confirmed to use that it's one of those issues that most people come up against and that is the work around!

 

It's all in and running now, although it feels like I've traded the issues of my previous set up for a new set 🤦‍♂️ the clutch has full travel but is quite heavy, the biting point is quite close to the fully out position of the pedal (as in just before I remove me foot) and the car clunks as it goes into reverse suggesting the clutch is not fully disengaging the shaft. What was meant to be a simple swap has turned out to be a real pain!

[Dave Clasper]

My Vitesse will clunk into reverse, unless I give it a few seconds in neutral first!.

Dave 

[Nick Jones]

3 hours ago, Dave Clasper said:

My Vitesse will clunk into reverse, unless I give it a few seconds in neutral first!.

Dave 

Touch it into first first to stop all the gears, the go for reverse. If you still get a crunch/clank the clutch is dragging.

 

Nick

[Dave Clasper]

On 21/07/2021 at 21:41, Nick Jones said:

Touch it into first first to stop all the gears, the go for reverse. If you still get a crunch/clank the clutch is dragging.

Thanks Nick, is all that action with the clutch depressed?

[glang]

Yes Dave, Nick means car stationary, engine running, clutch pressed continually. When put in first axle will stop anything from spinning so that it should then go in reverse without a crunch. If theres clutch drag when you come out of first to neutral the gears will spin up and crash for reverse. The other gears might be ok as they have synchros to fight against the clutch drag and make the gears stationary again but obviously that increases wear on 1st ring everytime you start off....

[Nick Jones]

Yes…. As explained above….

Nick

[aknight123456]

Thanks for all the replies. They were useful. We went with the spacer in the slave cylinder eventually. It got the car working but as described above. 

I fear the clutch is still dragging however, if you try to put it in first with the clutch depressed you can feel the car wants to creep forward slightly before the clutch is released. It clunks going into reverse most times. There's a metallic rattle as you push the clutch pedal in whilst moving (although this is hard to actually pin point as something in the clutch/gearbox. It makes a bit of a strange noise if you fully hard depress the clutch pedal and now it's started getting very hard to put it into 1st.

 

Any gearbox/clutch gurus who can suggest what needs to be done to fix this? (Beyond going back to the non overdrive 3 rail, which has definitely crossed my mind once or twice in this ordeal!!!) 

Thanks

[RobPearce]

20 minutes ago, aknight123456 said:

We went with the spacer in the slave cylinder eventually.

Hang on... a spacer "in" the slave? You mean between the piston and the pushrod? I can't see how that could help, because the spacer will either hit the circlip, in which case it's not adding any travel, or not, in which case it will fall out. What you need is a longer push-rod, surely?

[aknight123456]

Yeah so it was small rod of metal with a divet in it to allow the pushrod to sit in it. It's narrower than the piston so doesn't interact with the circlip and as far as I'm aware it hasn't fallen out! Here's one of the only videos I found talking about it...

https://youtu.be/jZci7tRrdoI

We're going to try a longer one extension piece in the hope that this will give the clutch fork enough range to work properly. I will report back with how it goes next week...

[RobPearce]

That video is a Mk2 with original gearbox. He's "taking up the 300 thou", which shouldn't be necessary or relevant - he's hiding some other issue. That's not actually very much and you might get away with a carefully machined spacer. If you need more than half an inch I'd be very wary of a spacer.

[aknight123456]

Yeah aware it's probably not the textbook solution and he's probably hiding the true issue however we cannot for the life of us identify what the true source of this issue is.

It's presenting us with issues which would suggest it's not got enough range in the clutch and so if this solves it then it's a viable solution in my mind. 

[RobPearce]

Have you checked the pivot pin in the RH side of the bell housing? Clutch drag on these gearboxes is very often caused by that pin falling out, so the operating arm is sitting half an inch too far back. I wouldn't expect that to cause short pedal movement, though, but it's definitely worth checking.

[aknight123456]

We have not checked the pivot pin as we haven't pulled the gearbox out. We did replace this on the rebuild though so not expecting this to be an issue.

 

We took the slave cylinder off and put a small (2-3mm) off cut of rod into the spacer (see below, the offcut can be seen in the top before we pushed it in, total of about 6mm extra length). Unfortunately this has not solved the issue. With the engine on she is still hard to get into gears and makes a strange mechanical rubbing noise when operating the clutch.

 

New working theory is possibly the clutch plate fingers being pushed in and making contact with the clutch plate however it's hard to say.

Needless to say it's been a disappointing morning as this continues to be an issue 😞

 

 

[RobPearce]

That rather suggests the slave cylinder throw is not the issue, possibly never was.

I assume you've checked you put the driven plate in the right way round?

Was the clutch cover replaced?

[Nick Jones]

49 minutes ago, aknight123456 said:

We have not checked the pivot pin as we haven't pulled the gearbox out. We did replace this on the rebuild though so not expecting this to be an issue.

I really wouldn’t assume this. They can be right little sods for escaping and will even climb out upwards sometimes. On our Spit it kept working out even with new bushes, good pin and new retainer sleeve. In the end I modified a long bolt and then put a nut on the bottom of it when it was still trying to climb out.

Nick

[aknight123456]

Yeah agree with you on that, it's definitely looking that way unfortunately.

We checked putting it back in, I personally wasn't there when it went back together the final time. The clutch cover was replaced as the engine rebuild came with new parts so we thought best to use the new stuff. It's an XRM clutch if that brand means anything to anyone. 

Nick, we actually did exactly what you mentioned there and replaced the pin with a bolt so that's why I feel it probably won't have fallen out.

I fear I'm at that point where we take the whole thing out again to reinspect everything...

[PeteStupps]

2 hours ago, aknight123456 said:

We have not checked the pivot pin as we haven't pulled the gearbox out.

I think you can see it from the engine bay without pulling the gearbox out, can't you? Might have to waggle the tunnel insulation out of the way but should be visible I think.

[aknight123456]

On 08/09/2021 at 15:00, PeteStupps said:

I think you can see it from the engine bay without pulling the gearbox out, can't you?

So, I checked the pin that I was sure would be there. It wasn't.

Got a new pin in there, lots of slop. Got a borescope in there, big gaps between the bronze bush and clutch fork. Basically whole top of bush warn away.

Gearbox is now out. Clutch fork shows reasonable amount of wear so that's being replaced. The bellhouse centre (rubber oil seal type) was snapped (with only about 300 miles on it) and completely disintegrated, again providing more slop in the set up.

When we took apart some old gearboxes to look for a new oil seal more often than not they were snapped in the same fashion. As was my old gearbox, now the new one too. 

One thing we did notice was that the clutch fork push rod was longer (and a similar size on both) than on my old and "new" gearbox (which again we're similar size). Making me wonder if mine had just both worn to a very similar length and probably be a probable cause for my original issue?

New oil seal centre on order. New bushes and pin in the bellhouse along with repurposed clutch fork which is all nice and snug. 

 

2 questions that have come from this;

1. Any one familiar and have a solution to the bellhouse oil seal centres snapping?

2. What is the correct standard length for the clutch fork pin?

 

Many thanks for all the help so far on this voyage of swearing!

[PeteStupps]

Wow, and ouch that's a major failure. Wonder which thing happened first, the break or the pin falling out.

Does the release bearing carrier pivot freely? If not it would be putting shear force on the oil seal tube every time you operate the clutch.

I've only messed about with scroll seal type bellhousings (and not many of them) so no idea if that's a common failure point.