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MK3 engine with a single rail gearbox issue


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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!

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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?

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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.

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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?

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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.

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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 by sparky_spit
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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!

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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

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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....

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