9 replies to this topic

[28hodge]

So I got bored and have had an annoying rattle coming from the engine since I got the car, I know in the past it’s had issues with the clutch and was sold at one point as a none runner as one of the owners got stuck trying to get the flywheel off to change the clutch with the engine in the car. The guy I bought it from had sorted this but like I say it’s always had an annoying rattle off throttle so i wanted to check the diff end float and also the transfer gears

Also the engine bay wants cleaning up and repainting, and I might Re Bush the top arms and lower arms and tie rods.

Anyway engine out and cleaned then stripped down, was nervous the flywheel would be stubborn to get off but it came off pretty easily.

I was going to remove the transfer case but thought I’d clean it all first, whilst doing this I found a serious amount of end float on the primary gear 0.027 so way out of tolerance.

I turned the c clip around but it’s not made any difference. I think the following is correct -

Std c clip - 0.125
Std c clip backing washer - 0.164

Mine measure the following

c clip - 0.122
Std c clip backing washer - 0.156

So I can recover 0.011 but I need to recover the same again, the thrust washer from smallest to largest have a 0.011gain. I need to strip it down to get the thrust out and see what I have but what else can cause masses of end float on the primary?

I’m thinking I will split the box and block and check the crank end float and then reassemble from there depending on what I find.

The car was running well and gear changes where fine granted I have to heel and toe to avoid crunching unless going pretty steadybut unless I heeled and toed it, but that not unusual is it? Should point out that was at speed on road rally tests too.

I know it had new mains big ends and crank thrust washers and rebuilt not that long ago, as I have the receipts for them.

[GraemeC]

You got it out then!

The rear bush (top hat one) could be worn on the face that rubs against the c-clip backing ring - the fix would be to re-bush.
Are you running straight cut drops? If so 5-6 thou end float is OK (even on helicals considering this is a proper comp car).

You should be able to initially check the crank end float without splitting the 'box and block, but if you're this far in it may be worth checking mains & big end bearings too.

Edited by GraemeC, 24 April 2020 - 12:26 PM.

[28hodge]

Yeah it came out pretty easily I ended up taking the exhaust manifold and inlet off it to make it easier.

Not running SC gears it’s just std my metro engine components bar the cam. I think I can get the end float back in tolerance but only if I can the smallest thrust washer in now or the one in there has enough wear on it that I can get another 0.011 back.

To Re Bush with a new top hat in the primary I’m assuming that I would then need to have the Bush reamed to tolerance. The radial movement on the gear looks ok, need to get it off the check. Not sure where I can get that done at the minute as I now lancaster engines are shut.

The mains and big ends should be good. The guy who sold it as a none runner in on pistonheads and he originally rebuilt it. I’ve spoken to him a few times and he put new mains etc in it and barely used it. He sold it to the guy I bought it from who also never used it. It makes 65 oil pressure and never drops below 40 when hot so I think it’s all good on that side of thing. But to be honest if I end up seperate he the block and gearbox I might as well have a look. Am I ok to reuse all the stud and nuts off the caps if I do?

[GraemeC]

Yes, re-bush in primary would need machining. Phil @ Turbominis might be able to help there?

I’ve checked my stock - largest primary shim I have is .120” if it helps. Just turning the c clip around in the slot will take up some play - that where they tend to wear

Unless you’re feeling flush and want to upgrade then the studs & nuts should be OK to go again. Best practice would be to change them, but many people don’t.

[28hodge]

Hmm primary thrust is 0.119 so thanks for checking your spares Graeme but looks like it’s not going to do to much for me. Half the problem appears to be the slot for the c clip is pretty worn, how firm should the c clip be in the slot as mine appears pretty loose!

I turned it around but it made little difference. DTI on the end of the block shows approx 0.22mm so 0.086.

Starting to think pulling it totally to bits is the only way forward, the box was bought from MED as a fit and forget so I’ll have a look but think that’s good just to fit back onto a refreshed block. It will have been put together properly unlike the rest which hasn’t had much attention when put back together by the looks of things as it prob only done max 5000miles since being rebuilt

I messaged turbo Phil on Facebook a couple weeks ago about a head so will give him an ask and see if he can team the primary bushings, though the crank tail has some marks on it that will need flatting off to avoid scoring the inner of the bush.

[GraemeC]

C-clip should be an easy slide fit. It’s normally the clip that wears on the ‘ears’ though, rather than the crank itself.

[28hodge]

Hmm closest I can get it back to is 0.027minus 0.015 so 0.012 which is too far out to let it go, so I’ll have to get it rebushed and hope that brings it back into tolerance.

Clip slides on easily but yeah will rock side to side I’ll get a fresh clip and backing washer just to check that doesn't close the gap up and go from there. Think guessworks rebushes them?

[cal844]

Yes, re-bush in primary would need machining. Phil @ Turbominis might be able to help there?

I’ve checked my stock - largest primary shim I have is .120” if it helps. Just turning the c clip around in the slot will take up some play - that where they tend to wear

Unless you’re feeling flush and want to upgrade then the studs & nuts should be OK to go again. Best practice would be to change them, but many people don’t.

Turbo Phil is on here, great guy to deal with

[GraemeC]

Yes I think Guessworks does, as does ACDodd

[28hodge]

Ok so stripped the block and had a look at the mains and big ends, glad I did as a bit of evidence of wiping and also copper showing ever so slightly on 1 big end.

Car has very recently developed a issue on start up where oil pressure didn’t seem to initially be building for 1-2seconds then would leap up to 65psi ish (checked with 2 gauges). This was part of the reason I wanted to strip the engine along with the rattle that was evident when off throttle which I am guessing has come from there being to much end float on the primary gear.

Journals look good and in marked so caught in time. I was going to buy std mains and big end shells but having checked Haynes and measured the journals I’m not sure.

Mains measure exactly 2.000 Haynes says they should be 2.0012 - 2.0017 for 1275 engine. Mine is a mg metro engine with cam6232.

I’m a little wary of buying std mains as I think the running clearance is too great, has the crank been polished and is that why it’s slightly undersize? I only have clarke vernier digital calipers to measure with so they may not pick up the 0.001.

Apart from on start up car has never had a oil pressure issue it’s never below 40 when hot and I change the oil a lot, it very much doubt it does more than 1000 miles between oil changes.

Any ideas best way forward, I would have it ground 0.010 but I’m not sure I have any engineering ships open to do it at the minute, the one I would use are shut except for key workers.

Edited by 28hodge, 29 April 2020 - 04:49 PM.