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Is My Crank Fubared?!


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#1 JamesAlexander

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Posted 20 May 2026 - 04:29 PM

Hi all,
Just bought a 1275 to upgrade from my 998, not driven much but found clutch slipping at higher speeds in 3/4th and judder on take off without good revs.
Took the clutch off today as I suspected the oil seal was gone and found it was weeping a bit but the crankshaft taper is in this condition, can anyone tell me if this is scrap please?!
It’s an mg metro engine with sw5 and gas flowed head (apparently) and it’s definitely lively!
If it’s fubared is it saveable? 😬😬
Many thanks in advance for any advice!

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#2 nicklouse

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Posted 20 May 2026 - 07:46 PM

I would not run it.



#3 Spider

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Posted 20 May 2026 - 07:50 PM

If you've the funds, it would be best to replace it, but it can be dressed, left on the ugly side and as long as you get the flywheel on tight, it'll be fine. It's because the flywheel wasn't tight enough that has occurred.

To get it on tight enough, the method I've been using for a long while now, is to lap the flywheel to the crank with fine paste, clean both parts then put a lick of 3 in 1 or similar light oil on the crank taper, just a light lick and no more. Then heave down on the flywheel bolt as tight as you can, it'll likely be north of 200 lb/ft. Use Loctite on the bolt thread and no lock tab. The extreme pressure on the taper will break down the oil film and it will be on tight. You'll need a decent puller to get it apart again, something like the one KAD offer, it'll come off with a Pop, but it'll come apart clean.



#4 JamesAlexander

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Posted 20 May 2026 - 09:36 PM

Thanks for the replies, yes it was VERY easy to get off, no pressure at all!

 

I’d like to give it a go to save it and avoid an immediate engine rebuild.

 

Would you split the flywheel and clutch plate to lap it in and would g3 compound be a good choice?

 

Thanks Spider!



#5 Spider

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Posted 20 May 2026 - 10:34 PM

First, I'd dress the taper with a diamond lap to take off any high spots. You can find these in most hardware and tool stores.

 

I'd likely toss the flywheel you have, as short of having it internally ground, it would be difficult to save and I doubt it'd be worthwhile having it ground.

 

Start off with a fine lapping past, give it 10 spins and see what they both look like, that will guide you as to if you need to go to something courser, but don't start with that and if you do use a course paste, do the dead set bare minimum with it.

 

You'll see when both parts are 'there', they'll have an even dull appearance.



#6 JamesAlexander

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Posted 21 May 2026 - 06:19 AM

Thanks Spider, appreciate your help!!

#7 Aridgerunner

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Posted 21 May 2026 - 11:59 AM

My crank was not quite as bad as yours but had been filed once before by a previous rebuilder. The car worked fine when we got it and I was surprised to see the damage. Removing the flywheel was VERY difficult even with the proper puller.

I did what Spider has recommended (with new light weight flywheel) and the car is back together. I have only driven it about one mile here on our country road (no windows or interior yet) but it seems to OK.

Wish ya luck!

Edited by Aridgerunner, 21 May 2026 - 12:01 PM.


#8 Spider

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Posted 21 May 2026 - 06:03 PM

To give you an idea how tight they do end up when fitted by the method I use, this is one of  my own flywheel coming off;-

 

 

The puller there is a locally made Coxhead Hydraulic unit, 12 tonne.

 



#9 floormanager

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Posted 21 May 2026 - 06:30 PM

I did one horizontally and had to jump out of the way before it wiped out my shins!



#10 Quinlan minor

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Posted 21 May 2026 - 06:36 PM

To give you an idea how tight they do end up when fitted by the method I use, this is one of  my own flywheel coming off;-

 

The puller there is a locally made Coxhead Hydraulic unit, 12 tonne.

 

 

Even though I knew what was coming, that still made me jump!


Edited by Quinlan minor, 21 May 2026 - 06:46 PM.


#11 JimmyStinkpickle

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Posted 21 May 2026 - 07:07 PM

I took a slightly different approach:

 

IMG-7268.jpg



#12 JamesAlexander

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Posted 21 May 2026 - 08:37 PM

Oh great thanks for the reference, made me jump too! I could have taken mine off with a standard size socket spanner!

Got a new boss today and lapped it in, showing dull grey in boss and the crankshaft all the way up to the pitting so hopefully I’ll get a good fit tomorrow…

Cheers Aridgerunner, I’ll let you know if it works! Nice job jimmystink haha!



#13 pete l

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Posted 22 May 2026 - 02:38 PM

Chris, why no locking tab under the bolt head ?



#14 JamesAlexander

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Posted 23 May 2026 - 05:27 AM

It’s a verto so the locking tab is on the nut, all back in just got to get everything back on then give it a test…




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