Centre Main Strap Issues
Turbo Mini Forums

Morning Guys


Had my block machined for the Center Main strap and Graham pointed out it doesn't look right.
I need a 110% confirmation before I ring Mini spares & the machine shop to find out whats wrong here's a few pictures.








thanks
Stephen

looks like they took off to much of centre main cap??!!

Edited by clubbie70 on 14th Apr, 2015.

Nothing wrong with what you have. It's just that in cutting down the cap to the height of the bolt shoulder removes the thrust washer locating slot.

Usually we get around that problem by using a wide strap and cutting a new slot in the cap.



I recall that someone once said that they had problems with the sharp edge on the cap cutting into the thrust washer tab.

Edited by Paul S on 14th Apr, 2015.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Nope, that's right for a small-bore cap. You don't have to take so much off with a 1275 cap, so the original slot doesn't get machined away.

Edited by PhilR on 14th Apr, 2015.

Paul only in terms of the centre cap however the strap looks too thin. He will need a wider strap to cut the groove into or some pins pressing in?

On 14th Apr, 2015 Paul S said:
Nothing wrong with what you have. It's just that in cutting down the cap to the height of the bolt shoulder removes the thrust washer locating slot.

Usually we get around that problem by using a wide strap and cutting a new slot in the cap.



I recall that someone once said that they had problems with the sharp edge on the cap cutting into the thrust washer tab.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

This seems the standard way that 998 centre main straps are machined. If you have a light clutch you'll probably get away with it.

But I used a grey spring and it did as Paul mentioned (knocked the tab off and spun the bearings, wrecking the crank and block).

Pauls is the easiest fix. I had dowels fitted to stop the thrusts spinning.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk

Wil the think his issue is that the strap he has is too thin so the thrusts are flush when it's fitted. Carl did the same as yours and added some dowls into the strap to locate the tang on the thrust

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Ill upload another photo and you guys can see

But Paul your way of fixing it looks best way any chance you could help me out at all with that :) being cheeky and all

As you can see I have quite a big gap between the thrust washer and the strap

Like I said in your build thread. file a slot in the block and put the thrusts in the other way up. Quicker than making a new strap.

Thanks Slater

Ill properly get a new strap made its not to hard to get done

thanks for the help guys

File a slot in the block. Listen to what people suggest!

I'm taking Paul's Option.

Filing isn't gonna be 100% center either side and not sure if this will cause Issues when the engine is assembled. I appreciate the suggestion though

thanks guys

You could file it at 12 degrees if you want to....

You prefer weakening the strap

Other option would be to drill and screw the thrusts to the block & cap.

If something is worth doing, it's worth doing half of.

How would a slot in a strap weaken it?

I'm just not a fan of filing my block to fit thrust washer

And john that's a good idea but if the thrust wear won't the counter sunk bolts I've used start to wear and damage the crank?

On 17th Apr, 2015 Vegard said:
You could file it at 12 degrees if you want to....

You prefer weakening the strap

If something is worth doing, it's worth doing half of.

Not if they are counter sunk enough.

If something is worth doing, it's worth doing half of.

That looks a good idea john no more spun bearings but how do you drill and tap them?

I got Carl @ Force Racing to do mine. But I see no reason why you couldn't do it yourself.

You could also oil feed them at the same time if you are planning on running a strong pre-verto clutch.

If something is worth doing, it's worth doing half of.

Thanks john I'll take a look into it giving me some food for thought