15 replies to this topic

[DanJones96]

So ive finnished rebuilding my 1380 over xmas. Some old boy comes in just as i finished and asked me if i set the float clearance on the primary gear? This is the first mini engine ive built so i am a lil new to this. The clutch and flywheel is already on, i didnt ever completely remove the primary gear on the end of the crank at any point during the rebuild but the C washer did fall off so i had to put that back on, i was planing on putting the engine back in the car tomorrow. Is it worth stripping the clutch and flywheel off again to check the clearance? Also if it is worth it what should the clearance be?

[Dusky]

3-5 thou on a road car, yes its worth checking. The idler should have been checked too as its very costly if it goes due to incorrect tolerances. I hope all other clearances are checked? If not strip the engine again..

Edited by Dusky, 30 December 2015 - 02:45 PM.

[Cooperman]

First of all, did you measure the crankshaft end-float? That is far more important as it should not exceed 0.005" on a newly built engine.

The primary gear end float is not such an issue so long as the primary gear bushes are not worn. End float should not be over about 0.006".

If the crank end float is OK and you are satisfied the primary gear bushes are OK, then you could leave it & see how it runs. However, it is a simple job to pull the flywheel off and, to be thorough, it might be wise. It's your choice really.

[DanJones96]

Would i need to check the crank end-float if i didn't remove the crank?

[Dusky]

Depends on what you call a rebuild ofcourse.

[DanJones96]

I tool the head off, sump off, diff apart changed all seals and gaskets changed the valve stem seals and added seals to the exh valves and pretty much put it back together. Didnt take the crank out or the pistons basically left the block as it was . Wasnt a full rebuoild

[DanJones96]

Other than a sump gasket, rocker cover gasket and valve seals leak it was running fine before i took it out just went through alot of oil

[Dusky]

While youre at it it is really worth it. Especially the idler and crank end float. Ofcourse , if you're in a hurry it won't do any more harm. it won't be worse than it was prior the 'rebuild'.

[DanJones96]

I may just whip the flywheel off tomorrow morning and check the primary gear float just for reassurance, before putting the engine back in

[Cooperman]

Whenever a Mini engine is removed and taken off the gearbox it is wise to check/change the main, big-end and crank thrust bearings. The piston rings should also be changed and the bores lightly honed. That is cheap to do and well worth-while.

The crank thrust bearings do wear and the end float needs to be set to 0.002" to 0.005".

Never skimp on a Mini engine re-build because whilst the engine is out is the ideal and easy time to do all this. Also ALWAYS fit a new oil pump.

[crn1969]

When checking end float should I push the gear towards tho block and then put feeler gauge between other end of gear and retaining washer? Or leave with no pressure on it and measure gap at both ends of gear?

[MrBounce]

Take a look at the engine rebuild guide by AndyMiniMad here: http://www.theminiforum.co.uk/forums/topic/208519-step-by-step-engine-build-no-waffel-just-building/ 

 

I followed it when building my engine. Invaluable and super helpful.

Edited by MrBounce, 03 March 2016 - 05:19 PM.

[Spider]

Just looking at the Primary Gear in isolation of all else, I'd also be checking the Primary Gear Bushes to Crank clearance.

 

According to factory numbers;-

 

The clearance here needs to be 0.003 to 0.0045" for the Bushes to crank and the End Float for;-

 

      Pre-A+ is 0.0035 to 0.0065",

      for A+ is 0.004" to 0.007"  

 

If the bushes inside the primary gear are worn, it can lead to clutch shudder (or judder), oil leaking on to the clutch plate or having the centre torn from the clutch plate.

[Spider]

Since this topic has been raised, I'll have a little whinge here.

 

The new C Clips that are available these days are too soft for the job. It doesn't seem to take too many miles at all before they are bashed out and the end float that we carefully set on assembly is lost.

 

Is someone out there supplying decent C Clips these days?   I'm just about out of all the old ones I've had.

[cal844]

Take a look at the engine rebuild guide by AndyMiniMad here: http://www.theminiforum.co.uk/forums/topic/208519-step-by-step-engine-build-no-waffel-just-building/ 
 
I followed it when building my engine. Invaluable and super helpful.

Great thread by a great guy who knows his stuff