Thrusts?!
Turbo Mini Forums

A friend has a 1293 pre A+ which was supplied as a kit from Oselli and I built 3 years ago. He ran it in for 1000 miles and all was fine for 18 months until he fitted a Jonspeed flywheel with orange spring, the endfloat grew to around 80 thou.
On investigation the thrust washers are fine but the face on the crank has a 2mm groove in it where the phospher bronze has ground it away!?!?
Obviously to me the clutch adjustment caused the failure, but has anyone heard of a thrust washer itself being harder than a crank?
Odd I know.

Paul

I seriously doubt it!

Yeah, if you fit it inside out

not specifically thrusts, but many a time on cylinder heads fited with calsibro guides ive found that the stainless valve wears a lot more than the guide, so it is possible for the crank to wear first,

i saw one head recently that had really fooked rimflow valves, the fella , [who had a fair idea] reconed he'd done about 14k on the engine, the valves flopped about aimlessly in the guides bit on inspection it appeared the valves were badly worn, and upon measuring were found to be in the order on 0.003 of wear,he thought the head was scrap as this had caused the valve seats to be all shapes. but i pointed out they would clean up no bother,

so what your suggesting Paul is possible,


carl

WWW.FORCE-RACING.CO.UK PLEASE CLICK HERE

If the thrusts were cheap ones, coluld it be a case of them not having much embedability.

On 17th Apr, 2008 Vegard said:
Yeah, if you fit it inside out

I seriously doubt it!

It is not unusual for the harder material in a "plain" bearing to wear faster than the softer material (although this is a bit extreme).
Usual reason is dirty oil (damaged filter or passing filter bypass valve) and in the highly loaded areas any abrasive particles in the "dirt" get buried in the surface of the soft bearing material (but not the harder material of the crank etc.) and the softer material then becomes abrasive to the harder material.
It all depends on the film thickness of the oil and how far the abrasive particles stick out of the soft material.

Schrödinger's cat - so which one am I ???

^^^^^^

thats what I was getting at.

Rocker shaft is prime example. Shit and grit get stuck in the soft rocker bushings, wearing the shaft.

yes, but thats fortunate, as the shaft is MUCH easier to change than the bushings.

I seriously doubt it!

Another reason that could have accelerated the wear is if the clutch pedal is pressed down when starting the engine - lots of people do so because they have been told it avoids the starter motor having to turn the input and layshafts inside the gearbox in cold heavy oil.
However, the thrust bearings rely on hydrodynamic lubrication which will be ineffective at starter motor speed so we're talking boundary layer lubrication which, with a strong spring in the clutch and the pedal pressed down, means a VERY thin film of oil. So the abrasive particles don't have to stick out much from where they are buried in the soft material, to do real damage.

Schrödinger's cat - so which one am I ???

TThhh (sucks long and hard through teeth)

Jonspeed minis flyweel

Ive had two of these and i should have learned from the first experience never to buy another, but i did, and the second one was no better.

Loads of runout, ringear runout was silly and we had to add weight to the first wheel to get it balanced and take loads off the second one.

Having said all that, im wondering if the run out had anything to do with the extreme wear on the front bush of the primary gear. The slop in this bearing was massive and its only done 3k miles. I only noticed this wear about two weeks ago when we were trying to balance this new Johnspeed Minis flywheel. Looks like ill be fitting a floating bush in there.

Maybe i have just been unlucky and bought two inconsistent flywheels from the same manufacturer. They are not even the same design, resulting in having another 1.5mm or so (a little extra for a third strap, would have needed 0.9mm without the extra strap)off the backplate lugs, so thats 2.5mm in total including the 1mm i had machined off last year!!..

Anyone seen the thread on TheMiniForum on Johnspeed Minis H section rods. Its quite funny, lol.

http://www.theminiforum.co.uk/forums/index...62&hl=johnspeed

In the 13's at last!.. Just

I don't know what to say about that topic really...

All i can see (and don't take this the wrong way sprox) is someone who has paid for a set of arrow / whatever) rods, and considers anythign other than the free A+ rods that come free with every engine to be pants?

You pays your money, you takes your choice. That is the way I see things. Personally - I like the ability for there to be a choice of available components, from the most exotic, through two / three cost levels, then down to standard.

I've just shown a pic to a guy over here who races a 7-second drag car, and makes his own rods (or rather his father in law does on his CNC). He reckons those rods look just fine compared to what he runs in his engine.

Edited by turbodave16v on 17th Apr, 2008.

Dave, im not going to get into the does and donots of buying rods that appear to have a chinese origin, but i will say i have seen a set form a VW air cooled after they had been balanced , and they certainly did not look good, as i have said before , i have a set of arrow rods new unused , perfectly balanced and not a mark on them,

As sproket says attention to detail, ,to the naked eye they will look well finished, but a thou here and there in the wrong place soon adds up .

carl

WWW.FORCE-RACING.CO.UK PLEASE CLICK HERE