12 replies to this topic

[Raven coll]

Hi Guy's,
I am building a 1380 pre A+ with a 16 valve BMW head, for my brother inlaw, using bits and piece from specialist components
I have heard an option to improve thrust life is to modify the engine oiling to feed oil to the clutch side thrusts to improve there life when running a heavier clutch cover.
Does anyone know what's involved in the modification. As I have plenty of other prep work to do on the block for the BMW head a little more machining does not worry me.

1978 clubman
originally a 998

[Ethel]

not heard that one, the clutch only puts any load on the thrusts when depressed. There is a mod to feed oil to the transfer gear thrusts.

Hi Guy's,
I am building a 1380 pre A+ with a 16 valve BMW head, for my brother inlaw, using bits and piece from specialist components
I have heard an option to improve thrust life is to modify the engine oiling to feed oil to the clutch side thrusts to improve there life when running a heavier clutch cover.
Does anyone know what's involved in the modification. As I have plenty of other prep work to do on the block for the BMW head a little more machining does not worry me.

1978 clubman
originally a 998

[Cooperman]

The biggest cause of high wear rate on the thrusts is starting the engine with the clutch pushed down and sitting at traffic lights with the clutch down

[Globule]

I believe it was Fastcarl who came up with this mod, perhaps try a search for stuff he has done?

[mini13]

Its not exactly common but a few people running turbo engines with heavy clutches have done it,

a grey pressure plate will normally be ok esecially if on an engine that dosent see to many miles, but the double greys used on turbo engines seem to give thrust trouble probably because they see more road miles.

esentially you drill the thrusts and screw them to the block, and drill through to the oilway that feeds the centre main.

there is a picture in this thread.



http://www.theminifo...x...6382&st=210

[Ethel]

Interesting, I'm not sure how much the screws contribute. The oil film would surely be wiped out to generate enough friction to spin the thrust and hard steel screw heads must cause more damage than white metal bearings. Also, the oil going past the shells has to also go past the thrusts to get back to the sump. Suppose you might get a bit more flow. If it works then you'd just need to do the thrust facing the clutch n'est-ce pas?

[mini13]

the thrusts are screwed down to make sure the oil goes to the bearing surface side rather than behind the thrust,

[MRA]

Flow finds the easiest route.... and the easiest route being the one without any load

[Raven coll]

Flow finds the easiest route.... and the easiest route being the one without any load

Hi Guy's,
Thanks that some it up. Mra-mini's I think the drilling is done only on the clutch thrust side to encourage the oil out in that direction and it will just leak out through the main sheel as per normal to the front.

Cheers,
Craig.

[MRA]

Flow finds the easiest route.... and the easiest route being the one without any load

Hi Guy's,
Thanks that some it up. Mra-mini's I think the drilling is done only on the clutch thrust side to encourage the oil out in that direction and it will just leak out through the main sheel as per normal to the front.

Cheers,
Craig.

Yes I would agree with that...

However as Cooperman says its the duration that kills the thrusts. The pressure of course has an adverse affect which would accelerate trhe wear, encouraging oil to migrate to a position associated with high wear has to be a good thing

Although with 14psi a double grey would not be required

[pogie]

An interesting topic.

The clearance on the mains, big-ends and cam bearings is much less than that on the thrusts. Will having an oil feed to a bearing with such a large clearance lead to a loss in oil pressure to the rest of the engine? This could be controlled by carefully sizing the drilling to the thrusts, but I was wondering if this issue had been taken into consideration?

Edited by pogie, 17 May 2010 - 06:54 AM.

[John H]

Our Metro Van has a 2mm hole for the oil feed. I have been assured by fastcarl that although we will see some drop in oil pressure that it isn't significant enough to cause any issues.

The screws are also countersunk well below the actual bearing surface of the thrust bearings, so should never come into contact with the crank during the serviceable life of the thrusts.

I have seen in the past people use brass screws in case they ever come loose. We have threadlocked our steel ones in place.

If you are interested in this mod I suggest you visit:-
http://www.force-racing.co.uk

Edited by John H, 17 May 2010 - 02:58 PM.

[John H]

Tadah! Brass screws.