Thrust bearing clearance

[cadwell]

Can anyone advise me on this one.
Rebuilding my twin cam to go back in my rebuilt S4 and have come across a problem.

Crank journals are at 0.010”and perfect. Crankshaft endfloat is 0.016”with new 0.010”oversize bearings fitted!
0.010” oversize seems to be the thickest available. When I stripped the engine, the crank had standard thrust bearings/washers, so there was 0.036” end float!!

Workshop manual recommends 0.008 max whilst Wilkins book recommends 0.011 max, so I have at least 0.005” too much.
Anyone have any thoughts on this?

Peter

[StressCraxx]

Thicker thrust washers are available in 0.005" thicker increments from standard from the usual suppliers.

[cadwell]

You must know more than I do because all the suppliers I have tried only stock up to 0.005. I managed to get a pair of 0.10 from Denis Welch who is not a TwinCam specialist.
I was not aware that anything above .010 was actually made, but if you know otherwise I should be grateful for info n the source.
Peter

[StressCraxx]

You must know more than I do because all the suppliers I have tried only stock up to 0.005. I managed to get a pair of 0.10 from Denis Welch who is not a TwinCam specialist.
I was not aware that anything above .010 was actually made, but if you know otherwise I should be grateful for info n the source.
Peter

Hello Peter,

I stand corrected. I looked up my local supplier here and he only had the +.005" washers as well.

[rgh0]

Larger oversize were made in the past and I have a number of NOS 15 thou and 20 thou thust bearings. If you cant find anyone who has any NOS then you can get a bearing white metalled to increase the oversize and reduce the end float and put the white metal bearing on the non clutch thrust side. I have run engines like that successfully for mnay years before I found the NOS oversize bearings

cheers
Rohan

[cadwell]

Thank you Rohan, I hoped that you might chip in!

I suppose you wouldn’t want to sell me a pair of the 0.015” would you!

Thanks
Peter

[cadwell]

Rohan
I have searched for NOS thrust washers but cannot find anything applicable. I like your suggestion of white metalling the non thrust side bearing, which I will have to try if all else fails. Problem is finding any white metallers these days!

You say you have several NOS plus 15 washers. I will pay your price for a pair as I realise the rarity value.
Forgive my ignorance but I think you are in Australia? So I would be very happy to pay carriage, no problem.

Best wishes

Peter

[rgh0]

Hi Peter

I am currently in Germany and travelling around Europe until the end of june. I will check what stock i have to see if i can spare any oversize ones when I get back to Australia and let you know. I routinely use 15 thou oversize thrust bearings on my competition engines using the modified Datsun L16 crank as they have a slighly wider thrust bearing spacing than the standard Ford crank so I need to keep enough given their rarity these days


cheers
Rohan

[cadwell]

Thank you for your reply Rohan, I will look forward to hearing from you when you return home.

Best wishes

Petrr

[rgh0]

Hi Peter
Just back from germany and checked my spares and i have only one 0.015" thrust bearing left, which I need to keep for future engine builds. So sorry but i cant help you out.

Unless you have found some elsewhere finding someone to white metal a bearing to the size needed may be your only option. Companies that restore prewar cars may be able to help you locate someone who still does white metalling.

cheers
Rohan

[cadwell]

Hi Rohan
Many thanks for trying to assist me, and I hope you enjoyed your trip to Germany.
I have been investigating sae 660 bronze tube which has a lead content, I am thinking of machining thrust bearings from this, it seems to be the ideal material.
I would prefer to have equal thickness bearings on both sides. Making only one bearing would mean it has to be .010” thicker than the other side. In your experience would this be acceptable?
I would value your opinion on this and the bronze.

All the best
Peter

[rgh0]

The small shift of the crankshaft due to non equal thrust bearings is not crtical in my experience. i have seen two types of thrust bearings made for the engine. One type that has a copper or bronze running face and one that has a lead / tin running face, so a 660 bronze bearing should be Ok especially in the non clutch loaded side.

cheers
Rohan

[2cams70]

That amount of crankshaft endfloat and the requirement for that thickness of thrust washer to compensate is not normal. Something is not right. What is wrong? Is it the block where the thrust washers fit - ie the dimension across the thrust washer location surfaces too little? Or is it that that the thrust surfaces on the crankshaft are too far apart? The root cause needs to be established before resorting to extraordinarily thick washers.
Something has happened in the history of the engine to cause this. It didn’t leave the factory that way

[cadwell]

I don’t think that an extra 5 thou on the bearing thickness is extraordinary. After all these engines are 55 years old and may have needed the faces regrinding in the past.
Rohan’s suggestion of extra white metal is a good one and I have found two white metalling companies who could possibly do this.
However, unless anyone on this forum knows a source of 0.015” oversize thrusts then I will machine a pair out of 660 bronze which has a high lead content, and Rohan agrees, should do the job,

Many thanks for your assistance.

Peter

[rgh0]

The crank has been ground undersize and I presume the thrust faces were also ground. If the gap between the thrust faces is measured and the thickness between the thrust bearing mounting faces measured this can be verfied

cheers
Rohan