Just another Thrust Washer

[trolleybus]

I have one TW at .092 (marked STD)
and one TW at .097 (marked .005)

Wich gives me a float of .22mm or 0.00866"
Just outside the recommended tolerance.
So I need a +001 or +002, but they don't seem to be available from the usual suspects.
There is a place in the US http://www.customthrustwashers.com/ but still not sure if they supply the sizes I want. Has anyone used them?
Any suggestions will be appreciated.
Also! The TW I fitted 5000K ago have a white metal surface. (seem to remember purchasing NOS TW)
The rear one has appeared to have melted the white metal surface off.
There is no damage to the rear main bearing.
The car was running an auto, just converting to manual when found the end float problem.
Did have a problem with the oil plug at the end of the cam blowing out?
And was running an oil bypass for the rockers for a short time without blocking the original feed hole?
It is also possible that I put it in back the front or with a too smaller tolerance.
Anyone had this problem?

[Alec]

Hello Bernard,

take an over size washer to a machine shop and ask them to surface grind the back by the necessary amount.

I don't believe that an extra rocker oil feed is detrimental to the rest of the engine providing the engine is in good order. There is excess oil capacity from the pump in a sound engine.

Alec

[Clifford Pope]

I bought one of those US ones a few years ago but haven't got round to fitting it.
My recollection is they do a range of sizes. You only need a special one on the thrust side, and you can pick'n'mix with the thickness of the other washer to get different total clearances.

A previous owner of my car fitted an ingenious external thrust bearing on the end of the crankshaft. It's a roller thrust bearing pressed over the projecting end of the shaft, bearing against a sturdy metal bracket held on two threaded bolts to the bearer plate. There is a pad on the bracket. Adjustment is easy simply by loosening or tightening the nuts on the threads.
I did originally take the sump off and inspected the rear bearing block. There was no sign of damage, and the standard washers were doing their job. The external bearing just seemed to be precautionary.

It seems a clever and very simple idea, the only drawbacks I can see are you have to use an electric fan not the crank-mounted one, and you'd have to loosen one of the bolts and swing the bracket aside to change the fan belt. You could I suppose keep a spare ready in place strapped to one side.

[Mike Stevens]

A TR6 engine I had in a Mk1 years ago had a problem when a thrust washer dropped out leaving the crank thrusting onto the block! My local engineering firm fixed that with 2 large, semi-circular pieces of phosphor-bronze pinned and screwed into the block and main bearing cap. It is such a super job that I suspect that engine will never have a thrust bearing problem again! The downside is that the crank and block can now only really be used together, not swapped out.

I don't believe that 8 thou end float is serious, but as Alec said, getting a +5 thou one machined down shouldn't be difficult. Personally, I'd try myself on a surface plate with some (oily) fine wet and dry paper, working on the white metal side (that being the softest!). It'd need a good clean afterwards though.

Cheers,
Mike.

[Alec]

Hello Mike,

I would have to disagree with your suggestion, on two points, it is the steel backing that need to be made thinner and that it is next to impossible to lap a piece such as a thrust washer and keep it parallel all over. While I do like to do as much as I can myself, I would not try and do it that way.

Alec

[Clifford Pope]

I have one TW at .092 (marked STD)
and one TW at .097 (marked .005)

Wich gives me a float of .22mm or 0.00866"

When you say you "have" these, do you mean those are what are at present in place, resulting in O.00866 end-float, or that those are the new spares you have available?

If those are the ones in place, and are visibly worn, then surely a new one of each will be about right?
I'd buy a new one of each, Std and 0.005, plus a second 0.005, and try each combination.

Opinion on a US TR6 forum seems to be that starting a bit tight (eg 0.004 float) is fine as it's bound to loosen a bit in use.
It's not going to close up tight in use like a wheel bearing because it only does anything when you press the clutch, not continuously?

[trolleybus]

Yes those are one new spare and one from the past set up.
I am awaiting two from the US which should give me .005.
As far as I can tell Custom Thrust Washers are the only place that will sell an unmatched set.
Thanks for the replies.

[Mike Stevens]

I would have to disagree with your suggestion, on two points, it is the steel backing that need to be made thinner and that it is next to impossible to lap a piece such as a thrust washer and keep it parallel all over. While I do like to do as much as I can myself, I would not try and do it that way.

Yes, you're probably right Alec. Maybe I wasn't thinking right when I typed that. I still think that it might be a way forward though - if you're stuck for anything else.

Interestingly, the end float tolerance for the 2000 is stated as 6 to 14 thou, but only 6 to 8 though for a 2.5PI. Why? Also oversize thrust washers are quoted for the 2000 but 'not fitted' for the PI. Again, why?

This then begs the question, what about the 2500 carb engine? Was that treated as a 2000 (6-14 thou) or a PI (6-8 thou)? Apart from the crank throw, I can't see what the difference is in the bottom end of a 2000 and 2.5/2500.

I know my big saloon Guru (Les Noviss, who is sadly no longer with us) had no worries about fitted over-sized thrust washers to a 2.5/2500. I see that CW still lists them for the early Mk1 and later Mk2/all Mk2, the latter in standard and +5, +10 and +15 thou.

Cheers,
Mike.

[Clifford Pope]

The thrustwashers serve two purposes. One is to resist the thrust when the clutch is disengaged. The other is to locate the crank and limit its fore and aft drift.
The crank can only move as far as the big and little ends allow - it surely is very important that crank movement never exceeds the con-rod movement? Are the con-rod bearing surfaces greater (longer) on the PI etc?