Square Four MkI restoration complete - almost....

[nevhunter]

I think that's the way it's intended to be done. it's trapped and not able to be damaged, Unless you have bevel gears involved end float is not that critical unless it's not enough. Preloaded tapered rollers have none usually. The preload is part of the design concept. Nev

[roger.fellows]

Gui, having read and re-read, I think with sufficient care, your logic is not right.

Shims should be placed between the face of the crank journal and the thrust washer, and must have a diameter smaller than the journal.

You correctly state - as I see it - that you sandwiched the bush by having insufficient end-float.

Shims placed next to the journal can only INCREASE end-float - and that is what is required.

When you reassemble, including perhaps, checking with the engine plate mountings suitably bolted up, you need 2-4 thou end-float.

Somebody please correct me if I'm wrong.

[david.anderson]

Gui
As Roger stated the end float in thesquare 4 is controlled by the timing side bush only. Shims are placed over the end of the crank journal. The factory stated end float is 2 – 4 thou. To increase end float a thicker shim is placed between the crank journal and the thrust washer.
I would also check that the timing side bush has not spun in the crankcase.
David

[john.whiting]

i am not in favour of using thin shims.....its too easy to crinkle up a very thin shim as the fastener is tightened,thin shims sometimes break and fall out ,too........I would expect 005 ,or more to be a good choice,and never use a bunch of thin shims..........a bit much endfloat wont hurt anything......I also think its a good plan the install the crank (with roller) bare ,to check endfloat ,bearing contact,and general freedom of revolution.

[Paul_Linden]

When I rebuilt my mark2 engine, I set the end float on the crankshafts after they had been assembled in the cases with the camshaft and main bearings for the final build, i.e., not intending to split the cases again, and before the coupling gears and barrels went on. If you set the end float of the cranks on a test build, it may change slightly when you do the final build (due to different bolt tensions, gasket goo on the cases, parts seating differently, etc.)

[simon.holyfield]

When I rebuilt my mark2 engine, I set the end float on the crankshafts after they had been assembled in the cases with the camshaft and main bearings for the final build, i.e., not intending to split the cases again, and before the coupling gears and barrels went on. If you set the end float of the cranks on a test build, it may change slightly when you do the final build (due to different bolt tensions, gasket goo on the cases, parts seating differently, etc.)

Same approach as I used.

[Gui.dorey]

Hi everyone,

Having some discussions outside of the forum, I now realize I did have some things wrong. The problem was I had some shims in the boxes of bits that came with the bike that don‘t belong to it. They have an outer diameter which is the same as the thrust washer, so basically they could never work. This got me completely confused and made me get things backwards. Luckily I now did find a set of the proper shims among the rest of the parts.

As mentioned here the end float is only set on the timing side and the roller bearings on the drive side have no influence. The shims should have the same OD as the shoulder on the crank, so they won‘t push on the edge of the bearing bush, then comes the thrust washer, then the nut.

When I get my new bearing and in line bored again, I‘ll assemble the cases with the cranks just to check if I do have enough clearance available. If so, then the proper assembly with the camshaft and all the bits to set the end float. Then I should be good to go.

My plain bearing didn‘t rotate when it seized. However, it shouldn‘t be that critical if it had because mine have a groove on the outside so the oil passages wouldn‘t be blocked. But, I‘ve now learned that there are bushes without the groove, and for them the proper alignment of holes with the oil passages in the case is critical. The outside groove also only works properly together with a Morgo pump. If one has the original pump, the pressure and flow rate is not high enough to fill the grooves. At least that‘s what I‘ve been told.

[david.anderson]

It is actually easier to set the end clearance when the cases are split and you are working with just the timing side case.. One crank at a time into their timing side bearing with nothing to interfere with end float. After assembly you can check, but it more difficult at that stage.
There is no problem with the original oil pump being able to properly lubricate the timing side bushes irrespective of alignment of oil holes.
A further observation is that on dismantling the 4, I have never found the timing side bushes to align with the case oil holes. In one case the owner stated that he had originally aligned the oil holes so it is possible that the bush had spun a little in the case. The cases do get very hot. For that reason I would never fit a timing side bush that did not have the outside oil grove, unless it was peged in position so that the oil holes were permanently aligned.

David

[Gui.dorey]

Hi chaps,

To close up this story, I got the new plain bearing from Drags, and had it lined bored together with a mate. In the end it wasn‘t so difficult. It‘s more the setting up the milling machine than anything else.

A few late nights putting the engine back together, and this time making sure the end float on the cranks were set properly, and this morning the first start.

After checking that everything was running properly again, went off for a short run on the roads around the village, and she did very well. Mixture seems to be good, although I still can‘t shut the bi starter completely. She now starts on the first or second kick. Oil pressure is still quite high, but already went down to about 30psi after the short run, so not really worried about that.

Having some oil leaks from the gearbox. Not sure exactly where they‘re coming from, and will have to check it with more time. One seems to be from the output shaft, which would mean major surgery again... But all in all very happy today. Time for a very large beer now.

Cheers,
Gui

[simon.holyfield]

Congratulations Gui, you must be very relieved and happy.

On the bistarter, look at the lever and cable. I found it would foul my HT leads unless I strapped them down in a particular position.