Commando Cafe Racer Rebuild

Re: Commando Cafe Racer Rebuild 5th August 2009

Hi Stu,

nope, 2 carbs there as standard. Must be just the angle or the lighting. Nothing unusual in the carb dept. Not really impressed with the front brake mount, but I knew the previous owner (who did the brake conversion in the first place) and he rode around with it for a couple of years - before throwing a 'rod - so I know it's up to the job. Just wonder if I'll be able to get it past the pits for rego this time around, even though there's no change from last time. :?:

Thanks PLJ, I just might take you up on that. I'll dig out what I've got and see what sort of nick it's in first. Might be still a goer. Appreciate the offer either way.

Will take the transmission case cover off either tonight or tomorrow night and see what's going on with the clutch. That's the real worry at this time...

Re: Commando Cafe Racer Rebuild 5th August 2009

Well I took of the case and had a look, but can't see anything silly. Primary chain might be a bit tight, but not excessively so. Really hard to try and determine exactly where the sound's coming from by yourself, but one thing is for sure, it only makes the noise when in gear and clutch in. Maybe it's the gearbox, can't be sure - wouldn't surprise me though as muggins has pulled it to bits and put it back together (there were no leftover bits - I swear!) Have to rope in one of my mates to come around and assist.

Re: Commando Cafe Racer Rebuild 5th August 2009

With the assistance of a friend I ran it up again this morning with the transmission cover off, but before doing that I backed off the primary chain tension to the 9.5mm (or thereabouts) of slack the chain's supposed to have. Noise seems to be coming from the clutch basket. Hmmm.

A question if anyone can answer - is the basket meant to be loose on its bearing? If I squeeze the primary chain together with one hand at the middle of its span, the whole clutch basket moves forward by a mm or so, and this is without much pressure. When the motor's running, the chain tension seems to be varying widely, the chain flapping up and down. This can't be right - can it???? Heeeeeeeellllllllp please, anyone????

Re: Commando Cafe Racer Rebuild 5th August 2009

Not good, Pull basket and check the bearing in it. Hopefully it's not your sleeve gear bushings or trans bearings.

Re: Commando Cafe Racer Rebuild 5th August 2009

And if it is the clutch bearing, then ideally you should replace it with the correct tight clearance Norton bearing.

Re: Commando Cafe Racer Rebuild 5th August 2009

Thanks LAB and HN,

yep doesn't seem right to me. I've decided to pull down the clutch and investigate further. I've got the clutch spring compressor tool thingy made up, just need to obtain a gear puller to remove the cog off the crankshaft.

Re: Commando Cafe Racer Rebuild 5th August 2009

Pulled the clutch down today. Checked out everything along the way. Put it all back together. Same thing. Groan.
Not a waste of time though, the clutch driven plates had picked up some surface rust scale.
This is the worst one - the pressure plate.

Here's a typical plain plate:

And finally a sample friction plate:

I cleaned the pressure and plain plates up with wet-and-dry, they came up fine. The friction plates I had replaced by the engine builder - they're all brand new. Cleaned out the clutch bearing and gave the whole lot a good drink of fresh oil prior to re-assembly. I checked over the primary chain for kinks - all fine, but that too I think was replaced, I remember the mechanic showing me a damaged link - caused by the seizure - and pretty sure we opted for a newy. (Forgive my memory on these matters, it was about 7 years ago when I had the engine rebuilt.)
Checked the specs on the clutch basket 'slop' - 1/8" to 3/16". That would be about right then (approx 3 to 5mm). Primary chain is now too loose, will readjust tomorrow.
Only leaves the gearbox.

Re: Commando Cafe Racer Rebuild 5th August 2009

Ran it up again this arvo after checking and adjusting the primary tension. The chain had enough slop to rub against the primary case inner and when set to the correct tension does this no longer. Still makes the noise though. Why does it take so long to start up though??? I pull in the clutch and no noise. I select a gear and no noise. I give it a couple of revs and then say 10 secs after selecting a gear it starts up. This is trying to tell me something, but I don't know what it is. I'm beginning to wonder about the alignment of the two gears and the chain, these could be out as a result of the new crankcases (old ones 'rather' damaged when the 'rod was thrown) and or ignorance of the chappy who rebuilt it. Will look up in the documentation on how to check the alignment. Is the shim supposed to be put on between front crank and alternator rotor? That's where I took it off from, but how is the spacing of the cog on the crankshaft set? This is doing my poor widdle head in.

Re: Commando Cafe Racer Rebuild 5th August 2009

I went through all the documentation I have last night including the Tech Ref, workshop manual and parts diagrams, but could find no information on how to check (or change) the primary alignment.
So where do I go from here? Another hypothesis? Ok.
I recall the original clutch plates were the earlier fibre ones and were replaced by the chappy who rebuilt my engine with the later bronze ones (see pic above). The Tech Ref says this is fine and a desirable change, but mentions that the pressure plate would also have to be changed to the later (thinner) one. Anyone have any idea what the thickness of this plate is so I can check if I have the earlier or later one? Whatever it is, there's no sign of it ever being used - no scrape or slip marks. Trouble is, I can't see how this would result in the noise I'm hearing, but then again, better to fix all the known problems before tackling the unknown ones.
Any and all assistance appreciated.

Re: Commando Cafe Racer Rebuild 5th August 2009

Hi Daveamb
1)Most folk convert from bronze to sureflex, not the other way round.
2)The clutch throwout bearing is a cheap bearing, maybee $10 max. Why not replace it. You can buy one from any bearing shop. (But there is always some play here).
3)Is your clutch basket running 'true' when the engine is running?
4)How much end play does the gearbox output shaft have? (Should be no more than 0.01")
5) 0.230" thick plate for bronze plates 0.347" for fibre plates.

Re: Commando Cafe Racer Rebuild 5th August 2009

Hi Stu,

bigstu said:

1)Most folk convert from bronze to sureflex, not the other way round.

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I don't doubt it, although the Tech Ref says the opposite. If memory serves, the original ones looked like they were made out of cork and a couple of 'pads' had come off completely. At least this doesn't look like it would happen with the bronze friction material.

2)The clutch throwout bearing is a cheap bearing, maybee $10 max. Why not replace it. You can buy one from any bearing shop. (But there is always some play here).

Click to expand...

That is excellent advice. I thought it would be another BIG$ Norton part that would take months to source downunder. Is it really that commonly available?

3)Is your clutch basket running 'true' when the engine is running?

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A mm or so of wobble, but I thought this was within limits. The bearing seemed to be in excellent condition when I dismantled the clutch. Got to be some slop.

4)How much end play does the gearbox output shaft have? (Should be no more than 0.01")

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Don't laugh, but I am entirely ignorant as to where the gearbox output shaft actually is. (I better go and find out!) I know the final drive front cog is down there somewhere behind the clutch, behind the inner transfer case, but having never seen it in bits, I have no idea how the drive comes out of the gearbox. I s'pose it's all coaxial with the input shaft one running inside the other??

5) 0.230" thick plate for bronze plates 0.347" for fibre plates.

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Can't see any signs of wear on them at all, think they're brand new. Must 'borrow' the verniers from work and measure when I have it in parts again.

Really appreciate your responses. Same to all the others that have assisted along the way. This old girl is really close to travelling the road again, but so frustrating to be stalled at the gate.

Re: Commando Cafe Racer Rebuild 5th August 2009

Davamb
The 'sureflex' fibre plates are a solid fibre plate, the whole plate is fibre...there are no 'pads' on them. I think you are thinking of the old style 'Dominator' type plates. Go onto the Norvil web site, look at the parts lists, clutch, and Sureflex and you will see a picture of one.
The bearing is just an SKF ball bearing, the code on the bearing will sort you out. You can buy them open or sealed for use with a belt drive. They are £8 from Norvil and less from a bearing guy near you..
When I say 'output shaft end play' I mean if you grab the clutch basket and pull and push in and outhow much play is there?
Those dimensions I gave you are for the pressure plate thickness...This is the last plate with the gear teeth cut into it that the spring contacts. The reason they are different thicknesses is coz if you have sureflex plates you use 4 of them and if you have bronze you use 5 of them. So what I am saying is if you switched to surflex fibre plates you would have to have the thicker pressure plate (but if you do this make sure it is a steel one).
Good luck.

Re: Commando Cafe Racer Rebuild 5th August 2009

Much thanks guys,

I had no idea about the Sureflex plates, so the plates it must have had were the Domi ones you mention Stu. So the change to the bronze ones is an improvement over the Domi ones and if so, I'll leave them as is.
When I grab the clutch basket, there's no movement of any consequence, either side to side (hardly more than a mm) or in and out. I did this last night, but I do have wimpy little electronics engineer hands, not beefy mechanic's style ones! I'll back the primary chain tension right off and repeat this though.
Can't remember how many plates there actually were 4 or 5 - dunno.
There was also a 'dummy' plate which was just plain steel without teeth on either inside or outside which went in first - against the back of the basket - more like a shim than a plate. My 70 parts list does show such a shim and the earlier Dominator style clutch plates too, but it's not there in the 71 listing. Hmm, this needs further consideration.

Re: Commando Cafe Racer Rebuild 5th August 2009

Ahhh. That's it isn't it. It's the shim slipping against the clutch basket. It's supposed to be secured to the basket by what looks like flyspecs on my parts diagrams but are actually Drive Pins. There's nothing there, the shim just floats.

Re: Commando Cafe Racer Rebuild 5th August 2009

Ludwig you are correct, Sureflex not solid fibre, I was trying to describe what they look like visually.
I hope my Sureflex plates dont look tike that after 10000 miles!!! I have done 7000 on the Triton but of course they are not dealing with the enormous power and torque of a Commando. :mrgreen:
Davamb:
When you say drive pins I am not sure what you mean. On my belt drive version the first 'shim' as you call it is fixed with countersunk screws, as I remember.
I think yours should maybe be rivetted on...anyone else know?
Have you been on the Andover Norton website? If you google 'Andover Norton' and go into their 'webshop and price list' you can pick your model and it will take you to an exploded diagram....if you click on a part it will tell you what it is, its part number etc. try it with your drive pins...

Re: Commando Cafe Racer Rebuild 5th August 2009

Yes, I had an old standard Commando chainwheel that had the back plate riveted in....and the rivets had all sheared or broken. Never used it though, it was just amongst a pile of bits, but definitely the backing plate would originally have been riveted in

Re: Commando Cafe Racer Rebuild 5th August 2009

On this diagram the parts are shown as #43: Clutch Backplate Rivet, and are used to retain the shim (#42) to the backplate (or basket as I've been calling it).
primary transmission pic

Re: Commando Cafe Racer Rebuild 5th August 2009

Hi all,

firstly, thanks for all the help I've had on this point guys, I'd still be scratching my head and contemplating a bonfire it is wasn't for the assistance I've been getting here.

I've been in touch with my local parts suppliers (am I allowed to put in a plug for these guys - they've been a great help) and they inform me that my basket is "obsolete and not worth persevering with" and that the later one "had the plate securely riveted in permanently with three large rivets, and it never comes loose". They can do me a very good used one at a quite good price, so I'll go this way, though I think I need a matching pressure plate - the later one was thinner I believe. Can anyone confirm this?

It's still going to take me a week to get the new bits, so I think I'll tap some holes in the current basket and countersink the shim to take some set screws. Shouldn't take much effort and will allow me to get my 'driveway fix' that I've been hanging out for.

Re: Commando Cafe Racer Rebuild 5th August 2009

They can do me a very good used one at a quite good price, so I'll go this way, though I think I need a matching pressure plate - the later one was thinner I believe. Can anyone confirm this?

Click to expand...

The thinner pressure plate is only required if you are using the 5 plate clutch. If you use the 4 plate then the early "thick" pressure plate is used.

Re: Commando Cafe Racer Rebuild 5th August 2009

Thanks Ron.