Iso and Zee Plate Flex/Clearance?

I noticed today that the 1/2" axle stud that goes thru the rear isolastic mount fit up does not seem right. When the axle nuts are loosened, the zee plates spring outward as tension is released. There are spacers on each side that should take up the slack, but they do not seem to be long enough. I enclose a picture of the right side, but it may not show up very well. I guess there is at least 1-1.5 mm clearance on each side so that when the nuts are tightened the zee plates must bend inward to take up the slack. In the untightened state, the spacers are loose and will spin freely. The picture shows clearance on both sides of the spacer. They are both like this. This doesn't seem right. Should I make up new spacers or add shims so that the zee plates remain flat and straight? Has anyone else seen this? '
Thanks,
Jaydee.

Afraid I can't answer the question, but I can confirm my bike exhibits the same "issue", so I'd be interested in any advice too. Have to say that in the past I've just bolted it up, but with a rebuild under way might be a good time to do it right?

I just slackened the assembly of my Mk3, there wasn't any gap.

If the two 3/8" lower and rear spacers have extra washers to kick out the exhaust mount that could explain it.

The Z plates are the 2nd most over built factory item, 1st being the Al connecting rods, so Z plates ain't bending flexing but the frame gusseted tubing area is. I can flex the Z plates some on my Combats with spacer perfect sized so nips up w/o frame straing, so will be backing Peel's up with extra 4th mount tab. Spacers at rear of Z plate to clear exhaust would tip front of Z plate inward so the reverse of flex issue reported. Commando's are a kit you have to make work right so spacers need some custom tweaking to nip up w/o bind load on frame through Z plate strain. If spaces all replaced with alloy ya loose about 1/2 lb to lug around and they don't rust.

L.A.B. said:

I just slackened the assembly of my Mk3, there wasn't any gap.

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Thanks, LAB for going to the trouble to check yours. I don't know a moderator on any other board that would provide this kind of service.
I'll let ya'll know what I find.
Jaydee

With ALL the bolts slacked off , they may sit flat . Haveing a few T I G H T and a few loose can lead to that sort of thing .
Checking as you nip all the bolts up , or putting a straight edge on a plate might tell you something . Its all the tensions & the like .
Across the whole assembly . Tecnically a spacer washer ( extra ) would be slightly tapered ( File or Stone ) for full face contact . :?

Would it be possible one of the lower spacers is unequal in length?

Keith1069 said:

If the two 3/8" lower and rear spacers have extra washers to kick out the exhaust mount that could explain it.

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Keith nailed it. I have extra washers on the two other mount spacers, on both sides. This makes the entire Z plate stand off by the thickness of the washers. Then, since the iso bolt/axle doesn't have the extra washers on its spacers, it is off by the thickness of the washers and must pull in out of line.
I put the Dunstalls on when I was a kid and I did not add the washers. I've never had the Z plates off. Must have been done at the factory for some reason.
I'm trying to decide if I should just add washers on the iso bolt or remove the washers on the other ones. They are very difficult to access. I may just make some longer spacers out of stainless.
Thanks to all.
Jaydee

jaydee75 said:

I may just make some longer spacers out of stainless.

Jaydee

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hobot said:

If spaces all replaced with alloy ya loose about 1/2 lb to lug around and they don't rust.

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I like stainless too, but it is kinda heavy for a spacer

My bike had washers in there... I took them out trying to tuck the mufflers in for kickstart clearance. Trimmed the muffler isolator studs short, used half height jam nuts to gain swing arm clearance. Worked out well.

Z-plates are the 2nd most over build item in Cdo's, so much so they can be cut out to just a rim left and still handle their function fine. The Z plates mount is made to be stable for vertical downward loads of pilot pegs and muffler hangers, not sideways twisting force of skewed spacers, so skewed spacers will tip Z plate in or out pretty easy, but close observation will reveal its the frame distorting taking up the skew loads on final nip up, not the thick robust Z plate. Close observation/testing of the front iso tabs reveal the down tubes are pretty easy to twist too and adds to the spring back of THE Hinge onset. There are two type of peashooters, the nicer ones that have smooth tapper down to header OD and those that are crudely necked down to header OD so thicker where kicker passes by or rather clanks by. There are like 4+ variations of the header angle out of head and how well the headers tuck into frame and engine cases, which means custom bending by kicking and levering plus Z plate shimming to clear.

The other annoying Z plate feature to work around is the rear brake cable. Both my Combats had a notch worn away where cable rubs. Except Peel whose rear sets were fitted against instructions oneinarow for a straight cable shot at brake while missing the Z plate.

Peel will take advantage of the robust Z plates to help add to frame stiffness with 2 extra cross rear frame cross braces plus a rod link and 4 points of plate attachment. A fifth very heavy cross brace is provided for a side car mount the Z plates will help hold on to.

Keith nailed it. I have extra washers on the two other mount spacers, on both sides. This makes the entire Z plate stand off by the thickness of the washers.

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Although as per usual I didn't say what I was thinking! That is the kickout is often (usually?) done so the exhaust mounting fasteners clear the swing arm. Moving out the Z plate often reduces k/start to pipe clearance.