Suspension linkage question- completely stumped.

[northwind]

Just been back over at Matttheloony's place trying to finish up the install on his GSXR1000 shock. Nearly there- but there's one thing that's got me stumped with the linkage. Matt posted this a short while ago, but I think most people thought he was just mising something obvious- unfortunately not...

Bike is a '99 S. Basically, at the front of the linkage, where it bolts to the frame, there's 2 large washers that go between the linkage and the frame. But they simply won't fit now that we've come to reassembly. The linkage is the right way round- there's no possibility of getting it wrong, of course- and all the spacers are in the right bearings.

On close examination, the gap in the frame where the linkage fits isn't even- the spacer and both washers will fit right at the front of the slot, closest to the frame, but won't fit at the back of the slot, closest to the rear wheel. Unfortunately this means they won't fit where they need to go. I'd say it's between 1 and 2mm narrower at the back than the front, where obviously it should be parallel

Now, it was all together as usual when I stripped it, the spacer etc wasn't obviously wedged in or anything, and all parts were in the right place. There's no obvious sign of damage, though damage is the obvious conclusion I think since it's gone together fine in the past.

We've temporarily put it together without the washers... But I tend to work on the "there for a reason" principle. So, what should we do? Leave it as it is with no washers? File the frame down till it's square again ( )? Machine down the spacer? (I think there'd be clearance enoguh if we did this, though it'd be tight...)

[MrMessy]

Have you a picture? Will have a look in Suzuki workshop manual when I get home. Trying to picture which bit, is it where the dog bones bolt on? Is the new shock the same diemensions across the bottom where it bolts through? If it was narrower this would possibly cause an uneven gap?

[Sid Squid]

Messy: He means at the front of the linkage where it fits to the frame, not the shock lower mount. The 'dog bones' mount to the centre of the linkage.

Northy: Not a clue, the motor/suspension or other frame mounts haven't been disrubed I take it? Other than that I can't see how any stress/pressure that could distort the chassis could be applied.

I'm sure I appreciate what you're describing but could you perhaps take a picture anyway?

[Biker Biggles]

I take it you mean the solid bit of frame with the two protruding lumps where this assembly bolts through,just by where the sidestand is?That must be the strongest part of the frame and not likely to be damaged.The only thing I can think of is did you have to apply a lot of force to get the bolt out?Could you have bent one of the protruding lumps with the bolt holes in?I'm thinking perhaps you had to drift or hammer the bolt out?

[northwind]

Nah, that's one of the things that throws me- the whole thing came apart much as normal. I'd unbolted the shock from the top, so there was a fair amount of leverage applied when I took the linkage out, so there could have been resistance that I missed, but I don't remember anythign out of the ordinary. Absolutely no hammering, I did drift out the dogbone bolts but very gently. (just because of the restricted access to the bolts, not because they were stuck)

The engine's all in place and seems happy, the bike's been binned a couple of times but not seriously, unless it has a secret history and a huge amount of repairs. The shock linkage had been stripped before (it's an 18000 mile bike, but had the standard shock in, so I was a bit surprised... but overall it's been superbly serviced so that could just have been a diligent dealer/previous owner at work.)

I agree, I don't see how it could possibly have got damaged, at least not in this way. A twist ought to have spread the lugs apart, not compressed them, and the bolt wasn't overtightened (it's pretty high torque anyway, that one). The left hand face is absolutely smooth, the right isn't so neatly machined but doesn't look damaged. With the spacer arrangement, you'd expect that any sideways impact (HOW?) would bend both lugs, not just bend one in.

I'll be back over tomorrow, I'll see about getting pics then, plus I'll take my Measuring Thing and see how out of true it is.

Anyone know what the washers are actually for? I'd thought grease retention, but then why don'tthe other linkage bolts have them... To be honest, if it was my bike I'd just rebuild it without, but I'm not really comfortable doing it on someone else's...

I can't be sure off the top of my head but are there any bearings in the linkage? I think there is. It could be that one or both of the bearings may have come out of it's seat and is stopping the washers from seating correctly.

The washers would be there to act as a barrier between the frame and the bearings/linkage. Two different metals rubbing together continuously would get ugly, especially as the frame is the one that would wear quickest.

[northwind]

There's needle bearings, but the actual width of the spacer and the washers is too much, so it'll not be that. Take your point about wear surfaces though, hadn't considered that. Bugger. Quite a lot of sideways potential in an SV linkage, more than enough to have it rub, and the needle bearing surround is steel.

The bearing is solid in the linkage and doesn't touch the washers. They sit either side of the spacer which sticks out a mm or so from the bearing at each side.

[northwind]

Yep, but the bearings can slide on the spacer- whole linkage has a little play.

[NedSVS]

The washers stop the hardened steel spacer making indentations in the relatively soft aluminium frame. In the worst case the indentations could in theory make the spacer captive if the lugs were pulled in under enough torque. On the other hand, without the washers and not enough torque, the spacer could rotate and wear the faces of the aluminium lugs on the frame.