How do I tell if I've got a bent frame?

Hi guys. I need to tap into the font of knowledge again, and hope you can help me!

I've been looking to install a CBR F4i shock on my Vf500, and have loosely assembled everything so I can have a bit of a measure up for the linkages.

I've noticed that the lower link sits to one side in it's bracket, and that the top mount for the shock seems to be drilled on an angle - that is the holes aren't level when viewed from the rear of the bike. It's niggling me that all this stuff doesn't sit right in the middle of the brackets, although I notice from CMSNL.com's parts fiches that there are no spacers either side of the shock linkage or the lower suspension link. Is this why? Are Honda's tolerances that wide?

Has anyone got any measurements that I can take to make sure this frame is straight? It looked OK before the bike was stripped, but now it's just a bare frame I want to make sure it's right before I attach anything to it.

Any information would be extremely gratefully received.

If it does turn out to be straight, I'll be starting on that exhaust I first mentioned about 6 months ago in the new year!!

Thanks in advance!

Gareth

I thought I'd take some pics to explain what I meant above!

[image: Posted Image]
In this one you can see the shock installed in the bike. I've put a long bolt in the top mount so you can see the angle of the hole relative to other visible parts of the frame.

[image: Posted Image]
This one shows the top mount of the shock pushed against the left (as sat on the bike) side of the mount.

[image: Posted Image]
And finally this one shows the linkage pushed to the right of the lower link, which is also pushed to the right of it's mount in the frame.

I've looked at the frame closely and can't see any obvious impact damage. The two upper rails of what would be the subframe seem to be at different heights, could the bike have been down and tweaked the subframe??

Is this serious? Can it be untweaked?

Just a shot in the dark, but are there spacers where the swing arm mounts to the frame?
You may have them switched/missing... Sorry, not much help, but had enough of these DOH moments myself to not discount them completely.

[image: View Post]Rice, on 23 December 2010 - 11:32 AM, said:

Just a shot in the dark, but are there spacers where the swing arm mounts to the frame?
You may have them switched/missing... Sorry, not much help, but had enough of these DOH moments myself to not discount them completely.


Not as far as I can tell. Swingarm sits tight on left hand pivot point, and the preload on the bearings is adjusted on the RHS. Know what you mean about the "Ah, where does this spare bit go" moments though!!!

Use a level and get the top of the frame level. Then run a longer, absolutely straight bolt through the top shock mount. Is that level?

[image: View Post]GazVF500, on 23 December 2010 - 10:54 AM, said:

[image: Posted Image]
And finally this one shows the linkage pushed to the right of the lower link, which is also pushed to the right of it's mount in the frame.

I've looked at the frame closely and can't see any obvious impact damage. The two upper rails of what would be the subframe seem to be at different heights, could the bike have been down and tweaked the subframe??

Is this serious? Can it be untweaked?


Hi, there should Not be that much Free Space top or bottom IMO, it needs washers, shims, something to prevent that much movement especially the lower pivot.
From the frame pic it does look like the rear sub frame is slightly bent. If you can solidly hold the frame down, you can twist the rear mostly back into place with a long pipe/bar.

Thanks for all the information so far, gents!

Yes, it does look like the left subframe rail is low. Raising this up would, due to the parallelogram setup in that area of the frame, pick the frame rail up and move it to the left.

I will definitely try the long bolt idea, I have a digital spirit level and can get some 10mm bar to put through the bolt holes.

Cheers guys!

Gareth