Subject: RE: Disk front ends
Author: murp-@aol.com
Date: Jan 29, 2001, 1:15 PM
Post ID: 1705168498
David,
After sleeping on this little problem, I realized that the offset of
the hub does not have any bearing (bad pun) on the question of why your
LHS disk would not line up with the LHS caliper. What is relevant is the
spacer width. I can't believe that the bearing carrier (the type for
mounting a disk) for the left side would have a different width than the
right side bearing carrier, as I think the same part should be useable
on each side. If identical bearing carriers are used on each side, and a
spacer of the same width is used on each side, and identical disks are
used, then (theoretically)the disks should be in the same relative
positions with respect to the calipers. In other words, everything
should line up if everything is symmetrical. I don't think anyone (even
an Italian) would design something asymmetrical when it is not necessary
and when a symmetrical design would be easier for every reason.
I have done some thinking about why my hub is offset by 1.3 mm to
the right. If the bearing carriers were of different widths (ie if the
right bearing carrier on the right was thinner by 1.3 mm) then if the
spacers were the same width, then the rim would then be equidistant from
each fork leg (exactly in the middle). But, I really doubt that anyone
would design this scenario for no good reason. Therefore I have come to
believe that the hub was designed to be exactly in the middle (same
offset both sides), and that a 1.3 mm offset of the rim does not matter.
So, the end result is that I am going to reassemble the wheel so
that the hub is in the middle. I hope that when I get a bearing carrier
for the left side, it will have the same width as the right hand side
part.
Unless, of course, someone with more knowledge than me tells me that
I'm wrong......
Brian
David Washburn wrote:
| I just finished assembling my front end and ran into a little problem. I got the twin disk spacer from Moto Int. so I could run my single disk on the left side instead of the right. It put the disk too close to center of the wheel and I could not get the caliper on without shimming the whole wheel left. I considered getting a custom shim made but Brian writes: "Before disassembly, I measured the offset of the hub on each side of the wheel (with respect to the outside edge of the rim) and found that the right side is offset 6.3 mm (+/- 0.1 mm), while the left side of the rim is offset 7.6 mm (+/- 0.2 mm). I thought that this was peculiar (that the right side of the hub is on average 1.3 mm closer to the outside edge of the rim than the other side) in view of the fact that installing a disk on the LHS is a common option." Aha, so if this is the correct offset then there is a good reason why my disk is a little off. If I mixed up the bearing carriers while installing new bearings it would be off 1.3 mm by Brian's calculations. I guess I have to pull the wheel again, switch the carriers and remeasure. For those who have Guzziology there is a nice chart that shows fork tube dimensions and spacing. Here is a quick quiz: (1) What big block Guzzi has the narrowest spacing from tube center to tube center? (2) What big block has the widest? (3) What do they have in common? Answers: (1) V7 Sport; (2) Eldorado/Ambassador/V700; (3) They all have 35 mm. tubes (K.O. I expect you did well on the quiz?) The Lemans, T, T-3 et. al. share dimensions and fall in between the two extremes. The disk brake Eldo is an odd duck that shares parts with the T in some cases. Other parts are unique. Proceed with caution and take measurements from the correct parts as the dimensions of T-3 bearing carriers are not the same as Disk Eldos. If you can, read the discussion of bearing carriers in Guzziology. It makes interesting reading for those of us restoring disk Eldos. David in NYC |