Lengthening modern USD forks

I found this mod on Lorcan's site, 750turbo.com/forum/viewtopic.php?t=4737 , and thought it would be of some use to others building specials here. It got me thinking about the discussions here about custom machined drop crowns. Based on Lorcan's idea, I'm thinking forks using flat top clamps such as the GSXRs, could be further extended if necessary, by welding a suitably shaped block of aluminum to the top and then machine this out from underneath dropping the top clamp further down over the head tube. Only problem I can see is warping of the upper clamp from welding, but welding it and allowing it to cool while the forks are assembled could reduce the problem.
I might pick up another sacrificial GSXR upper clamp and give myself some ride height options.
Has anybody seen this mod or heard of anyone doing this before?

Post edited by: Fossil, at: 2007/01/07 19:23

Thats funny.My machinist is stoping by in the am. to discuss this very topic.But I was going to suggest that we cut the clamps off a doner tree and weld them under the existing clamps.This opens my eyes to an alturnative. Thanks.What do you think of this idea?

If you want to make a gullwing upper t/clamp, have someone cut one from solid stock. Have you ever seen a stock from the factory upper or lower alloy t/clamp that has any welding on it at all?!? If you try to reinvent the wheel, you will pay for your mistakes with your skin (or your life).

Ride Well.

mark1122 wrote:

Thats funny.My machinist is stoping by in the am. to discuss this very topic.But I was going to suggest that we cut the clamps off a doner tree and weld them under the existing clamps.This opens my eyes to an alturnative. Thanks.What do you think of this idea?

I thought about just that, cutting up 2 triple clamps and having them welded back together but, just my opinion, I would rather not mess with the structural integrity.
There have been a number of bikes in Streetfighters Magazine over the years using slugs to lengthen the forks. Slugs were considered fine years ago as long as the joint was between the triple clamps. I personally saw a set of 8" slugs (threaded joint below the lower triple clamp) snap on a Triumph chopper. With modern USD forks, the stanchions are aluminum therefore I would not feel comfortable using slugs with a threaded aluminum joint even if is between the triple clamps.
About the only feasable option is a drop crown upper triple clamp or deal with short forks

893cv wrote:

If you want to make a gullwing upper t/clamp, have someone cut one from solid stock. Have you ever seen a stock from the factory upper or lower alloy t/clamp that has any welding on it at all?!? If you try to reinvent the wheel, you will pay for your mistakes with your skin (or your life).

Ride Well.

I've seen lots of stock parts from Brit, European and Japanese bikes welded and machined for repair or to modify the part. Most of these mods I've seen were for serious vintage race bikes. But, no, I haven't seen a Japanese triple clamp welded. What's the problem? warpage? failed welds?

Yes, and yes,

The problem with welding any high stress aluminum part is knowing what you are welding. What aluminum alloy is that part, is it a forged part, is it a cast part, what is the proper filler rod to use, should it be re heat treated or stress releved, will it turn into silver colored rubber, will it warp? I've seen lots of steel parts welded and machined, and I've seen a few aluminum parts (mostly engine castings) repaired by welding, but I have never seen a welded aluminum t/clamp.
Cutting a new upper t/clamp from a solid chunk of alloy may not be easy or cheep, but its a lot easyer and cheeper then a skin graft.


I've seen lots of stock parts from Brit, European and Japanese bikes welded and machined for repair or to modify the part. Most of these mods I've seen were for serious vintage race bikes. But, no, I haven't seen a Japanese triple clamp welded. What's the problem? warpage? failed welds?[/quote]

So this modification shouldn't be tackled by just any welder, but is feasible as long as the welder has the knowledge and experience to do this work?

Sure, go ahead, and if he knows how to do skin grafts thats a plus too.


Fossil wrote:

So this modification shouldn't be tackled by just any welder, but is feasible as long as the welder has the knowledge and experience to do this work?

893cv wrote:

Sure, go ahead, and if he knows how to do skin grafts thats a plus too.


Fossil wrote:

So this modification shouldn't be tackled by just any welder, but is feasible as long as the welder has the knowledge and experience to do this work?

nevermind

Post edited by: Fossil, at: 2007/01/08 02:09

Post edited by: Fossil, at: 2007/01/08 02:25

Post edited by: Fossil, at: 2007/01/08 02:39

Post edited by: Fossil, at: 2007/01/08 14:14