Hi folks! Just thinking about Steering Fork modifications for a sidecar rig. I'm guessing that some companies that do mods to reduce Trail may weld up the Triple Tree parts and then redrill fork tube holes in brackets at a new angle to reduce Trail? Others may fabricate new Triple Trees? Seems like it might be possible to simply install triple tree in a solid jig for accurate alignment and zero movement, then over-bore existing fork tube holes at the new desired angle. Then fabricate a simple tubular spacer insert for oversized triple tree holes, to take up gap of old tubes with new larger hole. Tubular spacer would need a slit down the side so it can compress. May want to fab spacer so there's a slight ridge at top and bottom edges to help keep it from walking up and down in new triple tree hole. Seems to me this would be one of the easiest and cheapest methods to reduce Trail, yet as effective as custom triple trees? I would assume [uh-oh] that most topnotch machine shops can do this. Thanks for any feedback! XL
Sounds like an elegantly simple solution. My first thought is that there may not be enough material in the outer edges of the tree to retain significant strength. I guess the amount of movement would vary with each bike.
What you're thinking of is close to this at Liberty: http://www.sidecar-industry.com/tripletree/tripletree.htm Liberty makes lowers and modified upper clamps. Bobmw is right- there's not enough material to hog out the lowers to increase the rake. http://www.perrysmotorcycles.com/ Perry's solution of all new billet trees is elegant and is pretty cheap.
I have decided to just leave my forks as they are, but I believe there is a simple way to move the entire assembly forward a bit by adding a second second set of trees behind the first and attaching the two together.
In the Netherlands they are called "Ed Pols platen", when you Google that you'll find info and pics Here's some info on Halflive's page ( in Dutch ) CLICK
We use to make as set of clamps similar to the ones above for the BMW air heads, Moto Guzzi Tonti frames and some Honda's but had to batch build them, There is so little demand for these that the last batch of 10 for BMW it took us over 3 years to sell. We may make them again in that we are working with a company with a new water jet table that thinks that they can water jet them out which would cut way down on the amount of machine work needed and get the cost way down. Jay G DMC sidecars 866-638-1793 www.dmcsidecars.com
Sounds good, Jay, the water jet should do the trick nicely! I was just looking for my usual - something for nothing ha!
This type of sysem is nothing new and has been done ... and does work quite well . One good thing about it is that it does not change the angle of the forks and still reduces trail. It also does not affect ride height which can b egood. 'Raking ' the forks with different trees or modified trees can cause complications with various things such as bar mounts, bar mounted fairing clearances etc. The system of moving the whole fork assembly forward does not create these issues and retains the stock triple trees. Yes, there are other issues even with this sytem with fixed fairings and so forth but over all It is a good system. We have discussed producing this type of an item for quite a while and may still do so at some point.
take a look at how Harley modified their triple clamps to reduce the trail for side car use. Any decent machine shop could do the same to yours.
For anyone finding this topic through the searchfuntion: I have the drawings with measurements for the MZ on my computer somewhere !
Thanks very much for those pictures, MotoJ, NitroMax & Claude! That could be a big help in my build. No doubt a picture is worth a thousand so that's a good 7,000 + word's worth there!
