gxsr front conversion question

OK I made up my mind and I'm going with a 93-95 gsxr 750 front end and wheels. My question is if I use the stock stem, what do I use for the upper tree? I guess the question is how do you mount the gsxr tree to the stem? Will the kz bolt work by just screwing it in or do I need to have machine work done? I did a search and couldn't find anything about mounting the top tree. There was a lot of stuff about changing the stem but no top tree stuff.

Post edited by: donthekawguy, at: 2007/09/06 03:22

Unless you want a custom top triple made use the stock GSXR. I think the KZ stem is a smaller OD than the ID of the hole in the top triple. So a sleeve will need to be made to take up the space. I'm using all the GSXR stuff on my 900 I'm building. I'm going to have the lower clamp machined so the GSXR stem can be sunk into the clamp an 1/8" or so. This will expose enough threads to use the Gsxr stem safely.

Later, Doug

All the weight is on the lower clamp, so I think machining it is a bad idea, if you are determined to machine one of the clamps do the top one.

I am using a GSX front end and cutting the stem at an angle so I can put a round bar inside it and weld it back together 1/8" longer. Then it will be chucked in the lathe and turned back down to stock diameter.


By cutting the stem at a diagonal, it allows me to lay a much longer weld and retain the strength. The stem should actually be stronger than stock when I get done.

i have read some posts on this and it seems very popular to remove to kz stem and put it into the new bottom tree. by welding a sleave on the bottom of the kz stem it can be pressed into the new lower tree and then welded in.then it just bolts up useing the new top and bottom trees, with the old kz stem.
i have a 02 zx12 front end for sale if interested.

steell wrote:

All the weight is on the lower clamp, so I think machining it is a bad idea, if you are determined to machine one of the clamps do the top one.

The way I figure it is the stem has two kinds of stress; tension and shear. There's also bending but tension and shear will most likely fail before bending would.

Machining the lower clamp to move the stem further in doesn't change the two stresses. The stem is still going to have the same tension and it's still going to have the same area that shear stress is working against.

The solid blue line in the image is the current recess for the stem while the dotted blue line shows the future recess of the stem.

Later, Doug

Post edited by: StreetfighterKz, at: 2007/09/05 12:19

I had a KZ stem built up with weld then took it and the GSXR stem to the machine shop and had them turn the welded KZ stem down to match the GSXR stem. The top of the GSXR stem was cut off and machined out to fit over the KZ stem as a bushing to match the upper triple clamp.

StreetfighterKz, keep in mind that this is just a discussion and I am merely posting my opinion (fwiw)

I agree about the stresses encountered by the stem, but my concern is the lower clamp. It's my opinion that Suzuki has done everything they can to lighten the GSXR series, including using finite analysis to determine the minimum amount of metal they can use in that clamp and still do the job safely. And KZ's weigh more than the GSXR's, thus putting more stress on that clamp.
Consider the stresses involved when you hit a bump hard or drop the front end after a wheelie (I know, no one does wheelies )

I just hate to even think about the lower clamp breaking :woohoo:

My concern may be totally baseless, but I think it's worth thinking about.

all good point guys.i will take them into consideration when i do mine this winter .Fossil i like what u did to the top tree i may try that also..thanks guys.

Cool thanx for all the ideas. I'll print this out and add it to my collection of old posts.

Steell,

I wasn't trying to argue. If that's the way it came across then I'm sorry. I've mocked up the front end and have enough threads for one of the two nuts Suzuki calls for on the stem. I figure 1/8" should be enough to get the proper thread engagement without weakening the lower too much. The bike is going to be used 95-98% on the dragstrip so I don't have to worry about Ohio's notorious potholes.

Later, Doug

You're fine, it just seems that some people get upset when I disagree with them and take it personal when in reality I'm merely expressing my opinion and not facts. So I wanted to make sure that you weren't taking it wrong

My memory is not what it once was, but I seem to recall reading somewhere that stunters were breaking the GSXR front ends much more often than any other bikes, and this was assumed to be because Suzuki had lightened the front ends as much as possible. That makes me a little concerned about removing any metal from it, hence my decision to add a little metal (and strength) by cutting it at a diagonal and welding it back together with a bar inside it to lengthen it. I'm using a GSX front end, and I'm not sure if the GSX and GSXR front ends are the same.

I do tend to worry (perhaps to much) about the safety of my modifications, if a 1/8" thickness will do, then I'll use 3/8" just to make sure

My brother is even worse, he can't just nail new pieces of wood together, he has to use glue, and then add metal strapping for additional support in addition to the nails.