Topic: Front end swapping?

[fennec]

Hello everyone,

 So I have been browsing through the forms and wanted to see if I could get some more information from you all concerning front ends. I am currently working on a CB 750 (I have a 72 and a 74 model). When I pulled the (broken) triple tree off the top, the bearings were shot to hell. nothing but ball bearings floating around. Because the current forks seem to be also done, I wanted to see what kind of possible front end swaps I could do.

What I really want to do is take a 'newer' dual caliper sport bike front end. Is there an easy way to see what kinds of triple trees would be able to easily mount to the K frame?


~Luis

[martino1972]

a question like this you want to ask here..>>>>http://forums.sohc4.net/index.php?board=2.0

[eurban]

Your not going to find a modern triple tree that will slide into the 750s neck and fit.  You could cut the weld and remove the steering stem from the 750s lower tree and use it to replace the the stem in different lower tree, or you could have a custom tree fabbed up. Some in this site have used parts from more modern sports bikes like the CBR in combination with some machine work to bring the two eras together . . .The 77/78 750s tripple tree will fit without modifcation but that is hardly new technology, although it is dual discs.  The first generation GL1000 front end /triple tree will also fit directly into the 750 headstock and give you dual discs with spoke wheels.  Again, hardly modern stuff.  . . .

Go to the Tech Forums page and search for "front end swap," "cbr", "dual discs", "gl1000" etc etc, as this subject in some form or another comes up frequently.  Also your's is not a post about a bike build, so it doesn't belong in the project shop.  The "sohc4 bikes" forum is were it belongs and it will get alot more traffic there.

[fennec]

Thanks for the update... I re-posted in the other forum section.

[bradweingartner]

Your not going to find a modern triple tree that will slide into the 750s neck and fit.  You could cut the weld and remove the steering stem from the 750s lower tree and use it to replace the the stem in different lower tree, or you could have a custom tree fabbed up. Some in this site have used parts from more modern sports bikes like the CBR in combination with some machine work to bring the two eras together . . .The 77/78 750s tripple tree will fit without modifcation but that is hardly new technology, although it is dual discs.  The first generation GL1000 front end /triple tree will also fit directly into the 750 headstock and give you dual discs with spoke wheels.  Again, hardly modern stuff.  . . .

Go to the Tech Forums page and search for "front end swap," "cbr", "dual discs", "gl1000" etc etc, as this subject in some form or another comes up frequently.  Also your's is not a post about a bike build, so it doesn't belong in the project shop.  The "sohc4 bikes" forum is were it belongs and it will get alot more traffic there.

Not entirely true. With a different bearing up top a modern triple doesn't appear to be a very hard swap... on paper. I'll let you know in a couple weeks when I actually bolt it together.

[eurban]

Not saying that it is not possible, but tell us how easy it was after you do it succesfully . . . .  . . .

[bradweingartner]

Not saying that it is not possible, but tell us how easy it was after you do it succesfully . . . .  . . .

According to my measurements and the checks I've done I'm pretty sure it's all going to bolt up.

The hardest part is likely going to be getting the old races out of the head...

[coyotecowboy]

Hey Brad, what frontend are you planning to use?  Inquiring minds want to know

[bradweingartner]

Hey Brad, what frontend are you planning to use?  Inquiring minds want to know

Well, I have an 05 GSXR600 and an 06 R6 front end sitting at home in Michigan while I'm working in Las Vegas. I haven't even SEEN my new R6 front end yet 

As far as I can find out the stem dimensions are pretty well the same between them. I've ordered up some bearings, and some other goodies and I'm going to start taking some measurements when I fly home this weekend... I'm picking up another 550 frame in a couple weeks when I'm done for good here in the desert and I'll have some real definitive results then.

So anybody who wants the step-by-step on making this work, just hold on to your nuts a few weeks and I'll give you the answers, good bad and otherwise. I'm the first to admit when I'm wrong but I really don't see this being a major inconvenience!

Also, since I have two sets of forks and don't expect to do this project twice I might have some forks Available! 

[eurban]

Headstock / steering stem for the 500/550s is a different size than the one on the 750.  What bike is receiving the GSXR/R6 transplant?

[bradweingartner]

Headstock / steering stem for the 500/550s is a different size than the one on the 750.  What bike is receiving the GSXR/R6 transplant?

74 550

When I did a rough tape-measurement between the GSX-R forks and the 550 I found the triples were awfully close to the same distance apart, leading me to believe that the stem lengths are ball-park similar.

If the 750 stem is indeed around an inch longer than the 550 then there would definitely be a problem there. However, I do know that people have swapped other late model sport bike forks onto 750s without swapping the stem. It's going to come down to the actual donor bike in that case I guess.