Great info source for matching steering stems, fork swaps.

[BigSherm]

Dudes,

Check it. Go to the all balls bearings website, (goallballs.com) and find steering head bearings for your frame. I input my 1978 CB750K and got this page - http://www.goallballs.com/Product_Lookup_results.asp

Now, click on "Click to buy online" on the left of the screen (it doesn't make you buy them), and get to this page - http://www.goallballs.com/Product_lookup_results_shop.asp?zipcode=37042

Now, click on "Details" under "Steering brg - seal kit" and it takes you to this page - http://www.goallballs.com/SHOP/shopexd.asp?pagefrom=Ret&id=582

Here's the good part - it lists every bike that those bearings fit!

So by using this tool, I can tell at a glance that a front end (forks, triples, everything) from a CB400F, GB500, Ascot, etc. will bolt on to my bike using the stock CB750 steering head bearings!

Now, for my next trick, (listen up streetfighters) check this for way more options - Use this chart, http://www.ohiocaferacers.com/OCRStemSizes.pdf and find your steering stem size. For example, my 78 CB750 uses bearings of this size - Upper: 26 x 48.5 x 15.2, Lower: 30 x 50 x 14.4

The info from this to remember is the first measurement of upper and lower. In my case, 26mm upper and 30mm lower stem sizing.

Now, you know the measurements of your stem, there may be another section in the same chart (http://www.ohiocaferacers.com/OCRStemSizes.pdf) that has those 26 and 30mm stem sizes. for example, I found "Upper: 26 x 47 x 15, Lower: 30 x 55 x 17"

Disregard the - "47 x 15" Upper and "55 x 17" Lower because you only want to know other bikes with the same stem size, not the size of the area where the bearing sits in the frame of that bike.

Ok - here's the money shot. Go back to goallballs.com and input any bike from that other section with the same stem sizes, and when you follow it to the "Details" page, it will list every other bike with your same stem size! For streetfighters, this covers even new bikes that aren't listed on the Ohio cafe racers site.

Using this, I found that virtually every CBR600, 900, 954, 929, VFR, CB1100F, and even newer CBR1000rr front end has the same stem size as my bike, making them virtually a bolt-in swap!

Ahh, but you say "what about the length of the two stems? If the CBR stem is shorter, you're screwed because it won't reach through your steering head."

That's when you use your stock CB750 stem in the CBR triples, because they have the same diameters where it counts. You also use your frame's stock size steering head bearings because the stems are the same size.

HAHA! Now all I have to do is source an eBay CBR1000rr front end, complete with the latest radial brake and fully adjustale suspension technology and hook my bike up!

Of course, you could use this data to create a custom bearing set to fit your frame with a stem that is not the same size as yours, but if the new stem is too short, you've just increased your cost substantially because you'll need to get a longer stem custom made. Typically, modern sport bike front ends complete with brakes, triples, forks, and axle (not the wheel) go for about 500-800 bucks on eBay. That's CHEAP for the height of suspension and brake technology.

-Sherm

 

[Ease]

Nice!

Should help many!

I'm gonna post this on another site if it's ok with you. I'll give credit to you.

 

[BigSherm]

Go right ahead, Brother.

Sherm

 

[hillsy]

Great info there Sherm - well thought out.

The only thing I would add is that modern front ends are generally shorter than older style - so you will lose ground clearance if you adapt a modern front to an older frame (which may or may not be an issue)

Otherwise, SWEET ;D

 

[deadhand]

This is great! I'm going to use it and pass it along!

 

[Ringo]

Great info, thanks for putting this together!

 

[Drewski]

That's good info! 8)

Often a simple way to make the swap is to press the stem out of the "old" bottom triple and press it into the "new" bottom triple. Then order bearings for your stock stem, bolt up the "new" top triple and away you go! If you have a complete new front end you're off to the races! That method worked for me on my KZ1000/zx10r conversion. 8)

As mentioned earlier, be careful about overall fork length. New USD forks do tend to be shorter than the "classic" bikes! Also, be aware of the triple clamp angle (stem to fork tube). Most of the modern bikes have a much flatter angle. This can cause contact between the forks and the gas tank at lock! I had to move the fork stops quite a bit to prevent this issue on my KZ.

One other hint. As bikes got newer, fork tube sizes increased. Manufacturers were looking for added stiffness and better handling. When I was looking for a new front end for my '74 Kawasaki H2, I found a '85 Yamaha FZ600 as a candidate. I bought it and started to rip into it when I was startled to see that the "new" FZ upper fork tubes were the exact same diameter as the "old" H2 tubes! Even the triple clamp angle was identical!! I just slipped the FZ forks into the H2 triples and I was done!

If you have a 70's vintage bike, look at 80's bikes for possible replacements. Consider smaller displacement machines. You might get as lucky as I was! ;D

Good luck!!

 

[theboxrules]

Just stumbled across this topic even though it has been dormant. Excellent info but the original links are dead. I think the new link is https://www.allballsracing.com/.

 

[RpBet]

Excellent Find!! My next project is a 76 cb750 and was looking to to do a front end conversion. This is good balls!


Thanks, Sherm.