Topic: CBX Triple Clamp Swap in CB550

[the B.N.G.]

So after doing a search, I found no relavant info.  I am doing a 79 CBX upper and lower triple clamp swap on my 74 CB550 so that I may keep the standard 35mm forks.  Does anyone have any information on the specs to machine the stem so that I may use the standard CBX roller bearings?  It looks to be about a 10mm difference in bearing seat height on the stem but if anyone has an exact number, that would greatly help to speed up my process at the machine shop.  Thanks in advance.

[fastbroshi]

I'm curious as to the why of this swap. 

[Retro Rocket]

Yeah, me too. Why don't you just get tapered bearings for the 550 front end, there'snoneed tochange clamps unless you are using larger forks...

Mick

[the B.N.G.]

There are a few reasons to the swap.  The 79 CBX has alloy top and bottom brackets.  The bottom having four bolts instead of two.  This not only saves a little weight, but also improves the trail to match that of the CBX because of the different geometry.  This makes for a huge improvement when on the track because of the change in angle of the front forks.  Not to mention, when using clipons, the upper mount doesn't have that stupid looking bar mount cast into it.  My question is, does anyone have exact specs on machining the stem? I can always take a measurement once I convert from balls to rollers in the steering head and machine the stem accordingly, but if anyone has already done this then it would save me the time of trial and error fitting, machining.  I find it hard to believe no one has done this.  If I have no takers, I will post up the results next week as I fit it up.

[Retro Rocket]

Measure the diameter of the bottom of the stem, you may be able to press the 550 one straight in, i have done this with a GSXR set of clamps, coincidentally the Honda stem was the same diameter as the Suzuki one.

Mick

[the B.N.G.]

Mick,
Nice, will do tomorrow and post some pics.  Thing is, that the CBX stem is a little longer to accommodate for the difference in the upper clamp.  If I forgo the upper washer or mill the upper clamp, the stem from the 550 should work.  Will look closely tomorrow night and post results.  It just seems easier to turn the CBX stem to match bearing height than to mill the CBX upper.  Regardless, it isn't a straight swap, but should be worth it when the trail matches up.  It is never as easy as it should be if  you do it correctly!  Laughing

[fastbroshi]

  You mentioned the track, is that where you're taking it?  If you're just doing it on the cheap or trying to be period correct I understand, but a GSXR setup might be well worth it if not.  I'm planning a racebike with a GSXR front end, besides checking tank clearance and new bearings it's a straightforward swap.   Very sharp geometry.
 

[Retro Rocket]

Here's a nice 550 with GSXR front end and modified GSXR swingarm, wheels are also GSXR.



Mick

[turboguzzi]

there are a few sites, sudco for instance, that list the exact dimensions of all the tapered kits out there, you should be able to get dimensions in a few seconds by crosschecking.

TG

[754]

You are not changing rake, your are changing offset..unless the CBX trees are raked.. in which case the trees Must maintan same distance between then as stock.
 You change in off sett changes yor trail.

 If you got both trees side by side with bearing tension rings and top trees and nuts, it pretty easy to see where to shim, cut, or thin a piece of the assembly

[ohiocaferacer]

Why not use SL350 trees??

They are 35mm.....4 bolt lower.....alloy top with no bar mounts....and the stem length is the same as the stock CB550. Not sure there is a rake difference in the trees.....but it would be a direct bolt onto the stock frame and forks.

Here is a pic of my CB350 race bike with SL350 clamps and CB550 forks. I dont have any good pics of the polished top clamp.....but it cleans up real nice.

[turboguzzi]

hei ohio, nice idea, nice bike too,

what's the offset / tube to tube span compared to stock cb500?

TG