modern forks on cb450

F

forcefanajd

Over 1,000 Posts
has anyone here done it?? im looking for someone with first hand experience as its something id like to do to my bike eventually, maybe not right away but i want to know whats involved before i get my hopes up on doing it.
 
i want USD forks....im not sure if im gonna be able to do it or not just kinda looking into it for future reference. obviously id need a swingarm to so i can make a modern rear wheel work out back but i think thatd be a lot easier to do than forks thats why im looking here first.
 
well i realize id have no choice but to use modern wheels.....not a huge deal as far as im concerned, if done right i think it can look good. ive just gotta get steering stem diameters i guess....
 
crazypj said:
There are various SAFE ways to fit original wheels to more modern forks,
PJ
Click to expand...

using shims?....either way i wouldnt mind modern wheels its just a matter of finding the right ones and having them the correct color
 
......or new bearings to suit the new axle and old wheel.

Here's a link:

http://www.thebikebearingshop.co.uk/index.htm

Click on "Find a Bearing" and search....

Too hard? OK - here's an example:

Honda CB550 / 750 front wheels all run a 6302 bearing (15x42x13.....ID x OD x WIDTH). Now a GSXR 750 / 1000 runs a 6205 (25x52x15). So, you need a bearing that's 25x42x13 to put the CB wheel on the GSXR axle.
Lo and behold there's a 6905 bearing that's 25x42x9.
BINGO ;D
OK, it's a bit narrower than the stock bearings, and you'll have to machine up some 25MM ID spacers to mate the whole she-bang in the middle but it will work and it's far easier than trying to make a slimmer axle fit in the GSXR forks.
 
Yep - you won't find a bearing to suit every wheel swap (like my GSX / FZR swap....PITA :-[....).
 
I predict you'll lose interest trying to do this conversion before it's finished. You're talking a lot of work here. Lots of custom machining work, trial and error.
 
buy a cb750 (77-78) front end.

install progressive springs and cartridge emulators.

bolt on cb900f calipers (twin piston).

if you want spoked wheel fanciness and no comstar wheels, buy a '79 CB750 front wheel, and CB900f slotted rotor.

done.


seriously, this is much easier, cheaper, more likely to work correctly, and practical.

best yet, you know it works because I did it.

now, you don't have to worry about:

machining fork clamps to fit
finding steering stem bearings that fit (and work)
shortening the steering stem
figuring out correct axle spacing
figuring out correct wheel bearings
machining an axle
getting the fork length all wrong and fucking up your rake/trail
spending shitloads of cash on parts to find that they won't work


EDIT:

this pic shows it (minus the twin-piston caliper, hadn't put it on yet in this pic.

6600_1085934150362_1286658449_30208822_8198106_n.jpg


plenty of stopping power.
 
There was a CB350/360 build thread with a USD front end on it. I can't remember if it was on this forum or that other cafe forum.......about 6 months ago I think. Anyone remember????
 
It was Uniac who built that. Nice piece of engineering but now his bike has a 17" cast front wheel with the original spoke wheel in the back. Check out Ohio Cafe Racers, they have plenty of experience mating modern front ends to 350s. Personally, not my cup of java.
 
borzwazie said:
buy a cb750 (77-78) front end.

install progressive springs and cartridge emulators.

bolt on cb900f calipers (twin piston).

if you want spoked wheel fanciness and no comstar wheels, buy a '79 CB750 front wheel, and CB900f slotted rotor.

done.


seriously, this is much easier, cheaper, more likely to work correctly, and practical.

best yet, you know it works because I did it.

now, you don't have to worry about:

machining fork clamps to fit
finding steering stem bearings that fit (and work)
shortening the steering stem
figuring out correct axle spacing
figuring out correct wheel bearings
machining an axle
getting the fork length all wrong and fucking up your rake/trail
spending shitloads of cash on parts to find that they won't work


EDIT:

this pic shows it (minus the twin-piston caliper, hadn't put it on yet in this pic.

6600_1085934150362_1286658449_30208822_8198106_n.jpg


plenty of stopping power.
Click to expand...

BEAUTIFUL bike....

but where in the hell did you get progressive springs for the forks from? i cant find any anywhere.
 
i had cb750 forks and sold them because tey were practically identical....they were left over from my last build......thats why i want USD forks.
 
borzwazie said:
buy a cb750 (77-78) front end.

install progressive springs and cartridge emulators.

bolt on cb900f calipers (twin piston).

if you want spoked wheel fanciness and no comstar wheels, buy a '79 CB750 front wheel, and CB900f slotted rotor.
Click to expand...

I'm confused by two things here- I thought '78 750's had progressive springs and why couldn't you use a spoked '78 front wheel-is the cb900f rotor? Wouldn't it be easier to find a '78 cb750f front end that's already running dual disk?
 
DrJ said:
It was Uniac who built that. Nice piece of engineering but now his bike has a 17" cast front wheel with the original spoke wheel in the back. Check out Ohio Cafe Racers, they have plenty of experience mating modern front ends to 350s. Personally, not my cup of java.
Click to expand...

Excel rims are on the way to correct that issue (it drives me nuts). Still need to figure out the front hub (machine from scratch or modify a harley unit), but thats a story for a different day.

On topic, unless you have the money (i'd budget over $2000 for everything, you don't realize how much this stuff costs until you get to the gritty details) and the time/machines at your disposal, i'd pass on doing it. I'm with DrJ on this one, you'll probably lose intrest before you're done with it.
 
Kev Nemo said:
I'm confused by two things here- I thought '78 750's had progressive springs and why couldn't you use a spoked '78 front wheel-is the cb900f rotor? Wouldn't it be easier to find a '78 cb750f front end that's already running dual disk?
Click to expand...

'78 CB750F has comstars, not spokes. The '78 K models have spokes but it's the older 6-bolt pattern and leading caliper that would not match up with the 5-bolt 900F rotor.

My forks did indeed come with progressive springs but I have no idea if they were stock or not. For that matter, my CB450 has progressively wound stock springs...I ended up using the CB450 springs because I lowered the forks about 2 inches (CB750 forks are roughly 2 inches longer than the 450's) and I didn't want to cut up good springs.

How did I find out all this stuff? Pure dumb luck. Happened across parts here and there and found they'd all fit together. The '79 front rotor wouldn't work, since the rotor is much larger and the caliper I have was trash (and parts for it are not available).
 
borzwazie said:
'78 CB750F has comstars, not spokes. The '78 K models have spokes but it's the older 6-bolt pattern and leading caliper that would not match up with the 5-bolt 900F rotor...
Click to expand...

I know that my cb750k fork lowers have bolt spots for a second caliper; the next trick would be removing the speedo drive and installing the other disk.
 
same front end was attach to my old road racer..exception cb 900 1980 calipers(42mm single pistons) clamping down on 18" cb350-360 discs(twin) worked great ,,,but only 3\4 of the pad worked on the discs,,,and racing the top half of the pads would almost come into contact :eek:......cb 750 to 78 will bolt on the a cb 350 lump,,but the tubes will rise over your top by 2 inches. 35mm to race or a 33mm to cruise,,,,,stick with stock :-X
 
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