SBK fork brake ?

[mookieo2]

My friend gave a me a set of SBK forks from his 748. I got them home and did a brief check and unfortunately they are the old ones w/ I think is 40mm hole spacing for the rotors. He says he should be able to find the old calipers and rotors for me. Is this a downgrade in brake performance? I know he upgraded to the 65mm when he swapped his forks. I really wanted to get theses SBK forks on. Especially for the price.

[OverCaffeinated]

Get these

Adapter

[mookieo2]

That`s a great idea but at $189 + shipping I could get another set of adjustable forks for a $100 more on ebay. Is it possible to swap the lower parts?

[OverCaffeinated]

Motowheels also has adapters to mount 40mm calipers on 65mm fork bottoms. So there must be benefiets to either setup. In an effort to answer your original q about whether you will be down grading, it depends on what you are starting with. What bike do you have and what is on it now?

[mookieo2]

It`s a 2002 750 w/ non adjustable Showa`s. I `m assuming I have the 65mm spacing w/ 320 mm rotors. If the rotors are the same size I don`t think it will be a downgrade. My friend says he has the old calipers. If my rotors will work than it should be almost the same. The forks are from a `97 748.

[Smokescreen]

I did a similar swap on a 95 M900.  I put on the 749s front fork, and while there are obvious differences, I just wanted to point out, in my case, there was a different offset on the rotors.  I ended up getting 6mm spacers in between the fork and the calipers to take care of the issue.  these need to be solid bits though as you don't want flew there. 

The spacing of the mounting bolts won't constitute a downgrade in and of itself.  You need to realize that the brake performance will depend on your choice of pads too.  So please don't use the pads you get with the calipers, just go out and buy some new ones, nice punchy ones if you wanna feel it.  And don't worry about perceived up or downgrades in brakes.  With the seriously uprated forks, you will be able to use whatever brakes you have much more efficiently.  That's what really matters. 

When I did the swap to the 749s forks, I only had one pad choice because of the iron full floaters on the M900.  The brake action went from mostly one finger braking, to mostly three finger braking.  With a supposed upgrade in caliper.  But keep in mind I was doing the build in the first place because the bike was crashed when the front brake overwhelmed the front fork causing a bottom out and skip lockup.  Then a nice pretty 35mph lowside that ruptured a cf tank, destroyed bars, rearsets, exhaust, and tweaked the frame....  Now the brakes offering a smidge less grab, but a lot more feel, the bike is much more rideable.  Of course I spend another $700 having the front and rear resprung, rebuilt, and set up for its new rider at Racetech, so obviously I don't believe this is a place to cut corners.

[OverCaffeinated]

Is the top of the 748 fork 50mm or 53mm?

[mookieo2]

I did some measurements. Confirmed top is 53mm of SBK forks. Brakes are 40mm. Would it be possible to just swap the lower part where the brakes mount to? The lower tube diameter is 43mm just like my monster. I also checked the distance between the center of axle and top of lower part and they are the same. They look to be the same dimensions all around. Thanks for the help so far.

[Smokescreen]

Sure, it's possible.  All you have to do is disassemble the forks and rebuild with the new lowers.  You might could even use your sliders as well if the dimensions are the same.  You may however, want to have a suspension pro do this, as refilling the oil is tricky.  Too little, and you get bubbles, too much and you get oil leakage and seizing... 

[2001cromo]

Mike,

The 40mm gold lines are functionally identical to the 65mm one(s) you've got now. Only difference is the mounts and the brake pads. The pistions in the calipers are the same 30/34mm.

The axle/fender are exactly the same as what you've got now so the front wheel will bolt right up and the brake rotors will also line up (the 749/999's are different and require offset as already mentioned) but the 748/916/996/998 all bolt right up with regards to wheel/fender/ and 65mm brake caliper.

The things you'd need to change:
1) upper triple needs to be 53mm, you can either bore a stock one from 50mm to 53mm or get an aftermarket one.
2) shim the lower triple from 54mm to 53mm and  .5mm or 20g aluminum stock works great. (I've got extra if you need)
3) 53mm clip ons
4) and for you since they're the earlier ones, you'll also need 40mm brake calipers. These will use your current brake lines fine.

Oh yeah, don't bother trying to get the lowers off from the stanchions as you'll have a REAL HARD time getting them off.

I did this swap my self on my bike a few years ago.

I'd also highly recommend getting the forks redone for you at the same time too.

~Terry

[mookieo2]

Thanks T,

I just wanted to make sure that the Rotors where the same size. I didn`t think it would be worth it to get smaller brakes. I would of just got my stockers rebuilt then. I should be able to get the calipers from my friend when he finds them. The other stuff as far as fenders and triple being done I remember from our last discussion. I am also going to get new springs and oil installed.