Topic: My550 forks on my 750?

[Shtonecb500]

The assembled forks are the same length as the 750, the fork lowers are the same length, is there any reason why I shouldn’t install my 550 forks with TNK tubes and  race tech internals on my 750 - direct swap 750 forks out and 550 forks in.

I know the 750 and 550 forks have different internals - what you guys think?

 

[bwaller]

If they're the same assembled length, why not. The difference would have been the springs.

[scottly]

I run 550 springs in 750 F2/3 forks on my 404 lb Seeley.

[bryanj]

759 wheel and disc wont go into 550 forks and caliper

[newday777]

759 wheel and disc wont go into 550 forks and caliper

What is different other than the brake disc/rotor?
The same hub and rim on the 550 as the 750.

[bryanj]

750 disc is bigger so the caliper mountings are in a different place to compensate

[newday777]

750 disc is bigger so the caliper mountings are in a different place to compensate

I know the disc is different.
Other than that the wheels are the same aren't they?

[WhyNot2]

I've got 550 forks to go on my 750 as well. Did not know about the disk and caliper being different.

Guess a direct swap is not in the cards.

What about the swing arm, is it a direct swap?

[Scott S]

750 disc is bigger so the caliper mountings are in a different place to compensate

 I thought the 750 caliper holder compensated for that? I've gone the other way and used longer 750 forks on a 550. I ran them up through the triple and mounted clip ons. I used the 550 caliper/holder/disc.
 Couldn't you just swap those parts over from the 750?

[scottly]

750 disc is bigger so the caliper mountings are in a different place to compensate

No, the caliper mounting locations are the same on both the 550 and 750 fork legs; the 275mm 550 rotor must be used with a 550 caliper and it's arm, and the 295mm 750 rotor must be used with a 750 caliper and it's arm. I went through this 12 years ago when 754(RIP) sent me a 550 caliper by mistake.

[Don R]

 Scotty coached me on this when a 550 fork setup appeared in my pile of stuff. The castings say 341 on them just like 750. I think the brake caliper is smaller and the arm is angled downward to reach the smaller rotor.  Some guys have used the 550 brakes in a dual setup to reduce weight.
 I bought the 550 length 21 13/16" (2"shorter) tubes and built a set of 341 forks for my Drag bike.
 I also have 550 progressive springs in my lowered 750 F1 forks, so far they are a treat.
  The 550 triple trees have a shorter stem and less (45mm) offset but I recently realized I had a set with a welded stem in my 750 Hot Hod bike. I removed them to use the original K1 rhino horn and gauges. A thread on road racers here says the 45mm offset is quicker turning.

[WhyNot2]

I know the difference between the calipers, but didn't realize the arms were.

So, shouldn't I be able to use the 750 arm and caliper?

Seems all I'm doing is removing the 750 forks and replacing with 550 forks. I have both complete setups.....550 forks with caliper, arm, lines, and master cylinder.

The complete front end from a 550.

All I'm looking for now is a 350F front wheel with disk, (this is for another project)

[Scott S]

 Yes, you should. The caliper/hanger/rotor all have to be from the same model.

[WhyNot2]

Yes, you should. The caliper/hanger/rotor all have to be from the same model.

Thanks bro....

[Shtonecb500]

Differences in damper rods in the 550 vs 750 - could I use the 550 damper rods inside the 750 fork lower even though the 750 damper is larger diameter? Anyone swapped different Internals into forks?

The top of the 550 damper is bigger where the seal is, has a smaller diameter and is about 1-2mm longer overall length.

The one with brass is the 550

[Alan F.]

View the damper rod as a piston with a piston ring, if it fits the other fork tube ID no problem.

Longer damper length will give longer suspension travel.

[Shtonecb500]

I ended up drilling out the 750 damper rods and installing the straight rate springs that were in the 550 forks - test ride when the weather is little nicer.