Brakes delinked now shudder during braking.

Hello everyone, longtime reader here.

I've delinked my brakes because it's fun.
Currently have vtr lowers, 600rr calipers, new brembo pads, new brakelines, 600rr master at the front and new seals in fork.

Assembly went well. During testdrive I noticed a shudder in the front while using the front brake at +-50% brake force and up . Braking very slow, no shudder. The shudder is not feeled in the brakelever.
The shudder happens for example when applying the brake from 50mph(80km/h).

First thing came to mind were the brakedisks. The strange thing is that before the conversion I didn't have any problems...

Things I've done:
- Checked head bearings, were original. Replaced the bearings, smooth stearing now, no play when front wheel is in the air and rocking the forks.
-Front tyre replaced.
-Checked calipers, all pistions move smooth.
-Checked brakedisks with a dialindicator, in spec.
-Checked bobbins brake disk.
-Just checked, front brakes are dragging maybe to much...

Does anyone have a idea?

 

I had the exact same symptom on my 92 VFR after swapping some parts around. A bad shutter but nothing felt in lever at all.

Solid rotors from a 91 VFR that I had on a VF1000R with VFR forks. They were perfect condition, no shudder, when I pulled them and installed a VTR1000F front wheel with floating rotors.

Rotors got put aside, and I used them on my 92 VFR that I rescued / refreshed. Bike done, first test ride, I was so excited. BAD shudder at moderate braking and above, but good stopping power. Made zero sense and I was really confused. Even questioned if I installed the same rotors, but I knew I did. The brake pads were slightly used and already heat cycled, but looked new with zero abnormal wear or contamination.

Frustrated and perplexed, I found a lonely stretch of road and did a series of hard accelerations and hard braking. Shudder went completely away after the third or fourth one I think. Absolutely perfect and smooth now for a couple thousand miles.

Still can't completely explain it, but I think the rotors must have had some inconsistent corrosion from sitting around a while before being used again. But didn't "clean" up with normal braking. They did not look corroded or discolored AT ALL when assembling the bike.

Well that was a long story that probably doesn't explain your situation, but it sounded EXACTLY like what I experienced. Good luck!

 

Thanks for sharing! Worth the try to do a series of hard brakin.
I haven't ridden much in the last few years so maybe that plays a role. I prefer to find the real cause before buying new rotors.

 

Had the same issue when delinked my XX: an EARTHQUAKE at strong braking!

The problem was just old and damaged fork bushings; once reserviced the fork, the phenomenon vanished

 

Update. Checked calipers and pistons, all smooth. Went for one hour testdrive, braking at different speeds.
Shudder is still there. Above 50mph and up gives a shudder. Brakes feel good though.

I'm gonna take apart the forks, maybe there's something wrong.
Only issue during install was one oilseal needed some force to drive it in. (aftermarket seals).
Bushings are all new , original.

Search continues!

 

Before you do anything else, why not attach a dial indicator to the fork legs and check the runout of the disks? The alloy carriers are easy to accidentally knock and give the symptoms you describe. If they are bent, it is fairly simply to use a pry bar to straighten them.

 

mmmhh... by proceeding by exclusions, I'd check the disks planarity.
If forks are fine, and calipers are fine too, I can't figure out anything else.

What about steering bearings?

 

I've purchaced a dialindicator a few weeks ago. There was to much runout on one disk(0.3mm). Ccarefully prying the disks did make it a lot better.

Headbearings are replaced, were original. Steering is smooth and there is no play when lifting the front and rocking the forks forward.

I'm missing something but it has to be something in the forks/calipers/disks/headbearing. Not much more parts to check. Wheelbearings are good.

Will check everything again this weekend.