Any one familiar with anti-dive on brakes/forks?

What would cause pulsing upon brake application? Not the usual suspects so far.

A friend has an 84 Honda 700 Nighthawk with anti-dive on the front brake. His problem is a long pulsing on brake application. He feels the pulsing does not relate to wheel speed.
He has taken the forks apart and cleaned them, new fork oil, he has measured rotor runout and replaced one rotor, so rotors are now within spec, wheel runout is within spec too. He's rebuilt the calipers, and just rebuilt the anti-dive unit and the pulsing is still there.

There is a bushing on the lower caliper mount to the anti-dive unit that appears to him to be slightly elongated, could that little play be it? It's a discontinued part of course....

Wheel bearings? He doesn't think so. Tire?

Any help is appreciated.
Kent

OKC_Kent wrote:

What would cause pulsing upon brake application? Not the usual suspects so far.

A friend has an 84 Honda 700 Nighthawk with anti-dive on the front brake. His problem is a long pulsing on brake application. He feels the pulsing does not relate to wheel speed.
He has taken the forks apart and cleaned them, new fork oil, he has measured rotor runout and replaced one rotor, so rotors are now within spec, wheel runout is within spec too. He's rebuilt the calipers, and just rebuilt the anti-dive unit and the pulsing is still there.

There is a bushing on the lower caliper mount to the anti-dive unit that appears to him to be slightly elongated, could that little play be it? It's a discontinued part of course....

Wheel bearings? He doesn't think so. Tire?

Any help is appreciated.
Kent

Am guessing the pulsing is present with front brake application and not noticable during rear brake only application.

If applicable, loose spokes?

With mechanicals ruled out, am also thinking tire, and if not already done, would consider:

Balance;
Tread wear (especially cupping);
Tread separation;
Out-of-round (circumference, not rim run-out).

And from way out in left field - - - would assure chain being in good condition, well-lubed and not kinking, and sprockets also in decent condition.

Sorry am not familiar with anti-dive, but wondering whether both forks are reacting equally.

Good Luck!

Edit -- may not matter whether anti-dive is equal on both forks, because am vaguely recalling that some oem anti-dive systems only use it on one fork.

i disconected the anti-dive on the suzuki 1100 i had years ago,it was run off the front brakes .

Patton,
It only happens on front brake application. It is on one fork only. He has mag wheels so no spoke problem. No sprockets/chain as this is a shaft drive bike.

When you say "out-of-round" you mean the tire, right? I think he checked mag wheel side to side wheel runout, not circumference runout. I'll ask him to check the tire.

Plummen,
Do you remember how you disconnected the anti-dive? Remove parts and just insert plugs I guess?

Thanks

it was back in late 80s early 90s but i think i just had to remove the extra brake line from the calipers to anti dive unit and installed shorter banjo bolts in calipers.this was on an 82 gs1100e suzuki;)