Fork Brace GPZ

[shah269]

http://www.murphskits.com/kbbrace.htm
OK.....this is going to sound odd.
When I first got my GPZ it's tires were let's say half worn and she had an odd tendency to pull into turns.
Talked to a few of the older guys here at my job an they thought that since my bike didn't have a fork brace it wasn't happy seeing lateral forces. So I went ahead and ordered this little fork brace.
Looks great! Felt great! Fixed the problem real quick!
But quickly noticed two things.
1) The tires were not only half worn but the front tire exhibited a decent amount of feathering, thank you Dunlop.
2) Though the cornering issue was solved the front end seemed more lively and stiff then it did before. The font end dive was cut almost by 25% and the bike at speed felt more nimble.

Now I'm about to slap on the new Continental tires and am not sure if I should keep the fork brace on.
What do you guys think? I'm not doing any harm having them on there am I? And better question why didn't Kow give these bikes fork braces from the factory?

[jschmidt]

Is your bike old? If so, you're covering up a problem with the fork brace. The problem is that your fork bushings are worn. The brace stiffens up the front end but it also causes the forks to bind. This binding is exacerbated by the worn bushings, which explains why it seems to cover up the original problem.

How many miles on your bike? What year? Most bikes made after the 80s don't really benefit much from an aftermarket brace, at least off the track.

Also, neither symptom you gave is a symptom for a fork brace. Diving into turns is affected by rake, trail and tire profile. Rake (and to some degree trail) is affected by preload and springing. For example, if your springs are maladjusted or simply too soft, they'll compress when your bike leans into turns (or when you brake) steepening effective rake. Having the rear preload or ride height set too high will do the same thing.

Uneven tire wear is also affected by under or over damping. Dunlops seem to be more prone to cupping than some other brands, as well.

You should have asked this old timer.  

[shah269]

1996 - 19k miles.
When I got her her front forks seals were shot!
So had the forks rebuilt.

As for my riding style....ah.......well......I don't use the Z for what it was designed for. I've had her all the way down to the pegs more than once. The fork brace really woke up the bike and lightend the steering feel, once the bike was moving. It also seems to correct that odd tucking / pulling in that was taking place around long corners.

[1KPerDay]

My stock GPz handled very well when the suspension was newish. Now at 23K without any attention it's a little tired. But I suspect freshening the oil and seals will fix the front end good as ever.

The Superbrace did make a big difference on the ZZR though... but I wasn't ever happy with it stock.

[shah269]

Well I for one loved how it gave the bike almost the same bounce as the VFR in the turns.
Wasn't too happy how jittery it became when it hit bumps.
My main concern is, am i hurting my bike with this thing on there?

[jschmidt]

Did they rebuild them or just replace the seals and fluid? Unfortunately with a well used bike, its often difficult to know how it should feel. I'm pretty confifent I'm right about this. But others can weigh in.

[shah269]

They charged me $300 for both.
I knew the fork seals were totally shot, and at the moment as sad as it sounds with out looking at my receipt I can't with full accuracy tell you if they rebuilt the forks or simply took it apart, cleaned it, and replaced the fork seal.
But I'm going to say that they just disassembled, checked and reassembled the forks.

[PhilBiker]

My stock GPz handled very well when the suspension was newish. Now at 23K without any attention it's a little tired. But I suspect freshening the oil and seals will fix the front end good as ever.

I can tell you at 73K miles getting ready for my fourth set of oil and seals (third change), it really does freshen up the front end!  The rear suspension on my bike, however, has never been touched!   It's like a 70s Buick in the back!  Bounce - Bounce - Bounce.

[1KPerDay]

Any tips on the procedure?

[PhilBiker]

Have a shop do it.  

I can't remember the viscocities, but the oil in the GPZ nonadjustable forks makes for kind of slow response in the damping.  More touring that sport.  Some people like upping the viscosity to make for a stiffer more sporty ride.  I tried it and went back to stock.  But I'm commuting and a little touring, if I were riding more aggressively I may like the heavier weight oil.

[jschmidt]

Any tips on the procedure?

Well, its really different for every fork, but the basic principle is that each fork has one or two removable bushings. On modern cartridge forks, the bushings come out with the tube. On older damper rod forks, the busings are in the fork leg and come out pretty easily with a pick as they are split. Some forks don't have replacable bushings.

[shah269]

Have a shop do it.  

I can't remember the viscocities, but the oil in the GPZ nonadjustable forks makes for kind of slow response in the damping.  More touring that sport.  Some people like upping the viscosity to make for a stiffer more sporty ride.  I tried it and went back to stock.  But I'm commuting and a little touring, if I were riding more aggressively I may like the heavier weight oil.

The local Kow mechanic recomended the higher viscosity.
But I guess he didn't notice the tires.
I looked at my papers and it was a check, replace and fill situation with my forks.
No rebuild. Just made sure that all was working well.

[PhilBiker]

Speak of the devil....  I just noticed my right fork seal leaking yesterday on the way home from work. I noticed some gunk while cleaning the bike Sunday.  It has been about 4 years since I had the oil changed....  Looks like we're goin' back to the shop.

I just had major engine work done - with fresh seals and oil change this bike will be running like a sonofabitch!  Well, except that spriongy rear suspension.....

[jschmidt]

Just be glad it happened now instead of a month from now.

[1KPerDay]

Speak of the devil....  I just noticed my right fork seal leaking yesterday on the way home from work. I noticed some gunk while cleaning the bike Sunday.  It has been about 4 years since I had the oil changed....  Looks like we're goin' back to the shop.

I just had major engine work done - with fresh seals and oil change this bike will be running like a sonofabitch!  Well, except that spriongy rear suspension.....

Throw on a take-off from a ZZR1200... supposed to fit but you'll lose an inch or so of height or something.

Or spring (pun not intended) for a new shock.  

[PhilBiker]

Or spring (pun not intended) for a new shock.  

Not intended, huh?  

[shah269]

How fat are  you guys that your bikes have saggy asses!

[Connierider]

You have some great advise here.I work at a bike shop and we set up a bunch of track day/race bikes. I would like to add just make sure when installing the brace you aren't causing binding.
Another thing you might think about is emulators to give you some adjustability as well as better handling abilities.

[shah269]

You have some great advise here.I work at a bike shop and we set up a bunch of track day/race bikes. I would like to add just make sure when installing the brace you aren't causing binding.
Another thing you might think about is emulators to give you some adjustability as well as better handling abilities.

Well the one I got came with good instructions and is very well built. It just snaps into place and you tighten it to secure the left and right frok.
As for emulators Say wha?

[PhilBiker]

Cartridge emulators.  I think the GPZ has a cartridge fork already.