Maybe I won't feel so bad if I tell myself I'm restoring it - bent fork issue

[tfranklin]

I briefly mentioned the bent forks in another thread, but another problem has surfaced (or I noticed it) because of it. It's been so windy you couldn't hear it, but the front brakes are scraping. I'm sure it's because the forks are bent and the pads aren't perfectly square with the wheel. It's not off far but no small adjustments I make (i.e. twisting the tube a little left or right) make any difference. Of course, until I took them off they were fine. I had hell getting it back on and lined up enough to get the spacer back in the front wheel and the fender on straight.

The wheel spins, it just rubs. I guess I said all that to ask my question, can the forks be straightened or do I need to look for a new front end? Another pair of hands would sure help so you could move both forks at the same time and see if there is a sweet spot. I'm assuming there is one, because it didn't rub before I moved it.

I'd rather be making fun mods. Like a seat that won't numb my ass after 30 minutes. :bang head:

 

[twistedmax]

I cant help you with the forks :confused2:but theres a seat in fla that you could try out !:biglaugh:

 

[dannymax]

I briefly mentioned the bent forks in another thread, but another problem has surfaced (or I noticed it) because of it. It's been so windy you couldn't hear it, but the front brakes are scraping. I'm sure it's because the forks are bent and the pads aren't perfectly square with the wheel. It's not off far but no small adjustments I make (i.e. twisting the tube a little left or right) make any difference. Of course, until I took them off they were fine. I had hell getting it back on and lined up enough to get the spacer back in the front wheel and the fender on straight.

The wheel spins, it just rubs. I guess I said all that to ask my question, can the forks be straightened or do I need to look for a new front end? Another pair of hands would sure help so you could move both forks at the same time and see if there is a sweet spot. I'm assuming there is one, because it didn't rub before I moved it.

I'd rather be making fun mods. Like a seat that won't numb my ass after 30 minutes. :bang head:

T, brake pads will often rub on the rotors causing a slight scraping sound. If the wheel spins freely with the front off the ground you probably don't have an issue, but, first maybe you should verify whether or not your forks are bent....then go from there.

There are better ways to do this but I would simply dismantle the forks and roll the chrome, inner tube on a flat surface...a counter top or kitchen table works well if wifey's out! :biglaugh: You should see right away if either one is bent.

 

[RaWarrior]

I'm not aware of any way to straighten a bent fork. You can do the "roll check", or just get a level or other suitably sized straight edge and stick it next to it, then slide it around the outside.

My R1 calipers make an ever so slight hiss at all times. You can only really hear it if you're coasting with the engine off, I only actually hear it when I'm wheeling it around the garage, and that time I....*ahem* ......ran out of gas at 130mph.

Get the wheel off the ground and give it a whirl. If it drags in one spot or constantly, look into it more. If it spins fine, I wouldn't worry about it. Do you have any strange handling issues? I imagine bent forks would wreak havoc on stability and handling.

 

[gamorg02]

my front brakes hiss, a tiny bit, scrape noise, only heard at low low rpms. no dragging tho.

 

[jedi-]

If the forks are bent don't even try to straighten them. Just buy a second hand front end or you could buy new tubes. A company "forks by frank" will sell any tube ant any given length. Don't quote me but I think they'll cost about $200.

 

[satariel666]

Funny, I was straightening the forks as far as I remember so I cant agree.

IMHO 3-5mm of bent is ok for straightening, more must be considered very precisley...

 

[mattness]

my brake bads make a rubbing noise too but not like a scrape or a screech or anything out of the ordinary

 

[MaxMidnight]

WOW! Before you go to the trouble of dismantling the forks there are a couple of things you should check first!

1) Make sure that the forks are square in the yokes.
Loosen the front axle clamp bolt and axle.
Lift the front end off the ground and support the frame. Put something under the wheel so it can't drop down.
Loosen the upper and lower yoke clamp bolts and give the fork assembly a shake so that all parts can get into their natural position.
Tighten and torque the top yoke clamps, remove the support from under the wheel and give it a spin. Tighten and torque the bottom clamps.
Tighten and torque the axle and then the clamp bolt.

Is the pad still rubbing?

Checked the brake disK's for run out - ideally with a dial test indicator.
If you don't have access to one then use (say) the top of an an axle stand as a fixed point near one side of the disk to see if the gap changes.

If it does then you need to find out if the disk is warped or not sitting square on the wheel.

Unless you know that the front end has been clouted then the above is more likely to be the cause.

A small bend in a fork tube can be straitened without issue. I'm less sure if it is the slider.

 

[tfranklin]

Thanks for all the replies. I know the forks are bent, you can loosen the tube on the bike, twist it and watch the brace move. I know we used to straighten them all the time on dirt bikes, but I never tried on a street bike.

The brakes are constantly, lightly applied, if you spin the wheel it goes around less than once before it stops. I took the brakes apart and pressed the cylinders back in, put it back together. It's nothing to do with the brakes. I'm going to give MaxMidnight's advice a try, I do believe there is a sweet spot there.

I guess if I get no joy, off they go and down to a machinist. Maybe he'll be honest enough to tell me I need new tubes if I do rather than charge me and still have the same problem when I get them home.

 

[tfranklin]

Now I get 1.5 rotations before it stops, still rubs but not as loud. When you guys let go of the bars, does your bike track straight? I'm pulling left, to ride with no hands I have to lean way right. On the center stand with the front tire off the ground, the wheel automatically swings left. (this is not new)

I might live with it for awhile. I don't know.

 

[gamorg02]

i've heard straightening forks is a no no

 

[satariel666]

i've heard straightening forks is a no no

Why?

 

[gamorg02]

Why?

i don't know exactly. just most manuals say don't ever try to.

 

[satariel666]

i don't know exactly. just most manuals say don't ever try to.

70% of mechanics also says that crankshaft cant be repaired.
Many tales Garret, some are tru some are not.

The truth is that forks flex +- 20-30mm in the extreme conditions like hard braking or hard acceleration . Second is very good visible on the dyno runs with some serious rockets like turbo busas.
Just IMO.

 

[gamorg02]

70% of mechanics also says that crankshaft cant be repaired.
Many tales Garret, some are tru some are not.

The truth is that forks flex +- 20-30mm in the extreme conditions like hard braking or hard acceleration . Second is very good visible on the dyno runs with some serious rockets like turbo busas.
Just IMO.

understood. i thought it had to do with the fact there is very limited amount of metal on the forks so bending them and then back makes them weaker...

what do you mean the forks flex 20-30 mm in extreme conditions? which way?

 

[MaxMidnight]

I had a bent fork tube straitened on a Bonneville that I had many moons ago which went on to give several years of good service.

There is, however, a limit beyond which you shouldn't straiten forks - so best to speak to someone who does this on a regular basis for advice.

 

[satariel666]

understood. i thought it had to do with the fact there is very limited amount of metal on the forks so bending them and then back makes them weaker...

No they're stronger then You can imagine.
High grage steel.

Remember my crash year ago?
I sold my forks on parts but first I needed to disassemble them.
I've tried to straighten inner tube in a vise with 3" pipe, long about 2 meters long.
I was not even able to move it back a 1mm...

what do you mean the forks flex 20-30 mm in extreme conditions? which way?

Forks tubes need to be flexible, not soild and an diamond.
If they will be solid they will broke in the first attemp of braking.

When You're braking hard form lets say 130 mph,
they can flex even by that much, forward or rewind with conventional forks.
With USD its a half less.
Just IMO.

 

[RaWarrior]

Any bike should track straight if you let go of the bars. Mine is straight and steady. If you have to lean to counteract the tendency of the bike, it suggests the forks aren't holding the wheel perfectly straight. Like a car you always have to hold the wheel slightly to one side because of poor alignment.

 

[one2dmax]

All a bent fork will do is make the whole assembly cocked when riding it. The wheel will center itself and you'll just have one arm reaching out farther then the other one. The fork won't make it rub in one place either. It will either rub all the time or it won't (and even then I would say it's an axle not the fork).

It's not uncommon for the rotors to have a "high" spot or even be out of round (egg shaped) where it rubs the top of the caliper in one area. The rotor itself could be warped as could the wheel.

I've ridden on bikes with pretty bent forks at speeds that most of you would shit (try 150 with a 2005 that went end over end). Not saying I condone that activity at all.

I would not straighten a fork if you can feel a creased area. This usually occurs where they come out of the lower triple. If you can feel the ridge, crease, seam then replace it. Otherwise straightening won't hurt anything.

Last I knew Franks Forks (Forking by Frank) did not have tubing large enough for our bikes (even the smaller years).

Forks do indeed flex but maybe not to the extreme Prezmek is saying in normal riding conditions. That's why the inverteds feel so much better. Much less exposed tube to flex and better fluid control.

Sean