This has been fork rebuilding week - for Gorilla and jacob. Plus forks for the Husky bike and the extra bike build (suggestions for names?).

After finding a bent fork on the new bike, which was straight to the eye, we decided to check all fork tubes and throw half of them away.

Here's what we found. Would you consider this usable? We decided to reject any fork that didn't show straight on a straight edge.



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To me that particular tube needs replacing.Dunno if a machine shop can straighten slightly bent forks,they probably can but is it cost effective.

PS.....were the bent tubes u came across involved in low speed accidents,or what?

Quote from: adidasguy on August 11, 2013, 03:58:31 PM
This has been fork rebuilding week - for Gorilla and jacob. Plus forks for the Husky bike and the extra bike build (suggestions for names?).

After finding a bent fork on the new bike, which was straight to the eye, we decided to check all fork tubes and throw half of them away.

Here's what we found. Would you consider this usable? We decided to reject any fork that didn't show straight on a straight edge.

I wouldnt use them. Once bent they are unsafe IMO

I don't know the origin of all the parts in the Bike Cave.
As mentioned, we discarded those tubes. Even though the bend sometimes was 1/16" to 1/8".
Just wondering if anyone considers them usable.
They are in the box of metal destined for the scrap yard.
I'm sure there is a point - maybe under 1/16" - where a forks would still be OK to use.

I've ordered a dozen sets of fork bushings, too. After Gorilla's fork issue (which seems the forks were way over 8k miles and totally worn out) we will start replacing bushings on all pre-2004 forks when seals get replaced.

I've straightened a gun barrel and a lot of other things using an axle bearing press. I think if you are talking about 1/8th inch or less then I would love to try to straighten them out.

regards
Mech

you gotta sing or whistle this while its happening!! 

Really!!! Scrappin em? If I had a few extra bad fork tubes....I'd be making a new shop stool!!

Isn't runout .2 or .5 of a mm?

I was always led to believe so long as there is no kink in them they are ok. Then again, I'm from Africa where NOTHING gets thrown away.

Tubes can bend just below the bottom clamp due to normal braking and flexing. Its the weakest point and totally normal for mass produced non performance bikes made with cheap parts . If both tubes are bent the same amount and the bent sections don't run over seals or bushes 1.5mm max will be acceptable. I will bet most GS5 forks are running out by this amount and the owners are not even aware of it 

I have just had a set of tubes of a `78 XT500  straightened and rechromed by this company.

http://www.pittedforks.co.uk/fork-straightening.php

They got the runout down to 0.04mm (0.0015")

Rolling tubes on a sheet of glass will show up large amounts of run out but the accurate way to do it is with vee blocks and a DTI.

were those the tubes that were on my bike adidas? man such a small bend and they couldnt hold a single seal.

I recall your tubes were good. Seems the top bushings were worn and allowed the tube to move around a little at the top - enough to let oil leak out of the seal.

ah okay

GS fork seals leak due to the fact the forks legs are a couple 1000's ths under to start with. Get a wee bit of wear, some pitting (yea shittey chrome) and its nighty night for the seal.
Cool.
Buddha.

That makes sense Buddha, any simple drop in replacements? ie Honda CB500 ect. Perpetually leaking forks (I did the seals in January and one has started leaking again) are my only complaint with my GS. Or should I just do the job properly with OEM seals and new bushes.

based on what we found, the upper bushings were work so much that you could feel the tube wobble around at the top of the lower tube where the seal is located. That wobble would cause leaks around the seal. There is a top bushing just under the seal that was work. New ones are on order to make that set of forks un-cursed and usable again.
The lower bushing if worn would cause wobble but I think the one under the seal is more critical for that.
You can get leaking if the is inward or outward force on the forks. The fork brace is the last thing to tighten down. Do that before the wheel goes on and the wheel can cause the bottom of the forks to get forced in or out, straining the top of the fork.
Next to last to tighten is that bearing sleeve on the bottom of the right fork. Pry open to let it slide a little.

First one fork goes in and snug the bolts.
The other fork should slide straight in. If not, then you either have a bent fork tube or the lower triple is bent from a crash. Twist back & forth and they should slide right in in perfect alignment.
If the first fork doesn't go straight in, you have a bent lower triple or the triples are not aligned (as when first assembling a bike) so loosen the top triple so it can rotate a little to let the first fork go in.

The order we use is:
1. Forks in triples and tighten down
2. Fork brace on but not screwed down (has to be there before wheel goes on)
3. Wheel on and tighten axle. Spacer on right fork slides back & forth so the for is straight and where it wants to be.
4. Now tighten the bolt for the spacer on the right fork
5. Now tighten down the fork brace.

Everything should be aligned because the forks were free-floating (so to speak) to be where they wanted to be before things were tightened down.

Quote from: adidasguy on August 13, 2013, 04:11:56 PM
based on what we found, the upper bushings were work so much that you could feel the tube wobble around at the top of the lower tube where the seal is located. That wobble would cause leaks around the seal. There is a top bushing just under the seal that was work. New ones are on order to make that set of forks un-cursed and usable again.
The lower bushing if worn would cause wobble but I think the one under the seal is more critical for that.
You can get leaking if the is inward or outward force on the forks. The fork brace is the last thing to tighten down. Do that before the wheel goes on and the wheel can cause the bottom of the forks to get forced in or out, straining the top of the fork.
Next to last to tighten is that bearing sleeve on the bottom of the right fork. Pry open to let it slide a little.

First one fork goes in and snug the bolts.
The other fork should slide straight in. If not, then you either have a bent fork tube or the lower triple is bent from a crash. Twist back & forth and they should slide right in in perfect alignment.
If the first fork doesn't go straight in, you have a bent lower triple or the triples are not aligned (as when first assembling a bike) so loosen the top triple so it can rotate a little to let the first fork go in.

The order we use is:
1. Forks in triples and tighten down
2. Fork brace on but not screwed down (has to be there before wheel goes on)
3. Wheel on and tighten axle. Spacer on right fork slides back & forth so the for is straight and where it wants to be.
4. Now tighten the bolt for the spacer on the right fork
5. Now tighten down the fork brace.

Everything should be aligned because the forks were free-floating (so to speak) to be where they wanted to be before things were tightened down.

Awhile back i installed & tightened an aluminium "reload" fork brace,then wheel on & tightened-up.This new order of replacement made much better sense so i just redid it....now the forks can't possibly have any lateral stress while sitting.
Thanks man.

Quote from: adidasguy on August 11, 2013, 03:58:31 PM
This has been fork rebuilding week - for Gorilla and jacob. Plus forks for the Husky bike and the extra bike build (suggestions for names?).

After finding a bent fork on the new bike, which was straight to the eye, we decided to check all fork tubes and throw half of them away.

Here's what we found. Would you consider this usable? We decided to reject any fork that didn't show straight on a straight edge.

id straighten that at home and ride on, no worries. happens all the time smacking rocks and trees.

if there was any sign of a ding, corrosion, or wrinkles, id scrap it.

if you pulled all the forks off and checked them at a typical bike night, id bet 1/2 were like that.

The couple that are bent under 1/8" we'll probably hold on to and straighten.

Quote from: bryan88 on August 13, 2013, 02:26:25 AM
That makes sense Buddha, any simple drop in replacements? ie Honda CB500 ect. Perpetually leaking forks (I did the seals in January and one has started leaking again) are my only complaint with my GS. Or should I just do the job properly with OEM seals and new bushes.

I had a guy who had oil seals in different sizes. Only problem was, he had to have the forks to fit em ... and they were not cheap. AQnd he wont clean or do nothing ... or even mail it out, or even do work for walk in's ... he was like contracted to race shops and nascrap shops.
Sadly, no solutions ... no sense spending 200+ on em ... Katana forks are better made and seal up a lot better ... so no use doing anything to a GS fork set.

Cool.
Buddha.