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Replace bent triple tree?

17K views 39 replies 10 participants last post by  CheapBassTurd 
#1 · (Edited)
Four weeks ago I went down doing 60 mph. The bike developed a severe wobble that quickly got worse and I went down.

I haven't determined what caused the wobble yet. That's something I'll do more looking into once I fix some damage from the crash.

Most of the damage from the crash is cosmetic, stuff I'm not worried about fixing. However, the front wheel is misaligned with the handle bars and front fender.



I tried the easy stuff first. I loosened all the bolts on the front and compressed the front forks to see if things would line up. That didn't work. I got more aggressive by securing the front wheel and twisting the handle bars to try to get things to line up. That didn't work.

Over the weekend, I pulled the front forks. One of the forks was easy to remove. The other fork would not turn and was difficult to remove. I was able to finally remove the fork by using a rod and tapping on the top of the fork until it was out of the top tree and then it was easy to remove from the lower tree.

Since I had so much trouble removing the fork, I expected it to be bent. I checked both forks by rotating them on a piece of plywood and then using a straight aluminum bar. Neither fork is bent.

I cleaned up the forks and triple trees. I was able to install the forks relatively easily. No sticking when putting the forks back on.

After reinstalling the forks, the wheel is still out of alignment. Now I figure one of the triple trees is bent.

How do I check a triple tree to see if it is bent? I'd prefer not to buy replacement parts unless I need to. At this point, I'm thinking I'll buy a replacement bottom triple tree and see what happens.

Any advice?

Thanks in advance.

BTW, I came away from the crash with some rash on my knees, some bruises, and a severely strained wrist. I was wearing all the gear. The rash occurred because the knee pads in my pants twisted out of the way and the pants wore through. The jacket is also toast, but did it's job in protecting my upper body. I don't think any amount of armor could have prevented the twisting injury to my wrist. After 4 weeks, the road rash is almost healed and the wrist is coming along nicely. I'm in the process of purchasing replacement gear. I was lucky.
 
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#2 · (Edited)
tjduexjr,
If the upper fork legs are Not bent or bowed it seems very unlikely to me that the triple clamps, either upper or lower would be bent.

I can only suggest that the top and bottom clamps are slightly twisted out-of alignment. You may have to slightly loosen the Top Nut under the handlebars and start over.
(Notice the arrow on the handlebar clamps? Points forward/up, tighten completely, then tighten the rear bolts.)

ps, Glad you were able to sort of walk away. I've been pretty lucky myself, several times.
 
#4 ·
When I had the forks off, I looked at the alignment of the triple trees. The top and bottom move independent of each other without an issue. I did briefly check the steering head nut just because I think it being too loose may have contributed to the original wobble issue, but I didn't spend too much time on this yet since the wheel is still out of alignment.

Since the upper and lower trees move independent of each other, I didn't think about them needing to line up in any specific way prior to installing the forks. Are you saying the upper and lower trees need to be in some type of alignment prior to installing the forks?

I apologize if I'm asking a super basic question. While I'm an engineer by trade, I'm a noob when it comes to working on the front end alignment of a motorcycle, so I'm still building my mental understanding of how it all works.

Thanks.
 
#3 ·
Maybe the steering bearing adjuster nut Under the top triple clamp is a little 'slack', that could be part of/ all of the reason for the wobble in the 1st place.

Most likely they need a little more grease anyways, so I've read.
It has been called the "Asian grease shortage".
 
#6 · (Edited)
I can't say for sure that the bars are bent and the front fender isn't tweaked. Here are my observations, though.

I use the bar risers and the top triple to determine when the bars should be straight. When I have the bars oriented to what I believe is straight, the front fender also points straight. The wheel does not.

When I point the wheel straight, the fender does not point straight and the bars, through the risers and top triple, also do not point straight.

When I pulled the front fender off this weekend to remove the front forks, there is no indication of stress on the holes for the bolts, meaning it doesn't look like any of them have been stretched. The fender itself doesn't look like it is out of alignment with itself.

If there is another way to tell if the bars are on crooked, or the fender is tweaked, I'm all ears. Happy to try anything to prove that the misalignment is an easier, less expensive, fix.

Can the bar risers get out of alignment with the top triple?

I do appreciate the feedback and suggestions.

Thanks.
 
#7 · (Edited)
If the two triple trees are free to move independently of one another, then inserting one fork leg will do the job of properly lining them up.

What would be of interest and possibly helpful would be a picture looking at the forks with the cowling removed (and even the instrument cluster, if you can manage it), no wheel installed, but the front axle loosely inserted through the fork. This should be done with the bump on the ignition lined up with the bracket fitting on the frame, which centers the triple tree pretty well.



Then, without moving anything, take a picture from the side.

Sorry about the quality of my pictures; it's getting dark here, and sorry not to take a photo from the side.

This is one of those situations where, if everything is as you say, it must all work. Since it isn't, there may be something weird going on that a picture might give a clue to.

Tom
 
#8 ·
Have you closely examined the triple trees for any signs of stress cracks or fractures?

Tom
 
#9 ·
tj,
The pics help. Wish I had camera AND understood how to do pics.

How easily does the front wheel turn from side to side, when front wheel is off of the ground?
I'll suggest that it should not 'Flop' to the steering stop! The tapered steering bearings need 'just a tiny little bit of pre-load'.
Might be a good time to snug the spanner nut under the top triple clamp a smidge. Don't want anymore wobbles.

With all parts assembled, BUT NOT Tight, treat the front forks like your old bicycle! Straddle the front tire between your knees and twist the handlebars in the direction desired.

You need the triple clamps just tight enough to keep fork legs at proper height, front axle not quite tight, top nut not quite tight. Yeap, that means the handlebars may have to come off and on once or twice. NO, maybe NOT, you've got bar Risers. Might have room for a wrench?

Once alignment is achieved, snug the lower triple clamps, Top Nut, top triple clamps, f axle. Then proper torque in same sequence.
 
#11 ·
I've already tried what you suggest. It was the second thing I tried. Everything loosened, straddle the front tire and twist the handlebars. Hasn't worked, and I tried many, many times.

With the bar risers, I can just get a socket over the top nut, so don't need to remove the bars to adjust.

Actually, the nut takes a 32mm socket. Posting this just because I couldn't find this information anywhere. Hopefully if someone searches in the future, they'll find this post.

I know something is up somewhere. Even though I was able to reinstall the forks fairly easily, there was still some resistance and playing required to install the second fork. The first fork goes in with almost no resistance. The second fork is tougher. Doesn't really matter which side fork I put in first, it goes in easy, the other side/second fork has some resistance.

I'll take pictures when I can take the bike apart again. Will likely be this weekend before I can get to it.
 
#10 ·
I'll take things apart again and take some pictures. Just to set expectations, I probably won't be able to get back to take things off the bike until the weekend.

I didn't do a close inspection of the triple trees to look for signs of stress cracks or fractures. I looked things over, just not closely.
 
#12 · (Edited)
I bought a VT500 at an auction way back (for too much money!) and upon loading it and unloading it, it seemed "off". A test drive around the block confirmed my suspicions that something was out of whack, the bike would track straight, but it had to be leaned to the left a little to do so. Surprisingly it was still stable, even though something was out of whack.

I did some measuring to see if something was bent, but my measurements were so close that I couldn't tell anything for sure. I ended up trailering it to a Honda dealership and asked them to have a look at the front end. When they pulled the axle (with difficulty) the whole front end sprung so badly that you couldn't even get the caliper bolts to line back up to reassemble it! Final estimate on the bike was, a lightly warped rim requiring truing, a bent disc that would have to be replaced, both fork tubes were bent, and the bottom triple was pooched. Needless to say the repair costs would have far exceeded the value of the bike, so I just brought it back home and sold it cheap to a guy that was going to try to fix it. Funny part was, it looked fine until they started unbolting things.

Long story but it kind of has a point... Lol. If you can disassemble and reassemble the forks with everything going together smoothly and nothing really binding or rubbing, it's more than likely not bent, but possibly an alignment issue (and bent bars?). Looking forward to seeing some pics of the front end as well.

Edit: When you jack up the front and give the wheel a spin, does it spin true with no draggy spots on the disc rotor? Just wondering if your wheel might be tweaked a bit, 60 is a pretty fast drop!
 
#14 ·
Edit: When you jack up the front and give the wheel a spin, does it spin true with no draggy spots on the disc rotor? Just wondering if your wheel might be tweaked a bit, 60 is a pretty fast drop!
I tried this when I had the bike apart and reassembled over the weekend. The wheel appears to spin true, at least with respect to drag on the disc rotor. I can't say that the rim isn't tweaked since I didn't measure anything, just eye balled for a quick check.
 
#13 ·
Here's the alignment procedure I learned from a BMW mechanic. (Yes, some BMWs have telescoping forks.)

1. strip the forks down all the way to check the tubes for straightness without the sliders on them using vee blocks and a dial indicator.
2. assemble the triple trees and fork tubes off the bike and clamp the steering stem in a vise with the fork tubes horizontal and use a level to bring each tube horizontal then lay it across the both tubes to check the triple tree for twist.
3. assemble the sliders and axle to the forks (with the assembly still in the vice) and check for free motion through the range of fork travel.
 
#16 ·
Though I stand by my contention that triple clamp damage is rare; IF the forks are straight and you can put in one tube but the other is a problem, it would suggest a bend or crack in either the top or bottom clamp. It would be difficult to bend one without destroying the fork unless there was a direct impact on the clamp itself......or the wheel was forced over with enough force for the lower clamp to smash against the stop with enough force to crack or damage it....

...I would check the fork tubes again very carefully and if they still look good then I'd take a VERY close look at the clamps....particularly the bottom one.

Can't recall if you said but when it's easy to install the first tube, that is in either side right?



Cheers,
Dave
 
#22 ·
tj,
So ok you have confirmed that the fork legs slide into the lower triple clamp easily. Either one of them first, slides clear thru the top clamp easily also.
The problem is the second leg slides thru the bottom triple easily, but then needs 'some persuasion' to go THRU the top clamp.

Sound correct?

I'll suggest that all it could take is 'normal' production variances between the top and bottom centering of bores to create .010"-.020" of mis-alignment. Possible? Perfection is kind of hard to achieve.

Occasionally I see triple clamps that have been 'over-torqued', imagine that!
I have to spread the gap of the clamp with a flat blade screw-driver to allow the leg to start OUT or IN.
 
#23 ·
tj,
So ok you have confirmed that the fork legs slide into the lower triple clamp easily. Either one of them first, slides clear thru the top clamp easily also.
The problem is the second leg slides thru the bottom triple easily, but then needs 'some persuasion' to go THRU the top clamp.

Sound correct?
Yep. That sounds correct.

I did purchase the triples that were for sale in the link. When I take things apart, I'll compare the triples I bought to the triples I take off the bike to see if there is anything visibly different. If there is, I'll try the new triples to see what happens.
 
#28 ·
Wheel aligned

First the short version, the front wheel is aligned. The bottom triples were bent slightly. I replaced them with the used triples I purchased and everything went back to being in alignment.

Here is the longer version. I wasn't able to work on the bike yesterday. Life has a way of getting in the way of plans. No worry. I was able to do the work today.

I removed the upper fairing and took pictures. (Edit: I'm not sure why the pictures are not showing up. I'll try to fix and re-post.)

All of the pictures are taken with the bars pointing straight ahead as shown here.


This is a head on shot. You can see that the front fender and wheel are not aligned with one another. You can also see that the front wheel is twisted with respect to the forks.


Front shot without the fender.


Side shot without the fender.


From the side without the wheel.


I disassembled the rest of the front and removed the triples. It was fairly obvious that the triples were tweaked when I set them on a piece of flat plywood and felt the gaps between the wood and the triples. I then spent some time convincing myself that I wasn't just imagining things being tweaked because I expected them to be tweaked. I think this is the best set of pictures to show the difference between the triples that came off the bike and the purchased triples.

Triples off the bike. You can see that the gaps at the bottom of the triples between the two sides is not the same. It's not a big difference. It's much easier to feel than it is to show in a picture. As I think about it now, I could have measured the difference, but didn't think about doing that at the time.


Here is what the gaps look like with the purchased triples. I didn't realize this pic was so bad until I posted it here. Might not show as easily as I'd hoped.


I reassembled the front end. I didn't take as many pictures on the reassembly. Here is the end result with the purchased triples and the front wheel installed. The wheel is no longer twisted in the forks.


I finished the reassembly of everything and then went for a quick test ride. The bike feels fine and the wheel is no longer out of alignment.

Thank you to everyone that offered advice during this journey. A special thank you to ThumperBob for the link to the triples for sale.

--Tom
 
#30 ·
First the short version, the front wheel is aligned. The bottom triples were bent slightly. I replaced them with the used triples I purchased and everything went back to being in alignment.

Here is the longer version. I wasn't able to work on the bike yesterday. Life has a way of getting in the way of plans. No worry. I was able to do the work today.

I removed the upper fairing and took pictures. (Edit: I'm not sure why the pictures are not showing up. I'll try to fix and re-post.)

All of the pictures are taken with the bars pointing straight ahead as shown here.


This is a head on shot. You can see that the front fender and wheel are not aligned with one another. You can also see that the front wheel is twisted with respect to the forks.


Front shot without the fender.


Side shot without the fender.


From the side without the wheel.


I disassembled the rest of the front and removed the triples. It was fairly obvious that the triples were tweaked when I set them on a piece of flat plywood and felt the gaps between the wood and the triples. I then spent some time convincing myself that I wasn't just imagining things being tweaked because I expected them to be tweaked. I think this is the best set of pictures to show the difference between the triples that came off the bike and the purchased triples.

Triples off the bike. You can see that the gaps at the bottom of the triples between the two sides is not the same. It's not a big difference. It's much easier to feel than it is to show in a picture. As I think about it now, I could have measured the difference, but didn't think about doing that at the time.


Here is what the gaps look like with the purchased triples. I didn't realize this pic was so bad until I posted it here. Might not show as easily as I'd hoped.


I reassembled the front end. I didn't take as many pictures on the reassembly. Here is the end result with the purchased triples and the front wheel installed. The wheel is no longer twisted in the forks.


I finished the reassembly of everything and then went for a quick test ride. The bike feels fine and the wheel is no longer out of alignment.

Thank you to everyone that offered advice during this journey. A special thank you to ThumperBob for the link to the triples for sale.

--Tom
No problem Tom. Glad it all worked out for you.
Bob
 
#34 ·
Good news. Like some of the others I was skeptical that your triple was bent without bending the forks but as you described the issue, it was becoming clear that the triple was indeed damaged. I figured it would probably be the lower. Glad you got it all fixed up (I'd love to see the pics if you can get them posted)

Cheers,
Dave
 
#36 ·
Four weeks ago I went down doing 60 mph. The bike developed a severe wobble that quickly got worse and I went down.
did u figure out the cause of the wobble?

i had a wobble last week, a really bad one. super serious... my bike was doing figure eights almost.. gladly i controlled it. lasted like 5 seconds... i was going like 80 85 with luggage in the back.

my theory was that i had too heavy load on the rear wheel and that caused the wobble on the front.

glad u made it ok.
 
#38 ·
Can't say I figured out the cause of the wobble for sure. Similar to you, I suspect it's mainly due to loading the bike too much toward the rear, plus the inclusion of the knobbies. I'm sure both were contributing factors, but I can't say for sure if either were the ultimate cause of the wobble.
 
#37 ·
A tip on wobbles/pre-tank slappers.

The bike, like a shopping cart wheel, starts with a minute oscillation that
is unfelt but is at a frequency that will build on itself. Sometimes quite quickly.

There's a few good tips such as relax while backing off the throttle.

Spreading out the knees and elbows is very effective if it's a wind induced wobble.
The change in drag and airflow will break up the oscillations.

If it's coming on at high speeds it can nearly always be broken smooth by chirping
the rear brake a time or two, and just backing off the gas. In a second the bike is
tracking dead straight.
Whether the cause is a loose or tight steering head,
low pressure in the front tire, or a front knobby,
a heavily packed rear end (weight biased rearwards),
rigid arms of fear,
the end result is the same with this type of wobble.
It can be killed very quickly. It can turn ugly quickly
also. This method prevents the front tire from using
energy from the rear as traction is lost and speed is dropping
8 mph in that same second. The front has to "drag" the rear
tire around as opposed to feeding off of it. The abrupt change
in forces stops the wobble cold.
 
#39 ·
Thanks for the advice. For a couple of months after the accident, I did a bunch of research trying to figure out what went wrong and how to control it if it happens again in the future. As you can imagine, advice is all over the board. It seems that a lot depends on the cause of the wobble.

I've also watched many videos with people that have succeeded in riding out a wobble and people that weren't successful. I did try to ride out the wobble and just let the bike oscillate in hopes that I could get through the experience. However, I think the conditions and knobbies hurt me.

There was a fog and thin mist that morning, which meant the road was slightly moist. As the bike was wobbling worse and worse, the front end eventually washed out. When that happened, I went down. From all the videos I've watched, the successful recoveries occurred when the bike didn't lose traction.
 
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