Author Topic: AM831 - The flex-fix  (Read 7844 times)

StefanB

AM831 - The flex-fix
« on: March 23, 2022, 03:03:44 AM »
Received the new bolts yesterday, wery well made. I am still waiting for the bearings I ordered. I haven't read everything regarding the flex problem so I could use some help. Is this where the new bearing and bolt should be used?



slo

Re: AM831 - The flex-fix
« Reply #1 on: March 23, 2022, 10:49:06 PM »
Yes, the new bolt goes on the upper mount on the rear triangle as marked in your picture.

JJJ

Re: AM831 - The flex-fix
« Reply #2 on: March 24, 2022, 03:50:34 AM »
Received the new bolts yesterday, wery well made. I am still waiting for the bearings I ordered. I haven't read everything regarding the flex problem so I could use some help. Is this where the new bearing and bolt should be used?

Good move to start a dedicated thread ;-)

StefanB

Re: AM831 - The flex-fix
« Reply #3 on: March 25, 2022, 06:57:31 AM »
I have received my enduro bearings. The fit perfectly on the new bolts but the holes in the frame are to small. I will have to find out a good way to make them bigger.

By the way. What is the screw inside the new bolts for? The original does not have this.

TSBC

Re: AM831 - The flex-fix
« Reply #4 on: March 25, 2022, 09:15:34 AM »
I got my 6703 bearings from Fast Eddy on ebay (seem fine at this point).  Fit the frame great (I'm sure the tolerances here vary with paint, etc with one requiring a tiny press in and the other side dropping in just right.  I followed JJJ's advice and tapped the bolts in until I could tighten them down around hand tight and then tightened the grub screw down to hold everything tight.  Seems good so far and definitely less flex back there wobbling it side to side (haven't ridden it yet to test)

JJJ

Re: AM831 - The flex-fix
« Reply #5 on: March 25, 2022, 10:30:10 AM »
I have received my enduro bearings. The fit perfectly on the new bolts but the holes in the frame are to small. I will have to find out a good way to make them bigger.

By the way. What is the screw inside the new bolts for? The original does not have this.

You need to scrape away the paint and excess resin inside the recess to find the original 23 mm diameter.

If you don't know what the grub screw is for, BEWARE, your bearings are at risk! I explained that on the mailing list:

Important reminder: only tighten the bolt "finger tight", the purpose being only to compensate the axial clearance. The "finger tight" sensation is a little difficult to feel with the tight fit of the bolt. Tighten while turning the link; when you feel a crunching sensation in the link, stop and back-off a little until the turning becomes smooth again.

It's the role of the M8 grub screw to hold the bolt in place, tighten that one sufficiently when you've finger-tightened the bolt. Beforehand, insert the grub screw through the tip of the bolt. You can then use a 4 mm Allen wrench to tighten it through the bolt head.

emu26

Re: AM831 - The flex-fix
« Reply #6 on: March 25, 2022, 07:14:29 PM »
You need to scrape away the paint and excess resin inside the recess to find the original 23 mm diameter.

If you don't know what the grub screw is for, BEWARE, your bearings are at risk! I explained that on the mailing list:

Important reminder: only tighten the bolt "finger tight", the purpose being only to compensate the axial clearance. The "finger tight" sensation is a little difficult to feel with the tight fit of the bolt. Tighten while turning the link; when you feel a crunching sensation in the link, stop and back-off a little until the turning becomes smooth again.

It's the role of the M8 grub screw to hold the bolt in place, tighten that one sufficiently when you've finger-tightened the bolt. Beforehand, insert the grub screw through the tip of the bolt. You can then use a 4 mm Allen wrench to tighten it through the bolt head.


Cudos to you JJJ.

You have put some effort and thought into solving this when the when manufacturer is nowhere to be seen.

Well done.

scourge

Re: AM831 - The flex-fix
« Reply #7 on: March 27, 2022, 07:03:40 PM »
Crap. I must have missed the install instructions.  I just put the bearings on and tightened to 17nm. I rode it once like that already.

JJJ

Re: AM831 - The flex-fix
« Reply #8 on: March 28, 2022, 03:54:10 AM »
Crap. I must have missed the install instructions.  I just put the bearings on and tightened to 17nm. I rode it once like that already.

 :o You probably busted all four bearings! Didn't you feel them crunching?

scourge

Re: AM831 - The flex-fix
« Reply #9 on: March 28, 2022, 12:44:47 PM »
Not at all

scourge

Re: AM831 - The flex-fix
« Reply #10 on: March 28, 2022, 01:09:46 PM »
Well, I took the bolts off and it feels like three of the four bearings are not smooth anymore. Luckily I have three replacement bearings ready. The two new ones popped off easy. How do I get the one bearing off that was already in the rear triangle?

Jotegr

Re: AM831 - The flex-fix
« Reply #11 on: March 28, 2022, 08:05:05 PM »
any way we can edit the top post with JJJ's instructions? Might be helpful!

JJJ

Re: AM831 - The flex-fix
« Reply #12 on: March 29, 2022, 09:48:20 AM »
How do I get the one bearing off that was already in the rear triangle?

Like you do other frame bearings, hammering it out from the other side with a bearing extractor or just a tube. Here you only have access to the inner race, so the bearing will most likely be damaged in the extraction operation. To do only if the bearing is already damaged...

TSBC

Re: AM831 - The flex-fix
« Reply #13 on: March 29, 2022, 07:52:05 PM »
Thought I'd post JJJ's email here with the original instructions:


"The bolt diameter is somewhat close to its upper tolerance limit (at least for the ones I mounted), so it doesn't go smoothly through the 6802 bearing. It doesn't require too much hassle though (gentle tapping until you reach the threads in the link). The advantage is that it fits snugly in the bearing.

The edge of the bolt head is somewhat sharp, so you will probably need to sandpaper it a little.

Important reminder: only tighten the bolt "finger tight", the purpose being only to compensate the axial clearance. The "finger tight" sensation is a little difficult to feel with the tight fit of the bolt. Tighten while turning the link; when you feel a crunching sensation in the link, stop and back-off a little until the turning becomes smooth again.

It's the role of the M8 grub screw to hold the bolt in place, tighten that one sufficiently when you've finger-tightened the bolt. Beforehand, insert the grub screw through the tip of the bolt. You can then use a 4 mm Allen wrench to tighten it through the bolt head.

DO NOT use the bolt to squeeze the 6703 bearing into its recess. The 6703 bearing should be in its final position before you insert the bolt. If necessary, use a bearing press to fit the 6703 bearing in its recess.

Since the recess for the 6703 is not so "clean", depending on the paint and resin jobs, there may be a break-in period after which you may need to tighten the bolts a little more."

StefanB

Re: AM831 - The flex-fix
« Reply #14 on: March 31, 2022, 03:35:46 AM »
Replaced the bolts with new bearings today. I'm glad you posted the instructions again so that I only fastened it "finger tight".

No i can finish my built of the bike and see how it rides. :-)

Thanks JJJ for the fix.