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Manitou marvel pro problem with stiction when thru axle completely closed

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Schnazel

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Discussion starter · #1 ·
Hello forum,
I have manitou marvel pros on two bikes, one of them is harsher and not so plush compared to the other. Both have fresh service. I notice it especially on mild bumps and trail chatter, and generally th fork sooms harsher. (Both abs+ and same shim stack).

I disassembled the fork completely to check for defects and found none. When I insert the bare stanchions into the casting I cannot feel play, when I insert the legs seperately there is a tad bit of play which in my opinion is the necessary amount.

Now comes the tricky part: when I put in the stanchons and let them go, they slide in smoothely without additional force (when I have the lower assembly on the hub with the axle put through, but not tightened).

When I tighten the axle the last 1/4 revelation the binding/stiction issue returns. Then I screw the axle out again 1/4 to 1/2 revelation its alright and smooth.

Any idea what can cause this? My hub is a DT hub 20mm with adapters for the 15mm manitou thru axle. Iam thinking of putting some 0,1mm washers betweent the hub and spacers to see if that fixes the problem. A 1mm Oring is way too much, I suppose its in the ballpark of 0,5mm at max.

Thank you!
 
Discussion starter · #3 · (Edited)
Will measure that in the evening. I tried it with another set of wheels and its the same.
The fork had the hexlock qr which I exchanged for the simpler manitou through axle. Apart from that the paint from the flanges at the dropouts of the fork has worn of (where the dropouts make contact with the hub caps). Maybe thats where material is missing.
 
Discussion starter · #4 ·
Hey, I measured the axle and the spacing seems fine. Its as wide as it should be (according to my digital caliper). I cleaned the dropouts and polished the facings flat, also the insided of the dropouts. I reassembled the fork and greased it a little bit more than usual. first ride seems fine.

What I have now is a knocking sound like a thumb/thumb when abs + is fully opened on top out. The other fork is quiet on top out. Any idea? Didnt see anything unsual in it.
 
Discussion starter · #7 ·
Sorry for the late answer, have been busy.
The 27,5 fork is a stock Marvel Pro with iso air and reshimmed ABS+ damper (currently production trail). The one with the thumb sound is a 29er marvel comp that I fitted the internals of a defect Marvel pro 29er into. So it has the rebound assembly of the Pro (which I had to work a bit on to make it fit because the pro has tapared stanchions) and the slightly different (to the comp version) air spring assembly. And it also has a reshimmed abs+ unit. The parts are all in working order, I compared them to the 27,5 stock marvel pro.

the thumbing does not seem to have an effect on the forks performance, so its ok with me, but nonetheless found it odd because I cant make up where it originates
 
#8 ·
The three things that can make a fork like that thump on top-out.

1. More air pressure than the top-out spring and bumper can handle.
2. Rebound damper topping out before spring side (parts mis-match).
3. Rebound damper not working. Usually due to damaged or held open shim.
 
#9 ·
Perhaps I can hijack the thread a bit.

Manitou Minute Pro 140mm. Original owner, bought on bike24.de

I opened it up to change travel and regular service - it seems that the air assembly is not per specifications.

Smaller issue:
My air spring kit is 121-26976-L003 - I can't find this anywhere in Manitou service material. It is a bit weird that I have this assembly that is never mentioned anywhere in Manitou material I could find? What would this kit be if it is graded by firmness?

Problem I have:
My air piston when opened it, takes seal 062476 - which IS NOT what is per rebuild kit (doc # 46-28564).
Per rebuild kit, this is seal is for R7 PRO. 068348 is seal for Manitou Minute Pro.

Question: did I get the wrong air piston in my Manitou Minute Pro from factory?
If not, if it is ok, do I need to order R7 seal (062476) for this to work?

If I want to replace the whole air piston, which one (code) would I order then?

Thanks
 
Discussion starter · #10 ·
Dougal said:
The three things that can make a fork like that thump on top-out.

1. More air pressure than the top-out spring and bumper can handle.
2. Rebound damper topping out before spring side (parts mis-match).
3. Rebound damper not working. Usually due to damaged or held open shim.
Click to expand...
1. Air pressure is around 90PSI, that should be completely ok for this fork.
2. rebound assembly and air spring come from the same donor fork. I measured every part to make sure it fits. But this seems to be the most plausible explanation indeed.
3. The rebound damper was indeed stuck when I received the fork, but I pulled the assembly apart and it works now flawlessly. Can see the needle valve when turning it, rebound is also completely fine. Can tune from "fork is absolutely dead" to "fork jumps 15cm into the air"
 
#11 ·
Goran_injo said:
Perhaps I can hijack the thread a bit.

Manitou Minute Pro 140mm. Original owner, bought on bike24.de

I opened it up to change travel and regular service - it seems that the air assembly is not per specifications.

Smaller issue:
My air spring kit is 121-26976-L003 - I can't find this anywhere in Manitou service material. It is a bit weird that I have this assembly that is never mentioned anywhere in Manitou material I could find? What would this kit be if it is graded by firmness?

Problem I have:
My air piston when opened it, takes seal 062476 - which IS NOT what is per rebuild kit (doc # 46-28564).
Per rebuild kit, this is seal is for R7 PRO. 068348 is seal for Manitou Minute Pro.

Question: did I get the wrong air piston in my Manitou Minute Pro from factory?
If not, if it is ok, do I need to order R7 seal (062476) for this to work?

If I want to replace the whole air piston, which one (code) would I order then?

Thanks
Click to expand...
Minute Pro 140mm was a rare beast, most of them were only 120mm. Earlier Minute Pro were MARS air, the later were ISO air. ISO air are all the same just longer/shorter to fit with travel.
ISO air pistons are alloy with rubber isolators underneath. The T section seals they used are no longer available and can be replaced with o-rings or quad-rings with backup rings.

The numbers you're mentioning sound like individual engineering part numbers where the kits containing those parts have different, retail level, part numbers.
 
#12 ·
Schnazel said:
1. Air pressure is around 90PSI, that should be completely ok for this fork.
2. rebound assembly and air spring come from the same donor fork. I measured every part to make sure it fits. But this seems to be the most plausible explanation indeed.
3. The rebound damper was indeed stuck when I received the fork, but I pulled the assembly apart and it works now flawlessly. Can see the needle valve when turning it, rebound is also completely fine. Can tune from "fork is absolutely dead" to "fork jumps 15cm into the air"
Click to expand...
90psi could be the problem. An overwhelmed negative spring is when the bumper compresses enough that the coil spring runs out of stroke.
Increasing the bumper length can help. I've got some work to do on this myself soon.
 
#13 ·
Dougal said:
Minute Pro 140mm was a rare beast, most of them were only 120mm. Earlier Minute Pro were MARS air, the later were ISO air. ISO air are all the same just longer/shorter to fit with travel.
ISO air pistons are alloy with rubber isolators underneath. The T section seals they used are no longer available and can be replaced with o-rings or quad-rings with backup rings.

The numbers you're mentioning sound like individual engineering part numbers where the kits containing those parts have different, retail level, part numbers.
Click to expand...
Thanks. Just ordered and waiting for an all inclusive 32mm seal set 141-28528-K009, so it should contain all combos.

Re Iso air piston, it is red anodized and 27mm (26,98) wide.

I tried placing in a gold anodized one from Tower Expert, I also have at home, but it is too wide.

Would you know the code or equivalents from other forks for the red 27mm wide one so I know what to order if it fails? Can I use the Machete ones?
 
Discussion starter · #15 ·
Alright, my problem reoccured and I disassembled the fork. I measured the Hub, its 99,90 with the digital caliper. So that should me alright. Another Manitou fork works flawlessly if I put it on the hub.

So the problem remains. I have the fork completely stripped, wipers removed and all. I put it on the hub and insert the axle but dont tighten it all the way. When I pull the stanchions out and release them, they slide all the way in on their own. When I tighten the axle the fork is sticky and the stanchions will only go down when i push them down. Releasing the axle half a turn and it slides again. When I put a 0,1mm washer unter the hub adapter (20 to 15mm) the fork is even stickier when the axle is torqued down. So I am out of ideas what could be the problem. I checked the axle and the inner contact surfaces between dropout and axle and cleaned/polished them, but they seem fine.

Maybe the surfacesof the dropouts are somewhat twisted and when pulled together by the axle the fork twists and the bushings produce stiction. Any ideas?
 
#16 ·
Schnazel said:
Alright, my problem reoccured and I disassembled the fork. I measured the Hub, its 99,90 with the digital caliper. So that should me alright. Another Manitou fork works flawlessly if I put it on the hub.

So the problem remains. I have the fork completely stripped, wipers removed and all. I put it on the hub and insert the axle but dont tighten it all the way. When I pull the stanchions out and release them, they slide all the way in on their own. When I tighten the axle the fork is sticky and the stanchions will only go down when i push them down. Releasing the axle half a turn and it slides again. When I put a 0,1mm washer unter the hub adapter (20 to 15mm) the fork is even stickier when the axle is torqued down. So I am out of ideas what could be the problem. I checked the axle and the inner contact surfaces between dropout and axle and cleaned/polished them, but they seem fine.

Maybe the surfacesof the dropouts are somewhat twisted and when pulled together by the axle the fork twists and the bushings produce stiction. Any ideas?
Click to expand...
Can you measure the fork legs at the bottom with/without the axle torqued? To see if it's spreading or squeezing.
 
Discussion starter · #17 ·
Yeah I tried that, it appears to squeeze them but its hard to tell. When I put the fork onto the hub I have to pull the legs apart a tiny bit to slide it on.

I thinks its more an alingment problem of the casting. I tried to measure the stanchions as good as I could manage and they are evenly apart from another and on the same plane.
So I suppose the casting somehow twists or gets out of parallel when I tighten the axle. Its kinda weird to be honest because it would be obvious that its squeezed together by the axle but putting in a washer makes things worse.
I think I should look out for another casting.
 
#18 ·
Schnazel said:
Yeah I tried that, it appears to squeeze them but its hard to tell. When I put the fork onto the hub I have to pull the legs apart a tiny bit to slide it on.

I thinks its more an alingment problem of the casting. I tried to measure the stanchions as good as I could manage and they are evenly apart from another and on the same plane.
So I suppose the casting somehow twists or gets out of parallel when I tighten the axle. Its kinda weird to be honest because it would be obvious that its squeezed together by the axle but putting in a washer makes things worse.
I think I should look out for another casting.
Click to expand...
From over here I'd say you need new lowers. I'm sure it's possible to solve the issues with them. But it will take some planning.
 
Discussion starter · #19 ·
I think so,too. I bought a 29 marvel yesterday I found on ebay, in excelent condition. Hope the lowers will fix the problem. I need a long steerer tube unfortunately (I am 1,94m tall), so there is limitef supply for complete used forks that have enough steerer left.
On the other Hand I could buy a new fork like a machete, but it is internally quite similiar with the machete being boost (which I dont need) and heavier...
 
Discussion starter · #20 ·
Alright, I installed a new (used) casting today and its better. I think its now in the realm of normal. With some burnishing it could be even better though. The Casting is way easier to put on the axle now also. Would be nice to find some marvel pro stanchions with an uncut steerer or at least 21cm of tube left.
 
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Schnazel
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