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Trunnion mount RS Deluxe shock doesn't rotate freely around the lower mounting hardware?

4180 Views 25 Replies 9 Participants Last post by HollyBoni, Dec 29, 2021

HollyBoni

Discussion Starter · Oct 17, 2021

2

I have a Horst link bike with a trunnion mount Rockshox Deluxe Select+. I noticed that if I take out the upper trunnion mount bolts, it's a bit hard to move the shock side to side. It barely wants to rotate on the lower shock fixing bolt, there is a lot of friction. I noticed that there is paint missing on the mounting hardware, and on the shock fixing bolt.
Is this normal? I haven't had a full suspension bike in ages, but I thought the shock should have some kind of bronze or teflon bushing. Mine only has mounting hardware like on the picture below and that's it. The shock barely pivots as the suspension cycles up and down, but I thought the shock should still rotate more freely. I took everything apart and greased things up a bit, but same result. As soon as I tighten up the shock fixing bolt, there is a lot of friction.

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cirecc

· #2 · Oct 17, 2021 (Edited)

Did the fixing bolt get over torqued or hit? There should be a bushing in the eyelet.

The mounting hardware looks right though.

HollyBoni

Discussion Starter · #3 · Oct 17, 2021

cirecc said:
Did the fixing bolt get over torqued or hit? There should be a bushing in the eyelet.

The mounting hardware looks right though.

I don't think so.

I haven't seen the bushing but I guess I haven't looked hard enough, i'll check again. So there should be a bushing in the eyelet, and the mounting hardware spacer gets pressed into that? Should the spacer rotate freely in the bushing? Should anything rotate on the fixing bolt itself at all?

bigb73

· #4 · Oct 17, 2021

Real World Cycling/ Enduro Fork Seals make needle bearing kits for rear shocks depending on the frame that you have.

www.enduroforkseals.com

6mm & 8mm Thru Bolts

The best in aftermarket bicycle bearings, components, and suspension products.

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cirecc

· #5 · Oct 17, 2021

I don’t think that the spacer rotates freely in the bushing, it just rotates around the bolt.

Cleared2land

· #6 · Oct 17, 2021

^^^ That sound like a torque issue. If torqued to specification, the DU bushing shouldn't be rotating.

Chris2fur

· #7 · Oct 17, 2021

Where there is virtually no rotation in the lower eyelet throughout the full range of travel, it's actually a good thing to have a very stiff bushing at that end. That end of the shock gets nothing but "head on" impacts which would not be good for a bearing and, if you had a looser bushing, would possibly get looser over time. Sounds like having the bearings at the top and a tight bushing at the bottom is perfect for what you describe.

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Jayem

· #8 · Oct 17, 2021 (Edited)

The shock bolt may have worn and may be slightly bent. I've had bikes where the bushing also wore the shock bolt, although it's a much slower process, it still happens and requires a new bolt eventually and shock hardware, including the bushing. In short, all of that stuff wears, the bushings wear the fastest, but the other stuff does wear too IME and it's not unheard of to need a new mounting kit AND bolt. There's also the chance that something was just off with the tolerance, but you don't say how long you've owned the bike. If it's after a short period, probably bad tolerance, if it's a long period, probably due to wear and maybe slight bend in the shock bolt. Does the shock bolt come out easily with no forcing or punching?

Hawthorn

· #9 · Oct 17, 2021

HollyBoni said:
I have a Horst link bike with a trunnion mount Rockshox Deluxe Select+. I noticed that if I take out the upper trunnion mount bolts, it's a bit hard to move the shock side to side. It barely wants to rotate on the lower shock fixing bolt, there is a lot of friction. I noticed that there is paint missing on the mounting hardware, and on the shock fixing bolt.
Is this normal? I haven't had a full suspension bike in ages, but I thought the shock should have some kind of bronze or teflon bushing. Mine only has mounting hardware like on the picture below and that's it. The shock barely pivots as the suspension cycles up and down, but I thought the shock should still rotate more freely. I took everything apart and greased things up a bit, but same result. As soon as I tighten up the shock fixing bolt, there is a lot of friction.

A couple of shots of your worn out parts will help heaps, the shock supposedly will rotate on the hardware as there is a du bush in the eyelet, some times due to tight tolerances the whole assy works around the bolt that should keep everything together. There are times that even tightening the bolt won't help as the hardware acts as a stoper between the mounting points and the bolt's thread length usually is as much as it needs to preload the hardware to prevent it from spinning. If for any reason the interface of hardware and frame mount surface wears it will spin as clamping force will not be sufficient to overcome the friction between du bushing and hardware bush. I hope I make some sense here!

HollyBoni

Discussion Starter · #10 · Oct 17, 2021 (Edited)

Thanks everyone. I'll take out the shock tomorrow and shoot some pictures.

The bike is about 1.5 months old, but i've taken apart all the pivots when it was about a week old and I noticed this back then. The shock fixing bolt doesn't seem to be bent, it goes in and out very easily.
My main worry is whether the frame which is carbon is going wear down as the mounting hardware rotates.

That bearing kit looks super interesting for sure.

Jayem

· #11 · Oct 17, 2021

Hawthorn said:
If for any reason the interface of hardware and frame mount surface wears it will spin as clamping force will not be sufficient to overcome the friction between du bushing and hardware bush. I hope I make some sense here!

There's only one bushing, it's in the eyelet of the shock. A bushing is a type of bearing. A Delrin Urethane, DU bushing is still present on some shocks, but not nearly as common anymore. I've had some of the RS stuff come with an IGUS or DU type bushing with the same specs, so there are other bushings that would work, plus the Fox IGUS bushings also work on RS, so one could try that, but you need the full Fox hardware kit due to their "hat" shaped bushings. Not sure what you mean by "the hardware bush". Again, there is one bushing (sometimes with two parts if it's a fox 2-peice) in each eyelet. The other stuff is hardware and not intended to provide a bearing surface.

Jayem

· #12 · Oct 17, 2021

HollyBoni said:
Thanks everyone. I'll take out the shock tomorrow and shoot some pictures.

The bike is about 1.5 months old, but i've taken apart all the pivots when it was about a week old and I noticed this back then. The shock fixing bolt doesn't seem to be bent, it goes in and out very easily.
My main worry is whether the frame which is carbon is going wear down as the mounting hardware rotates.

That bearing kit looks super interesting for sure.

I wouldn't recommend a ball or needle-bearing kit here. That's a very limited rotation location. The upper link would make much more sense for a ball/needle bearing interface. The lower one rotates a little, but it's generally not going to benefit from such a kit. The concern though is that if it's not rotating on the bushing, it's eating away metal-to-metal surfaces and that isn't good. Some times pressing in and out the shock pin and bushings a few times will get them to wear down enough or loosen enough that they will function properly. A shock bushing remover/installer tool is a good investment anyway if you own an FS bike. You can make your own with enough threaded rod and some properly sized spacers.

You have options, the first thing I would try is a new shock hardware kit from a different manufacturer, like try a Fox kit.

Hawthorn

· #13 · Oct 17, 2021

Du supposedly has to work around the hardware pin or whatever you call it, but not the hardware on the bolt.
I find igus bushings much better than du though as they tend to rotate more freely and wear rate is better, du's as soon the coating wears are gone, igus seem less prone to wearing as are selflube I think.

brash

· #14 · Oct 17, 2021

Had same issue you did, took the whole lot apart and it was painfully apparent, the bottom bolt was bent like a banana!

New bolt and back in business, however I bend the bolts pretty much every 6 months. I just bought a few of them and when I give the shock a service it gets a new bolt while it's out.

Trunnion, whilst amazing at jamming a "big" shock in a little space (stroke vs eye to eye) is not the best for structural integrity.

Could be worst, could be bending damper shafts I suppose.

Christopher Robin

· #15 · Oct 18, 2021

HollyBoni said:
I have a Horst link bike with a trunnion mount Rockshox Deluxe Select+. I noticed that if I take out the upper trunnion mount bolts, it's a bit hard to move the shock side to side. It barely wants to rotate on the lower shock fixing bolt, there is a lot of friction. I noticed that there is paint missing on the mounting hardware, and on the shock fixing bolt.
Is this normal?

Without pics, it sounds like the bushing/pin interface is just tight. I always found Cane Creek bushings to be stupid tight. I don't remember how my Rockshox stuff felt but it could be just that (which isn't the end of the world). The paint issue sounds like it just chipped when the shock was maybe removed and installed a few times over. On some bikes, I've had fixing bolts come with a washer so the bolt doesn't wear the paint when you tighten down. On some other bikes, that wasn't the case.

HollyBoni

Discussion Starter · #16 · Oct 18, 2021

6

So here are the pics:

On this video you can clearly see that the shock hardware is rotating.

Shock fixing bolt with paint missing:

Wood Varnish Cylinder Metal Font

On the non drive side the frame has a little spacer, I think it protrudes a tiny bit from the carbon, and that touches the shock hardware.

Hood Automotive design Automotive exterior Carbon Personal luxury car

This is how it looks out of the frame (my hardware is raw, not black):

On the drive side where the bolt threads into it looks like there is no insert or anything like on the other side:

Hood Automotive tire Motor vehicle Automotive design Automotive exterior

Shock hardware:

Wood Camera accessory Hardwood Wood stain Audio equipment

Drinkware Beverage can Camera lens Aluminum can Tin can

I tried to clamp the center sleeve in a vice and move the shock, and the sleeve won't rotate in the bushing.

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Hawthorn

· #17 · Oct 18, 2021

The pin rotates on the bolt, this is eithher because of not enough clamp force from the bolt or loose tolerance between frame and pin. After some time usually corrosion sets in and it becomes even harder for the bush to work. Remove the pin and du bushing from shock and replace all worn out parts. Igus bushings are less prone to get stuck or corrode

HollyBoni

Discussion Starter · #18 · Oct 18, 2021

Hawthorn said:
The pin rotates on the bolt, this is eithher because of not enough clamp force from the bolt or loose tolerance between frame and pin. After some time usually corrosion sets in and it becomes even harder for the bush to work. Remove the pin and du bushing from shock and replace all worn out parts. Igus bushings are less prone to get stuck or corrode

I tried to clamp the center sleeve in a vice pretty dang hard and it wouldn't rotate inside the bushing so there is no way the shock bolt can put enough force on it. The bike is 1.5 months old, and I noticed this when it was about a week old so I don't think it's corrosion. Should I still replace the bushing?
I think i'll try to contact the manufacturer as well, but as usual i'll probably just get some completely incompetent customer service guy.

Jayem

· #19 · Oct 18, 2021

What is the shock hardware, is it steel? Fox/RS make steel and aluminum hardware. It looks like your shock bolt might be aluminum and the steel hardware is eating into the aluminum. Not that it would really matter that much, but I'd want to match the hardware with the bolt composition. It looks like the hardware axle is probably locked in there by the bushing and so the hardware is using the shock bolt as a bushing, which is why the coating is wearing off, but that also looks like a crappy coating, hard to say what is going on there. Aluminum bolts should be anodized and that will wear off, but it's not like paint and shouldn't flake. I think the options are to order another hardware kit and hope the tolerances are a little better. If not, take it to a machine shop and get the shock eyelet reamed to spec, that will likely do it. If it's in the warranty period, get the shop to switch it out, likely for a different shock that has the proper spec. Take pictures and provide them to the company.

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HollyBoni

Discussion Starter · #20 · Oct 18, 2021

Jayem said:
What is the shock hardware, is it steel? Fox/RS make steel and aluminum hardware. It looks like your shock bolt might be aluminum and the steel hardware is eating into the aluminum. Not that it would really matter that much, but I'd want to match the hardware with the bolt composition. It looks like the hardware axle is probably locked in there by the bushing and so the hardware is using the shock bolt as a bushing, which is why the coating is wearing off, but that also looks like a crappy coating, hard to say what is going on there. Aluminum bolts should be anodized and that will wear off, but it's not like paint and shouldn't flake. I think the options are to order another hardware kit and hope the tolerances are a little better. If not, take it to a machine shop and get the shock eyelet reamed to spec, that will likely do it. If it's in the warranty period, get the shop to switch it out, likely for a different shock that has the proper spec. Take pictures and provide them to the company.

The center sleeve is aluminium, the spacers on the side are aluminium, the little spacer thingy in the frame is aluminium, the shock bolt is steel. It looks like the shock bolt is painted, it flakes off easily.

So should the center sleeve rotate freely in the bushing?

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