Mountain Biking - Santa Cruz Blur (Classic) - play in the pivot joints after service
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XC Down Under
05-18-09, 10:58 PM
Hey - I'm looking to get some feedback on a recent service I had on my Santa Cruz Blur (Classic model). At the time of the service the originally designed bearings were replaced with SC's newer line. They are supposed to be more robust and used in the BLT. Before riding out of the shop I reviewed the mechanics handy work... I applied the brake and waggled the back wheel from side to side to see if there was any "play" in the bearings. To my surprise there was, enough for me to question his work. The mechanic advised it is common for the Blur to have an amount of play but I do not recall this being the case on previous services, nor when I bought the bike several years ago. Is this common place with these bearings? Can anyone offer their experience of bearing replacements with their SC? Cheers
05-19-09, 05:57 AM
When my wheels get here I'll put my 08 LT together and let you know if there is any play in it.
Play or flex? All bikes have a certain amount of flex... but I don't think it's the norm (or acceptable) for the rear to have 'noticeable' bearing play when the wheel is "waggled" from side to side. How much play, by the way - can you describe it?
I would also double check where the play is coming from, in this order:
- the quick release (or axle mount)
- then the hub bearings
- then the main swingarm bearings
- then any 'other' secondary pivot bearings in your swingarm
Generally speaking a pivot area can wobble because:
- there is play in the bearing itself (which is what your mech is saying)
- the bearing 'seat' (press-fit or clamping area) is loose for whatever reason
- the bearing bolt is not tight enough
XC Down Under
05-19-09, 06:11 PM
Cheers Pocko -
* It's definitely play, and not flex. I'm not applying any pressure to the shock, or to the bike for that matter.
* It's not the quick release or hub (I swapped out the rear wheel with another one and the problem persists)
* All bearings apart from the one nearest the bottom bracket is tight. The bearing nearest the bottom bracket is tight within the housing, it cannot be turned any more, BUT the difference with this bearing compared to the others is I can still turn the bolts round when even a small amount of pressure is applied to turn them, the effect is that of the bolts turning freely with no 'bite' (this the mechanic said was normal). The problem is not shared by any of the other bearings.
* The play comes from the bearing nearest the bottom bracket. Similarly to testing if there is play in the crank housing by holding one of the cranks still and waggling the other you 'feel' the amount of play whilst moving it from one side to the other. The problem with the suspension I am (trying to) describe is no different in this respect... holding the front brake on I motion the rear wheel forwards and backwards, the wheel does not actually move, because of the applied break, but I do feel the play in the bottom bearing. I need only move the wheel say 10mm in either direction when my hand is on the tyre, and I feel the movement in the bottom bracket before resistance is met. I suspect this translates to maybe a couple of millimeters in the bottom bearing.
* I can waggle the wheel fwds and bkwds to create this issue, not side to side as I first suggested.
... I can waggle the wheel fwds and bkwds to create this issue, not side to side as I first suggested.
Other things come into play (no pun intended :) ) if the motion is forwards and backwards. Just so this is eliminated, check the rear brakes as a precaution. If you've got disc brakes, when engaged, some brands can produce a 'knock' or a 'play-feeling.' It is caused by the brake pads wobbling inside and within the caliper body. This is normal. I would also check the rotor-bolts or the caliper mounting bolts. Some V-brakes can also knock at the bosses, but is uncommon with the good-stuff.
... The play comes from the bearing nearest the bottom bracket. Similarly to testing if there is play in the crank housing by holding one of the cranks still and waggling the other you 'feel' the amount of play whilst moving it from one side to the other. The problem with the suspension I am (trying to) describe is no different in this respect... holding the front brake on I motion the rear wheel forwards and backwards, the wheel does not actually move, because of the applied break, but I do feel the play in the bottom bearing. I need only move the wheel say 10mm in either direction when my hand is on the tyre, and I feel the movement in the bottom bracket before resistance is met. I suspect this translates to maybe a couple of millimeters in the bottom bearing.
The bearing nearest the BB is usually the main swingarm bearing. Best way to be certain of this is to get a mate to lock the rear brake and rock the bike forwards and backwards for you. While your mate's doing that, hold a portion of the swingarm as close as possible to the main bearing. You should 'feel' the swingarm knocking if it's the bearing. If you can sense this, next thing to do is see if you can get a finger to touch part of the swingarm and the body (bike frame) next to the bearing - at the same time. If it's the bearing you will sense a dislocation between the two.
If the play isn't there, I would check the shock eyelet bushings next (check them both). Also check if the shock unit itself has developed an internal "knock."
I'm not familiar with your particular bike, so my comments are generic... so in saying that, I would say that play you're experiencing is not normal. In fact, play in ANY bearing can cause damage because it will be subjected to a series of micro-hammering over a period of time during use. Same reason why headtubes ovalize when the headset is left loose.
The real dilemma you have here is that your mechanic is suggesting that you accept this as normal (which could very well be, although I have my doubts). Hopefully others with the same bike as yours would chime in. B2B has one so it would be interesting to hear what he says when his bike's up and running. Once you're really sure that the play is coming from the main swingarm bearing, I would suggest sending SantaCruz an email and see what they have to say? (and stay off the bike in the meantime just to be sure).
XC Down Under
05-20-09, 06:30 PM
Thanks again. I'll go through these tests and report back later today.
XC Down Under
05-24-09, 12:00 AM
Sorry for the tardy reply... been a bit hectic up here with the storms off the east coast.
* It's not the brakes, these I checked. Nor is it the shock bushings or the rotor bolts.
* After removing the bolts from the bearing nearest the BB, and knocking out the pivot axel I noticed the lower link arm that connects the rear triangle to the frame to be the issue... after closer inspection and "waggling" the bike as described prior, there was slight movement of the lower link arm when secured to the frame. In other words the bearings were securely fasten despite the rotational movement of the ring bolts that held it together.
So, to recap -
1. The knock comes from within the housing closest to the BB
2. The knock is a result of the lower link arm not being a tight fit when the pivot axel is inserted. It is this knocking sensation which is the result of this fit. I can see this movement with the pivot axel removed and I waggle the rear triangle. I assume this to be the problem.
I hope this better describes the problem. I can't say I've ever experienced this issue before. I'll ping Santa Cruz an email to see what they have to say. Thanks again.
Cool... it's good you were able to narrow it down and isolate the problem. I hope SantaCruz can sort things out for you.
XC Down Under
05-24-09, 05:04 PM
Thanks. I appreciate all the help. I'll add a post when I hear back from SC in the event B2B encurs the same problem.
XC Down Under
06-04-09, 05:33 PM
More of an update to my problem for anyone who experiences the same issue and turns to SC for help... I'm afraid getting any valuable assistance from SC tech crew is like extracting teeth. So far the only suggestion is as follows [SC quote] "It sounds like that one axle which will not snug down might be the issue. You will want to take the axle out and file it down a millimeter or so. If they are not snugging down properly then the link will slide around just a bit."
I'm totally astonished that this is their recommendation. First, the issue of play is one of lateral movement, perpendicular to the frame, not medial. Second, filing away any material from the axle will only exacerbate the issue.
I've emailed back to SC to arrange a time to discuss this further. Frankly, the support is pretty shoddy... poor turn around time, and despite me trying to arrange a time to speak to someone (even where I foot the bill calling from Australia) the email replies are one liners with very little constructive feedback or recommendation (arghhhh!!)
More as and when I hear back, although I think I'll now visit another mechanic to get their opinion.
Sounds like a normal Santa Cruz problem to be honest.
XC Down Under
06-04-09, 06:34 PM
Ok, after speaking to Danny from SC, he re-affirmed the action to shave off a couple of mm from the axle ends. The reason being... the lower link arm is likely to have 'condensed' over time owing to the wear and tear of the material (aluminium). The fact that the pivot axle runs freely after the bolts have been tightened suggests the bearing housing is not snug down, and by shaving off 1-2mm's either side of the axle will allow the bolts to properly secure and snug down the axle. He sounded pretty confident this would fix my problem.
He also advised the "play" as I described it is not normal despite what the mechanic at my local bike store (back in Sydney) suggested.
It will not be for another week that I can look into this (came off my ride last weekend and damaged my back and gotta rest)... which reminds me, for anyone looking for a helmet I recommend the Specialized Decibel, it literally saved my life!
06-05-09, 05:39 AM
...yeah, I don't see how shortening the axle could help...but hopefully it does fix your problem. Keep us updated!
Oh, and I'm glad you're okay after the crash...hope you feel better soon!
XC Down Under
07-31-09, 11:03 PM
Just an update on this problem... it worked!! By reducing the pivot axle 2mm I now get a snug fit with no play in the BB bearing. Thanks SC for the assistance, I was somewhat scepticle but it did work out as advised, thanks.
FYI... I did find the full instructions online for anyone seeking step by step instructions:
08-01-09, 06:14 AM
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