Slipping / cracking shimano xt freehubs
I have been having a LOT of problems with multiple failures of new Shimano XT freehubs in the last few years. Making a loud cracking noises, or worse, slipping, usually on engagement after freewheeling, but sometimes later, even after a few crank revolutions, which is even more unexpected and dangerous.
All of them have been Shimano XT and bought form Chain Reaction Cycles in Ireland.
I have had the same problem with 2 complete rear wheels (the most recent only purchased a couple of months ago), and 2 XT hubs (bought specifically for the freehubs because it was better value than the freehubs alone).
Having had yet another failure today (one so bad I can't just ignore or live with), and reading up on the net, I still can't tell for sure whether CRC in particular has had a very large bad batch, or if Shimano has put out bad stock to multiple shops, distributors, and suppliers.
One thing is for sure, this is not an isolated problem. There are multiple instances documented online.
Today’s freehub will go in the bin. I have swapped it out for one I had on a spare wheel. This new one has also only had a couple of months use, but I remember also suffers from occasional cracking noises and slips. So, I have removed the seal from the rear, and flushed it out with oil before fitting.
While I hope this works (should grease be making the pawls stick from the factory), I suspect they are just plain defective, and that Shimano should have issued a safety warning and recall.
If anyone knows of a safe and reliable freehub body that will fit to XT hubs, please post, as I need one for both my bikes!
Last edited by xr600; 08-26-2012 at 02:57 PM.
Wow I thought the XT hubs were good, I was just about to buy a set of these to fit my new ZTR Flow 26" - 32 Hole White Rims.
Shimano XT M756A Rear Hub Black, 135mm QR, 32 Hole
Shimano Deore XT M756 Disc Front Hub Black, 32H, 100mm
Last edited by Trail_Blazer; 08-26-2012 at 09:28 PM.
I wouldn't try to put you off buying those wheels, I would go ahead anyway.
What I am talking about here is a potentialy HUGE batch of faulty Shimano freehubs, which I think I have been falling foul of, for what seems like at least the last few years.
I'm not going to blame CRC here either, unless they have been having a lot of complaints from others, and still selling them of course.
I have been doing some more on-line research and would like to retract my last post advising to go ahead and buy that rear hub anyway.
The XT756 is (I think) the hub I have on my 2 mountain bikes now.
(I have also taken the freehubs from 2 new XT hubs that had the small flange)
NONE OF MY RECENT FREEHUBS HAVE NOT SLIPPED OCCASIONALLY FROM NEW!
All the Shimano freewheels (on the cross country biased ranges) appear to be the same junk.
They all regularly have the same problems(I have experienced 1 & 2)
1) Slipping freehubs due to bad pawl engagement
2) Straight from new, the cones work loose
3) Grating noise leading to freehub seizure
4)The cones actually self tighten causing complete hub faiure
Time will tell if the slipping can be cured by flushing out any grease with oil
You may find posts on forums from people saying htis only affected some older hubs. Not true, they are still on sale.
My advice is, don't but any XT (or any Shimano for that matter) rear hub from recent years (who knows if 2012 /2013 hubs will be OK).
The front hub seams to be great ... as it should be!
Avoid this one. The 756A is more like a glorified Alivio rear hub. Mush worse sealing than plain 756 and I suspect worse quality bearing races too. Entirely different innards than good old 756, of which there are a HELL of a lot in use currently, even to the point it's the go-to hub for value minded cyclists (around here at least, I get to build more wheels around those than any other hub).
Originally Posted by schristie11
This is getting a lot more complex than I wanted . lol
Now I'm wondering if I should pony up for a Hope or king or DT rear hub.
Those hubs are great, can't really go wrong with either one.
Originally Posted by schristie11
My hub of choice is Hope Pro 2 SS/Trials, but it's really loud. There are some technically superior hubs, but value wise, this one is better in the end. May not be your cup of tea however, if you want a full complement of cogs on your cassette.
Take a look at Nukeproof Generator rear hubs. They have proven themselves. One of these is what I would have picked if I wanted a full-cassette hub for a budget build. Basically they are generic Taiwanese cartridge bearing hubs, but Generators have 30 POE freehubs and are sealed better than most.
What I want is a low drag quiet low maintenance hub rear with instant engagement.
Maybe one with cartridge bearings, so I can swap them out easy instead of having to grease the bearings.
I want to use a full 10 speed cassette and quick release mounts.
Any ideas are welcome, I have another thread on this topic:
Good and Quiet Hubs - Mtbr Forums
When I set out to find a hub with similar properties (except I looked for a singlespeed hub), I ended up with True Precision Poacher hub. To my knowledge, more silent and quick engaging hub simply doesn't exist. Shimano used to make silent clutch hubs for police bikes, but these had no support for disk brakes and are hard to find.
Originally Posted by schristie11
True Precision also make hubs for full cassettes.
I ran mine for almost a year without any issues. Then went to a fixed gear trials hub, because I also run Hammerschmidt, which has its own coasting mechanism.
Downsides of TP hubs are weight, price and possibly vulnerability to water ingress. Because of this suspicion I only rode mine in fair weather and in sub freezing temperatures, so can't confirm this.
I'm going to reuse my TP hub in a burly DJ/street build. Like the quietness and the engagement too much to part with it. Sadly, TP SS cogs are proprietary and cost $35 each, plus international shipping, and I need different gearing (32-16) than the one I used with HS (24-20).
FLUSHING WITH OIL WILL NOT FIX A SLIPPING (FROM NEW) SHIMANO XT FREEHUB
Well today I tried my bike on a 12 mile loop, with the new (200 miles ish of use) Shimano XT freehub fitted. I first flushed it with oil, as this freehub, taken from a spare wheel with a split rim, also suffered from the occasional slip from the very first ride, but I had just lived with it.
Well all was well, until 3 miles from home, when pulling away from a traffic light stop, there was a now familiar loud cracking noise from the freehub, and the pedals slipped forwards 1 or 2 POEs.
Enough is enough! Shimano have cost me a lot of money in the last couple of years with this problem.
I will now have to buy 2 alternative new rear wheels / hubs for my 2 mountain bikes, that I cannot ride with any peace of mind with a problem like this.
I will never choose to buy a Shimano rear hub again, as they have completely lost my confidence in their quality of freehubs. I must have gone through at least 5 in 2 years. While I lived with them they ruined many a ride. I spent hundreds on possibly unnecessary other drivetrain parts before knowing for sure that it was multiple freehub failures all along. Shimano must have known, and should have recalled the lot. What a disgrace!
Well after 3 months on my XT M775 wheels, the rear hub is not doing well. The free hub feels very loose and its making nasty crunching noise when it spin. I'm taking it to the shop tomorrow to hopefully get a new freehub under warranty.
2013 Transition TransAM 29er
2012 Banshee Spitfire 26er
2005 Trek Bruiser urban single speed
Turns out, the free hub on my XT hub cracked in half. And, according to the bike shop, Shimano won't warranty it either (despite the fact its 3 months old). Looks like I'll pay for a new free hub and just sell these XT wheels.
I learned my lesson, I'm not buying a Shimano wheels/hubs again.
2013 Transition TransAM 29er
2012 Banshee Spitfire 26er
2005 Trek Bruiser urban single speed
It's a real shame. Whatever people used to think of Shimano's one time monopoly etc. at least you used to be able to count on reasonably reliable performance from their components. I just dont believe that's the case anymore. They have damaged their reputation in recent years, by producing short lived, throw away drivetrain components in particular. But these freehub body issues are totally unforgivable.
They are just plain defective from new.
MBR Magazine agrees, XT freehub is faulty !
In the October 2012 issue of MBR magazine, page 111, they are group testing all-mountain wheelsets.
The Shimano XT Trail WH-788 £360 pair.
"One thing that's been disconcerting is from the very first ride the Shimano freehub body has cracked and slipped loudly."
They give the Shimano wheels a score of 6 out of 10, the lowest on the test.
While it was nice to see a magazine print an honest statement, about what the buyer faces these days (and has for some considerable time) when they buy any Shimano rear hub, I wish they had gone a lot further.
A score of even 6 is still unjustifiable for a wheelset, where the rear hub is unrideable at best, and at worst is plain dangerous. Common sense dictates that a score of 0 is what is required here, much the same as you would expect to give to a handlebar which snapped off at the stem on a routine first test ride.
This is not something that is safe to just live with, if you really think about it. You cant even change the freehub body at your own cost to rectify the problem either, as any replacement Shimano freehub body will invariably suffer the same slipping problem, right out of the box. At least that has been my experience with my last 3 rear wheels, and as many new separate rear hubs, bought specifically for the freehub bodies.
The number of near misses, ruined rides, and hundreds of pounds spent on unnecessary drivetrain parts, thanks to Shimano exploiting me on this issue, makes my blood boil.
Originally Posted by VTSession
I wouldn't trust the LBS, I would send the hubs or just freehubs into shimano because shimano has never refused to warranty anything I have ever sent in. And yeah... many times the LBS's have said, no-way shimano won't fix that, and every time shimano has fixed it. For instant, last month I was riding a brand new moots pro that I just got done building up with all XTR drive components that I bought online at the beginning of this year, anyway, the "clamp pivot pin" on the my front derailleur snapped, so the front derailleur slid down into my crank, and that destroyed... my new XTR crank, my new XTR front derailleur, my new XTR chain, my new XTR rear wheel (the front derailleur and chain ripdded spokes right out my new stans notubes rim).So I had a total failure. Anyhow... I called shimano and they told me to take the bike to my LBS, and those guys were like, shimano won't cover any of this. Anyhow... to make a long story short... shimano replaced everything, they even had a new stans rear wheel built up for me, and they also gave me a new XTR wheel set for free. So like I said don't trust any LBS, send it directly into shimano because shimano will make it right.
775 freehub disassembly?
Well, another dead 775 freehub to report. About 9000 km on it, in wet & muddy conditions. Started to make funny noises and slip sometimes.
Has anyone had success in picking one apart? I failed to do it, and here's the story.
I ground a 21 mm hex socket into a 2-prong tool to fit the cup in Shimano freehubs. Used it on earlier freehubs (ones designed for steel axles), such as 756, all was fine every time. Tried it on a 775, had to create more torque than ever on a cup and finally a piece of cup cracked off from the stress. The cup itself did not move at all. Maybe there's threadlocker involved..
I was also unpleasantly surprised to find the back rubber seal on freehub to be attached permanently to the body (as if welded), as opposed to it being removable on earlier models. This of course complicates any attempts to flush the freehub with solvents or oil, as mentioned above.
To sum it up, Shimano seem to have went further in their policy of modular freehub replacement by taking steps to complicate freehub maintenance.
What are your experiences guys?
Please feel free to necropost here if you're from 2013 or later and still have experience with 775 freehubs.
Last edited by J. Random Psycho; 12-05-2012 at 03:00 PM.
I suggest heating the part in either boiling water or with a propane torch. If its some kind of loctite its plastic and almost all plastics gets a lot weaker at 100C. I have no experiences with shimano but I know what you're talking about. I have a new model ringle I tried to take apart but it refused. But i had no real interest in getting apart since its a **** taiwan hub anyway. But yeay they are hard to fully tear apart. Maybe i'll have a go at it in a few years. But I kinda doubt it.
Keyword here is slx
Yes, if I encounter another such freehub I'll use a heat gun on it, set to 125 Celsius. Perhaps it's indeed threadlocked.
I also forgot to mention, that after the cup cracked I attempted the screwdriver and hammer method on the remaining slot. Cup didn't move either, and the pressure was such that the screwdriver end was taking some visible damage. But this desperate method has been successfully used on some earlier freehubs (not by me).
I've got an update on this.
Originally Posted by J. Random Psycho
The rear hubs being now sold as FH-M756 at CRC come labeled FH-M756A, but they are no longer like glorified Alivio. Although the insides are still different from plain 756, they are not necessarily worse than these and I'd say certainly better than 756A design that I was talking about.
There are now rubber contact seals at both sides. Cones look better polished. Locknuts are still hexagonal Alivio style, not round flanged 756 style; this feature can be used to identify plain 756 at first glance from either side. Another large external difference is how the non-drive side looks. On plain 756 it's a big, tall rubber cone. On "bad" (old) 756A it's a large diameter, low height black dome. And on "good" (new) 756A it's black and flat with a small diameter, low cone in the middle.
My guess is that Shimano has recently merged 756 and 756A into this design.
I just found this thread through a google search.
I have a black 36h fh-m756 xt hub that I bought while working at a shop. probably came from hawley, but maybe qbp, maybe j&b; I don't remember.
I had problems with the freewheel catching and acting like a fixie, but not enough to cause derailleur damage, just enough to be a pain.
I figured I too had a damaged freehub, as a few days before the non-freewheeling started I had a "chain-slip" on a steep climb; I figured it was related to a worn derailleur and crappy housing, but now I think I know what happened.
I pulled out the axle and went to remove the freehub body fixing bolt with a 10mm allen wrench and the bolt just fell out. I worked the freehub off the body and immediately noticed that the teeth that keep the freehub from spinning on the hub were severely damaged, as though the body fixing bolt had loosened and the whole freehub had spun around with respect to the hub body, chewing off about a 1/4 of the teeth from the hub body (freehub body looks and spins fine when taken off the hub). the threads in the hub body where the fixing bolt goes in were a bit damaged (but really hard to see down in there) but I was able to get the bolt to thread on. There were only 8 of 9 bearings on the drive side, I suspect this allowed the freehub to wobble off of the teeth more easily.
I've never heard of a freehub body fixing bolt coming loose, let alone backing all of the way out. the hub is about 2 yrs old and I do ride a lot. The bearings came out quite clean except the missing one... about a year ago I had to retighten the drive side locknut, but I only loosened the axle, never removed it, so I know those bearings were absent from the factory.
Even if I warranty this succesfully, I'll still have to rebuild my wheel, and the rim really isn't in good enough shape to do that. the ideal course of events would have been for this wheel to become an eventual backup.
And I thought I was buying a reliable hub.
edit: freehub is cracked!
here are full-size pics: https://plus.google.com/photos/10034...LCm7Z3Z5d_UxAE
It doesn't happen often but yes, freehub bolts can self-unwind. Because of this I not only check drive side locknut tightness on Shimano hubs (including new ones), but also the freehub bolt.
And there's your answer. Cracked freehub body loosened the bolt slightly. Since it was no longer locked in place, it walked out. The hub itself was probably of adequate quality, the freehub probably had a small defect. Shimano should warranty that hub, and if you don't need the replacement hub for a wheel rebuild...ebay it?
Originally Posted by PretendGentleman
Klunkin' Ain't Easy.
Cracked FH body
Was a replacement from August. I'd had issues with the hub loosening (I think the axles are too long to get a proper adjustment) so a friend's shop had all the internals sent out and replaced them for me including a new FB. Last weekend I hear a nasty noise out back but the FH wasn't slipping. I had ANOTHER spare lying around from a friend who said I'd need it one day. Just pulled it off and guesss what? Cracked. Cassette was torqued to spec on install so who knows...
Obviously, you're not a golfer.
I have to wonder if these cracked freehub bodies are coming from Singapore or Malaysia. It seems Shimano's parts were much higher quality when manufactured in Japan, even if the designs of those Japanese parts were dated.
Originally Posted by sjordan72