I’m having problems with my rear DT Swiss hub (240 ratchet).

The bearings have been replaced twice by the LBS over the past few months. They keep going tight for some unknown reason. The original bearings lasted 4+ years.

All the parts are there, including the internal spacer. The replacements bearings aren’t originals but okay quality. The mechanic is DT Swiss trained, but doesn’t know why this is happening.

Any ideas what could be causing this?

Sounds like the Non-DT bearings are out of spec and too wide, which is causing binding.

Replace them with some proper DT ones.

Thanks Hatter.

Would that explain the gradual deterioration (they work fine at first)? I suppose if they are the wrong width they might be under side load resulting in premature wear.

Doubt the bearing size is an issue, they’re 6902s, nothing special, maybe they’ve been installed slightly off centre, but again, that’s not what i’d go for, did they lose the shim maybe from the first changeover?

Failing that, not sure what could be an issue, the bearings go in to their fitting well on 240s, they have an axle through them that’ll align them no matter what, can’t see a failure mode like this without something else happening?

I’ve had it where installing a new free spinning cheap bearing into the hub shell makes it turn into a notchy mess. Pull it out and it’s fine again. Out of tolerance outer race make sense like Hatter says.
Also, installing the bearing by the inner race would see the bearing die really quickly..

IIRC there’s no ‘step’ to stop the outer race of the outer bearing when you press it in. If you press the outer bearing in with a drift that presses on both races, but if you’re pulling against the freehub body at the other end without also pulling on the *inner* race of the *inner* bearing, and you aren’t careful, you can load the bearings against the spacer and kill them fast.

That said, it’s a while since I’ve done it- anyone confirm?

I’m pretty sure there is a step as you press one side first, then inset the axle and press the otherwise. I’m pretty sure you cant drift a bearing all the way through

I put some cheap bearings in a 350 to see how long they would last, took the out a week later, notchy and horrible.
To be fair the two decent ones cost more than the whole set f&r.
As a test it was pretty conclusive.

Definitely a step that you seat the bearing against. Suspect they are not fully home. I’ve seen the similar symptoms when axle support bearings close to, but not fully seated.

question for @rustychain,
are they 240s or 240 EXP as ive foud this https://www.dtswiss.com/en/ratchet-exp-maintenance-notice
after having issues with my hub free wheeling in both directions

Thanks for all the responses.

They are actually Spline One hubs (EX1501 wheel set) which a Google suggests have 240 internals (not EXP).

https://www.mtbr.com/threads/review-dt-swiss-spline-one-wheelset.1169234/

It looks like the first thing to do is strip them down to make sure no parts are missing and then try some decent bearings and make sure they’re properly seated.

The only thing that can possibly be missing is the shim ring that sits behind the ring nut. See Page 11 of this document {apols for the long URL).

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.upgradebikes.co.uk/files/technical/reynolds/DT-Swiss-240s-Technical-Manual.pdf&ved=2ahUKEwj4zf7B5qbwAhUOTcAKHWl9BlwQFjARegQIGBAC&usg=AOvVaw2ZYMmyokwkOCTE8G-idKUl&cshid=1619814317283

OK so, what’s tight? Is it the entire hub on the axle? (ie, as the wheel revolves). Or is it the freehub on the hub? (which you generally discover when it starts pushing the chain instead of freewheeling?). The second’s got one really specific cause I know of, with DT. The hubs are basically just a big stack of spacers when you look at it and so any resistance can only come from the bearings themselves, or an interaction of that stack of spacers. (which 9/10 times, means the little washer on top of the centre bearing is damaged or mislocated, or it’s something to do with the spacer inside the star ratchet)

Really cheap bearings are never a good idea but you don’t need anything fancy or “genuine”, I don’t know what brand DT use but FAG, Koyo, SKF etc are basically interchangable and excellent.

If I remove the freehub, the wheel still only you rotates a few times and the spindle feels notchy. To me that says it’s something to do with the main wheel bearings/installation. Would you agree?

@BearBack – in the freehub rather than the hub body?

I’ll try some reasonable bearings this time around to see if that helps.

I’m referring to hub body. But the freehub also has a positive bearing stop at the inboard side.

Spine 1 hubs use smaller bearings than 240 hubs. 6802 vs 6902
same bearings as freehub body in the spline hubs.

That’s sort of what I was getting at- don’t both the freehub bearings press in from the same side? As they’re the same size, the second one can’t have a stop or the first one wouldn’t fit in.

Rustychain
Free Member

If I remove the freehub, the wheel still only you rotates a few times and the spindle feels notchy. To me that says it’s something to do with the main wheel bearings/installation. Would you agree?

Yup, can only be really. I think they’ve fitted really shit bearings tbf, it’s the simplest answer and if I’m understanding your symptoms, is a perfect fit.

When it’s fully stacked/assembled there’s various things that I can think of that could present similarly but with the freehub off the whole thing’s basically relaxed (part of the “stack of spacers” is missing) so at that point it’s literally just a barrel rolling on the axle on two bearings, there’s no other interaction that could cause notchiness.

I had a binding front 240 hub from new. Took the bearings out and they were smooth.Put in decent replacements and binding again.
I came to the conclusion the hub machining was out and squeezing the bearings when they were pressed in.
Maybe the posters bearings had been binding from new and never realised it.

@joeegg – Out of interest, what did you do to resolve the problem in the end?

My hub has been fine for four years ie with the original bearings. That suggests that the hub machining is probably okay?

The replacement bearings were fine at first (ie the wheel span freely) but stiffened up after several rides.

I’ve ordered some decent replacement bearings and will report back.

Thanks once again for the thoughts and ideas.

I just slowly filed the hub housing until I could press a bearing in without it feeling rough.
It’s imprecise but so far seems ok. The bearings are thin walled so I suppose they are more prone to deformation.
I regularly take end caps/freehubs off to check for roughness but maybe a lot of people run them until there is play or noise.

I had a binding front 240 hub from new.

Hub only or in an aftermarket built wheel?
Massively uneven spoke tension could distort the hub shell to the point it ovalizes, but that’d be a really sh*tty build.

The hub was on a pair of expensive DT road wheels.

Was it notchy when under compression on the bike just when you turned the hub in your hand?

DT hub bearings are designed to work under compression and can often feel rough when out of the bike when new, put them in a frame or fork and the notchiness tends to vanish after a few rides as the seals wear in.

The hub was on a pair of expensive DT road wheels.

Golly, that takes some cojones to break out the file rather than return/explore warranty.

I’ve fitted some decent 6902s and the rear wheel now keeps on spinning. 😊

It appears that the cheap bearings fitted by the LBS were to blame. 🤞

Thanks again for all the responses.

@rusty I need to do my 350 rear hub bearings with fresh 6902’s, the official vid shows lots of unique tool required, did you have all of these or are some not actually needed?

You’ll need the ring nut extractor and the proper ratchet grease, the rest are basically to ensure you can get the bearings in out with minimal chance of damaging anything.

Do you ‘need them? No, a standard set of bearing drifts and presses will work but not using them will require more care to avoid mistakes.

I have the full tool kit and it does make it all pleasantly fast and painless.

oikeith
Full Member

@rusty I need to do my 350 rear hub bearings with fresh 6902’s, the official vid shows lots of unique tool required, did you have all of these or are some not actually needed?

There’s one unique tool you need to get to the centremost bearing, the one held in with the ratchet ring. Everything else can be done with sockets like most hubs, it’s just easier with the proper tools. And you can refit the seal using the freehub.

but not the official DT tool- it’s ironically a bit shit, it has a square end so you can’t easily put a socket on it to use a breaker bar or whatever, best you can do is clamp it in a vice. Bad design. Mine is an ebay special that has a 1/2 inch adaptor, way better but I now can’t find it online. There’s lots of 3rd party ones that have a hex end so you can stick a socket over, that’s the second best way. The ratchet takes some force so having a big breaker or an impact gun makes things simple.

Oh yeah lastly there’s a really good chance that your centre bearing doesn’t need changed at all and can just be left alone. 350s have cheaper bearings but they’re still decent and that bearing’s well protected. They’re not hubs that changing all the bearings at once is really the best way, if you’re diy’ing it, just do what’s needed.

@oikeith the only specialist tool I used was a copy ring nut tool from eBay and the correct DT grease as others have mentioned.