Other hub bearing install question for the technicians

[RebornRider]

I installed new bearings in my DT Swiss rear hub using a threaded bearing press. I stopped squeezing as soon as I met firm resistance. The axle turned smoothly, but with a lot of drag. I used a soft face hammer to pound on the end of the axle as if I was removing the bearing, but with less force. After a couple of hammer whacks, the axle turned much more freely. There was no lateral play in the axle that I could feel.

Assumptions and the question: I think the bearing outer races are supposed to be pushed against the shoulders in the hub. I assumed that was the source of the firm resistance. It seems as though the axle shoulders push against the inner races, which I assume is to apply preload to the bearings. I think there is a tolerance problem with my parts - either the hub shoulders are too close together or the axle shoulders are too far apart. I think this results in too much preload.

So, have any of you had this issue, and what did you do about it?

 

[Gary]

It seems as though the axle shoulders push against the inner races, which I assume is to apply preload to the bearings.

Not really.
the inner bearing race of each main hub shell bearing should sit against the step on the axle but the other side of each inner race sit against a spacer on the freehub side and an end cap on the disc side. Whith the the whole lot re-assembled tolerance should be such that the bearings spin feely rather than preloaded heavily.
Have you done the freehub bearings too and do you have the correct DT swiss tools for your hub? They're pricy but you do need them.

 

[DtEW]

I installed new bearings in my DT Swiss rear hub using a threaded bearing press. I stopped squeezing as soon as I met firm resistance. The axle turned smoothly, but with a lot of drag. I used a soft face hammer to pound on the end of the axle as if I was removing the bearing, but with less force. After a couple of hammer whacks, the axle turned much more freely. There was no lateral play in the axle that I could feel.

Assumptions and the question: I think the bearing outer races are supposed to be pushed against the shoulders in the hub. I assumed that was the source of the firm resistance. It seems as though the axle shoulders push against the inner races, which I assume is to apply preload to the bearings. I think there is a tolerance problem with my parts - either the hub shoulders are too close together or the axle shoulders are too far apart. I think this results in too much preload.

So, have any of you had this issue, and what did you do about it?

View attachment 52787

I haven’t had this issue, but I’ve had the opposite issue in other cartridge-bearing hubs in which the axle didn’t sufficiently apply enough preload to old-but-otherwise-fine bearings, which resulted in play that can’t be removed from the system without specific (and unavailable) shims.

Therefore, I would just find the middle between the too-preloaded initial pressing, and the free-spinning post-hammer-tap state. Because your new cartridge bearings should quickly loosen-up as they polish the surface (but really more of a narrow track on the race) onto-which the balls are now preloaded.

 

[RebornRider]

I see now that the hub and axle shoulders do not force a preload. Both the axle and hub shoulders are in the inner bearing faces, with the axle pushing on the inner race and the hub pushing on the outer race. I think my issue is caused by the distance between the hub shoulders being a bit less than the distance between the axle shoulders.

With the bearings pressed in to the hub shoulders, the axle shoulders are trying to push outward on the bearings, but the bearing interference fit prevents the bearings from moving away from each other. This resulted in the binding I observed. When I used the soft-face hammer on the axle, I moved one of the bearings ever so slightly away from its hub shoulder, which removed the excessive preload.

I replaced the freehub bearings and had no problem with them. I didn't drop any pawls - woohoo!

I use a press marketed as "TENYBIKE" (which is surprisingly well made) along with some homemade fixturing to accommodate the axle sticking out.

 

[Bigtuna00]

You could always send the hub to Hambini...

 

[cozzy]

What model of dt hub?

 

[RebornRider]

According to the '19 carbon expert specs, it's a 360.

 

[Mikerb]

Manuals | DT Swiss

Looking at a couple of the manuals ( above) could it be that you have used bearings sealed on both sides? A couple of the manuals seem to suggest the bearings are sealed on the outside only. An inner seal on both bearings may be enough to reduce the clearance you experienced?

 

[RebornRider]

The OEM bearings I pulled out have seals on both sides. The seals have "DT Swiss" molded into the plastic.

 

[Mikerb]

The manuals do show the use of specific tools/drifts to remove/replace the DT Swiss hub bearings. From what you have described I assume they ensure the bearings are spaced in accordance with the width of the axle shoulder. So what you have done appears in effect to have achieved the same ends.
ps cartridge bearings do not require preloading. They only require that any lateral play is removed.

 

[RebornRider]

The manual also suggests that you can drive the bearings too close together using the DT Swiss tools. At this point I think my assembly is okay. I can't feel any side-to-side play and the hub spins smoothly.

 

[Mikerb]

yep I read that as well in the 350 manual so you have done it right. Its a very different arrangement to the Formula hub in the standard Roval Wheels. Both bearings sit hard against their hub surfaces and the axle interface to them is adjusted by cone nuts on the non drive side. The same criterea applies there also however in that the cone nut adjustment is only just sufficient to remove any sideplay and if you tighten it beyond that you start to bind the axle. Well done for doing the job without the DT Swiss tools....just like most bearing removal and replacement it just takes basic, even home made tools and some common sense!