jonny7

I am currently working on a vintage Trek 2300 (the neon yellow CF one). It's a 7 speed so it has a 126mm rear spacing. The freehub on the rear wheel (Mavic MA 40 with a Shimano 600 hub) was dead -- or at least I've got to find a way to repair it as it is currently spinning both ways -- so I've swapped it for another one that I had lying around. Both are 31mm.

While dissassembling the whole thing I've had trouble removing the axle as the cones and spacers were "seized". I've finally managed to remove them on both sides but I forgot (doh!) to measure the axle on each side. I've reassembled the wheel trying to get an equal number of threads on each side, but now when I put it back in the frame something is clearly wrong. The locknut on the DS barely gets out of the cassette body and so the cassette almost touches directly the chainstay. There clearly isn't enough space for the chain. When it goes on the smaller cog it simply gets stuck between the stay and the cog. It seems like an extra spacer could fix the issue (there already is a 1.3mm spacer on the DS) but I'd like to understand the cause of the issue.

I might have made a mistake somewhere as I'm not totally used to this kind of procedure. Any idea? Thanks a lot!

zandoval 

I am having trouble following ya... Can ya take a pic of the parts laid out in a line?

70sSanO

Generally on Shimano freehubs there’s about 6mm or 7mm between the edge of the freehub body and the outside of the locknut. I’ve done a lot of freehub mix-n-match in the last year.

On the drive side there is typically the cone, seal on a metal spacer 1.5mm, a washer and the locknut. Usually there are no other spacers. Washers range from 1mm to 2mm thick and locknut from 3.5mm to 5mm thick.

For a 7 speed you have to be missing something.

You can Google the hub and get an exploded view and parts list that sometimes gives widths of spacers, etc.

John

Edit added: The ball bearings are 1/4”.

More: If it is a freewheel, you definitely need spacers, between the seal and the locknut, on the drive side

alo

It sounds like a spacer is missing.

oberwl

To make it simple, you need about 5mm front locknut to end of axle on each side so that the wheel sits in the drop outs correctly. So set your Drive Side first since you will adjust front the NDS. You will know right away if the set up is correct because you will need the axle to be extending further than the freewheel body. The figure out the NDS spacers and nut.

KCT1986

If you changed the freehub body, there could be a slight difference in how deep into the freehub the bearing cup sits. If the cup is deeper within the body, even if the cone, spacer w/seal, washers, locknut are the same as before, the distance from the tend of the freehub body and locknut/frame will be reduced. The total over locknut distance (OLD) will also change slightly.

Does it seem that the OLD seem narrower? Does it seem that the dishing of the rim has changed?

If the frame allows, add a thin washer to the drive side under the locknut. If there isn't room for an additional washer, check to see if the locknut on each side is the same width. Many older Shimano hubs use a 3.5mm on the drive side and 4.5mm on the NDS. If this is the case, swap the positions to increase the DS.

70sSanO

When I first read you post, I didn't process the 31mm. I commend you on measuring the freehub body (cassette) length to make sure you were installing a 7 speed and not an 8-10 body.

Shimano made, in very general terms, two types of shoulders on their freehub bodies, one is a thin shoulder for shallow recessed hubs, and the other is a thick shoulder for deep recessed hubs. The splines are the same. This is just a general statement and there are a few differences and some nuances. Shimano's 600 FH-64xx uses a thin shoulder.

This should not impact the locknut to the freehub body edge, but it will just make the overall assembly wider and make it impossible to get back to 126mm since those extra mm's have to go somewhere.

Apart from that, I'm guessing that the DS cone from your 600 hub is not as thick as the one designed for the replacement freehub body. Wheels mfg (https://wheelsmfg.com/products/hub-parts/all-cones.html) gives a great illustration of this. If that is the case, then a spacer might solve everything.

The one other part of all of this is that in the late 80's/early 90's mfgs started to make their dropouts 128mm to accomodate either a 126mm or 130mm OLD. There is a good chance your Trek 2300 will accept a 128 or wider freehub. The one caveat is the axle for a 126mm OLD freehub is 137mm, with 5.5mm on each side beyond the locknut. As the OLD increases, that amount decreases. I have no problem with 5mm and some will say 4.5mm will work, but there will be a point at which you should get a wider axle, (141mm for a 130mm OLD), and grind/file it down so it won't interfere with the quick release.

John

CliffordK

If your wheel was previously setup properly, the rim should end up exactly centered between the lock nuts. You can buy a "Dishing Tool" to measure. If you have vertical rear dropouts, or rear dropouts with adjusters, you can get a good estimate by putting the wheel in one way, then flipping it around backwards and checking again.

Depending on the hub, at 126mm, you often have zero spacers, or simply a washer on the left side. Over years of upgrades, I've often moved all the spacers from the left to the right. One should redish, but one may be OK if the change is minimal.

jonny7

Sorry for the delay, I was out on the roads!

It is a cassette. And I have the setup you mention. Doesn't seem to me like anything is missing from the original parts (although I might be wrong) so I'm thinking it's either something I'm not doing right or a problem due to the swap. I should probably mention that the "new" freehub was taken on a set of wheels with 105SC hubs.

Tried to restart the process with ~6-7mm to balance both sides. They're pretty much equal. But as you can see on the pictures below the locknut doesn't get that much out of the freehub body.

Looking at both freehubs they look identical. I'm having trouble measuring the precise depth of the body but from what I can actually measure it looks pretty identical.

I could try playing with the spacers or adding another spacer but it could still be a beginners mistake that I'm not seeing here. I'm really not used to play with wheels. As this is a side project I'm in no hurry and just want to learn.

Here are a few shots:






You can clearly see on this last picture that the gap between the last cog and the dropout is wrong.

70sSanO

It looks like you have a ton of thread showing on the DS and NDS. I bet the OLD isn't 126mm wide.

Here is a 105 1056 7 speed I have...



I'm guessing whatever cone you are using is sitting too deep. The NDS on my hub looks the same as yours.

If everything is turning smooth, I'd add washers to the DS, center the axle and check the dish.

John

jonny7

Hi John. You're totally right. The OLD is 121mm. This really puzzles me as I don't think I've changed anything on the wheel except for the freehub. I'll try to swap back to see if the cup is indeed different. If not then I'll add spacers as you say.

70sSanO

Provided everything turns smoothly with the bearings running on bearing surface, the only other thing is the rubber dust seal.

Where you add washers/spacers should ensure the seal runs against the dust cap and not behind it.

Yours is an odd situation, but I think the cone width, including a seal groove vs. separate seal grooved spacer, might be the culprit.

John

Edit added: There is a possibility you flipped the DS and NDS cones. Thankfully, I’ve not experienced that one so I don’t know the impact.

KCT1986

See the attached of a pair of hubs of the estimated vintage of yours.

Note the differences in the spacer on each, both right and left side. Since both are 126 OLD, there must be some differences in the location of the bearing cups. Don't know if each was designed to place the freehub end in the exact same position relative to the dropout, but they should be close.

Since your unit is only at 121mm, adding spacers/swapping locknuts are your easiest option. Adding to each side, while keeping the right side as close as possible to the dropout will keep the dish to a minimum, giving you better dishing and hopefully keeping the rim centered.

jonny7

This seems to be the final answer yes! I ended up swapping the whole axle with the spacers and locknuts and it now seems to work just right. So the freehubs, in spite of lookin exactly the same, must have slightly different cups.

Bill Kapaun

Note the different part numbers for the DS cone assembly and FH body.
Keep the DS parts with the specific FH body they came with. That keeps everything in the correct relationship with the DS drop out.

70sSanO

I’m a previous post I suggested looking at cones from Wheels Mfg to get an idea how they vary on thickness; with pics. While some DS cones are for 126mm and others 130mm, they show dimensions that vary between 9mm to 16mm depending on the application.

In many cases the OD and ID are virtually the same. And the length of the actual bearing section are also very close.

This is probably your solution. Since 7 speed freehub bodies span a lot of years, and the quality drops as times goes one, you’ll need to find a cone that fits the replacement freehub body. Or get a spacer that will get you there. If the cone works, you just need to get the dust seal in the right spot.

John

Edit added: Some cones include the dust seal, but usually they are wider. However with a mix-n-match it is possible that the seal won’t line up with the dust cover and you can’t make it work.

Oh yeah… Shimano changed the diameters of the dust cover and seal over the years just to throw another curve.