jimmuller 

Um, I think you mean miamijim. That's not me.
- jimmuller. (One of the other jims, and who knows little of 7400 freehubs other than if something is free it might not be worth it)

kc0yef 

excellent mansplain

Dave Mayer

Uniglide.

Best upgrade for the 7-speed 7400 hubs is to install a 7403 8-speed Hyperglide freehub body. This way you don't need the impossible to find #1 threaded cog used on the 7400 and 7402 hubs. And you can use modern Shimano cassettes, except ones that start with the useless 11-tooth cog. Good luck finding these - AFAIK the last one of these on the planet is sitting in my spare freehub bin.

You would need a standard Shimano rear axle cut to roughly 140mm. The axles used on the 6/7 speed versions are just too short.

You will also want a way of removing the old freehub. There is an impossible to find unique tool for this, but I personally would remove the outer shell of the old freehub, including the gazillion little ball bearings, and use a big metal bench vice to unwind the remaining core.

Make sure you install the appropriate washer(s) between the freehub body and the hub shell. I forgot this on one of these hubs, and the damn thing tightened up during a ride to the point where the freehub no longer rotated. Then I was riding a fixed gear for the next 20 miles.

Recommendation: get a modern 8/9/10 speed Shimano cassette rear wheel and use your old 7400 hub shell as a candle holder.

SJX426 

my bad! Senior Moment!

dddd

Normally, an 11t cog causes problems with any freehub made before 1995 or so, since the splines are a little too long to allow the 11t cog to fully compress the cog stack.

We've had to modify the spline length (using bench grinder) on many occasions by taking off a millimeter or so to allow an 11t cassette to keep the cogs from rattling.

As for using any other freehub body on any pre-1997 Dura-ace hubshell, the method of attachment is completely different and I would not expect to be able to do this.

Even with the many non-Dura-Ace freehubs Shimano made, and which all used the same hollow bolt, interchanging them very often is stymied by differences in how far the spline is located inboard of where the largest cog sits and how far from the spoke flange.
I once tried to put a 7700 titanium freehub body on an 8s Ultegra hubshell, and the cogs ended up sitting too far away from the spokes. It was way off, would have required re-dishing and left-side axle spacing and so couldn't be used to build a strong wheel.

Ex Pres 

To add to the DM post above - You'll never find a new 7403 freehub body [I tried], so you'll need a donor hub. You'll get the longer axle & skewer that way, too. The tool, while hard to find, is not impossible. My LBS has one - yours might.
If you don't already own the 7400 STI, then use 8 of 9 on your current hub to go w/7700 shifters, or 9 of 10 with 7800. EDIT: actually with the 7400 RD, you'd need to use 8 of 9 with a 10s shifter.

chapel

So is it weird that my 11t cog fits my 7403?

dddd

That is quite unexpected unless someone added a 1mm cassette washer/spacer before installing the cassette, or unless the splines were shortened by a like amount.

11t cogs don't have enough strength where the splines are cut into the cog, since the OD is so small at the base of each roller relief.

Thus, 11t cogs have a solid ring built onto the OD of the inboard end of the splined integral cog spacer, and there is a ring of metal inside of the cog itself where no splines are cut, which limits how far the cog can go onto the splines while being secured with the lockring. These features keep 11t cogs from splitting open under the forces that the chain and splines apply.

Perhaps these 7403 freehub bodies were designed with 11t cog use in mind, since the 11t cogs were offered with the previous versions, but I just can't recall any 8s road cassettes offered with 11t cogs back then.
I also don't specifically recall any 11t lockrings from that vintage that would be needed to secure an 11t cog.

chapel

I'll snap a photo. I rarely use the 11T cog anyway...

chapel

Here we go. It's a SRAM piece. Popped on with no issues at all.

dddd

Did you install the 11-28t cassette yourself? Do you recall if the splines had been visibly shortened? A lot of these bodies have been modified!


These 11t freehub bodies were usually tagged as Hyperglide-C-compatible, but again perhaps the 7403 Dura-Ace gruppo had some 11t compatibility at this time, before the "C" designation appeared in the mid-1990's.

Dave Mayer

They don't.

Possibly the 7403 freehub was ground down near the end to take the small cog. The freehub shell is pretty thin, and I would be very careful in doing this mod. And then later checking for cracking of the shell. My pal at work has cracked 3 Shimano (unmodified) freehub shells in the last 2 years, but he a very fit 250-pounder.

My theory is that the shop torqued the cassette lockring down at 500 foot-pounds. Anything fits if you use a big enough wrench. I'll bet that there are a lot of younger shop guys that have never worked on the older generation of Shimano freehubs, before the Hyperglide-C thing.

In any case, I would not be contesting a bunch sprint in this 11 tooth cog.

Finally, unless someone is running some kind of franken-mico-drive type of drivetrain, no one needs an 11 tooth cog in the rear. For some reason the manufacterers make them, presumably because of misguided market demand (shop guy to customer: "you can go 60mph in this cog!"). But I don't buy these cassettes.

chapel

I didn't notice. I did install it myself. Went on no problem. what do you guys normally see when you try to put an 11t on? side to side movement?
This is the cassette:
PG 850 Cassette | SRAM

The wheels were standard equipment on some kind of Moots bike.

Dave Mayer

So I pulled two freehubs out of my spares bin - the Dura-Ace 7403, and a Dura-Ace 7700. The latter is fully compatible with 11-tooth cogs.

I took an 11-tooth cog and placed it on each. On the 7403, there was about 2mm of engagement between the end of the freehub and the cog. On the 7700 there was 4mm.

So on the 7403 - I would not apply any serious torque on the 11 tooth cog.

Another problem: since the 11 tooth is sitting 2mm too far outboard, assume that it is not possible to tighten up the lockring enough to take the play out of the cassette. The rest of the cogs and spacers may be floppy.

miamijim

The 11's were more designed for hybrids and mtb's with 46 big and 36 middle rings.

700X38 Hybrid 53X12= ~121 gear inches 46 X 11 = ~115 gear inches

Without derailing this into a 'gear inch' thread there are other reasons as to way 11's are really bad cogs.

But, as stated, 7400 series DA hubs are only designed to go down to 12t cogs.

miamijim

P*%#@B*^@#T pic hostage work around pitty bump....

ThermionicScott 

Thanks for updating the thread, @miamijim.