masi61

I have a couple of NOS Dura Ace 7400 7-speed freewheel (not freehub) bodies along with some random 7s freewheel cogs but I don’t think I have any spacers. I was wondering if anyone familiar with the Dura Ace 7400 7-speed freewheel would know the thickness (width) of the spacers for this freewheel. Also, how many spacers are needed? Thanks for any help and bonus points awarded if you could post a link to an exploded diagram (PDF file) of the 7400 freewheel (7-speed) from Shimano tech documents.

SurferRosa

Your "anyone" is @pastorbobnlnh.

Dave Mayer

I just measured a 7400 7-speed freewheel cog: 1.9mm and the cog to cog is exactly 5.0mm. You do the math.

This freewheel has 2 unique cogs: the #1 and #2 threaded. The rest of the cogs can be replaced with Hyperglide cogs from either an H22 or HG37 freewheel, with a few minutes of grinding. IIRC, the HG37 freewheel spacers are width compatible with the Dura-Ace body.

BTW: because the HG cogs are Hyperglide, they shift worlds better than the older clunky original Uniglide cogs.

KCT1986

The spacers for 7s are 3.1mm thick. Comes in 3 different configurations.
Spacer for large splined part of freewheel body.
Spacer for smaller splined part of freewheel body. Available in larger OD or smaller OD, depending on tooth count of sprockets used.

Number of spacers needed depends on the sprocket used. Some sprockets have built-in spacers already. Sprockets are of 4 different types, large or small splined, threaded and outer threaded.

Search the Shimano Tech docs (MF-7400) for details and the EV doc/parts list for sprockets available for each position, and which sprockets are the built-in spacers type.

Here is an old diagram of the configuration.

pastorbobnlnh 

KCT1986 has covered it all. Well done. I have nothing more to add.

KCT1986

Forgot to mention, if the very middle sprocket is not the built-in spacer type, the spacer behind it (hub side) should be the larger OD type. The smaller OD type in this position may not properly secure/support the larger splined sprockets behind it.

mpetry912 

I have a very few spacers and cogs. ebay is a good source for open stock parts too.

the 17T small spline cog is hard to find. these are the best freewheels ever.

you might also have luck with down-spec spacers (not DA). remember that the spacers are different for 6 vs 7 speed builds

shimano diagrams in PDF format are here https://si.shimano.com/en/manual/sea..._model=mf-7400

/markp

dddd

Perhaps my favorite freewheel ever, identically dimensioned to the rarer Sante MF-5000 freewheel.

One particular "gray" spacer pictured above has a stepped/tapered OD, so it extends past the OD of the larger spline behind the middle sprocket.
Otherwise, the 3rd-largest cog would be unsupported, thus able to slide over next to the middle cog, leaving the three largest cogs loose and flopping around.

I've built up many a 7s Dura-Ace freewheel, several having HG cogs in the five largest positions, arriving at 12-28t and 12-32t.
A mail-order firm briefly cataloged and sold these custom-built HG 7s freewheels in the 1990's for around $189.

I've also used the D-A 7s freewheel to make a couple of "Uniglide Ultra-6" freewheels, by removing the externally-threaded smallest cog and fitting an O-ring (or a 600 freewheel's threaded ring) to close the resulting gap exposing the bearings after the small cog was removed (the 600 freewheel's threaded sealing ring got sanded thinner, then pounded in flush).