sjpitts 

First, I guess I should note that it is controversial that DA 7400 cranks use ISO taper at all, as I have seen many people say they are JIS. But I am pretty sure they are ISO based on reliable sources.

What I don't know is if there is any difference between the 7400, 7401, 7402, and 7410 cranks. Are they all the same? All ISO?

I am just wanting to make sure that I can swap cranks with someone and not have an issue.

Thanks

Old Fat Guy

7410 is a different length that the 740x series.

added: Sutherland's lists Shimano 7400 series as having a Campy taper.

sjpitts 

Thanks.

Now I was assuming that ISO==campy taper. Is that not accurate?

I guess it does not matter to me, as I am just looking to swap 7400 for 7403, but I guess I should be clear about this.

Old Fat Guy

Yes, ISO=Campy. I think 7400 would swap w/7403, though I've never done it.

kh777

Great post. I was wondering about the taper issue too. I have a DA 7400 drive-side crank and a FC7400 BB. Velobase says the BB is campy square taper, but yet their listing for the crank FC-7400 says JIS...

In my case, somebody in their infinite wisdom installed a Shimano 600 (6400) left crankarm, and I was trying to figure out the deal with the taper...

RFC

I have switch 7400 and 600 cranks back and forth without any problem. I never knew there was an issue.

Old Fat Guy

It's not with 7400 and 600/6400. They both use a 112-113mm BB. 7410 uses a 103mm BB.

sjpitts 

Now wait a second, I thought the 6400 would have been JIS? I know they close and can be swapped to some extent, but are they not different?

chi-james

I'm pretty certain that my DAs are 7402, based upon the profile of the crank arms and that they are part of an 8-speed group. The confusing thing is that velobase lists the 740X cranks as being JIS, while listing the BB as campy/iso. The only difference I can tell between the 7400 and 7402 is that the 02 is 5 grams lighter. Besides this there shouldn't be an issue switching cranks from a 6-speed with cranks on an 8-speed right?

Old Fat Guy

See here:
https://www.sheldonbrown.com/bbtaper.html

sjpitts 

That does say that Campy is generally ISO, and Shimano is generally JIS, and it does address some of the issues that exist in using ISO cranks on JIS spindles and vice versa.

But it doesn't specify which Shimano are not JIS.

It was my understanding that for Shimano, the DA 740X crank and BB were ISO, the rest were JIS (or now octalink/hollowtech). It had something to do with Shimano thinking their top end racing cranks had to be the same as Campy for marketing reasons.

But I thought that all the 600 and below (6400, 6200, and such) it would all be JIS.

So you can swap the 600 and 7400, as they are close enough to work in most cases, but they are not technically the same. Right?

Jared

PS--I am not sure about 7200. What does sutherlands say about that?

Old Fat Guy

7200 is a different beast altogether. To the best of my knowledge a 600 would be JIS, not sure about later 64xx.

gaucho777 

I'm often surprised at the lack of information available from parts manufacturers. For what it's worth, I just got off the phone with Shimano customer service. The person I spoke to could not confirm taper on the 7400 cranks/spindle. Their computer system does not contain taper info for the 7400 group, and he did not have access to a spec book going back that far. Their website contains specs for some of their products, but only goes back as far as the 7700 series. I guess it goes to show how the internet has changed expectations in terms of availability of information.

In any event, I will take a side by side comparison photo of a 7400 spindle and a pre-'94 Campagnolo spindle when I get home this evening (though any differences may not be discernible with the eye).

3alarmer 

Hi:
You also might want to look here:

https://www.bikeforums.net/showthread...=#post11792463

where I got some pretty educational responses.

Certainly the woman at Phil Wood was right on in
recommending their JIS unit for my 1978 Campagnolo
crankset, even though the original spindle (see photos)
seems to be ISO.

miamijim

Shimano literature states that 7400 and 6400 are interchangeable.

sjpitts 

I just double checked Sutherlands 6th, under "Non-JIS Bottom Bracket Spindle Interchangeability" it lists "Campy" as the closest taper size for 7400 and 7600.

7200 and 7300 are listed as JIS.

I haven't found 6400 in it.

Interestingly, some other "high end" JP cranks are listed as Campy-- Superbe Sprint, Sugino 75 mighty, Specialized.

And also, it lists some as Campy, and some as ISO, so maybe Campy does not precisely equal ISO

Ex Pres 

You are correct for pre'94 tapers.

miamijim

But pre '94 is as close to ISO as your going to find without it actually being labled ISO.

kh777

Anyone know what the "KB" code on Dura Ace 7400 BB and Crankarm means? It appears the square opening on the back of the crankarm is bigger across the flats compared to another ISO crankset (Campy Veloce, Sugino 75) The DA opening is ~13.9mm vs 13.5/13.7 on the Campy/Sugino 75. It almost seems like *this* KB-coded versione is JIS?? AFAIK, the difference with JIS and ISO is the end dimension (across flats) - with the ISO being ~0.2 mm smaller than JIS (both having a 2° taper per side), or something like that.

I have a Dura Ace crank marked KB, and a BB-7400 113mm spindle, marked 70-W KB (from an italian BB set). Using a digital caliper, the spindle nose (not exactly at the tip of the nose, but right after the bevel) measures 12.7x mm, and 13.7x mm at the end of the taper (the tapered flats section is about 15mm long). I don't have any pre-'94 campy spindles laying around, but 2000s Record and Chorus (102mm) spindle nose measures ~12.6x/13.6x (their tapered flat section is 17mm long; I measured along a 15mm section right after the bevel). I also don't have any "known" JIS spindles onhand to measure - except a 135mm Phil Wood BB that I'm guessing is a JIS (since they don't make one in ISO that big).

In terms of insertion of the spindle into a FC-7400 right spider marked KB (hand pressure; not torqued down to spec), the BB-7400 spindle leaves a ~5.4-5.5mm space between the spindle nose and the spindle bolt seat. Versus ~2.9mm for the Chorus. In all instances, the back of the spider is around 2mm of reaching the end of the taper. The reason the Campy didn't bottom out is because it has a longer taper (~17mm vs ~15mm on the 7400). While it's hard to measure exactly, comparatively, the Chorus might be another 0.5mm closer to reaching the end of taper.

When the 7400 spindle is inserted into a FC-6400 arm (same protocol), it leaves ~7.1mm space. A Chorus ISO spindle seems to fit better (goes in further) - leaving 4.2mm, vs the 7400 spindle at 7.1mm.
I also inserted the 7400 spindle into a Veloce crankarm. Since it doesn't go in very far (leaving a ~9mm space), I'm inclined to think this 7400 could be JIS.

Not sure what to think, aside from the 7400 crank and BB seem to mate better with each other, and possibly the 6400 crankarms are ISO (even if Campy and ISO are not precisely equal).

EDIT - I think I found out the two-letter code (KB) is the date code (Feb 1987)

gaucho777 

Thanks for all the date kh777. (What's with all the 7s? - )

I don't know if these photos will help. Not much to take from these photos that hasn't already stated above or previously posted, but since some people are more visually inclined and since I did promise to post some photos:

Campy (Super Record?) spindle and Dura-Ace 7400 spindle




Campagnolo spindle with Super Record arm (left) and Dura-Ace 7400 arm (right)


Dura-Ace 7400 spindle with Super Record arm (left) and Dura-Ace 7400 arm (right)


The first two photos are not much help (at least to my eyes). The last two photos show that both crank arms sit deeper onto the Campagnolo spindle, with the Campagnolo crank arm sitting deeper onto both spindles than the DA arm.

mazdaspeed

I have 7401 cranks on a UN54 bottom bracket FWIW.

MetinUz

What size spindle?

mazdaspeed

115mm iirc

stronglight

Looks like both 7400 and 7402 cranks should fit perfectly on a 7400 bottom bracket axle.

Here is a Shimano parts and specifications sheet for the Dura-Ace FC-7400, FC-7402, and BB-7400 which I just uploaded. Parts descriptions at the bottom of the page also show possible interchangeability of individual parts with other Shimano models of the period. This was printed in 1989.

https://farm5.static.flickr.com/4128/...bdfc60e9_o.jpg

jeffpepperdine

Sorry to bump a really old post, but I am now fighting this battle. I have a 7400 crank that I intend to install in an italian frame with 70mm bb. I thought I was just going to be able to order the standard shimano UN54/55 in 70x113. According to sheldon, "If you install an ISO crank on a J.I.S. spindle, it will sit about 4.5mm farther out than it would on an ISO spindle of the same length." This seems to contradict mazdaspeeds note above, as it would suggest that using a 115 JIS spindle would put the crank 6.5mm further outboard than the original 113 ISO (or ISO like) spindle.

I'm having a little trouble wrapping my head around this, but let me give it a shot. If I was to order a JIS spindle, should it not be 4.5mm less on each side, so I should be looking for a ~103-105 JIS spindle?

Has anyone here successfully used a non Dura Ace bottom bracket for DA 740x cranks? and if so, which ones at what spindle lengths?