Classic & Vintage - Do all DA 7400 cranks use the same ISO tapered BB spindle?

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

7410 is a different length that the 740x series.

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

7410 is a different length that the 740x series.

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

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.

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.

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

Great post. I was wondering about the taper issue too. I have a DA 7400 drive-side crank and a FC7400 BB. Velobase (http://velobase.com/velobase.com/ViewComponent.aspx?ID=F3075BAA-C7B4-4B22-B6DE-821D7D7B7B97&Enum=119&AbsPos=8)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...

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

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

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

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

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?

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?

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?
See here:
http://www.sheldonbrown.com/bbtaper.html

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

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?

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

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).

Hi:
You also might want to look here:

http://www.bikeforums.net/showthread.php?695462-1978-Campagnolo-New-Record-Crank-Spindle-Replacement&p=11792463&highlight=#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.

Shimano literature states that 7400 and 6400 are interchangeable.

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

(snip)

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

You are correct for pre'94 tapers.

so maybe Campy does not precisely equal ISO


You are correct for pre'94 tapers.

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

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)

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
http://i850.photobucket.com/albums/ab69/gaucho510/IMG_1618.jpg

http://i850.photobucket.com/albums/ab69/gaucho510/IMG_1619.jpg

Campagnolo spindle with Super Record arm (left) and Dura-Ace 7400 arm (right)
http://i850.photobucket.com/albums/ab69/gaucho510/IMG_0970.jpg

Dura-Ace 7400 spindle with Super Record arm (left) and Dura-Ace 7400 arm (right)
http://i850.photobucket.com/albums/ab69/gaucho510/IMG_0971.jpg

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.

I have 7401 cranks on a UN54 bottom bracket FWIW.

I have 7401 cranks on a UN54 bottom bracket FWIW.

What size spindle?

What size spindle?

115mm iirc

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

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.

http://farm5.static.flickr.com/4128/5191317529_43bdfc60e9_o.jpg

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?

JeffP, it's not hard to find the correct 113mm Italian 740x BB and/or spindles. I have 2 bikes equipped with them, and didn't pay up for either.

Edit: I looked at ebay - the current listings' offering prices are ridiculous.

I think you may find success with a 1980s campagnolo bottom bracket also. 111mm might be a little short (later chours/athena), but a 115mm might be a little too long, but pretty close. I would try a record double BB, post CPSC and see how it goes.. I think the italians were 114.5mm. If I read all the evidence closely I conclude that your cranks are ISO so I would stick to ISO spindles.

I think you may find success with a 1980s campagnolo bottom bracket also. 111mm might be a little short (later chours/athena), but a 115mm might be a little too long, but pretty close. I would try a record double BB, post CPSC and see how it goes.. I think the italians were 114.5mm. If I read all the evidence closely I conclude that your cranks are ISO so I would stick to ISO spindles.

The more I read about this the more confusing it seems to get. haha. Looking at the photos posted in this thread, and through other documentation, it seems that the 7400 crank fits close to ISO, but the 7400 bottom bracket seems to be closer to JIS standards (as per this thread) (http://www.bikeforums.net/showthread.php/812839-BB-for-DA-7402-cranks). Which means I would want a JIS spindle near 113? and the crank would fit deeper on a ISO spindle, so it would need to be 115+? Or maybe I'm a confused sole. Regardless, I'm trying to establish an affordable route; if I wanted to spend $90 there are plenty of NOS 7400 BB's on ebay.

I think that it might be JIS "low-profile" which is closer to ISO/campy. So I think to say the 7400 BB is JIS is mis-leading. You could try the JIS spindle, but I would try something even shorter than 113. You could always go to recyclistas and test fit a bunch of BBs. Personally, I'd rather have the crank engauging more spindle so I would use a campy BB if it works.. or I'd just buy the NOS one off ebay. $90 ain't bad given the quality of the BB.

I'm the one who measures all the spindles, and who posted.

The picture was intended to show clearly that 740X-series spindles are JIS. All of them, and not "part-JIS". I have verified this a few more times since measuring the exact JIS dimension of 12.9mm (measured 3mm from the end).

Campag spindles measure in the 12.7-12.76 range, while other ISO bb spindles measure as small as 12.65mm, so that is completely different territiory from the totally-consistent JIS 12.90mm.
Even low-end JIS spindles from every manufacturer are totally accurate based on perhaps hundreds of spindles I've measured.

There were pre-740X Dura-Ace spindles that did measure slightly small, but only from that early generation, and the difference was slight (only a few thou at most).

I would go for a Shimano cartridge bb, since they seem to last forever, are very economical (bargain of century imo) and are also at least as light (or lighter if it's a UN7X/9X) as the original 740X bb.

I usually select a shorter, 110mm cartridge unit for 740X cranks (to improve chainline) if there is an extra couple of mm between the small chainring and the chainstay, which can be fine-tuned with a spacer under the cup flange, later, if needed.
I've even used 107mm once (on my Merckx), since that was the only length less than 113 which came Italian-threaded.

I don't understand why folks prefer cup/cone to the newer units, especially considering that both XTR and Dura-Ace gruppos evolved to the lighter, longer-lasting cartridges.

Lastly, the 2-letter stamping is the date code.
1st letter is the year, A=1976, K=1986, and A=2002 starting again. 2nd letter is the month.
Pre-1976, the 1st letter changed approximately quarterly, or 4 times per year.

Shown is a 740X spindle being measured.

http://farm8.staticflickr.com/7115/7100808691_1ba5b71450_z.jpg

I'm the one who measures all the spindles, and who posted.

The picture was intended to show clearly that 740X-series spindles are JIS. All of them, and not "part-JIS". I have verified this a few more times since measuring the exact JIS dimension of 12.9mm (measured 3mm from the end).

Campag spindles measure in the 12.7-12.76 range, while other ISO bb spindles measure as small as 12.65mm, so that is completely different territiory from the totally-consistent JIS 12.90mm.
Even low-end JIS spindles from every manufacturer are totally accurate based on perhaps hundreds of spindles I've measured.

There were pre-740X Dura-Ace spindles that did measure slightly small, but only from that early generation, and the difference was slight (only a few thou at most).

I would go for a Shimano cartridge bb, since they seem to last forever, are very economical (bargain of century imo) and are also at least as light (or lighter if it's a UN7X/9X) as the original 740X bb.

I usually select a shorter, 110mm cartridge unit for 740X cranks if there is an extra couple of mm between the small chainring and the chainstay (to improve chainline), which can be fine-tuned with a spacer under the cup flange if needed later on. I've even used 107mm once on my Merckx, since that was the only length less than 113 which came Italian-threaded.

I don't understand why folks prefer cup/cone to the newer units, especially considering that both XTR and Dura-Ace gruppos evolved to the lighter, longer-lasting cartridges.



Thank you dddd,

I believe this post really pulls everything together. I am happy to hear you've successfully used shimano cartridges.

This morning, before doing my research, I ordered a 115. I have since changed it to a 107 (which was the only other italian this particular supplier had available). I will try this when I get it and hope for the best, and if not, will order another in 110 or 113.

- J

Hopefully you won't need much or any of a spacer, but if you do there is no worry of losing your lockring threading on the other end if the (cartridge) bb is moved over more than a couple of mm (Shimano's cartridge units and most others have no lockrings).

And by the way, "low profile" is used simply to refer to a style of crankarm that uses a shorter bb spindle, as on the final 7410 version.
There is no "low-profile-specific taper".

Hopefully you won't need much or any of a spacer, but if you do there is no worry of losing your lockring threading on the other end if the (cartridge) bb is moved over more than a couple of mm (Shimano's cartridge units and most others have no lockrings).

And by the way, "low profile" is used simply to refer to a style of crankarm that uses a shorter bb spindle, as on the final 7410 version.
There is no "low-profile-specific taper".

what do you make of the phil wood, low profile JIS taper?

what do you make of the phil wood, low profile JIS taper?

Awhile back I did extensive measuring and comparisons of the ISO and JIS tapers, my conclusion was that the angle of taper was almost identical but what changed was the cross section area. Think of a triangle, JIS is at the base while ISO is closer to the top. Phil taper is somewherein the middle.

Jeff, I have an Italian DA BB available....

http://www.bikeforums.net/showthread.php/630014-Bottom-bracket-and-old-crank-compatibility?p=10560897&viewfull=1#post10560897

http://www.bikeforums.net/showthread.php/630014-Bottom-bracket-and-old-crank-compatibility/page2?highlight=iso

Jeff, I have an Italian DA BB available....

Just an FYI, I'm way to cheap to pay the $90 asking prices on ebay right now, but please let me know what you have / condition, and how much you want for it shipped to Victoria, BC.

Your detailed research in this field is much appreciated.

Regards,
- Jeff

I realized last night that I had a 113 UN54 English thread in my bin. And given that English threads are a smaller diameter than Italian I was able to slide it right in. The Crank is torqued on. I've got ~3-4mm of clearance right now. (113-107)/2=3mm. So it's going to be close with the 107 spindle. If it doesn't fit, I may be able to get away with a 1 or 2mm spacer on the drive side, as noted by dddd.

Interestingly, the chainline with the 113 spindle is ~145mm which is well over the recommended 142.5 by Sheldon. So if I can shave a few mm off, I'll be laughing.

Lastly, assuming there is some flex in the crank under load, how much clearance do I need between the rear stay and the small ring to be safe?

297483

I realized last night that I had a 113 UN54 English thread in my bin. And given that English threads are a smaller diameter than Italian I was able to slide it right in. The Crank is torqued on. I've got ~3-4mm of clearance right now. (113-107)/2=3mm. So it's going to be close with the 107 spindle. If it doesn't fit, I may be able to get away with a 1 or 2mm spacer on the drive side, as noted by dddd.

Interestingly, the chainline with the 113 spindle is ~145mm which is well over the recommended 142.5 by Sheldon. So if I can shave a few mm off, I'll be laughing.

Lastly, assuming there is some flex in the crank under load, how much clearance do I need between the rear stay and the small ring to be safe?

297483


I'm of the same opinion favoring a shorter chainline for a few good reasons.

I like to see about 2mm clearance to the chainstay, to cover for years of use and maybe one good re-torquing.
The small chainring size affects the clearance. Your photo shows very generous clearance.
I have sometimes used belt-sander paper held stationary against the chainstay to machine down the rotating chainring. Some thicker/better rings have a ridge/step or lip "corner" below the teeth that can benefit from being cut down. I protect the chainstay paint with tape first, as even the smooth side of the paper will be showered with abrasive dust. The tape thickness can be adjusted to regulate the "feed" of the cut.

I could only recommend a bb that I've measured, but at least the Phil bb's are laterally adjustable.
Don't forget to get a Phil splined tool if you don't have one already.
I am usually wary of any published taper descriptions from catalogs including Phil's or even Sutherland's.
There are some generalizations sometimes applied that can affect the effective length of a spindle, but I've always found JIS to be very exacting vs. other tapers.

Okay. One more question.

I received the 107 bb that I ordered a while back, and finally had a chance to try it last night. With it, I've got about 0.5mm of clearance between the small ring and the chain stay, which I am definitely not comfortable with. So, I have two options. Buy a new 110, or put a spacer on the 107.

I probably would just go the spacer route, except I ran into another quirk that I haven't had to deal with before. If I space the drive side out 1.5mm, then the non-drive side cup will recess into the bb shell another 1.5mm. This will start to expose a few threads of the bb shell. This would then be a collection point for water, and corrosion. This must be a common issue with spacing shimano cartridge bb's, but I can't find any reference to it online. Thoughts?

Thanks,
- Jeff

Interesting thread here. I'm very new to using Italian threading, as in only used it in the last 3 months or so. I knew that the BB shell was 70mm instead of 68mm for English threading, but I had no idea the tapers were like this, for the Shimano 7400 & 6400 cranks, which I happen to have both of. I currently have the 6400 cranks on the Miele (closest I have to Tri-Color), with the F*G Italian-threaded BB, and everything "seems" fine, by eyeball, though I haven't run cables yet, just a chain. I'm not fully understanding all this yet, but it sounds like I "accidentally" found a pretty good combination, no? I had read that Campy & Shimano weren't really interchangeable, so I was wondering why mine worked this well, & thought maybe something was worn, in a very fortunate way, LOL. ;) BTW, I also have a newer Campy Veloce BB, and it would be pretty cool, if I could use the 7400 cranks with that. Not that I will, but it's useful to know, just in case. :)

Interesting thread here. I'm very new to using Italian threading, as in only used it in the last 3 months or so. I knew that the BB shell was 70mm instead of 68mm for English threading, but I had no idea the tapers were like this, for the Shimano 7400 & 6400 cranks, which I happen to have both of. I currently have the 6400 cranks on the Miele (closest I have to Tri-Color), with the F*G Italian-threaded BB, and everything "seems" fine, by eyeball, though I haven't run cables yet, just a chain. I'm not fully understanding all this yet, but it sounds like I "accidentally" found a pretty good combination, no? I had read that Campy & Shimano weren't really interchangeable, so I was wondering why mine worked this well, & thought maybe something was worn, in a very fortunate way, LOL. ;) BTW, I also have a newer Campy Veloce BB, and it would be pretty cool, if I could use the 7400 cranks with that. Not that I will, but it's useful to know, just in case. :)

There is a good chance that it will work with a campy bb, but I would wager that in order to get clearance and a decent chainline, your spindle is at least 115... Google just told me that a newer veloce bb comes with a 115.5 spindle. I have to be honest, I'm incredibly jealous of the accidental success. ;)

I always check the chain line before upgrading the BB. The stock on one of the bike was 122.5 mm. Optimum chain line was 118 mm with the 8-speed cassette, so I ordered a cheap 118 mm UN55 BB. You can always fine tune the chain line with aluminum spacers (1-3 mm). If the small chainring is about to make contact with the frame, then you need to add at least a 3 mm spacer to the drive side.

I always check the chain line before upgrading the BB. The stock on one of the bike was 122.5 mm. Optimum chain line was 118 mm with the 8-speed cassette, so I ordered a cheap 118 mm UN55 BB. You can always fine tune the chain line with aluminum spacers (1-3 mm). If the small chainring is about to make contact with the frame, then you need to add at least a 3 mm spacer to the drive side.

Appreciate the advice. I didn't have a bb to start with, so I wasn't able to determine chainline / clearance until I tried a bb.

Further though, what do you do about the non drive side cups on shimano cartridge bottom brackets when you are using spacers? It will dissapear into the bb shell leaving thread exposed that could rust.

Appreciate the advice. I didn't have a bb to start with, so I wasn't able to determine chainline / clearance until I tried a bb.

Further though, what do you do about the non drive side cups on shimano cartridge bottom brackets when you are using spacers? It will dissapear into the bb shell leaving thread exposed that could rust.

The UN55 has at least 3 mm exposed on the non-drive side.

The Shimano BB-M952 (BC1.37x24 Octalink) comes with spacers on both sides. I added 3 mm to the drive side, and 5 mm to the non-drive side of my Bridgestone 400.

I've just assumed that the grease in the threads will keep rust away, at least here in dry California.
And I wouldn't intentionally ride my merckx in wet weather or on wet roads normally.