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Installing a Shimano BB-7703....(10 posts)

Installing a Shimano BB-7703....SS_MB-7
Jul 21, 2002 8:36 AM
I am trying to install my new Shimano BB-7703, however, the Park BB tool that I have (BBT-2) isn't long enough to get past the BB's 118.5mm splined axle to tighten the driveside shell. According to Park's website, the BBT-2 is the tool for XTR M952 and Dura-Ace 7703 cartridge bottom brackets with the 20 tooth spline pattern.

Also, my BB did not appear like the one below:

Instead of having a driveside cup with 6 notches, mine is similar to the one below, which has the 20 tooth spline.

Is this OK and/or normal?

Lastly, my non drive-side cup did not include a lock-ring. Fortunately, I can use the lockring from my XTR BB on my MTB. Is this item readily available?

Ride Hard,
Mike B.
Here's a pic of the BB-7703....SS_MB-7
Jul 21, 2002 8:39 AM

Mine looks identical to this one. Should the non drive-side not have a lock-ring?

Ride Hard,
Mike B.
I might be misunderstanding but...Quack
Jul 22, 2002 6:05 AM
Can't you remove the axle, install the drive side cup, and resinstall the axle? I haven't done any BBs with triples but on all of my doubles, I install them this way. On the Dura-Ace BBs, I know the axle slides right out from both cups with nothing more than an o-ring on the center shell preventing separation.

My .02.
I'd agree with you, however....SS_MB-7
Jul 22, 2002 7:06 AM
I'd agree with you, however, the drive-side cup does not appear to be removable like the non-drive-side. Unlike the Dura-Ace BBs listed at, mine came with sealed bearings, not the ball and needle bearings.

Ride Hard,
Mike B.
re: Installing a Shimano BB-7703....TJeanloz
Jul 22, 2002 7:48 AM
The BB-7703 is the Dura-Ace bottom bracket for the triple chainring. It does not have needle bearings like its much-maligned sibling the BB-7700. To install it, you need Shimano TL-UN74-S or similar. It should just be a question of torquing each side in.

I don't think the non-drive side cup's lockring should be removable, but I don't have one in front of me, so I don't know.
Jul 22, 2002 10:10 AM
Thanks for the info.

Yes, you are correct that the 7703 does not have needle bearings, but instead uses sealed cartridge bearings.

Like the picture of the 7703, the non-drive-side cup does not have a lock-ring, only the 6-splined cup. My XTR BB (similar to D-A), has the 6-splined cup as well as a 6-splined lock-ring. However, it uses needle bearings like the 7700. I wonder if the fact that the 7703 uses sealed bearings has anything to do with the absence of the lock-ring. Also, do you know if the drive-side cup is removable?

Ride Hard,
Mike B.
Jul 22, 2002 10:39 AM
The drive side cup is non-removable.

The sealed bearings provide better low-maintenance performance than the needle bearing design, and Shimano concluded that triple chainring buyers would be more concerned with function than light weight- hence spec'ing the heavier, but lower maintenance, sealed design.
I just spoke with Shimano's customer service here in Canada...SS_MB-7
Jul 22, 2002 10:56 AM
I just spoke with Shimano's customer service here in Canada and they confirmed that:
1 - BB-7703 comes with sealed bearings as opposed to the needle bearings;
2 - there is no lock-ring on the non-drive-side cup;
3 - the drive-side cup is not removable from the BB so when the bearings are trashed, the whole BB needs to be replaced; and
4 - the installation tool is TL-UN74-S.

Ride Hard,
re: Installing a Shimano BB-7703....pmf1
Jul 22, 2002 11:28 AM
The lock ring is removable. I just bought a triple DA BB for my wife's bike (along with a triple upgrade kit). The lock ring comes lose. It looks an awful lot like the Ultegra BB -- a cartridge unit. In my experience with the Ultegra BB, the lockring is not really functional. Just unscrew the BB with the BB tool on both sides.
3 different BB tools for ShimanoKerry Irons
Jul 22, 2002 6:17 PM
I've got one (probably like yours) that will fit the cup splines but is too shallow to reach the cup splines due to the larger splined axle ends. A friend has a tool that is just like mine but the inside is "deeper" which allows it to reach the cup splines. Both of these tools take a socket drive. Based on this, I ordered a new tool - it fits, but takes a 24mm wrench (can't use my torque wrench unless I find a 24mm socket).