Shimano road disc brake caliper pad retainer bolt - hex-head replacements for cack slotted cheese head original..

[wafter]

While Shimano's fairly recent, first gen flat-mount road and gravel disc brakes (105 BR-7070, Ultegra BR-8070, GRX BR-RX810) are generally well regarded, they evidently get a lot of (deserved) flak for their use of a soft, cheese-head screw / "pad axle" to retain the pads. It seems these corrode, sieze in place then become damaged when removal is attempted.

While there are aftermarket (usually Titanium) alternatives it seems that Shimano have addressed this issue on their later / current calipers - fitting a (hopefully tougher) hex-head bolt instead of a cheese head.

I've been trying to track down the correct replacement item to retro-fit to my 105 R7070 calipers as a preventative measure. This has proven less-than-straightforward but I think I've found the right one. Train of thought below; heed at your own risk!

Shimano SLX BR-M7110 Pad Axle & Snap Retainer - Y2GM98020 - SJS Cycles, £1.99​

According to the SJS site, this is listed as correct fitment / "A" match for:

- Shimano Ultegra BR-R8170 (2nd gen. flat mount)
- Shimano 105 BR-R7170 (2nd gen. flat mount)
- Shimano SLX BR-M7100

It's also listed as a "B" match for:

- Shimano Ultegra BR-R8070 (1st gen. flat mount)
- Shimano Deore XT BR-M8100
- Shimano SLX BR-M7000

Looking at the exploded diagrams for the BR-R8070 and BR-7070 we can see that both use the same cheese-head "pad axle" (part no. Y8J798060 including the "snap retainer"); which suggests that the Y2M98020 above from SJS should also be a "B" match for the 1st gen 105 BR-7070 calipers. This also holds true for the earlier post-mount RS-505 non-series / pseudo-105 road calipers that marked Shimano's first foray into discs for road groupsets.

I hope / suspect that these are a "B" match because the head profile and finish are different; while being otherwise geometrically identical.


The pad axle for the GRX BR-RX810 (as well as GRX BR-RX400 and Tiagra BR-4770) has a different part number to the two road groupsets from the same era (part no. Y2EN98010 including the "snap retainer"); I think because it has a different finish (black as opposed to the silver BZP finish on 105 and Ultegra); however I can't find any official sources that confirm this supposition. Equally I'm not sure what the crack is with Dura-Ace parts.

I'm interested to hear any thoughts on this and might take the plunge and buy a couple of these hex-head replacements if I can be reasonably sure they'll fit..

​

 

[13 rider]

I had the dropped siezed bolt it wasnt pretty getting it out . Every time I clean my bike I just undo slightly and redo and occasionally grease the threads .
Going to look into the replacements though
Thanks for the info ,did you pick this up on a Francis Cade YouTube ?
Ring SJS they seem pretty knowledgeable and will give you the correct answer

 

[wafter]

I had the dropped siezed bolt it wasnt pretty getting it out . Every time I clean my bike I just undo slightly and redo and occasionally grease the threads .
Going to look into the replacements though
Thanks for the info ,did you pick this up on a Francis Cade YouTube ?
Ring SJS they seem pretty knowledgeable and will give you the correct answer

No worries and yes, I got the heads-up from Francis' video (and his hatey-mechanic, who I tend to agree with some of the time).

Sounds like the struggle is real! Mine have been refitted with copper grease and the bike never intentionally sees any wet, but for the sake of a few quid it'd be good to get some peace of mind. Fap knows why they were never hex-head in the first place; cheese head screws have no place on a modern bike!

I did consider bothering SJS, but tbh am only likely to buy from them if I place another order due to the postage cost.. and there's nothing else I need currently so they'll probably come off ebay as they can be found for £1.99 inc. postage.

 

[13 rider]

Yes the struggle is real . I decided to change my pads during the first lockdown and basically destroyed the bolt head . I restored to drilling the remnants out not recommended. Due to the cosmetic damage caused to the caliper during this process I eventually got the LBS to change it so tha £2 bolt cost me £100

 

[wafter]

Yes the struggle is real . I decided to change my pads during the first lockdown and basically destroyed the bolt head . I restored to drilling the remnants out not recommended. Due to the cosmetic damage caused to the caliper during this process I eventually got the LBS to change it so tha £2 bolt cost me £100

Bugger - what a crappy situation

 

[cheys03]

The retailing bolt on my rear calliper seized in place - removed by welding a strip of steel to the remains of the head and turning. I refuse to pay the high cost for a replacement so use a split pin which came with the new pads.

Similar to:
https://www.ebay.co.uk/itm/17470382...ar=473887282355&widget_ver=artemis&media=COPY

For many reasons this is a theoretically inferior solution, but I can honestly say it’s been absolutely fine and I have no fear of a bolt seizing again. Looks pretty neat as well, so long as the tails are pointing inwards.
I’ll do the same with the front calliper next pad change.

 

[Jenkins]

Had the seized bolt on the front brake of my (non-flat mount) 105 brakes, even after a previous pad change and the use of Coppaslip on the bolt thread. The bolt head was too soft to even use one of those removal kits. Why not use a split pin instead?

The affected bike is now on SRAM instead (although this was planned)

 

[wafter]

I'd agree that in many ways a split pin is an inferior solution to a bolt; however predisposition to seizing probably isn't one!


Having found these on ebay for £1.99 posted I dropped the seller a message to ask about compatability. The initial answer was "computer says no", however they did agree to measure one for me. This in itself was a win so I didn't ask for every single dim / a comprehensive engineering drawing; just what I thought was most pertinent to avoid wasting too much of their time.

The bad news is that the dims are slightly different between those sent to me for the hex-head Y2GM98020 and the slot-head Y8J798060 removed from the 105 caliper on my bike. The good news is that I think they'll physically fit but are just a bit longer. The shank OD is the same at around 3mm nominal, the thread apparently the same at M4.

The exceedingly helpful Kevin from Woolyhatshop on ebay suggested the total shank length (underside of head to end) on the Y2G is around 27.2mm, while my Y8J measures around 25.7mm. The groove for the split pin on the Y2G is apparently around 25.2mm from the underside of the head, my Y8J measures around 22.8mm.

I measured to the most inboard face of the 1.1mm wide split pin groove, Kev didn't specify. From my Y8J dims I can see that the major diameter portion of the bolt shank beyond the split pin groove at the very end of the bolt is around 1.8mm long. Kev's dims suggest that on the Y2G this portion is either 0.9mm long (if his measurement is to the inboard face of the groove) or 2.0mm long (if the measurement is to the outboard face).

I suspect in summary that he's probably measured to the outboard face of the groove and that, other than the head formats the only meaningful geometric difference between the original slot head Y8J798060 and hopeful hex head replacement Y2GM98020 is that the latter is around 1.5mm longer.

Based on this assumption the axle should physically fit, but will likely just position the snap pin outboard by another 1.5mm. This shouldn't be an issue since it's only a belt-and braces measure to prevent the bolt / axle becoming completely detached if it shakes loose; while there's nothing else around the caliper that that modest increase in length should affect.

In a final supporting argument, the Y2GM98020 hex-head bolt / pad axle is original fitment on the SLX BR-M7110 caliper; which I strongly suspect is the same basic unit as the 105 BR-7070, Ultegra BR-8070 and GRX BR-RX810. They all look geometrically identical, are very nearly all the same quoted mass and all take the same pads. All these calipers came in at about the same time when the flat-mount standard was just taking hold, and it seems unlikely that Shimano would invest in the tooling to make loads of different calipers for different applications when one size would fit all.. pics below for comparison:

TL;DR: Proposed replacement hex-head pad axles looks slightly different but research suggests they should fit. I've bought a pair; if you choose to do the same (or wait until after I've got mine!) please consider buying from Woolyhatshop on ebay as they've been very helpful in my efforts to confirm compatability

 

[I like Skol]

https://www.cyclechat.net/threads/s...in-spring-clip-y8jz98010.224990/#post-4992044

 

[wafter]

https://www.cyclechat.net/threads/s...in-spring-clip-y8jz98010.224990/#post-4992044

Thanks - that's reassuring!

Do you recall the shank length on yours? Appears to be a different part number, head shape and finish to those I've just ordered..

 

[I like Skol]

Thanks - that's reassuring!

Do you recall the shank length on yours? Appears to be a different part number, head shape and finish to those I've just ordered..

I'd have to take one out and measure it and that won't be happening today. I know they were a bit longer than the originals.

 

[wafter]

I'd have to take one out and measure it and that won't be happening today. I know they were a bit longer than the originals.

Ta - no rush. It seems that the one pictured in your thread is that fitted as standard to Deore LX calipers - including the flat mount items which again, seem to be identical to the 105 / Ultegra / GRX / SLR items I've already listed. The difference appears to be the finish, head shape and possibly length. Plus, "yours" are about £5 for the pad axle and clip assy, "my" one-step-beneath SLX items can be had for £2ea.

It seems that while the calipers are apparently identical, Shimano fit the crappy slotted cheese-head screws to the road and gravel versions, while the MTB calipers get the hex-head... the reasoning probably being that the latter are more likely to get exposed to nastyness and seize..

 

[Ming the Merciless]

Use a split pin, cheap, effective, don’t corrode in place, retain pads perfectly, easy to remove when time.

 

[wafter]

Use a split pin, cheap, effective, don’t corrode in place, retain pads perfectly, easy to remove when time.

No thanks

 

[wafter]

Bits arrived today, somewhat disappointingly via Amazon but it is what it is.

The replacement axles are different to the originals in several ways, but this doesn't affect their function:

They've gone into my 105 BR-7070 calipers fine, with no functional differences caused by the discrepencies in dims.

There was a double-take when I weighed each offering as the originals are only around 30% the mass of the replacements; meaning they must be made of something lighter. They're non-magnetic and the obvious material is aluminum; which would explain their reputation for being Dairylea-soft..


I'm happy with the outcome - the replacements should be less prone to seizing, easier to get out if they do seize and the hex head removes the possibility of marking the caliper if the screwdriver slips in the head. On the downside they've added a whole 3.5g to the bike's mass..

Was hoping to get out for a bit on the Genesis today, but the weather's put paid to that