disc brake caliper retaining bolt ruined

[Wycombewheeler]

I decided it was time to check the pads on my shimano rS785 disc calipers, however it seems the retaining bolt head is made of cheese butter and the screwdriver has destroyed the groove. Any ideas on how I can remove the bolt to remove the oads? Or am I now in a position of needing a new caliper?

[Brucey]

the screw is probably seized into the outer caliper half (which is, unlike the other half, threaded to accept the screw).

If this were my bike I would get someone to put a blob of MIG weld onto the screw head.  The heat will free the seized screw threads, and you will have something to grip/swing on/grind a slot in. There are lots of other ways of addressing this issue, but that is the one that will work most reliably and most quickly IME.

The screw is listed separately as a spare part;

http://si.shimano.com/pdfs/ev/EV-BR-RS785-3743.pdf

To avoid a repeat performance

-  use a screwdriver that fits the slot exactly and push it firmly into the slot when undoing it. This can make about x10 difference to the torque that can be exerted before the screw is damaged in any way.
- put a little copper-ease on the screw threads when reassembling
- don't overtighten the screw; there is no need, bearing in mind that there is also a retaining clip on the back of the screw

hth

cheers

[Gattopardo]

Is it a Philips or straight slot?

[Wycombewheeler]

Is it a Philips or straight slot?

straight.

[chriscross1966]

A left-handed twist drill might be your friend if you can get it started, sooner or later the heat from the drilling will free  it off and at that point the LH nater of the drill will unwind the screw..... would be helpful if it was a phillips/allen/pozi/torx though

[Wycombewheeler]

A left-handed twist drill might be your friend if you can get it started, sooner or later the heat from the drilling will free  it off and at that point the LH nater of the drill will unwind the screw..... would be helpful if it was a phillips/allen/pozi/torx though

if it was torx or allen chances are it wouldn't have been damaged in the first place.
drill bit seems more promising than the welding approach, as I don't have the kit. Like this? http://www.diy.com/departments/ptx-screw-bolt-extractor-drill-bit-set-5-pieces/693454_BQ.prd?ecamp=Seapla&ppc_type=shopping&ds_kids=92700019145819990&gclid=CO6u_MyI49ICFWgz0wodfPYDRA&gclsrc=aw.ds.ds&dclid=CJ2Tls2I49ICFciJ7QodXwQN0w  seems to have very mixed reviews.

[Aunt Maud]

They're ezeouts and they don't go in a drill, but are used with a thread tap handle. You can also get sets in screwfix and machine mart.

[aeolus]

I would first use some release fluid on the thread then try heating the end of the bolt that sticks through (having removed the safety clip) with a soldering iron or heated up chunk of metal + more release fluid.
It is just  possible to get pointed pliers on the bolt between the pads and get an assistant with another pair of pliers on the protruding bolt end  - there is more access if you are lucky enough ? only have the plain not Icetech finned pads.

If you have to drill it out, a through bolt would work or the split pin that Shimano supply in the kits of brake pads ? do they know something ?

Replacement bolts are available from SJS.

Best of luck.

[Torslanda]

You have to ask which knobhead thought a slothead screw would be such a good idea...

[chriscross1966]

They're ezeouts and they don't go in a drill, but are used with a thread tap handle. You can also get sets in screwfix and machine mart.

No... proper left hand drill bits, possibly then followed with an EZ-Out, but you can get left hand spiral drill bits...

For instance, this looks like a sensible set to own

http://www.ebay.co.uk/itm/252731377225

[Wycombewheeler]

You have to ask which knobhead thought a slothead screw would be such a good idea...

shimano marketing probably.

[Wycombewheeler]

I would first use some release fluid on the thread then try heating the end of the bolt that sticks through (having removed the safety clip) with a soldering iron or heated up chunk of metal + more release fluid.
It is just  possible to get pointed pliers on the bolt between the pads and get an assistant with another pair of pliers on the protruding bolt end  - there is more access if you are lucky enough ? only have the plain not Icetech finned pads.

If you have to drill it out, a through bolt would work or the split pin that Shimano supply in the kits of brake pads ? do they know something ?

Replacement bolts are available from SJS.

Best of luck.

ice tech pads, no room to get pliers at the middle. it is possible to get at the far end of the bolt. Just need some release fluid.

Think I'll try release fluid and pliers first then look at these left hand drills.

Thanks everyone for all the help.

[Torslanda]

If you're good with a drill and have a supply of new sharp bits, then why not try drilling the head off the screw?

I've done it before on disc bolts (M5) but not tried it with anything as delicate as a pad retainer. If you should happen to knack the thread it's not the end of the world, just use a split pin instead...

[aeolus]

'ice tech pads, no room to get pliers at the middle'

If you push the pads fully retracted you can get pointed nose pliers in the gap - i would not worry if the springy thing gets damaged as they come with a new set of pads.

Using two pairs of pliers together will give the best available torque to turn the bolt.

[DaveSheff]

I've got exactly the same problem.
Did you succeed - which method worked?

[Brucey]

surely you can get a hacksaw blade between the pads, cut the retaining bolt in half, remove the unthreaded end, and finagle the pads out.

Then you can access the middle part of the bolt and swing on it like a chimp.

If you can file a couple of flats on it, an adjustable spanner might shift it.

cheers

[rafletcher]

Next fettling job for me - remove retaining pin and add some copper grease. I usually do it to all bolts but haven’t - yet - to the pad retaining ones.

[Frangipannier]

surely you can get a hacksaw blade between the pads, cut the retaining bolt in half, remove the unthreaded end, and finagle the pads out.

Then you can access the middle part of the bolt and swing on it like a chimp.

If you can file a couple of flats on it, an adjustable spanner might shift it.

cheers

Just want to add that this approach freed up the ruined retainer bolt on my Shimano hydraulic calipers. I used a couple of small cable ties to move the pads out of the way, then cut the bolt with a Dremel, leaving enough room to wiggle the (non-icetech) pads and spring out. Next, I filed the top and bottom of the bolt and used mole grips to loosen it, then I was able to unscrew it the rest of the way with a large, flat-headed screwdriver.

Hope this helps someone!

[Brucey]

further to the above I note that in some cases shimano allow use of a split pin in place of the threaded 'pad axle' pad retaining pin. This appears to be  listed on the EV techdoc eg for BR-M495

https://si.shimano.com/pdfs/ev/EV-BR-M495-2394B.pdf

Note that there is more than one split pin listed for shimano brake pad retention (even with the same model of pads, it varies with the caliper) and the head shape of the pin varies as well as the thickness. The head shape probably makes most difference when the threaded pad axle is replaced by a split pin.

cheers

[FifeingEejit]

further to the above I note that in some cases shimano allow use of a split pin in place of the threaded 'pad axle' pad retaining pin. This appears to be  listed on the EV techdoc eg for BR-M495

https://si.shimano.com/pdfs/ev/EV-BR-M495-2394B.pdf

Note that there is more than one split pin listed for shimano brake pad retention (even with the same model of pads, it varies with the caliper) and the head shape of the pin varies as well as the thickness. The head shape probably makes most difference when the threaded pad axle is replaced by a split pin.

cheers

Some Shimano brake calipers come with split pins rather than bolts, it's usually the lower end models.
I've used split pins off the shelf in place of destroyed/lots bolts as permanent replacements on Shimano and Avid brakes with no adverse effect yet.
It's like the bolt does little more than stops the pads being ejected through vibration when the brakes are released.

[Brucey]

yes indeed but I hadn't previously noted the substitution of one with the other as being an 'approved' method.  That matters if you are working on other people's bikes.

Shimano split pins come in 2.7mm or 3.2mm thicknesses. In the grand scheme of things both are probably overkill; car brakes often use much longer pad retaining pins which are not even twice the thickness.

cheers

[FifeingEejit]

yes indeed but I hadn't previously noted the substitution of one with the other as being an 'approved' method.  That matters if you are working on other people's bikes.

Shimano split pins come in 2.7mm or 3.2mm thicknesses. In the grand scheme of things both are probably overkill; car brakes often use much longer pad retaining pins which are not even twice the thickness.

cheers

Aye, I've been quite surprised at just how basic/weird car disc brakes can be when compared to their miniature sized bike ones.

I'm mildly miffed by the fact that my hot hatch has single pot calipers front and back with the outboard pad being adjusted by sliders... that inevitably seize up.
The pads are head on by spring clips IIRC and are incredibly fiddly to fit
More like BB7s with an automatic adjuster than 4-pot Saints.

[Brucey]

single piston sliding calipers look crude but allow the whole car to be packaged slightly better because the effective track width of the suspension can be increased anytime the wheel offset can be increased and/or the brake discs can be pushed outwards. Single piston calipers allow this, and they are cheaper to make. There is also an argument about potential for cocking pistons in the bore of the calipers too. Finally the pads in sliding calipers can be retained without pins in some designs; the idea is that the pad backing cannot escape once the caliper is assembled.

 Materials in the sliding bushings/seals are different between manufacturers so the exact maintenance regime varies but there is normally a special lubricant for the bushings; for example in Hondas IIRC the bushing lube is a special (50% by weight) MoS2 concoction. If the boots split or the pins are not maintained (eg every time the pads are changed) then sliding calipers can seize up. Lack of lube or the wrong lube causes the bushings to wear. Overall it seems a fairly reliable arrangement; I've spent more time dealing with seized up four-pots than I have sliding piston type calipers.

In car brakes if there are pad springs, they are normally intended to prevent the pads from rattling around.

cheers