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Caliper Bolts - Do you really need to replace them?

A

ArBee

New member
I am going to do my own Brake Disc replacement and I read somewhere that if you remove the brake caliper bolts you should renew them? I obviously will need to free the calipers off the discs to do the swop.

Is this entirely necessary? Anyone got any thoughts on that? Richard are you aware of this requirement?

RB.
 
Porsche do state in the workshop manual that you should replace the caliper bolts when refitting the calipers. I don't know if it is actually necessary, but they aren't hugely expensive, about £1.50 each.

The main problem will be getting them out, especially if they weren't greased with high temperature grease last time they were removed. The threads can pick up and tear the thread in the caliper, and in the worst case the bolts can shear when you undo them. If that's the case, you can have thread inserts fitted to repair them, which can give a stronger and less problematic solution for the future. I'm painting a 'Doom & Gloom' picture, and the job will probably go like a breeze.
 
Cant answer the question if its totally necessary but I would like to share a recent experience with you.

Had the car in with OPC Stratford last year and they couldn't undo the bolts, they were totall siezed in. They tried everything and ended up sending them away to be machined (I guess they drilled out the bolts and machined new holes etc) which would have cost a small fortune if they hadn't been doing it free under good will [:)]

Maybe its worth replacing them to stop them siezing in the future, but i dont have an opinion on this. But I would suggest using the correct torques to prevent over-tightening. I dont know if a lubricant such as copperease is reccommended on somthing like this?

Any other ideas?
 
Thanks Guys,

Wonder if I should start a course of penetrating treatment before I get started just to help the process along for when I get around to doing it as I plan to replace all four discs at the same time and knowing my luck (I could fall in a barrel of t*ts and come out sucking my thumb) at least one will stick.
 
I've replaced 6 disks over the past 3 years, never had any problems at all, and never replaced the caliper bolts, although u are meant to replace them. Removing the caliper bolts (in my experience) was one of the easiest parts of the job, the hardest usually being loosening the disk itself from the hub (when Copperease has not been used) as they usually rust quite badly on the inside and rear. Always make sure u use the correct torque settings tho.
It should be a doddle, and much easier than replacing pads.

If u haven't seen the link on changing disks already (http://www.porscheclubgbforum.com/tm.asp?m=231501)
Very helpful.

Good luck!
 
Well that has given new heart Rodney - thanks.
I have seen the guidance and will use it - I suppose this type of posting is what gives people like me the confidence to have a go myself.

Thanks

RB


 
I agree with the above.

You have a male steel threaded bolt going into a female threaded aluminum caliper. Sometimes they like themselves so much they will not come apart without stripping out the aluminum threads when you try to remove the bolt.

New bolts are pre-coated with anti-sieze. I think in the UK you call it copper slip or something like that. I use the silver stuff for things like this, which is really a thick grease with ground up metal/graphite particles. In the very old days lead was used.
 
ORIGINAL: Tool Pants

I agree with the above.

You have a male steel threaded bolt going into a female threaded aluminum caliper. Sometimes they like themselves so much they will not come apart without stripping out the aluminum threads when you try to remove the bolt.

New bolts are pre-coated with anti-sieze. I think in the UK you call it copper slip or something like that. I use the silver stuff for things like this, which is really a thick grease with ground up metal/graphite particles. In the very old days lead was used.
Click to expand...

We have two types over here copperslip and alumslip.... The names give a clue as to the ingredients and colour. I always use alumslip on the threads (and for the wheel bolts as per instructions - NONE on the contact 'domed' portion).

I bought new bolts when I fitted the 6 pot calipers and the bill for the four bolts was waaaaay more than £6.00.
 
ORIGINAL: tim court
I bought new bolts when I fitted the 6 pot calipers and the bill for the four bolts was waaaaay more than £6.00.
Click to expand...

There are 3 Bolt lengths:
Std: 72mm
Turbo: 77mm
PCCB: 85mm

The USA list prices are $2,83, $4.48 and $4.42 respectively. Maybe it's another case of rip-off GB.
 
ORIGINAL: MoC2S

The caliper bolts go through to the upright and AFAIK are stretch bolts .. ie, designed to be torqued once, and only once .. we are talking about primary safety here, is it really going to break the bank, or would you prefer to continue to see your family on a regular basis .. ?

2p, cheers, Maurice [:eek:]
Click to expand...

Here we go again.....[8|][:)]

The bolts are about 10mm diameter so any engineer will tell you the forces needed to stretch these beauties would be very large indeed. It would easily strip the aluminium thread of the upright.

The correct torque is 60 something ft/lbs which when compared to the 96ft/lbs you apply time and time again to the wheel bolts demonstrates this. The caliper bolt is acting more in shear, not tension.

Personally I think Porsche reccomend replacement due to the ease the thread can be stripped in the carrier, especially by a grubby bolt, so a nice new bolt correctly greased reduces this risk.

I always make sure the bolt, mating faces and thread is meticulously clean before greasing and stuffing back in.
 
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