cardinal sin?

[john 4d]

I've just replaced my brake caliper pistons,caliper seals and bridging seals.

Now, in order to remove two of the old pistons, I had to separate the two caliper halves. As it turned out spitting thecaliper certainlymade replacing the seals easy, I can't think of a way to do it, as easy, any other way, especially when fittingthe steellipped retainer for the lip seal.

Why then does the Hayes manual says that on no account should this be done?

Does anyone know the torque setting for the bolts holding the two halve together? And do I really have to replace the old bolts for new? The old bolts would not have been torqued beyond their modulus of elasticity and as such should be reusable. Any comments?

Regards

John

[dogsnadgers]

imported post

Hi

I split mine with no problem - just keep them as clean as you can.

I used the original bolts and tightened them up tight! I think about 100lb/ft but can't say for sure as it was a few years ago. Never had a problem though and as you say it sure makes replacing the seals easier. I put new pistons in as well.

Dave

[GDPR]

imported post

I think it's mainly to prevent the amateur DIY roadside wallies who tinker with their cars in less than ideal conditions from making a complete balls of it, and blaming Haynes, with the consequent litigation no doubt.

If you have the skills and nouse to do it properly, then there is no reason why not, IMHO.

Russ:dude:

[adieturner]

imported post

You are correct in thinking that the bolts should not have been tightened beyond their yield point John and as such should be OK. However, they are old and in both a hostile and safety critical area. Your local bolt stockist won't want more than a couple of quid a set (I'd guess) so why risk it?

Adie

[stustag]

imported post

adieturner wrote:

You are correct in thinking that the bolts should not have been tightened beyond their yield point John and as such should be OK. However, they are old and in both a hostile and safety critical area. Your local bolt stockist won't want more than a couple of quid a set (I'd guess) so why risk it?

Adie

If you do get new bolts make sure they have rolled threads as per the originals, I supplied Girling etc (and sub con's)with Fette rolling equipment for these bolts.

rolled threads are 10X stronger than cut threads

Easily identified by the burnished finish on the flanks of the thread and the smoothness of the major diameter

Stuart

[adieturner]

imported post

Good point Stuart.......perhaps we should add "not chinese"......I've seen some fasteners recently that are made from the same s**t as the noodles at our local takeaway!

[stustag]

imported post

adieturner wrote:

Good point Stuart.......perhaps we should add "not chinese"......I've seen some fasteners recently that are made from the same s**t as the noodles at our local takeaway!

No need to buy Chinese there are loads of fastener companies in Wolverhampton & Birmingham still making quality bolts, cap screws and nuts.

BUY BRITISH!!

[Stagdad]

imported post

stustag wrote:

adieturner wrote:

You are correct in thinking that the bolts should not have been tightened beyond their yield point John and as such should be OK. However, they are old and in both a hostile and safety critical area. Your local bolt stockist won't want more than a couple of quid a set (I'd guess) so why risk it?

Adie

If you do get new bolts make sure they have rolled threads as per the originals, I supplied Girling etc (and sub con's)with Fette rolling equipment for these bolts.

rolled threads are 10X stronger than cut threads

Easily identified by the burnished finish on the flanks of the thread and the smoothness of the major diameter

Stuart

Stuart ,

Any chance of a picture of both types, so us mere mortals know what to look for

Cheers Steve

[john 4d]

imported post

Thanks to you all, all your points taken. I had also contacted Graham at Paddock's, as they supplied the refurb. kit and also do 'new' for exchange calipers, I thought that who ever might carry out the refurb should know the figure. Graham came up trumps with 60 lbs.ft or 74-95 Nm for anyone else interested. With regard to Hayes, it amazing the paranoia something in print causes.

Thanks again.

john 4d wrote:

I've just replaced my brake caliper pistons,caliper seals and bridging seals.

Now, in order to remove two of the old pistons, I had to separate the two caliper halves. As it turned out spitting thecaliper certainlymade replacing the seals easy, I can't think of a way to do it, as easy, any other way, especially when fittingthe steellipped retainer for the lip seal.

Why then does the Hayes manual says that on no account should this be done?

Does anyone know the torque setting for the bolts holding the two halve together? And do I really have to replace the old bolts for new? The old bolts would not have been torqued beyond their modulus of elasticity and as such should be reusable. Any comments?

Regards

John

[stustag]

imported post

Hi Steve

Sorry I only have a video of the thread under a microscope:?

But a cut thread will have a rough feel to the major diameter of the thread and the flanks will have lines where the insert has made several passes to cut the thread.

A rolled thread will be smooth on the major diameter and the flanks will have shiny burnished finish to them (very shiny!!)

Stuart

[john 4d]

imported post

Well that's done and dusted, all torqued up. All a nice racing red (VHT caliper paint from Frosts £9 a can, £15 delivered! What a rip off, post office won't handle aerosols so it has to be couriered). Just to put a belt to braces I thought I'd dab a spot of locltite green rather than redon the threads, holds rather than sticks I understand. Well, beware of the bit that dribbles out of the back of the tapped hole.. it strips paint! So, no paint left, used up doing the brake drums as well, I now have two calipers that only look good at first glance but on closer inspection already have that 'used look'. Ah well I guess it's the job they do that's more important!

John

[Stagdad]

imported post

stustag wrote:

Hi Steve

Sorry I only have a video of the thread under a microscope:?

But a cut thread will have a rough feel to the major diameter of the thread and the flanks will have lines where the insert has made several passes to cut the thread.

A rolled thread will be smooth on the major diameter and the flanks will have shiny burnished finish to them (very shiny!!)

Stuart

Thanks Stu

Cheers Steve