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oldtuckunder

brake pad knock back

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Well, I never knew such things existed - only ever come across the use of residual pressure valves for this purpose.

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I'm not so sure, for road use.

There's always a little bit of runout on a disc and it pushes the pistons back until they juuuuuuuuuuuust don't touch the disc.   And they make no noise.

A spring will keep the pistons in contact with the disc.  Great for instant response, lousy for pad wear, but its for racing - you change the pads frequently anyway.  And the noise!   Constant pad on disc , scrape scrape. 

Chaqu'un a son brake mods of course!

John

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I have found that bearing spacers stiffen the hub/spindle connection diminishing pad push back and pedal travel on the first application. An inexpensive fix

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Not come across these before.  Found this picture in a Timken catalogue, but I'd be grateful for an explanations of how they work.  J.

image.png.3ccb91c054edee4cc88e1194c43b0ae7.png

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When i fitted the toyota four pot calipers to my 6 i found this made the pad knock back worse.

i put this down to the greater leverage on the wider spaced pair of pistons compared to a single piston

fitting the (much) thicker srub axle kit from cdd cured the knock back

steve

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As I have all the parts to hand and have been building hubs this afternoon......

Standard parts laid out in order

P1180931s.jpg

Standard set-up has both inner bearing races "floating" on the stub axle with bearing float being set by careful positioning of the castellated nut, which is not tightened, but held in place with a split pin. 

P1180932s.jpg

All bending forces are taken by the stub axle and the bearing races will rotate (slowly) on the stub in service.  Over-tightening, if only to shut up a whining MoT man who does not know better, causes more spinning on the stub axle and will wear a step in the bottom of it.

Spacer kit adds a tube between the standard bearings with shims used between it's outer end and the outer bearing to set the float (shims not very clear in the pic)

P1180934s.jpg

Assembled

P1180936s.jpg

With this addition, once the correct shimming has been determined the hub nut can be torqued up, clamping the bearing races together at exactly the right distance apart to give the desired end float. My preferred is just the barest hint of play felt with the wheel fitted - which is tighter than I would dare without the spacer due to the aforementioned spinning bearings issue.  Because everything is now positively clamped together the inner races won't turn on the stub axle and the spacer shares any bending loads applied with the stub axle, making the assembly considerably more rigid and reducing flex.

 

 

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Blimey..... that's certainly plenty of beef!

TRs have greater need than a Vitesse or GT6 as they use the smaller bearings and stub axle from the the Herald and Spitfire, yet have the bigger wheels.....

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Thank you, Nick!  Very differeent from the Timken diagrams, and very clear.

Did you fabricate the spacer?

"Torqued up"   Did you choose the tightness from experience, or is there one quoted?

John

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Shit! Steve those axles may be just what I am looking for for a totally different project- would you mind throwing up some measurements if you get the time/inclination please?

I am looking at the diameter (should be about 26.9 mm?), the overall length, and the fitted length -from where the taper becomes the shaft to the end of the shaft before the thread

I think I have found a modern cartridge bearing type hub that may bolt straight up and would mean (among other things) 4x100 pcd, vented disc ease and cheap as chips! The only part it needs would be stubs that fit- and these may be less hassle than turning some up- assuming they will sell separately that is.

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3 hours ago, JohnD said:

Thank you, Nick!  Very differeent from the Timken diagrams, and very clear.

Did you fabricate the spacer?

"Torqued up"   Did you choose the tightness from experience, or is there one quoted?

John

The TR version of them comes from TR Enterprises.

The Vitesse/GT6 ones (also fit the 2000/2500 saloons) have been coming from James Shackford, (Triumphstuff on ebay IIRC)  though I had the last of his stock and he wasn't sounding that keen on making more.

He quotes a torque figure in his instructions, which I can't remember offhand, but it's fairly modest.  You still fit the split pin.

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Hmmmmmmmmmmm!    Would those be difficult to fabricate?   Bit of seamless tube, sliding (?) fit over stub axle.   Turned to the right length, parallel ends.   Not to high precision, as the shims then adjust.   Shim supply might not be so easy?? 

Or am I naive?

John

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Hello John,

 

easy enough for you as you have a lathe I seem to remember? Solid bar would be preferable to give a greater wall thickness, but more work of course.

You don't need to use shims at all, if you turn up over length slightly, assemble and check the end float,  then skim one end to achieve the correct end float, 2 to 4 thou like the rear hubs on a saloon?

 

Alec

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If you machine your own tube then make it on the small side in order to make a thicker shim than normal.

Making a 0.010" shim is not fun. making the same in 0.1" is much easier.

A tapered ID is not a problem.

Roger

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10 hours ago, rustbuckit2011 said:

Shit! Steve those axles may be just what I am looking for for a totally different project- would you mind throwing up some measurements if you get the time/inclination please?

I am looking at the diameter (should be about 26.9 mm?), the overall length, and the fitted length -from where the taper becomes the shaft to the end of the shaft before the thread

I think I have found a modern cartridge bearing type hub that may bolt straight up and would mean (among other things) 4x100 pcd, vented disc ease and cheap as chips! The only part it needs would be stubs that fit- and these may be less hassle than turning some up- assuming they will sell separately that is.

My car is at the bodyshop presently so can’t measure.

the stub axcles, and hubs etc, are from Classic Driving Developments, so get in touch with them from their website maybe?

steve

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Ah! tapered ID, of course, or else different IDs at either end. Ambition bigger than ability, on my part, despite roger's confidence.

J.

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Again, ah!   Maybe possible with my tiny, rattly lathe.   

John

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