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Calipers: new, or recon?


Patrick Taylor

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Having had very little use in the past couple of years, the offside front (Type 14) caliper of the Bond is binding, and thinking that a bit of heat might help free it, I went for a drive. This resulted in brake fade, a lot of heat, and a blued disc. Not my wisest decision, in hindsight.

I have already replaced the brake fluid and believe it sensible to replace the discs as a pair, too. Which leaves the calipers: one working, one partially seized. I am not keen on 'only' fitting new seals, so the alternatives seem to replace them as a pair, either with new, or reconditioned, units. Given the relatively slim difference in cost (about £10 apiece at Paddocks), are there any benefits in taking the cheaper option? I am well aware of shoddy pattern parts and that re-worked Triumph parts might be better quality, but is this true in this case?

Finally, how easy is it to fit new discs and calipers? My only attempt at fitting new pads proved to be a real struggle, but perhaps new, uncorroded parts will be more straightforward. Given the heat generated (and the fact that I have some NOS ones) I intend to fit new bearings, too. I would regard myself as a competent mechanic: clutch changes, cylinder heads off & valves replaced, etc. in the past.

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2 hours ago, Patrick Taylor said:

How easy is it to fit new discs and calipers? My only attempt at fitting new pads proved to be a real struggle, but perhaps new, uncorroded parts will be more straightforward. Given the heat generated (and the fact that I have some NOS ones) I intend to fit new bearings, too. I would regard myself as a competent mechanic: clutch changes, cylinder heads off & valves replaced, etc. in the past.

Simple; I've done three Heralds and a Spitfire in the last year. I'd also suggest rebuilding your old calipers with seals and pistons. All the parts are available including stainless pistons if you want those, plus seal kits and if you split the caliper, the small seal between the two halves. The main requirement is to get them clean of rust; I sandblast and repaint before lightly honing the cylinder bores and replacing the seals. There have been issues with the replacement type 14 calipers, so using the old ones seems a better option.

The discs are only held on with four bolts into the hub; remove the hub, remove the bolts, knock off the disc, clean up the hub and replace the new disc, then refit to spec. As with the calipers the biggest problem may be removing them if they're rusted in place but a good impact wrench makes light work of it.

This was last week's work on the Herald:

IMG_0264.jpg.638ec96218a9bbb4346617d3e1eaa260.jpg  IMG_0546.jpg.19839469361d5ef65b5422c6e2d47f99.jpg

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1 hour ago, Colin Lindsay said:

Simple; I've done three Heralds and a Spitfire in the last year.

OK, it looks like I might give it a go, as I have a couple of seal sets in the drawer. I may not split the caliper, though: it sounds like 'here there be dragons' territory, like fully reconning a gearbox or rear pinion set. I just hope everything isn't seized -but suspect it will be 😒.

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24 minutes ago, Patrick Taylor said:

I may not split the caliper, though: it sounds like 'here there be dragons' territory, like fully reconning a gearbox or rear pinion set.

I've done that on a number of calipers, with no issues - I did ask if there was a specified torque for retightening, but there doesn't seem to be; it's just 'really tight'.. :) The impact wrench usually suffices.

It makes the two halves much easier to work on, especially if the pistons are really seriously seized. You can see the small rubber seal bottom right of the first photo.

DSCF5507.jpg.c0a27ce30a5892ae00705597f450cb59.jpg  DSCF5792.jpg.672d75bcaa2afb1dbefcdbd0625b19b8.jpg

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1 hour ago, Pete Lewis said:

i dont see any tab washers on calipers    where does it fit ..... nothing on any parts listing 

Pete

My  'Autodata' handbook shows a tab washer 'plate' (or two curved strips?) on the disc-to-hub bolts. But as mine has spring washers I'm assuming the tab washer is artistic licence! 

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On a personal level, I'd advocate the use of tab washers. A  bolt or nut relies on the interference pressure betwixt the underside of the (nut or bolt), and whatever the fixture is. If either slacks off, then it 'can' work loose. The tab being a sort of belt & braces approach to fixing parts in place.  Ideally, 2 bolts with tabs will hold tight against its neighbour.  

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2 hours ago, Patrick Taylor said:

Yes, that's what the diagram shows, but on the back of the hub.

If this is the Autodata manual, and the picture is J8 on page 105, it looks like this:

CAB278D4-79C1-40B1-B4BA-225317336D9B_1_105_c.jpg.7520d990106a2e46c85b01198ea8616a.jpg

Top two of the four bolts through the backplate are spring washers, bottom two are through a locktab. Bolts marked 8 are into the hub / disc through spring washers 9. 

 

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interesting mix of spring and tab washers, I wonder what the engineering thought was behind the mix in what appears to be the same operating environment. Obviously the tabs are the best method of locking the bolts/nuts

If any of the 8 bolts came loose they would have the same end result of jamming up the rotating hub and fixed components of the vertical upright, so why the difference in securing options. Irrespective always use new good quality spring washers, because there is some (PRC) china made rubbish out there!  

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10 hours ago, Peter Truman said:

If any of the 8 bolts came loose they would have the same end result of jamming up the rotating hub

No, they don't. What happens when the inner bolts come loose, well before any risk of interference with the hub, is that the steering arm and caliper mount become loose. Then you get vague and wandery steering, lots of loud knocking on braking, and a generally unsafe car. At least until Falls of Shin control, where you work out what the problem is and borrow the tools you need to fix it.

I suspect the use of a lock tab only on the bottom is down to those being the bolts that hold the steering arm.

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Now THAT'S interesting! Haven't seen that before, and definitely lock tabs. I suspect that because it's not in the Brakes section they've used artistic licence, maybe from another marque, as none of the original Herald or Spitfire manuals show the discs held on that way. If you want to use that method I'll be out in the garage later and will confirm if the backplate locking tabs are the same curvature, or indeed if any that I have from anywhere on the Herald will suit.

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