Dismantling Beta calipers

[mangocrazy]

I've had no less than 6 Beta calipers staring at me reproachfully from their container for best part of 5 years now. I started getting them refurbished by dropping them in a bucket of diesel and then forgetting about them for 6 months or so. I then retrieved them from said bucket and set about removing the handbrake actuating mechanisms on the rear calipers and sending various parts off for plating. After a further delay I handed all the calipers to the local jetwash people to clean up as best they could. They had access to aggressive cleaning chemicals that I wouldn't even know about, let alone be happy using. The calipers came back externally spotless and ready for dismantling.

At this point I could really do with a tumbleweed emoji or gif...

Anyway, this morning I could bear the shame no longer and decided to see if I could dismantle the rear calipers, despite only having a sketchy idea of how they worked. I selected one of the three rear calipers (how did I ever wind up with three?) and tried to get the piston to move, clamping the caliper in the vice and using a lump of 5mm steel plate I had handy. It didn't even budge a fraction, despite my best efforts. Being an impatient sort, I decided it was time to reach for the gas axe; OK, so it's not oxy-acetylene, but propane, but the principle is the same. After a minute or so of heat soak I started to hear bubbling noises and see some smoke, so decided that was probably enough. The piston would now move quite freely and, as a bonus, the handbrake actuator simply dropped out (the piston was uppermost in the vice, so gravity and heat worked sufficiently for it to drop out).

With the actuator removed, there was now a hole through which I could introduce a drift. I inverted the caliper in the vice so the hole was uppermost and proceeded to 'persuade' the piston using topically applied violence to leave its bore. After a short time it popped out, much to my approval. I then turned the caliper round so I could access the bore and seal, and removed the seal with a long thin bladed screwdriver.

The actuator on one of the remaining calipers put up a lot more of a fight, but with careful use  of water pump pliers gripping, twisting and pulling the actuator (and more heat) it finally gave best and came out. Once the actuator was removed, hammer and drift came into play and the piston was soon sitting on the cellar floor (I have a workbench in my cellar).

The last caliper was the easiest of the lot; it all came apart quite easily. So I now had three rear calipers in their component parts, sitting on the bench. The piuture below shows all three dismantled calipers, along with most of the tools used, chief of which being the blow torch. I'm a big fan of heat in dismantling things. Once the actuator mechanisms have been removed, there is nothing really that will be damaged by heat (unless you go really overboard). Even the seals were still in one piece and were removed with little fuss. They will be going in the bin, though. It would be foolish in the extreme to try and re-use them.

Next step - the front calipers, once I've figured out a suitable means of attack. And all the caliper parts will be dumped into a bucket of diesel and acetone mixture and left to ferment for a few weeks...

Is it wise to keep pistons and calipers as a pair, or can they be mixed and matched?

[peteracs]

Hi

I did not keep them as pairs due to various issues with individual items. I have yet to fire them up...


Despite the Haynes manual saying do not, I removed the spring in the piston to remove the inner parts as there was a fair amount of build up of crap in there and looking at yours, will probably be the same.

Peter

[mangocrazy]

Hi Peter,

I (probably rather foolishly) didn't look at the Haynes manual prior to stripping the calipers down, so didn't see the warning. I'm glad that I did decide to dig deeper as there were unbelievable amounts of crap in there. No way could you reassemble the unit without cleanng all that rubbish out. I was totally gobsmacked at the mini-engineering involved therein. Thrust bearings, spring loaded tubes - Lancia did a proper job there. Can't imagine seeing stuff like that in a modern car. Two out of the three were full of crap, the other one was noticeably better, but all needed a full stripdown and a leisurely and relaxing bath in cleaning/penetrating fluid.

Graham

[WestonE]

This is all good work. BUT can you get the bleed nipples out without snapping them? If they do snap off as they frequently do get some banjo blots with bleed screws built in. You can get new pistons and seals from Big Red or have them do the whole job. I would fit new stainless pistons. I actually have one pair of rear calipers done by Big Red and NOS ones on the car.

Eric

[mangocrazy]

Hi Eric,

One of the bleed nipples has already been snapped off, so your comment is bang on the money. It was done a long time ago, but the passing of time won't have helped the others, I know. The Plan is to immerse all the parts in a 50/50 mixture of diesel and acetone for a week or five and then try again. Even with snapped off bleed nipples I have had success drilling them out with a LH drill bit. It's tedious work, though.

Fully take on board your recommendation for bleed nipple banjo bolts - they're wonderful inventions. They've saved my bacon a few times. And they're de rigeur on motorcycle brake master cylinders - without them trying to bleed the front brake is an exercise in futility.

I'm mildly amazed that stainless pistons would be available for these calipers. Are these calipers used on other models besides the Beta? Once all the parts are cleaned up, if there is any doubt about any of the pistons I'll replace them with stainless. Thanks for the heads up.

Graham

[mangocrazy]

Just seen this on eBay for Beta rear calipers:

https://www.ebay.co.uk/itm/REAR-Brake-Caliper-Piston-Repair-Kit-for-LANCIA-BETA-1977-1984-1-BRKP164S-/283151865115

At £14.95 a side for a repair kit, it seems foolish not to...

[peteracs]

Hi Graham

Has me wishing I had seen it available at the time, may however still need it if my rebuild was not up to it....

Peter

[mangocrazy]

It's hard to understand eBay vs. website pricing at times. I bought 2 of the above kits and, due to a special offer, got the pair for £26.90 including delivery. A single rear piston on BiggRedd's site costs £19.95 including delivery. Buying off eBay will incur eBay and PayPal charges. How can an item bought on eBay be nearly half the price of something bought on the company's own website?

And it's not as if we are comparing like with like here; the ebay items are a 7 piece kit. The piston sold on the web site is a single unit. I'm not complaining, but I really don't understand the logic of it.

[mangocrazy]

The Bigg Redd parcel arrived this morning and everything looks spot on. The finish on the pistons is exemplary, replacements for all rubber parts which can potentially degrade or split are included in the kit and they even include a sachet of silicone grease for assembly. Can't fault it.

[mangocrazy]

Today I decided to man up and try to remove the bleed nipples from the 2 front and 2 rear calipers that still have recalcitrant bleed nipples. I've already successfully removed the bleed nipples from 2 front calipers and sheared the bleed nipple on a rear caliper.

I'm a big believer in heat when trying to persuade dissimilar metals to separate. Thermal expansion/contraction is one of the best ways to break a bond based on corrosion, I've found. The trick is to get as much heat as possible as deep into the bleed nipple and caliper body as possible, and the most effective way of doing that is by using the heat by-product of welding. So I got onto eBay and bought myself some M12 half/lock nuts. These (as the name implies) are half the height of a normal M12 nut. They also drop onto a bleed nipple with a millimetre or so clearance. This space can then be filled with weld and the weld pool will grip the bleed nipple all round and (crucially) transfer lots of heat down the bleed nipple and into the caliper body.

I used a cheapo stick welder from Aldi, as I still haven't got round to getting any gas bottles for the Mig set I bought ages ago. I'm pretty sure a Mig set would be better, but you work with what you have. Anyway, my cunning plan worked! (For the most part). 5 out of the 6 bleed nipples came loose and were removed without shearing, but either I got sloppy, over-confident or unlucky and the last and sixth bleed nipple sheared off when the nut was attacked with a 19mm spanner. So a qualified success then.

The remaining two bleed nipples have been drilled out as far as I can without damaging the threads and I will have to resort to trying easy-outs on the remains.

Oh the shame...

I hate easy-outs with a passion, but right now they seem to be the last available option. Oh well...

[Neil-yaj396]

How did you avoid the weld attaching to the caliper body, as well as the nipple?

[WestonE]

Hi Neil

I think the answer here will be that the bleed screws are steel and the caliper body nearby is aluminum. Graham will be using welding rods for Steel which are not interested in sticking to Aluminum. I am impressed that he is doing this with a Stick welder which are happier being used for fixing railings and broken farm kit.

It is a decent approach to a problem on so many Betas.

Eric
PS I also hate easy outs because they can fail leaving hardened metal where you need it least. 

[peteracs]

Every time I try to use easy outs I fail miserably, so have given up with them. As Graham says, heat and patience can solve a lot of these problems.

Peter

[mangocrazy]

How did you avoid the weld attaching to the caliper body, as well as the nipple?

As Eric says, I was using welding rods made for steel, which don't work with aluminium. I was initially concerned that the heat from welding might melt the aluminium of the caliper body, but in practice that wasn't a problem, probably because ali conducts heat away so quickly.  And Mig would definitely be preferable to stick, but the cheap stick welder did a very reasonable job. I did use good quality Lincoln Omnia 46 rods, which probably helped.

<edit> Having had a closer look at the attempts which succeeded compared to the one that didn't, on all the attempts that worked the weld pool had reached the threaded portion of the nipple and enclosed the 'waisted' part of the bleed nipple, meaning that when force was applied to the nut it was bearing on the largest section of the nipple. On the attempt that failed, the fracture was on the 'waisted' portion (where it invariably fails), meaning the weld pool hadn't penetrated deep enough. So I'd take the following lessons from this:

1. Definitely use a half-height M12 nut, as this will allow the weld pool to penetrate as deep as possible.

2. Use a MIG welder wherever possible, as stick welding generates slag which can weaken the weld pool.

3. Don't be shy about putting plenty of weld into the joint. In my view, the more the better. Ideally you'd want the gap between nut and nipple completely filed with weld.

[mangocrazy]

Just found this excellent video on Youtube, entitled 'Nipple therapy'... 

https://youtu.be/q0Q_5F1o_wY