Freeing up siezed brake cylinder pistons
November 24, 2020 at 6:38 pm #5596
OK so all my brake cylinder pistons have seized. I believe that when the brakes were “done” about 25 years ago (it’s not been driven since) the cylinders were also replaced so should be in good nick – if I can get the pistons out.
I’ve created an attachment so I can fit a foot pump to it, and have pumped it up to about 110 PSI but can’t get any more pressure into it. It’s been soaking in diesel for about a week already.
I’m thinking heat next…any top tips? e.g. how hot can I realistically heat it without causing damage?
November 24, 2020 at 7:10 pm #5599
From what I can see from your pics I suggest you repair them with new ones.
November 25, 2020 at 6:43 am #5601
Sadly the repairing with new option is about £400 more expensive so I want to exhaust all other options first.
November 25, 2020 at 10:35 am #5602Lindsay SieblerParticipant
Hi I would be drilling a hole in the back so you can use a pin punch ,to knock out the piston. If you do not want to weld up the hole, you can thread it and fit a small grub screw and seal it with Loctite or similar. Start with say 3 – 4mm hole Cheers Lindsay Siebler Australia
November 25, 2020 at 11:17 am #5603
Ben, If you think that knocking the wheel cylinders out is the end of your problem then imagine what the bores are going to look like after so many years of corrosion.Not only will you have chucked away the cost of the repair kits you’ll have wasted many hours better spent elsewhere on the car. You can buy a set of 6 wheel cylinders for an XK120 (as advertised on Ebay) for £242 all in, less the cost of the repair kits you won’t need (£80?)and your estimate for doing the job properly and safely looks fragile.We all want to save money, but there’s a time and place for that and brakes ain’t it I’m afraid.Hang on to the handbrake levers on the rear cylinders as they may differ from the aftermarket efforts.
November 25, 2020 at 12:40 pm #5604
A fair point Roger, I was thinking that they’re possibly brand new cylinders that have never actually been used, just sitting there for 20+ years since being fitted. So not trying to cut corners, just keeping my options open since being advised elsewhere that it’s definitely worth investigating this as a possibility.
I’ll give it another day to see if anyone else has an alternative opinion for me to weigh up, and if I still can’t get it free I’ll just stump up the cash.
November 25, 2020 at 1:28 pm #5605
<p style=”text-align: right;”>Ben: as l’ve mentioned before, l’m an instinctive, natural-born cheapskate, but l have to say l’m with Mel and Roger here. Brakes aren’t a component to economise too much on, so, as you say, perhaps best to ‘stump up’ on this one. Incidentally l didn’t know XK 120 items fit the bill – that’s a great tip. Also, bearing in mind that your car is a long-term project and may not be on the road for a year or so yet, maybe consider not fitting brake parts till you are nearer journey’s end? For now, keep ’em in their greaseproof wrapping! Tim.</p>
November 25, 2020 at 2:38 pm #5606
Ben and Tim, Yes, I should have said that the manual adjustable XK120 and in fact the XK140 brake hydraulics, are the same as the Phase 2 Allard fitment.The master cylinder is also the same.Jaguar also messed about with self adjusting brakes during the production of the 140, I believe, before reverting to the micram adjuster system at some point so be sure that what you buy looks the same.I assume the retailers are either unaware that they fit the later Allards, or feel that the average Allard owner can afford the premium for the same thing! None of the above applies to the Phase 1 brakes on Allards unfortunately.And Tim is quite correct when it comes to fitting new hydraulics.Don’t bother until you’re very very close to putting them into service.New or old, they do have a habit of seizing the pistons in the bores.I regularly have to tweak the front pistons on my cars, especially after a winter layup.Probably caused by iron pistons in aluminium bores coupled with hygroscopic brake fluid.
November 25, 2020 at 5:38 pm #5607
All very good points, I shall put this on the back burner. It just seemed like a sensible thing to do in isolation from all the other jobs I have on, and since my driveway is quite steep a logical step to make the brakes work for if I need to get the car out.
Instead I’ll just attach it to my car with a rope so I can drag it out if needed, and lower it gently back again. I can deal with the brakes in the spring (he says, ambitiously hoping it’ll be anywhere near needing them by then!!)
November 25, 2020 at 5:57 pm #5608james smithParticipant
I have had them seized in the past and I have made up an attachment which fits on to my grease gun which works every time.
November 25, 2020 at 6:07 pm #5609
Most interesting to hear that the brake m/c is relatively easy to get hold of, Roger. Would this, by any chance, also be the same unit as the ’48-’71 Morris Minor master cyl?
Which prompts me to suggest whether it might be a useful idea to have, under the ‘Technical’ section of the forum, a discrete sub-heading which lists alternative sources from other car makes, of Allard parts which some/many of us may well need for our projects/rebuilds/everyday running? Long-established Allardistes like Roger, Mike, Mel and Dave (to name just a few) have a wealth of knowledge re. such things which would be good to have readily accessible thru the Forum. Administrators – what do you think?
November 27, 2020 at 6:24 pm #5610
The Morris Minor master cylinder will not do, the bore is too small.
The standard bore on my M type and K1 with phase 1 brakes was 1″. When I fitted phase 2 front brakes (which P1’s have) I had more than the usual difficulty in getting a good “pedal”.
It didn’t have the usual mc but it was 1″ bore. I chatted with Paul at Power Track and eventually decided on a 1.25″ bore mc. This provides a bigger fluid displacement and has provided a much better “pedal”. The piston stroke remains the same but the bracket bolt spacing needed minor modification. I also fitted a remote fluid reservoir which many of the original set ups didn’t have. They have a combined reservoir which is quite small and needs constant and tedious replenishment when bleeding (which can be another problematic area that needs particular understanding for Allards).
Rick Newman and I are in the process of setting up a fully itemised Technical section for the website. The plan is to arrange a drop down menu from a Technical menu heading that will list the various Allard models and their component parts all under separate headings.
These will then be populated with technical information and advice. There will then be a separate menu heading for Suppliers which will be similarly set up. We will be welcoming information and advice from members which will need vetting before posting. We will be seeking the help of our own members as well as commercial suppliers for this.
It will be a big task so please bear with us. We need to configure and set this up with the webmaster and are advised that he may not be able to organise it for a couple of months.
In the meantime I will try to scan the illustrated 25 page Lockheed Service Manual. It covers the Allards fitted with phase 1 brakes. I will then do the same for another smaller manual I have for the phase 2 brakes.
Bear with me please.
November 28, 2020 at 11:10 am #5611
If there’s anything I can do to help configure / build this web capability I’d be more than happy, or even just to take a look and chat over the options. I’ve got quite a lot of experience of customising websites 🙂
November 28, 2020 at 5:03 pm #5612
Thanks Ben, I will chat with David Moseley who is in charge of developing the website and deals with Mike Mason who is employed to do the technical stuff.
David is keen not to interrupt its present smooth running during Members subscription time so we will likely attend to it around Feb.
November 30, 2020 at 4:55 pm #5615
Thanks for the extra gen. on the master cylinder spec, Mel – and the details around the XKs 120 and 140, Roger. Useful stuff. Tho, try as l might, l cannot seem to reduce a predilection on the part of my Special, to jump to the left when l apply the footbrake – particularly at speed. So far as l can see, there’s no weeping from either slave on the n/side front.
November 30, 2020 at 5:08 pm #5616
Well it’s obviously breaking more on the left drum than the right.
1.Check equal adjustment on each shoe to drum. 2. Ensure that the leading edge of the linings are cut back about 2″ from the end of each of the shoes. The leading end is the end the piston pushes against not the pivot end. 3.Drums and linings are in good condition and clean. 4.Shoes mate well to the drums. 5.All 4 cylinders/pistons are functioning correctly.
It may also be that your shoes and drums need a bit if use to bed in and that the problem you are experiencing will correct itself in use.
November 30, 2020 at 5:10 pm #5617
I’ve no idea why all that text jumped around after I sent it. All were in line before I clicked submit ???
November 30, 2020 at 8:03 pm #5618
Tim, I’d not be too happy at the pulling to either side if it were me.As well as what Mel writes, do the linings look as though the contact areas between shoes and drums look the same on both sides of the car?I really can’t remember touching the front brakes on the car at all when I had it here, although I did fit reconned Phase 1 rear cylinders, which took forever to stop weeping.I wanted to chuck them down the road and fit the Phase 2 rear cylinders, but TE was happy with them as they were.It didn’t get much use in his ownership.Perhaps 100 miles max.As the fronts are not seized(?) on the right hand side (they DO seize, solid or partially, very easily!!) I’d be whipping all 4 of the pistons out for a clean up generally, and a regrease with the red stuff.This is almost an annual event for me on Phase 2 fronts.They really work very well indeed if all 4 are functioning as they should, especially so on a lightweight car such as yours.
As a matter of interest, it is quite possible to believe that your Phase 1 rear brakes are perfectly OK, especially if the handbrake is functioning well, when in fact, hydraulicly, they are seized solid (and may have been so for years) especially if you are not a regular MOT man.It is quite legal to request your tester on the now voluntary MOT test, to use a Tapley meter, instead of checking the car on the MOT brake rollers.The Tapley meter will show all is well with the overall hydraulic braking performance, since rear brakes offer much less assistance, working or otherwise, and the hand brake will easily lock the brakes on the mechanical circuit, leading to the false conclusion that the rears are OK.
December 1, 2020 at 12:57 pm #5619
First of all, apologies to you, Ben for suspected thread-hijack. Please feel free to do the same to my next query 😀
Now, thanks to Mel and Roger for your further advice. All good tips, which l will follow up in detail when l get the car back from engine work with Royal Kustoms – it’s due to go to Jim T in January.
Does converting from Ph.1 to ph. 2 rear cylinders involve much machining or other changes, Roger? Incidentally it came as a massive relief when l learned that it was you who had basically rebuilt the car and got it roadworthy for Tony E.
Lastly, since l got the Special from Tony, 5 yrs ago, l’ve driven it regularly (once a week on average, l’d guess), as l’ve been developing it, so possibly nothing has had the chance to seize or stick. My TR3 gets less exercise!
So l can report that the Special is a lot less hairy, and a lot more predictable, than it was when l first (Sept ’15) took it out on the A1 with no indicators, x-plies which were down to ca. 12lbs/sqinch (l’m the idiot for not checking) and steering gear with about 5″ of play at the steering wheel rim. David Cornwallis rebuilt the steering box and the response is now as good as r/pinion. 🙂
December 1, 2020 at 1:07 pm #5620
Ph 1 to Ph 2 rears:
Involves cutting new section out of backplates and fitting Ph 2 cylinders (with levers).
Then revising the cable arrangement from the handbrake lever. Mike Knapman has done this and may advise better, I haven’t – yet – but have all the bits to do it. So far I manage to keep my ph1s working reasonably well. The cable handbrake piston arrangement in the bisector does occasionally fail and needs resetting. There is also an upgrade designed by Dave Hooper (I think) that involves introducing a spring to assist the piston to return. I haven’t done that either but it looks quite straightforward and involves drilling a hole to house the spring inside the piston. MK has details I think. If not I will have them somewhere !
December 2, 2020 at 10:17 pm #5621
Thanks again, Mel; again, invaluable info which will save me untold frustration and grief.
December 15, 2020 at 2:37 pm #5647
December 15, 2020 at 3:11 pm #5648
it’s not just your letter “T” that’s dodgy, your “U” clearly needs some lubrication too!! 🙂
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