I have an early Evans VP-1 fitted with Dunlop brake calipers dated 1969, Part No H52730, using Lockheed brake fluid. The rectangular (hydraulic) portion of the caliper measures approximately 11cm x 4.5cm x 2cm with 2 circular pistons with attached friction material, each 3cm in diameter. The non-moving part of the caliper, on the other side of the brake disc, has 2 matching circular pads of fixed friction material. The disc itself has lugs around the circumference which engage in matching slots on the inner wheel rim which takes a 5.00 x 5 tyre. The internet suggests that very similar calipers were fitted to Beagle Pups. Not surprisingly after all this time, two of the four pistons are seized solid.
Has anyone any suggestions please as to where I might find spares for these calipers - pistons, seals and friction material? Having got a caliper apart, I shall obviously check to see which cars of that period were fitted with Lockheed brakes, in the hope that I shall find a wheel cylinder of the same diameter using the same seal. But maybe there is a better source of spares.
Any suggestion very gratefully received.
John Lindsay.
Early Dunlop Brake Calipers
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JohnLindsay
- Posts: 88
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- Location: Nr. Colchester
Hi John,
I can't pretend to have any expertise on these particular calipers, but I have been working on Racing Car brakes for 25 years, so here's my two penny's worth!
Firstly, what sort of piston seals do the calipers have? If they are'standard size' 'O' rings, you might be lucky enough to get replacements from Clarendon Engineering. You will need EP rubber material (Dowty 2064) to be compatible with brake fluid. If they are square section seals, you will have to try to find a suitable existing caliper seal. Have a look at our web site:
http://www.apracing.com
Let me know if your pistons match any of our standard sizes. If you need friction material in sheet form, you could try:
http://www.classicbrakeservice.com
Good Luck!
I can't pretend to have any expertise on these particular calipers, but I have been working on Racing Car brakes for 25 years, so here's my two penny's worth!
Firstly, what sort of piston seals do the calipers have? If they are'standard size' 'O' rings, you might be lucky enough to get replacements from Clarendon Engineering. You will need EP rubber material (Dowty 2064) to be compatible with brake fluid. If they are square section seals, you will have to try to find a suitable existing caliper seal. Have a look at our web site:
http://www.apracing.com
Let me know if your pistons match any of our standard sizes. If you need friction material in sheet form, you could try:
http://www.classicbrakeservice.com
Good Luck!
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JohnLindsay
- Posts: 88
- Joined: Mon Jan 07, 2008 8:39 pm
- Location: Nr. Colchester
Steve,
That's really helpful, thank you very much indeed. I haven't yet popped a piston because I might have difficulty getting it back and I need it in place to help me apply air/hydraulic pressure to shift its seized mate - if you see what I mean. As soon as I have removed a piston, I shall indeed look on your website. Worst case, I could probably have some pistons machined out of a suitable high grade steel, and then I could select a seal of my choice. I was wondering where I might find the friction material - now I know!
Thanks again. I'll let you know what transpires.
John.
That's really helpful, thank you very much indeed. I haven't yet popped a piston because I might have difficulty getting it back and I need it in place to help me apply air/hydraulic pressure to shift its seized mate - if you see what I mean. As soon as I have removed a piston, I shall indeed look on your website. Worst case, I could probably have some pistons machined out of a suitable high grade steel, and then I could select a seal of my choice. I was wondering where I might find the friction material - now I know!
Thanks again. I'll let you know what transpires.
John.
Dunlop brakes
Hi John,
I have recently overhauled the brakes on my Alvis TE21.
Dunlop car brakes had circular forged steel pots with pistons that had a pip on the end that retained the friction material. Each pot is held on to the caliper by 4 1/4 bolts through a flange at the open end of the pot.
They came in various imperial sizes my car has 1 7/8 fronts and 1 3/4 rear.
They are common to 60s Jags and Alvis dunno about other makes.
The pots are quite expensive to replace approx £100 each ( the alvis has 8 ). They can be refurbished by machining out the the pot and fitting an insert
Rubber seal kits are approx £10 a pot.
The good news is that the steel used is quite high quality, so I found that although the brakes seized ON solid when I first tried them, after prizing the pistons out of the pots, a good clean up with wet and dry removed pretty well all of the pits. The seals are 1/8 thick so they easily ride over any minor pits with no leaking
I got my new seals from powertrack 01753 842680
Suggest you take pic of the caliper and send them an email. If you have a pic email me, I may be able to confirm that they look the same.
I have recently overhauled the brakes on my Alvis TE21.
Dunlop car brakes had circular forged steel pots with pistons that had a pip on the end that retained the friction material. Each pot is held on to the caliper by 4 1/4 bolts through a flange at the open end of the pot.
They came in various imperial sizes my car has 1 7/8 fronts and 1 3/4 rear.
They are common to 60s Jags and Alvis dunno about other makes.
The pots are quite expensive to replace approx £100 each ( the alvis has 8 ). They can be refurbished by machining out the the pot and fitting an insert
Rubber seal kits are approx £10 a pot.
The good news is that the steel used is quite high quality, so I found that although the brakes seized ON solid when I first tried them, after prizing the pistons out of the pots, a good clean up with wet and dry removed pretty well all of the pits. The seals are 1/8 thick so they easily ride over any minor pits with no leaking
I got my new seals from powertrack 01753 842680
Suggest you take pic of the caliper and send them an email. If you have a pic email me, I may be able to confirm that they look the same.
Peter Diffey
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JohnLindsay
- Posts: 88
- Joined: Mon Jan 07, 2008 8:39 pm
- Location: Nr. Colchester
Gents, thank you very much indeed for all this most helpful advice. I have now got the calipers in pieces and, apart from the rubbers, I reckon they are in reasonable shape for their age - there's just one bit of corrosion on one of the ali pistons, fortunately away from the seal area. The pistons don't have a pip, just threaded hole inthe middle (to aid removal?). The round pucks of friction material just sit on top of the pistons which are well recessed in the caliper and so the friction material is, in effect, a second piston in the cylinder. The diameter is Imperial, 1.25" and I shall now get on to Powertrack to see what they have in the way of seals. I will take a picture if I can ever get my digital camera to work again! I emailed Dunlop Aerospace yesterday but am not really expecting an answer. I can't imagine trying to stop something as heavy as an E type from 140; my wife happens to race a V8 Morgan, but that's much lighter and won't make 140, quite. The old VP-1 is much more staid, thank goodness.
A question for Steve, perhaps, with his considerable experience - the caliper is machined with a rectangular groove but the seals that came out were O rings (and they are rotten enough to be the originals). I know how rectangular rubber seals work in a caliper but why should an O ring pull the piston back the necessary few thou when you take your foot off the brake? Or does the system rely on the floating disc to knock the pistons back? (By the way, I have some EPDM O rings on their way in the post, thanks to your advice).
Regards to all.
John.
A question for Steve, perhaps, with his considerable experience - the caliper is machined with a rectangular groove but the seals that came out were O rings (and they are rotten enough to be the originals). I know how rectangular rubber seals work in a caliper but why should an O ring pull the piston back the necessary few thou when you take your foot off the brake? Or does the system rely on the floating disc to knock the pistons back? (By the way, I have some EPDM O rings on their way in the post, thanks to your advice).
Regards to all.
John.
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Flapperons
- Posts: 5
- Joined: Thu Jan 10, 2008 6:11 pm
- Location: South West
Hi,
This might not be applicable any more, but the same or similar sounding brake units are used on my Airtourer.
The last time I bought some spare parts (friction material) I got them from a company called BTR Aerospace in Australia. They had an address at 836 Mountain Highway Bayswater.
Although it was quite a few years ago now (1998 - yikes that 10 years - where does the time go) they used to have a parts list that contains all the parts required including circlips, seals, pistons etc. May be of help that the piston seal has two numbers against it 13020 and SP916B8.
You might turn up something on Google search on the above.
Hope this helps.
Dave Disney
This might not be applicable any more, but the same or similar sounding brake units are used on my Airtourer.
The last time I bought some spare parts (friction material) I got them from a company called BTR Aerospace in Australia. They had an address at 836 Mountain Highway Bayswater.
Although it was quite a few years ago now (1998 - yikes that 10 years - where does the time go) they used to have a parts list that contains all the parts required including circlips, seals, pistons etc. May be of help that the piston seal has two numbers against it 13020 and SP916B8.
You might turn up something on Google search on the above.
Hope this helps.
Dave Disney
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JohnLindsay
- Posts: 88
- Joined: Mon Jan 07, 2008 8:39 pm
- Location: Nr. Colchester
Again, many thanks for all this advice. From all these excellent leads, I am sure that I shall be able to solve the problem. Worst case, Dunlop Aerospace have confirmed that they still have the drawings and are looking to see if they can release them to me.
Incidentally, my first car was a Morris 8 and I have many happy memories from my student days of keeping it running with the help of all the local scrapyards!
Incidentally, my first car was a Morris 8 and I have many happy memories from my student days of keeping it running with the help of all the local scrapyards!
If they are simple pucks, then I think you could safely make your own by buying a set of modern pads, cutting the friction material off ( hacksaw and face mask ), carefully dressing up the surface and epoxying the material on to the old pucks, then grinding the pads down to the shape of the pucks.
I would not imagine that stopping a VP1 is exactly hard on the brakes, I guess you only really use them for taxiing,
I would not imagine that stopping a VP1 is exactly hard on the brakes, I guess you only really use them for taxiing,
Peter Diffey
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JohnLindsay
- Posts: 88
- Joined: Mon Jan 07, 2008 8:39 pm
- Location: Nr. Colchester
Just to put this topic to bed, Dunlop Aerospace (now Meggitt Aircraft Braking Systems) could not have been more helpful and managed to produce the original drawings from the late 60s. Among other things, this information confirms that the O rings I sourced based on SteveB's advice should do the job just fine. Also, I now have dimensions and specifications for the pistons and friction material.
And, as if that wasn't enough, the Beagle Pup Club, some of whose members are replacing their Dunlop brakes with Cleveland systems, has found me an owner who is willing to part with some of his old Dunlop bits!
So, my sincere thanks once again to everybody for their various suggestions.
John.
And, as if that wasn't enough, the Beagle Pup Club, some of whose members are replacing their Dunlop brakes with Cleveland systems, has found me an owner who is willing to part with some of his old Dunlop bits!
So, my sincere thanks once again to everybody for their various suggestions.
John.