Progress on Brakes

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steve lapp
Posts: 102
Joined: Sun Jan 30, 2005 10:48 am
Location: Ontario, Canada

Re: Progress on Brakes

Post by steve lapp »

Hi Tom:

So the large diameter seal must be stretched to fit over the flange and sit in that groove?

If I have this correct - pressure form the master cylinder is applied in the large bore diameter and that pushes the whole assembly against the spring, which means the pressure in the system side going to the front brakes is higher as there is effectively less area there due to the rod that is at the center of that area. Does the rod actually stick out the end of the cylinder - and is covered by a rubber cap or something?

I am thinking about solution based on above as the operating scenario. Maybe cutting a groove in the large part of the stainless part (the 32 mm) but with an ID that matches available seals. The seal would need to be oriented to resist pressure form the high side of the chamber, which will be the front brake fluid side.

Will look at detail when I get home tonight.

cheers
Steve Lapp
Ontario Canada
2013 Nissan Leaf, 2002 Prius, 56 Healey 100-4, 74 BMW 2002, 330 GT 2+2 s/n 6241, 54 Dodge M152 (listed by decreasing fuel economy)
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tyang
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Re: Progress on Brakes

Post by tyang »

Hi Steve,

Yes, the seal is stretched over the flange, and yes the rod protrudes out the end of the equalizer.

I'm sure there is a seal out there that will fit without modification.

Tom
'63 330 America #5053
steve lapp
Posts: 102
Joined: Sun Jan 30, 2005 10:48 am
Location: Ontario, Canada

Re: Progress on Brakes

Post by steve lapp »

Hi Tom:

I am not able to locate seals with the exact dimensions, however I did find the website below that purports to have rubber washers of every size. (I tried McMaster Carr, Spaenaur and Hercules for seals).

http://www.standard-gasket.com/rubber-w ... -sizes.htm - might be worth a try. The 19 x 32 mm one could maybe be sustituted with an inches 0.750 x 1.250, unless the bore is exactly 32 mm, which means you need more than 1.2598 inches to get some sealing contact pressure. I think you want EDPM material for DOT4. Or, as was suggested earlier, see if someone can turn them up from a larger piece of material. I suspect the surface finish of the rubber does not to be that spectacularily smooth as the compression fit will smooth it out to the bore surface. Let me know how you resolve this little bump in the road.

Can't make it to Connecticut this weekend, but car is on the road and handles much better with two rear shocks that both have fluid in them! I set the shocks halfway between the high and low damping range, seems good for spirited driving. Next - the silent block bushing in the rear springs.

Cheers
Steve Lapp
Ontario Canada
2013 Nissan Leaf, 2002 Prius, 56 Healey 100-4, 74 BMW 2002, 330 GT 2+2 s/n 6241, 54 Dodge M152 (listed by decreasing fuel economy)
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tyang
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Re: Progress on Brakes

Post by tyang »

Hi Steve,

Thanks for the research. I'm coming up blank as well, but Karps Brake Service has agreed to have some custom seals made. They checked their U.K. supplier and they don't have them either.

I'm writing a post about it today, but I'm going to try to see how much interest there is in buying a set of seals. The price will probably be about $20-25 a set to absorb the cost of the custom molds. Karps has a pre-order from a Ferrari Parts supplier, but this is a chance for everyone to order a set at cost.

Email me so I can make a list of people who want a set.

Tom
'63 330 America #5053
steve lapp
Posts: 102
Joined: Sun Jan 30, 2005 10:48 am
Location: Ontario, Canada

Re: Progress on Brakes

Post by steve lapp »

Tom:

How is proportioning valve rebuild going (or is it secretly bypassed)?. I am having fun(?) exploring the depths of the water pump seal system.

cheers
Steve Lapp
Ontario Canada
2013 Nissan Leaf, 2002 Prius, 56 Healey 100-4, 74 BMW 2002, 330 GT 2+2 s/n 6241, 54 Dodge M152 (listed by decreasing fuel economy)
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tyang
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Re: Progress on Brakes

Post by tyang »

steve lapp wrote:Tom:

How is proportioning valve rebuild going (or is it secretly bypassed)?. I am having fun(?) exploring the depths of the water pump seal system.

cheers
Hi Steve,

No, it's not done yet! I've been working with Karps in making new seals. I went on this wild goose chase with GT Car Parts trying to get them to send us one seal they supposedly had made for the equalizer, but after a couple promises, we still didn't get the seal. Ron at Karps even tried with no luck, so we've decided to make both seals from scratch. I'll be meeting the guys at Karps next week at the West Coast Party, so I should have an update by then.

It's taken forever, but I hope I get my car back together soon!

Tom
'63 330 America #5053
Melchior
Posts: 148
Joined: Thu May 03, 2018 11:44 am

Re: Progress on Brakes

Post by Melchior »

Hi,

I am restoring this brake booster right now and was able to dissemble the unit properly. I will have a new piston machined from stainless steel and will replace the bushing in the booster housing as both show little corrosion and it is my understanding that there should be as little play as possible to avoid leakage and provide a smooth glide of the piston.

I have two questions here: in this post several times a piston with 3mm is mentioned. My piston has more like 6mm or so and is definately much thicker than 3mm and there is no other. What do you mean with this 3mm piston? Do you have a picture of it please?

And second the milion Dollar question: did you get a seal kit with the correct dimensions and materials somewhere? I realised that the seal in the steel cup was of a much harder rubber than the rubber ring seated in the grove of the piston. This donut-shaped ring is of a much softer rubber material.

And finally, what´s about the rubber cap outside at the top of the booster - do you know where to get this one?

best regards,

Martin
250 GTE #3631 (series Ii)
chris
Posts: 219
Joined: Sat Mar 02, 2013 7:52 am

Re: Progress on Brakes

Post by chris »

Rubber cap is available from Cicognani. I do have an address for new brake balancer, they might be able to provide the seal kit. I can ask them for you.
John Vardanian
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Joined: Wed Sep 04, 2002 12:13 am
Location: San Francisco Area

Re: Progress on Brakes

Post by John Vardanian »

Hi Martin, I am trying to follow what you are saying re the 3mm vs. 6mm. Are you referring to how far the seal stands above the cup? It looks more like 3mm here. Maybe you can explain. I got that elusive seal from Karp's a few years ago. I cannot remember the name of the fellow I spoke with. Incidentally, the Cicognani part number for the end dust cap is 16308.

Also, you may want to do a search of "Brake Equalizer" in Tom's blog.

john
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Melchior
Posts: 148
Joined: Thu May 03, 2018 11:44 am

Re: Progress on Brakes

Post by Melchior »

Thank you Chris and John!

I made a typing error, the diameter of my piston is 16mm - see picture. What I do not understand is the previous post of Mike from 4th of May 2010:


I will happily submit to any flaming if I am wrong but I think the 3mm rod is designed to generate a bit of pull back on the piston in the brakes released position so the pads are off the disc.A bushing of sorts is inside the piston and the rod goes thru it. Minor flex of the thin metal leaves the bushing a bit behind and when the pressure is off the flex pulls the piston back.Mike


What does he mean? And which one is 3mm rod he is talking about?

I will look for the cap from Ruthland and hope it fits properly. I do have a new brake equalizer/booster (see picture) and the cap of this one does not fit the original equalizer as it sits too loose, it would come of quickly when the car is operated.

Regards,

Martin
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250 GTE #3631 (series Ii)
Melchior
Posts: 148
Joined: Thu May 03, 2018 11:44 am

Re: Progress on Brakes

Post by Melchior »

Melchior wrote: Wed Dec 22, 2021 7:50 am Thank you Chris and John!

I made a typing error, the diameter of my piston is 16mm - see picture. What I do not understand is the previous post of Mike from 4th of May 2010:


I will happily submit to any flaming if I am wrong but I think the 3mm rod is designed to generate a bit of pull back on the piston in the brakes released position so the pads are off the disc.A bushing of sorts is inside the piston and the rod goes thru it. Minor flex of the thin metal leaves the bushing a bit behind and when the pressure is off the flex pulls the piston back.Mike


What does he mean? And which one is 3mm rod he is talking about?

I will look for the cap from Cicognani and hope it fits properly. I do have a new brake equalizer/booster (see picture) and the cap of this one does not fit the original equalizer as it sits too loose, it would come of quickly when the car is operated.

Regards,

Martin
250 GTE #3631 (series Ii)
Melchior
Posts: 148
Joined: Thu May 03, 2018 11:44 am

Re: Progress on Brakes

Post by Melchior »

Cicognani, not Ruthlands - sorry.

Maybe I am too stupid but I can’t find a way to edit my previous posts here so all mistakes are safed forever….
250 GTE #3631 (series Ii)
abrent
Posts: 128
Joined: Wed Sep 11, 2002 1:50 am

Re: Progress on Brakes

Post by abrent »

Hi, I just noticed that the "replacement" equaliser in the photos is larger than the original GTE unit. This is possible as the Muira has the same set up as Ferrari but a larger equaliser, and is generally more available. (Who knew...). Don't use the Muira version in a GTE and vice-versa.

Rgs,

Andrew.
abrent
Posts: 128
Joined: Wed Sep 11, 2002 1:50 am

Re: Progress on Brakes

Post by abrent »

sorry - Miura... How embarrassing..
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