Help ID brake calipers

[HS30-H]

8 hours ago, Jeff Berk said:

Does anyone have an opinion on machining a modern bleeder screw to match the one used in the mk63?

Before you go to that trouble, check out your national suppliers of old Jaguar parts (mossmotors.com for one) and investigate caliper bleed screws for the Girling-Dunlop brakes used on 50s and 60s models such as the MK.1 through Mk.10, XK150 and early E-Type. The Sumitomo MK63 licensed a number of Girling-Dunlop patent designs which also used the ball-bearing type bleed screw system.

On 8/10/2024 at 8:42 PM, Jeff Berk said:

I have a Wilwood 1-inch master cylinder I bought off someone that I'm trying to figure out what to do with since I'm no longer going with the Toyota 4X4 brakes. Is there any advantage to installing this unit over staying with the OEM?

Larger bored master cylinders are not required. I have used both solid rotor and vented rotor type MK63 calipers on many of my cars over the years (still use them on four current cars) and I always use the stock 7/8" master cylinder. I even use the 7/8" bore on my 432-R replica with its Master Vac delete (pedal motion ratio is modified) and they work well. Nissan's own recommendation was to use stock MC.

A friend over here fitted a Wilwood 1" MC on his rally 240Z with vented rotor type MK63s and found that it gave a high and firm pedal feel but was hard to use. Switched back to a stock 7/8" MC which I supplied to him and he was MUCH happier.  

[Jeff Berk]

HS30-H

I learned of the similar Jag bleeder last night while researching the Sumitomo. It appears to have also been used in some Studebakers like the Avanti. A post on a Studebaker forum suggested just cutting off the tip of a modern bleed screw to create one.  The Jag screws, at least the one I found a reference to were 3/8" 24 thread although they also used a 3/16-inch ball.

Captain Obvious

The treading was a little messed up on the original bleed screw, possibly from being over tightened but the caliper's threads seemed to be fine. The old screws were tightened to the point where the flat tip was deformed by the ball bearing.

I just came back from the makerspace where I modified a pair of bleeder valves I had on hand. The photograph shows from left to right, an unmodified bleeder, a modified, and the original. The original likely had a flat bottom when new but was damaged as mentioned above. I decided to mill a shallow 3/16-inch diameter concaved surface to secure the ball instead of just making a flat surface. This was likely unnecessary. I then spun the 3/16 end mill by hand in the caliper where the ball seats to clean it up a little. I might try and assemble this and see if I can draw a vacuum with the valve closed to test for leaks.

[Captain Obvious]

Cool. I didn't think they were hardened, but had to bring it up just in case. Nice work.  

Edited August 15 by Captain Obvious

[Jeff Berk]

The parts are finally being shipped so that I can rebuild the brakes. In the process I learned a bit about purchasing through the Japanese sites Jauce (brake pads) and Amayama (4 pistons and seals). Mostly that fees can be far greater than the cost of the parts for the Jauce action site.  Note $0.0068 dollar to 1 yen. Amayama was reasonable with fewer line items.

 

[RIP260Z]

27 minutes ago, Jeff Berk said:

Mostly that fees can be far greater than the cost of the parts for the Jauce action site.

True, but sites like Jauce let you buy NOS parts and other rare parts, if you want, like I do, its the price that needs paid, otherwise there wouldn't be any restoration.

 

[Jeff Berk]

Looking at this diagram, it shows a dust boots that go over the pistons and rests on the inside surface of the caliper (Part 5). The original boots were held on using a wire spring clip. I'm assuming the clip is not needed since its not shown and the dust boot will seal well enough just resting on the caliper even as the pistons move in and out. Please correct me if I'm wrong.

[HS30-H]

7 hours ago, Jeff Berk said:

Looking at this diagram, it shows a dust boots that go over the pistons and rests on the inside surface of the caliper (Part 5). The original boots were held on using a wire spring clip. I'm assuming the clip is not needed since its not shown and the dust boot will seal well enough just resting on the caliper even as the pistons move in and out. Please correct me if I'm wrong.

Part No.4 on the diagram are the steel rings which retain the rubber dust seals (Part No.5) in the caliper halves. The rings are a tight push fit in the caliper casting, leaving a lip around which the dust seals grip. In this way the dust seals remain fixed in one place and the pistons are free to move past them.

Wire spring clips retaining the dust seals do not sound like original parts and may in fact be the work of a previous owner? The original steel retaining rings tend to rust over time and - in some cases - can all too easily get damaged/deformed when being removed. A previous rebuild/seal replacement may have forced some improvisation?

In any case, you do need the correct seal retainer rings as without them the seals are going to move away from the caliper casting as the pistons operate, uncovering the gap between the pistons and the caliper castings. They won't last long like that... 

[RIP260Z]

Jeff,

I pointed out these retaining rings in post 40, here is a link;

https://www.jauce.com/auction/w1147945499

Unless H30-H or Kats know of another place the get original or someone else who makes these, velo1955z is the only place I have found. I have another set of rings arriving today from Japan.

[HS30-H]

15 minutes ago, RIP260Z said:

Unless H30-H or Kats know of another place the get original or someone else who makes these, velo1955z is the only place I have found. I have another set of rings arriving today from Japan.

YJ auction vendor 'velo1955z' is VintageCraft e-za, the manufacturer of the stainless steel MK63 seal retainer rings and one of those classic one-man-band Japanese craftsmen. Great guy and a fellow member of Club S30 Japan. He makes all sorts of other interesting stuff too. https://www.vintagecraft-e-za.com/

I'm not aware of any other people who make the retainer rings in stainless steel. They are a boon as they don't rust and can survive multiple re-use, unlike the originals.

 

[Captain Obvious]

4 hours ago, HS30-H said:

Part No.4 on the diagram are the steel rings which retain the rubber dust seals (Part No.5) in the caliper halves. The rings are a tight push fit in the caliper casting, leaving a lip around which the dust seals grip. In this way the dust seals remain fixed in one place and the pistons are free to move past them.

If Part No.4 is a metal ring (no rubber) that retains Part No.5 (dust seal), then where / what is the hydraulic seal that holds the brake fluid in?

I've never messed with that caliper, but looking at the drawing it looks to me like the hydraulic seal is Part No.4. Which would then beg the question... What would hold ithe dust seal on?

Edited August 27 by Captain Obvious

[HS30-H]

1 hour ago, Captain Obvious said:

If Part No.4 is a metal ring (no rubber) that retains Part No.5 (dust seal), then where / what is the hydraulic seal that holds the brake fluid in?

I've never messed with that caliper, but looking at the drawing it looks to me like the hydraulic seal is Part No.4. Which would then beg the question... What would hold ithe dust seal on?

Yes, you're quie right. Well spotted.

Looking at the diagram again, it seems that they have NOT illustrated the dust seal retaining rings and that Part No.4 are indeed the fluid seals which slot into the groove inside the caliper casting.

Odd that they don't show the retaining rings on their own, but I wonder if this is a legacy of the old rebuild kits which used to come with the dust seals already fitted with their retaining rings inside them? Unfortunately they don't come like that anymore.

Anyway, as mentioned, the retaining rings are essential otherwise the dust seals won't work properly. Jeff Berk definitely needs a set.

 

Edited August 27 by HS30-H

[Jeff Berk]

I'm impressed by all the responses. First, part 4 is labeled as a "piston seal". I included a photograph showing the old one on the left. On the right is the old dust seal with the metal ring inside. I mistakenly assumed it was a retaining clip. I need to clean them up but at least the couple I looked at this morning look serviceable. I am also assuming that the dust seals likely came with these retaining rings back when Nissan supplied them. I had to purchase an aftermarket set because that's all I could find.

I really want this put together by tomorrow so I can register for my first autocross of the year this weekend.