When I purchased this 1966 3.8S S-Type at auction, the brakes were completely inoperative. So the first order of business was to make them sufficiently functional so I could at least move the car around without the drama of having to shift to Neutral and use the barely-functional handbrake.

I found the worst problem to be an internal fluid leak in the brake vacuum servo, so after some research, I ordered and installed the upgraded 4.25:1 unit from SNG Barratt. The original servos were 3:1 ratio, so the upgraded units should provide additional power assist. After bleeding all four corners, the car would stop well enough to move around the property, but test-drives around the neighborhood were still a bit scary.

Upon inspection, I found that the pistons in the front calipers were firmly or mostly seized. I was able to free up one piston in each caliper with just a little effort, but I wanted to plan a solution that didn’t rely on the original calipers being rebuildable.

After much more research, I found that rebuilt Dunlop calipers were scarce and expensive and often required sending one’s own calipers in to be rebuilt, which I could do myself if they are rebuildable. Various new and attractive 3-, 4- and 6-piston upgrade options are available (or have been), but the cost seemed unnecessarily expensive. Calipers from later Jaguars are said to be potentially useable with other modifications, such as replaced steering uprights, but those parts are getting scarce and expensive and would typically require renovation or rebuilding.

The option that seemed most attractive to me was to use Girling 4-piston calipers for the Volvo 240 series of sedans, which require only minor modifications for use on the S-Type. The Jag-Lovers forum and the International Jaguar S-Type Register contain several accounts from owners who have performed the Volvo conversion and were pleased with the results, and there are two excellent DIY instructionals available online (see attached pdfs).

After much shopping for good salvaged Girlings that I could rebuild, I discovered that Rock Auto carries Nugeon remanufactured Girling calipers for the 1984 Volvo 242 with solid rotors for the princely sum of USD $38.00 each, plus sales tax and shipping. A no-brainer, I thought, and ordered a right-left pair.

The Girling calipers are metric, so the 12 mm (0.472") mounting holes must be enlarged to 1/2 inch (0.500"), a simple process.

Another difference is that the calipers have two inlet ports to work with the Volvo dual-circuit brake system. To use them with the single-circuit S-Type, one must either devise a means of connecting the brake hose to both ports on the caliper, such as a wye or tee fitting, as shown in Brian Ternamian’s DIY, or the two halves of the calipers must be separated, the pistons removed, and communicating holes drilled between the pairs of piston cylinders so fluid in all four cylinders will receive pressure applied at either inlet port, as shown in David Kerr’s DIY. The unused inlet port is simply plugged. I liked this second option best, so I mostly followed David Kerr’s DIY.

The original S-Type front rotors are 11 inches in diameter and will not allow the Girling calipers to line up with both mounting holes. The diameter of the rotor must be reduced. I found many online references to removing “about 4 mm” from the “rotor,” but no explanation as to whether this was from the radius or diameter, nor could I find any specification as to what the finished rotor diameter should be. After much measurement and test-fitting, I determined that the finished diameter of the rotor needed to be 10-11/16 inches, so 5/32” (4 mm) must be removed from the radius of the original 11-inch rotor for a total reduction in diameter of 5/16” (8 mm).

Additionally, the Girling calipers do not directly center over the original rotors, which are just 3/8 inches thick. A thick stack of shim washers is required to move the caliper inboard so it will be better centered on the rotor. Rotors for a Series 2 E-Type are 1/2 inch thick, so a thinner stack of shim washers is required, and there is less risk of a piston reaching the end of its travel if the pads become excessively worn. The E-Type rotors are 11-1/8 inches in diameter, so 7/32 inch (5.6mm) must be removed from the radius. I opted for the E-Type rotors. Brian Ternamian did his own rotor re-sizing with a bench grinder positioned on the floor, but all of my grinders are mounted on benches or stands and I didn't want to spend the time to try Brian's method, so I had my local machine shop reduce the rotors' diameters on a lathe..

With the 1/2 inch thick E-Type rotors, I only needed one 3/32 inch-thick shim washer on each caliper mounting bolt to center the calipers on the rotors:




To check for centering, I “blued” the edge of the rotor with a Sharpie marker and scribed a center line. Over this scribed line I centered the seam where the two halves of the caliper meet:




The caliper mounting bolts use a lock washer plus a thick flat washer. Since the added 3/32 inch shim washer reduces the length of bolt thread that can engage the steering knuckle, one owner purchased longer bolts and shortened them to the new correct length. I decided to simply leave off the original flat washer and use only the lockwasher. This allowed the bolts to thread in very closely to their original depths.

The Girling caliper is slightly longer than the Dunlop, so the rotor splash shield needs to be trimmed slightly for clearance. Once I was happy with the clearance, I applied a little paint to the freshly-cut metal:




The S-Type brake hose mounts vertically near the top of the caliper. The Girling caliper inlet ports straddle the caliper vertical midline and face forward. David Kerr fabricated a new bracket and used longer hoses to have a nearly straight hardline between the hose and caliper. I liked Jaguar’s hose routing and didn’t want to fabricate a new bracket or mess with the tie rod lever, so I just made up some Arabesque-curved hardlines. The Girling calipers are metric, so they require 10x1 mm male fittings, and the S-Type is Imperial, so the female nuts to connect to the hoses are 3/8-24 inch UNF.




The hardlines may seem longer than necessary, but this is still only about half the tubing used to connect the two halves of the original calipers:



Here’s a shot of the installed calipers showing the two pistons per side:




One of the nice things about this conversion is that there are many types of brake pads available for the Volvo 240 solid disc calipers. Several S-Type owners like the EBC Greenstuff pads, which I have used on other cars, but I could not find a set in stock in the U.S. So I opted for a low-metallic set from Dynamic Friction. They seem quiet and stop well, but they can be easily swapped if I decide to try something else:



Since I had to remove the hubs anyway, I cleaned and repacked the wheel bearings and readjusted them.

I have new brake hoses and a full set of new Cunifer brake lines from SNG Barratt so that’s one of my next steps. But first, I’ve got to work on the steering. There’s about 4 inches of play in the steering wheel, and the play seems to all be in the leaky power-assisted Burman box, so that’s my next learning curve. Suggestions will be greatly appreciated.

I will eventually see if the original front calipers are rebuildable. If so, I will replace the original rear calipers (with 1-3/4 inch pistons) with the rebuilt front calipers (with 2-1/4 inch pistons). This is said to better preserve the original front-rear brake bias after upgrading the fronts to the Volvo 4-piston calipers.

For now, it’s nice to have brakes that work really well.

Cheers,

Don

 

all those are not minor modifications. I hear you can use XJ-6 calipers without mods.

 

Hi Jose,

My recollection is that the early Series 1 XJ6 may have used the same calipers and solid discs as the late S-Type, so they would not be an upgrade, and parts are just as hard to find as good S-Type parts. The later Series 1 XJ6 had vented front discs and 3-piston Girling calipers, but those calipers are also hard to find today, and even used ones that would require rebuilding are expensive. The late Series II XJ6 had 4-piston calipers and vented discs, and new parts are available and not terribly expensive, but my understanding is that they will not fit the S-Type without changing the uprights. I understand that 420 calipers can be used if the 420 uprights are also used, but again, availability is a problem. I'm sure I have some of these details wrong - hopefully other members will correct me.

The Volvo Girling upgrade cost me a total of about USD $280.00 including remanufactured calipers, new rotors and pads, Cunifer tubing and fittings, shim washers and machine shop time. It took a little time and planning, but in my opinion, the modifications were minimal, easy to accomplish, and the car was only disassembled and immovable for a day. But I understand that perspectives vary, and that owners working on concours show cars will have to maintain at least the appearance of origininality.

Cheers,

Don

 

The later S-Type an 420 had the 3 pot callipers which have a different bolt spacing and so if you have a MK2 or earlier S-Type you need the later hubs.

The 3 pot callipers are the same as early XJ6 and I understand the later XJ6 4 pot callipers can be fitted in place of the 3 pots as they have the same bolt spacing.

Overall the Volvo conversion looks a good option and aside from turning down the rotors is a largely bolt on kit, especially if you keep the dual brake line arrangement. One forum member on here turned his discs down with a bench grinder while the disc was on the car if I remember correctly.

 

The better way to go is the Fosseyway brake kits that are designed for both the MKII and 3.8s. They have both 4 piston and 6 piston kits made to work with the stock brake booster system. I have the 6 piston with slotted vented 12.5" rotors that provides excellent braking. Previously, I used the 4 piston Willwood kit but that is just not enough for more serious power and hard driving as I had them fade and loose braking after 2-3 hours of hard constant cornering. Now with the 6 piston Fosseyway brakes it can take any extreme prolonged abuse I can encounter. The kit works great as I did not need to change anything else and I highly recommend their brake kits.



https://www.fossewayperformance.co.u...grades-dunlop/
https://www.fossewayperformance.co.u...eries-1-and-2/ they have this 6 pot for the MKII and 3.8s

 

Hi Primaz,

I looked at the Fosseways, Wilwoods, Coopercrafts, M&C Wilkinsons, Limoras, a few options each at Barratt and Moss, and other modern upgrade kits I can't remember, but they all seemed like overkill. I'm never going to race this car. It's going to go to church and restaurants, and to car meets via country roads. And again, I spent a total of USD $280. What do a set of 4-piston Fosseways cost?

Cheers,

Don

 

I have a later December 1967 S Type and the brakes are not the same as the 420. I still have two pot calipers on the front which were on the early cars Dunlop and on mine and later cars Girling but basically the same design. The 420 had three pot calipers but these were never factory fitted on the S Type.

 

True if you are not really driving the car much you might as well stick to stock brakes. If you want better performance then I do feel the Fosseyway brake kits are well worth it. They make 3 versions, a better quality stock, a 4 piston vented option, and the powerful 6 piston 12.5" vented. People always underestimate the value of brakes and to me it is worth it for safety to build it a bit overkill. It became apparent to me than if you just drive you car thru the windy roads for any extended time 60 minutes or more you will feel the brakes heat up and start to loose their stopping ability, go longer say 2 hours and you can loose 75% of your braking. These cars are automatics so the brakes will fade very fast if you drive spiritly as you cannot downshift to slow down so you wear the brakes much faster. I first used the Willwood 4 piston kit for the Jaguar but that did not have vented rotors and it was not that much better than stock to me. Also the Willwood kit is about $700 US and the Fosseyway 4 piston is only about $300 more and a better design with better rotors. Yes the 6 piston is about double but for me I drive my car hard and having increased safety is well worth the price.

Standard Brake Upgrade (Dunlop)

Standard Caliper Upgrade for Solid Discs

The Standard Brake Upgrade for cars originally equipped with Dunlop disc brakes offers the most economical way to transform the way your car looks, feels and stops. The modern caliper is designed to be used with standard brake discs to reduce cost and simplify installation.

The light weight aluminium 6082 T6 billet caliper uses modern seals to give a reassuring pedal feel, offers a vastly increased brake pad area and improved wheel control by reducing your cars un-sprung weight. All our calipers are 100% compatible with your existing hydraulic system and maybe fitted without any permanent modification.

The Fosseway Performance uprated brake caliper incorporates the following features:

• Made in the UK
• Elegant design in a choice of finish
  • Standard silver anodized body
  • Optional easy clean black powder coated body
  • Optional extra durable black hard anodized body
• Modern four piston caliper design
• Strong and rigid 6 bolt caliper body construction
• Internal fluid crossovers
• Fully dust sealed
• High temperature fluid seals

The Standard Brake Upgrade includes:

• 2x Lightweight four piston calipers
• Stainless steel braided brake lines for the front of the car
• EBC Ultimax brake pads

Standard Brake Upgrade (standard silver) £695.00 + VAT

Standard Brake Upgrade (optional black) £745.00 + VAT

 

The 420 has the three pot calipers shared with series 1 XJ and some series E type. The entire 420 front subframe complete with brakes and Varamatic steering box will fit a MK2 or S type. If you can't find a 420 subframe, the uprights are a straight swap for MK2 uprights (hub carriers in old Jag speak?). The XJ uprights are different, but can be made to work with the top wishbone inverted. However, once you reach that stage, there's so much cost to replacing and reconditioning that it's easier and cheaper to follow the 420 to route and/or the upgrades suggested by Primaz.

The original Dunlop brakes work well at stopping the car, though they require a harder push than modern systems. As Primaz says, they can get hot and suffer fade after hard use. But they aren't nearly as bad as a Pontiac I once drove in the Rockies ... . Also the pads wear quickly and the cylinders require more maintenance than anything modern - for me the primary reasons for replacing them.

 

Thanks for the additional information, Primaz.

The standard Fosseway calipers appear to be copies of the Volvo Girlings I just installed. Even the pads have the same anti-rattle springs. So, presumably, they offer the same pad area and piston pressure as the Volvo Girlings. That's affirming.

Cheers,

Don

 

I think braking is so important that for me I would always go with new brakes with stainless steel lines and get high capacity based on your style of driving. If one can afford it the 6 piston with true vented rotors make a radical difference. To really stop well the rotors need venting to keep them cool and then the largest pads and powerful calipers will handle anything. If you are on a budget and do not have vented rotors then finding a way to route a flexible air duct to force air at the rotors can greatly help and that just takes some creativity and not much money

 

I don't know if you've ever tried to work with stainless steel lines yourself, but even on fully-annealed tubing, the hardness doesn't make it fun to shape and flare, often requiring hydraulic tools. And getting the flares to seal can take more wrench force than I like. And I would have hesitated to try bending stainless steel into the small-radius curves I wanted for my installation because stainless work hardens. If I ever work with stainless steel again, it will probably be with a pre-bent kit.

Cunife alloy (Cu (Copper) Ni (Nickel) Fe (Iron) and often manganese) offers a burst pressure rating of up to 19,000 psi (which is plenty), is far easier to work with, and while it will oxidize on its surface, it will not rust through. It will not last as long as stainless, or be as shiny (though I think cunife is beautiful). Depending on the current prices of copper and nickel, cunife costs about the same as stainless (sometimes more), so there is no real cost advantage. Unless I'm worried about a section of brakeline being subject to physical damage, such as very close to moving suspension parts, where steel might be more dent-resistant, I much prefer to work with cunife. By the way, Cunifer is a German trademarked brand name for products made of cunife.

I just noticed that your S-Type engine has been swapped to an LS1. No wonder you had trouble getting the car to stop!

Cheers,

Don

 

I give another vote to the last posts. An essential part of an upgrade (or simple maintenance) should be quality cunifer lines and braided flexibles.

 

I wouldn't go stainless, simply because it work hardens when bent. There is a higher risk of a flare cracking and leaking with stainless than ordinary steel lines or Cunifer.

I have driven my S Type across the Rockies and never experienced brake fade with standard Dunlop brakes. However, I know the road very well and know when to brake and when I can simply let the speed climb a bit until the next uphill portion.

 

Primaz,

We're getting the impression that you receive a commission on each set of Fosseway calipers you sell...

Cheers,

Don

 

Not at all. There is just not many options engineered for these early sedans. I was hoping my first upgrade of the Willwood brake would be enough, but that was not enough for my needs. It did make me more aware of how brakes are so important and how fast they can loose more than 70% of their stopping power. To me if you own a Jaguar then why skimp on the money for safety?

 

Well, there are many of us who think, if you own a Jaguar, why put a General Motors engine in it?

 

Since the last eleven posts have had nothing to do with upgrading the S-Type brakes, I have moved them to a new thread titled Discussion on Reasons for Swapping S-Type Engine to LS1.

Cheers,

Don

 

Sticking to the OP topic, here is the cost of other more standard or slightly upgraded brakes made for the 3.8s and you can see that some of these are actually more than the lower model Fosseway so to each their own, but these cars are over 60 years old, common guys when important things wear out replace them with either brand new factory or brand new upgraded level of new parts, why waste time with old, used, or anything else to save a buck, we are Jaguar owners

https://www.sngbarratt.com/English(U...e%20caliper%60

https://www.sngbarratt.com/English(U...e%20caliper%60

https://www.sngbarratt.com/English(U...e%20caliper%60

 

In summary: The original brakes were pretty well for most purposes, but, after half a century, design has advanced. Those who want to stay original, for whatever reason, can do so. It does no harm to anyone. On the other hand, if an owner wants something more modern, easier to maintain, functionally better, quite possibly more economical, it's perfectly sensible to replace the original with a bolt on upgrade.

A factor to keep in mind, especially if you don't do your own maintenance, is that upgrades can make life a lot easier or a lot more difficult for the mechanic.