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Installing a Spitfire Master Cylinder on a Federal Europa

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Grumblebuns:
 Installing a Spitfire Master Cylinder on a Federal Europa

This article started out as a one page basic nuts and bolts installation of a Spitfire master cylinder to the Europa, a simple bolt on , hook up, bleed and go description. My curiosity on changes to braking pressures and forces with the Spitfire installation resulted in the addition of the calculations and spreadsheet.

This article covers the Spitfire master cylinder conversion for both the S2 and the TC(S) Europa.

The Spitfire MC

Using the Moss Motors catalog as reference, there were two types of master cylinders used on the Spitfires, the large cap reservoir MC used on 1968 through 1975 Mk 3/4, &1500 Spitfires and the small cap reservoir MCs, used on 1976 through 1980 Spitfire 1500s. Both large and small cap MCs are dual circuit with outlet ports located on the left side of the MC. The significant difference between the two is the bore size. The large cap MC has a 0.875” bore and the small cap has a 0.70” bore. For the S2s and
unboosted TCs, the small cap reservoir MC is the one we are interested in (Pics 1).

One issue to be aware of with the Spitfire MC is how the home or return position of the primary piston inside the bore is set. With the stock Europa MC, the primary piston is retained inside the bore by the tipping valve in the full return position and  the end of the primary piston is flush with the end of the bore. With the Spitfire MC, the primary piston is not retained in any way inside the bore. When the retaining clip and washer are removed, the primary piston will pop out. The return position is determined by the spring pressure of the primary piston pressing against the slightly longer head of the  Spitfire push rod  (Pic 2). Because the push rod controls the return position of the primary piston push rod,  I believe it is imperative if not critical that the Spitfire push rod be used with this conversion even though the Europa S2 push rod will fit in the Spitfire MC.

The Spitfire MC reservoir is integral with the body and uses rubber grommets to press fit the nipples into the bore which should allow easy mounting of a remote reservoir. On the Spitfires, the master cylinder body is mounted at an angle so the reservoir is horizontal (Pics 3). When fitted to the Europa with it's horizontally mounted MC body,  the Spitfire MC reservoir will have a significant downward slope reducing total reservoir fluid capacity some what, more for the large cap MC than for the small cap MC.

The final issue for the Spitfire MC is the differences in the threads used in the outlet ports between the original stock Spitfire MC and the after market ones. Original OEM Spitfire MCs have 3/8-24 threads on both ports.  The two aftermarket master cylinders I purchased, the TRW and the economy MC, both have metric M10x1.0 threads. It’s unfortunate but it is possible to mistakenly thread 3/8-24 fittings into a M10x1.0  ports. 


 
 The Spitfire MC and the S2   

Converting the S2 to the Spitfire MC is just a matter of swapping the complete stock S2 master cylinder  with the entire Spitfire master cylinder assembly and push rod . With the same mounting flange configuration as the original Girling unit, the Spitfire MC will bolt up directly to the S2 MC bracket (Pic 4). With the slightly wider clevis used in some of the after market Spitfire MCs, a slightly longer clevis pin may be required for the conversion.

The one feature of the Spitfire MC keeping this conversion from becoming a true bolt on is the location of the outlet ports. The left facing ports of the Spitfire MC will either require jumpers or approximately two feet of new brake lines run from the MC to the junction unions on the front bulkhead of the S2.
Details of the jumpers, if used, will be covered in the TC(S) section which also faces the same issue. With the relatively short run, the fewer  number of overall fittings and the same amount of labor needed to fabricate new brake lines vs fabricating jumpers, it makes sense to just fabricate new lines to the original stock unions (Pic 5).
 


The Spitfire MC and the TC(S)


As with the S2, the Spitfire MC will bolt directly up to the TC(S) with no modifications. However in addition to the opposite facing outlet ports, the TC(S) has one other complication to contend with. The TC(S) brake rod assembly does not use a clevis at the master cylinder end .  The simplest solution is to cut off the welded clevis and thread the cutoff end of the Spitfire push rod. That end is then threaded into the TC(S) main brake rod assembly (Pics 6/7). 

Jumpers to connect the Spitfire MC outlet ports to the stock Europa fittings are identical for both the S2 and the TC(S). Both Europa master cylinders have 3/8”-24 threads for the forward port and 7/16”- 24 threads for the rear port while the Spitfire MC has M10x1.0 threads for both ports. The length of the 3/16” jumpers needed will depend on how the jumpers are routed to the stock Europa brake lines and fittings. For a simple “J” jumper, approximately 6” are needed.  3/8”- 24 male fittings on the MC end and 3/8”-24 female fitting for the forward jumper and 7/16”- 20 female fitting for the rear jumper
(Pic 8).

Like the S2, some may want to install new brake lines instead of jumpers. For the TC(S) however, new lines will have to be run to the rear of the car to connect to the PDWV.


Final Thoughts

One difference not previously mentioned with Spitfire master cylinder is that unlike the stock S2 and TC(S),  the Spitfire MC has a non stepped  bore. For reference, I measured the Europa master cylinders bores as follows:
S2 – primary/rear bore (front brake) 0.70” secondary/front bore ( rear brake) 0.66”
TC(S) -  primary/rear bore (front brake) 0.87” secondary/front bore ( rear brake) 0.84”
Spitfire – straight bore  0.70”

For both of the Europas, the difference in diameter between the front and rear bore is approximately 0.03”- 0.04”. On the stock Europa master cylinders, the smaller front secondary bore supplies the rear brakes. The larger rear primary bore supplies the front brakes. I created a separate calculations sheet detailing the various estimated hydraulic pressures and braking forces between the various master cylinders for the Europas. There is also an Excel spreadsheet laying out the bore sizes, master cylinder hydraulic pressures and caliper/wheel cylinder braking forces.

When used on the S2, the Spitfire conversion will result in the same bore size for the front brake but a slightly larger bore size for the rear brake when compared to stock. Keeping the same stock front calipers and rear wheel cylinders, the front braking force should be the same as stock while the rears will have a approximately 9% lower braking force. The end result is the same braking force as the UK spec S2 with an unboosted  single circuit 0.70” master cylinder. How many average drivers can discern a less than 10% reduction of rear brake force with the Spitfire MC.

For the TC(S), the Spitfire conversion will result in smaller bore size for the front and rear brakes when compared to stock. This will result in an overall higher front and rear brake force but with a longer travel.  Again as with the S2, the end result is the same as the UK spec TC with 0.70” single circuit master cylinder but without servo assist.  For owners of the TCS, one item of note is the smaller rear wheel cylinder fitted to the TCS which will result in a approximately 9% smaller braking force to the rear brakes when compared to the TC.

One important variable not mentioned in any detail is the difference in brake travel between the different master cylinders used with the Europas. Not having driven a Spitfire MC converted Europa, I can’t comment on the effect of the Spitfire master cylinder on front to rear brake balance and in the case of the TCS, the change in brake travel. In both cases however, the front to rear brake balance will change with the change to the Spitfire single bore master cylinder.  With the S2, the change may not be perceptible to most drivers. For the TC(S), the change should be definitely noticeable if the brake booster had originally failed.

I've included a spread sheet collated by a fellow Europa owner amassing a ton of data on Europa and Spitfire master cylinder. There is a line detailing the brake travel for each master cylinder that can be used as a comparison. He cautions however that some of information has not been verified by him, specifically the items highlighted in PURPLE, and should not considered as absolute truth. 

Again, please treat the information offered in this article with caution until verified by the user. I've included a Dropbox link of the main article, an expanded pictures page, a calculations page, a spread sheet showing the calculations for easier scan and finally the spread sheet of the Europa and Spitfire master cylinder data.

https://www.dropbox.com/sh/sf9yd61xpv2vlgl/AAAoOhR8Fai1cmW89dNVv6Moa?dl=0 

 

Joji Tokumoto
12/7/16
Rev 0

jbcollier:
Thank you for a detailed and carefully written article!  It will be very helpful for people working on their brake systems.  I have just one comment:

On a stock Lucas/Girling/Lockheed brake master cylinder, the pushrod does not function as the primary piston stop.  The pushrod is retained by a curved/cupped washer which bears against the circlip and provides the primary piston stop.  The pushrod has a flared end which is held between the curved/cupped retaining washer and the primary piston but it has a wee bit of play so it is free to move around.

So you can swap original pushrods with pushrods from a Lucas/Girling/Lockheed replacement master cylinder.

Aftermarket master cylinders are another matter entirely.  Generally I have found aftermarket master cylinders to not last as long as an original cylinder and I would recommend using Lucas/Girling/Lockheed cylinders if at all possible.

Grumblebuns:
The small wiggle room in the Europa Girling units. I believe, also pre-sets the brake pedal free play that most manufacturers recommend. The Spitfire arrangement has the primary piston hard against the push rod by piston spring pressure. As far as I can see there is no free play when installed on the Europa. Do you see a potential problem with this lack of free play? I don't know enough about the Spitfire braking system to see if there is a way to make free play adjustment on the car else where in the linkage.

I consider the budget Spitfire MC at $60 a pop as a consumable item. If the seals wears out, replace the unit. There is a more expensive MC replacement built by TRW (Taiwan COO) at $200. Externally and visually, it doesn't look any different from the cheaper MC and I'm not sure if it's worth the extra money but would this now be considered a factory replacement?   

jbcollier:
Yes, TRW/Lockheed makes master cylinders to factory specification.

Another consideration is that the factory maintenance schedule specifies replacing ALL hydraulic seals at 40K miles (70K kilometres).  I rebuild the calipers but replace the master and rear wheel cylinders.

2483R:
An interesting mod is to use a Land Rover master cylinder reservoir, Land Rover P/N AEU1045. It is a bolt on swap to the Spitfire master and results in a level (not sloped) reservoir with near equal fluid reservoir capacity for both front and rear brakes. Attached is a picture.

Regrettably, it will not work on a TC as the rear of the Land Rover reservoir hits the steering rack when installed. But a S2 master is more out in the open, so it may work there. Not having an S2 I cannot say, perhaps an S2 owner can try it and comment.

I would also comment the factory TC/Special master has a sloped reservoir, probably meaning it was originally used in a car where it was mounted at an angle, just like the Spitfire.

An alternative to using brake line jumpers in a large loop around the master is banjo bolts. A more expensive but also more elegant solution. Attached is a pic.

Using a Spitfire master makes a lot of sense, as the front calipers and rear wheel cylinders for a S2/TC came from a Spitfire. (although a Special does use a different rear wheel cylinder) But do make sure the front/rear brake lines are connected to the same master outlet ports as they are in the Spitfire.

IMO, brake balance is an issue, especially when using EBS green stuff pads on the front. On my TC it is easy to lock the fronts and not the rears. But on the other hand, balance may have been an issue with the factory setup. I’ve had a Spit master installed on my TC for almost 30 years, so long that it is hard for me to remember what the factory setup was like.

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