SPF brake firmness

I haven't driven my SPF GT40 in a few years due to a few factors. I got back in it today and found the brake pedal to be very stiff. I don't recall if that was the feeling last time I drove it. Anyone with experience care to comment? Could I have any new brake related issue with the car sitting for a few years?
 

Randy V

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I would consider doing a full inspection and if DOT 3 fluid was used that you’d flush the system with fresh fluid.
 

Brian Kissel

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Mike, just as your fuel line post, replace all your rubber brake lines before you put new fluid in. Those are known to rupture as well after sitting. I use Castrol brake fluid. It should not be used to top off a existing system, but use after a complete line replacement and flush. I could not get that information to load on my phone.

Regards Brian
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Lee Patterson

Supporter
Before tearing the car apart, exercise the brakes by moving the car some and gently exercise the master cylinders. Check fluid levels (reservoirs are up front under the nose attached to the AC cover - at least on newer cars - old SPF are on the tub next to the windshield frame). Once things sit a long time, stuff starts to bind up. SPF uses Wilwood calipers and master cylinders. They spec DOT 3 fluid. You can also use DOT 4 as they are compatible. Do not use DOT 5. Wilwood is now spacing DOT 5.1 which is the hi performance version of DOT 4 (NOT to be confused with DOT 5). Also exercise your parking brake if you use it. That could be stuck.

SPF uses Goodridge brake lines. These are not cheap. I would think twice before ripping them off. If necessary, a good flush of the system may be in order depending upon how lone the fluid has been in the system. Same for your clutch as it is similar.
 
No room to remove front just yet...I have to fix a file leak first.

Once I fix that, I can move the car around and see if things improve. A flush/replace is in the future. I have one of the first SPFs, so it has to be up near the windshield frame.

Thanks gents! At least I got it washed yesterday...
 
With some help from family, the front of the body is off and I will be trying to flush and refill the brakes and clutch. First off, I want to use my homemade pressure bleeder. Taking the old reservoir caps off tells me I have not taken care of this car...sad. I will want new caps and gaskets and perhaps can modify an old cap for the bleeder. I can't seem to find details on the specs for the original girling caps...I think it might be a P/N 64473143. Can anyone confirm this?

I measure about 2" outer dimension of cap, 1-1/4" inside reservoir hole and 1-3/4" outer dimension of reservoir threads.

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Lee Patterson

Supporter
Mike - google replacement Girling Master Cylinder reservoir caps. There are a bunch of hits. These may work for you - did not research the sizes.


As for flushing and bleeding, get yourself a Mityvac System. You can suck all the old crap out of the reservoirs to start and then attach to the calipers for bleeding once you suck many tanks of fluid through. When bleeding the calipers do the UPPER OUTER bleed screw first, then the UPPER INNER bleed screw second on each caliper starting with the rear ones, farthest caliper from the master cylinder first. There is no need to bleed the calipers using the lower set of bleed screws (this all per Wildwood). I would use the Wilwood new 5.1 fluid. it is NOT silicone based like DOT 5. It is an advanced conventional like DOT 3 and 4. You can buy a gallon of it which you will probably need - get it in pints as to not waste it once you open one. I used a pint per caliper when initially commissioning my system.



Jack the car up on all 4's and get the wheels off so that you can run through the sequence of bleeding and testing. You can get in the car to see how firm a pedal you are getting as you progress. It helps to have a second person but I did it by my lonesome.

Finally, it you want to replace the Girling metal cans with the latest SPF aluminum reservoirs, I have the part numbers for you. They are not that expensive and VASTLY better than their original setup.

Hope it helps.
 
Thanks for the advise Lee! I have been pressure bleeding for years. I am familiar with Mityvac as was the way I did it many years ago before I changed to pressure bleeding.

The problem I see with the Girling caps is that dimensions and thread pitch aren't described anywhere. There were changed to thread pitch at some time I read. I guess I just need to take a run at it and see if I get lucky.

I would be curious to know the SPF reservoir numbers as I head back there in two weeks and might be able to get them then. I will see how bad these look once I clean them out.
 

Lee Patterson

Supporter
The diameter and threads are listed on this cap. There are only a couple sizes:


Here is the Wilwood part no. You will have to source lines and fittings from the master cylinders. Not sure how SPF ran the early car hoses.

 

Doug Dyar

Supporter
Im my humble opinion, if you are going to replace the brake and/or clutch reservoirs, then you should relocate them to a place under the nose that's accessible without removing the front clip.


Superformance should have put them there in the first place...
 
Taking the front off isn't too difficult...just takes a couple people, some space and a couple of minutes. This is the second time I have done it in 20 years. The reservoirs look fine inside.

I am of the thought that the reservoirs and the caps were not meant to installed through that removable metal panel. It pretty much bottoms the cap out on the panel at or before sealing.

I saw a car at Superformance showroom that had evidence of this. Mine shows a little bit, but not nearly like this one.
PXL_20240829_181834411.jpg
 

Randy V

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Taking the front off isn't too difficult...just takes a couple people, some space and a couple of minutes. This is the second time I have done it in 20 years. The reservoirs look fine inside.

I am of the thought that the reservoirs and the caps were not meant to installed through that removable metal panel. It pretty much bottoms the cap out on the panel at or before sealing.

I saw a car at Superformance showroom that had evidence of this. Mine shows a little bit, but not nearly like this one.View attachment 153291

Re: Cap installed above panel - That’s clearly an uncharacteristic misstep on the part of Superformance..
 

Lee Patterson

Supporter
Those caps have the hole in the top. If the inner rubber gaskets are not solid across the inside of the cap, the hole allows fluid to spurt out hence creating issue. These caps were used on many British cars and hence the source of many issues. New caps with solid rubber seals inside would solve this problem. I do not believe the caps are bottoming out on the panel.
 
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