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Flush out and changing to Castrol SRF/Remote brake reservoir on S550 Mustangs

steveespo

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Guys and gals, I posted this on Facebook in response to questions a member had on there about mixing SRF brake fluid with other brands and hoe to flush it. I also shared some information I got from a Ford friend regarding SRF fluid impact on the clutch system seals and how to add a simple remote reservoir to use Fords' DOT4 LV fluid in that system.

Here it is;
I advised Dan A. on some ways to switch over, and it doesn't have to be that painful. 2 liters of SRF will do it using a
GM clutch reservoir and a bottle of Ford DOT4 LV you can avoid any potential deterioration in the clutch system. S550 clutch feed hose actually plugs right onto the GM nipple. To flush system I vacuum out the reservoir fluid and replace the reservoir with an auto trans version, or you can plug and cap the stock clutch nipple, but be sure to use both a tapered plug and a cap made of Viton, clamped on with a hose clamp.

Refill with the SRF and bleed about 5 ounces out of each wheel (RR, LR, RF, LF) ensuring that it is topped off between each wheel to prevent air entering system. Top off and drive to engage ABS 3-5 times, if you have an IDS or Scanner that supports the Ford ABS test function you can do it on the jack stands. This should flush most of any remaining old fluid out of the ABS distribution block. Finally, bleed 2 ounces more per wheel and top off. After each event do a 2 ounce per wheel bleed and you should have a SRF complete system. I do this flush each February to prepare for the new season kickoff at VIR.
For the clutch it's easy, I mounted the GM reservoir to the brake reservoir by wrapping a long zip tie through the mounting bracket holes, securing it just under the molding seam of the brake reservoir. This allows the stock clutch feed hose to bend naturally to the location and pushes right onto the nipple. Just fill with Ford LV and pump the pedal a few times, shouldn't be any new air in that system. At each brake bleed, I vacuum out the clutch fluid, clean the reservoir of the little black clutch dust particles and refill with the LV fluid. Simple and keeps those contaminants out of the brake system.
 
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TMSBOSS

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Steve Thanks

I guess my switching to a lessor brand of fluid for my clutch reservoir was a good idea. I use a DOT 4 but not the expensive Castrol. I save that pain for the brakes only.
 

boardkat

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@steveespo is there a way to buy the brake reservoir without the master cylinder? FR3Z-2140-B / BRMC219 are the part numbers i found for the auto w/ brembo brakes, but it includes the master cylinder..
 
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steveespo

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@steveespo is there a way to buy the brake reservoir without the master cylinder? FR3Z-2140-B / BRMC219 are the part numbers i found for the auto w/ brembo brakes, but it includes the master cylinder..
Sadly no, I purchased a complete assembly from Ford new, but you can find used MC w/reservoir for around $50 on eBay.
 

JeffV8

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For the clutch it's easy, I mounted the GM reservoir to the brake reservoir by wrapping a long zip tie through the mounting bracket holes, securing it just under the molding seam of the brake reservoir. This allows the stock clutch feed hose to bend naturally to the location and pushes right onto the nipple. Just fill with Ford LV and pump the pedal a few times, shouldn't be any new air in that system. At each brake bleed, I vacuum out the clutch fluid, clean the reservoir of the little black clutch dust particles and refill with the LV fluid. Simple and keeps those contaminants out of the brake system.
. Steve thanks for the info on how the stock clutch fluid line will fit on the GM reservoir. A lot easier than the Willwood line I bought. I made a braket to mount mine.
 

boardkat

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Divorced mine last night and zip-tied the clutch reservoir until I can get a proper mount made.

D105803D-BBF1-498B-8B00-9FA62902AC7C.jpeg


On another note, an older muscle car guy asked if I’d enlarged the clutch reservoir orifice (I didn’t) - did a little research and apparently this was as issue on the GTO (and other T-56 platforms), causing pedal hang during high RPM and/or power shifting due to fluid restriction. It *is* a much tinier hole than the original on the nipple in the combined reservoir - apparently GM did this on purpose to aid with pedal feel for street driving. That said, I have a stiffer clutch pedal return spring installed already (to help with high RPM shifting and to prevent the dead space at the top). Has anyone else given additional thought to this? Simple enough to drill out if there’s problems at least, but I’d like to avoid doing another competition day mod.
 
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boardkat

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Exactly how I did mine. Where is your fluid level plug though? Aren't you seeing the red "Brake!" warning light on the dash?
Took this pic when the car was still on jack stands waiting for my new brake setup. It got plugged in before I fired things up :)

... btw, did you see my comment above about the clutch reservoir orifice and issues the GTO crowd had? Interested to hear your thoughts
 

steveespo

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Took this pic when the car was still on jack stands waiting for my new brake setup. It got plugged in before I fired things up :)

... btw, did you see my comment above about the clutch reservoir orifice and issues the GTO crowd had? Interested to hear your thoughts
I have had no issues with the standard orifice on the reservoir. Maybe I will bore it out the next time I change the fluid.
 

302 Hi Pro

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Interesting notations on the GTO clutch issue & enlarging the clutch reservoir orifice. I divorced my clutch & brake system reservoirs years ago & used the GM part but never had a problem. Lucky I guess.

Thanks for posting this reminder to flush out both systems, mine is overdue. Also have an AT brake reservoir to install that will eliminate the MT reservoir nipple & rubber cap.

Thank you for the DOT 4 brake fluid advice.
 

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