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Tips
Tips

Spitfire Bleeding brakes

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T

Trevor Triumph

Jedi Knight
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On the 66 Spitfire I replaced rubber parts in the master cylinder and wheel cylinders. Using the MityVac to bleed the system, worked on the rear cylinders. The front right caliper produced lots of air bubbles but no fluid. When I connected the Vac to the bleed nipple on the left caliper, the vac showed suction but when I turned the screw nothing happened- no fluid, no bubbles. When I nearly took the bleed nipple out, without the hose attached, some fluid ran out. I wanted to drive the car this weekend. Hmmm... T.T.
 
For the bleed nipple that did not pass fluid, did you check that the nipple was open from the tube connection down to the crossdrilled holes behind the cone point? If the protrective cap was not fitted to the nipple it's not uncommon for the holes to fill with dirt and corrosion. I would not hesitate to remove the nipple and clean it out with a bit of wire.

On the nipple that allowed lots of bubbles, the air is probably coming around the nipple threads. Anytyhing behind the cone point does not matter since it is not incontact with the fluid while the brakes work. Therefore, consider removing the nipples and applying a wrap or two of Teflon tape on the threads to seal them during the bleeding process. If you buy "Speed Bleeder" nipples you will notice that they include a layer of some type of thread sealant for this same purpose.
 
HI
I have also used some SylGlyde grease around the nipple threads where they exit the caliper body. Makes a dam keeping the air out if you don't want to remove the nipple.
 
The right caliper bled air and fluid when a friend pushed the pedal. The left bled fluid on the caliper when I opened the bleed screw. I will replace/ clean the the bleed screw. Maybe some teflon tape is a good idea- the stuff is fifty years old. I could use some better sealing some days, too.
 
The Teflon tape will only be sealing the threads and only be effective during bleeding. The conical point at the bottom of the nipple is what seals against the caliper.

Regardless, I'm glad you got some better results with bleeding. Once you get the other nipple cleaned out I'm sure you'll have luck with that one also. While/when you remove the nipple you can place a piece of Saran Wrap over the threads of the reservoir and refit the cap. That will slow drips out the bleed hole. Putting a clean bolt in the threads will further slow the drip while you clean the old nipple.
 
Like this one Doug?
old-rusty-bolt-19767224.jpg
 
YUCK!

I've found bolts like that in the bottom the boot but thankfully not recently!
 
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