[LionZoo]

Noticed at the track this weekend that there is some seepage around the front caliper bleeder nipples. I noticed this last week at the track as well and ended up tightening the nipple to see if that would cure it, but it's still there. The situation is about the same as detailed here: http://www.lotustalk.com/forums/f91/brake-fluid-leaking-bleeder-valve-after-track-session-72167/

On the passenger side, the fluid is seeping at the base of the nipple. On the driver's side, the rubber cap also has moisture on it, as well as moisture on the base. Has anyone experienced and cured this problem before? I'm thinking about just getting two new nipples, but where can I get them?

 

[jds62f]

I've had this happen too. Since there are no published torque specs, my reaction was to take a wrench and tighten it up a little bit. I don't ever see any fluid, but occasionally I will see a little trail of what I assume is brake fluid that has evaporated from the heat in the caliper. Curious if others have gone further than just tightening them, so far its worked fine for me.

PS: when bleeding the brakes, I carefully monitor the position of the bleeder screw before I do anything and return it to the same position at the finish.

 

[LionZoo]

I tighten it as much as I can with a wrench, but am wary of using more leverage as the caliper is aluminum and I don't want to break it.

 

[jds62f]

I tighten it as much as I can with a wrench, but am wary of using more leverage as the caliper is aluminum and I don't want to break it.

Big IF, but if things are properly designed you'll break that bleed screw long before you break the caliper in the event you over tighten.

Also something I just found... ap makes our calipers ( can anyone confirm they make the 2pot ones as well? cp6126,cp5316,cp5317 look awfully familiar)

here is some info: http://www.apracing.com/drawings/In...=0&bcsi_scan_filename=2013_Brake Calipers.pdf

Notable: Stated recommended tightening torque on bleed screws for all calipers is 17 Nm.

 

[LionZoo]

Thanks! Sadly I always assume the detail engineering on the Lotus is not properly designed.

 

[spaparizos]

I had the same problem twice in the past. When it happened I also felt the pedal going a bit soft momentarily. I noticed that this correlates with me adding too much brake fluid after bleeding (beyond max) or with not tightening the screws as much.

Now I do exactly what jds62f does, I mark where my wrench was before I did the brake bleed and then make sure to tighten it to that position. I also got a nice 11mm wrench that allows me to put plenty of torque there.

My suggestion, try to tighten them even more and see what happens. And if this does not fix your problem, then replace them. If you over tighten them I believe the design will allow the screws to be damaged first and then the caliper.

Also, make sure to get a brake cleaner to spray on the caliper and wipe / clean your rim. Brake fluid is nasty on painted surface.

 

[LionZoo]

The bleeder nipples are AP Racing part number CP3720-173. They are M10 x 1.0 x 30.5mm.

 

[jds62f]

The bleeder nipples are AP Racing part number CP3720-173. They are M10 x 1.0 x 30.5mm.

Do you have the 2 pot or 4pot brakes?

 

[LionZoo]

I have 2 pot brakes.

 

[spaparizos]

By the way, if you do decide to replace the bleed screws and you don't mind getting a bit messy I have two suggestions. Try the speed bleeders for easier bleeding. And the BOE stainless steel pistons for less heat transfer.

 

[LionZoo]

I have a thing against speed bleeders so I'll be keeping the stock bleeders. I do eventually plan to go to the BOE pistons, but not for the time being.

 

[jds62f]

Hmmm, is there a place to source those bleeders in the USA?

Or are you planning to buy overseas, or from somewhere in USA and just match the specification of the screw

 

[Vulcan Grey]

there are lots of places to buy compatible bleeder screws. I think Essex (AP distributor in the USA) could supply the correct AP part # though.

 

[Motorcitydak]

If you contact Wilwood, they can re-machine the surfaces of the bleeder screws usually for $25

 

[Vulcan Grey]

New bleed screws are just a few $...

Or were you talking about the cone inside the aluminum caliper?

I've seen some AP calipers leak slightly before at the track, and it sometimes seemed like the bleeders were either too short to bottom out properly on the cone, before the threads stopped or the nut hit the caliper. Or the other problem was that the steel bleed nipple didn't expand as much with heat as the aluminum caliper, making the seal leak.

 

[LionZoo]

Bleeders are AP Racing PN CP3720-173. $3.25 each from B.R.I.T.S Inc. in Somona.

 

[KPLAL]

I thought that a different heat expansion between bleeding screw an caliper might cause the leak. So i tried screws out of stainless steel as well as aluminum. Unfortuntely there wasn't a noticable difference between these materials. So the calipers leak and leak and leak. Just a little, but you notice it in the brake pedal and the car starts pulling a little to one side.
After all i ended up with a regular M10X1mm steel bolt with a copper seal. Now it's sealed on the top and it works great. For brake bleeding i remove the bolts and use the regular bleeders.
It works fine to me for more than a year now. I'd be afraid of tightening the regular bleeding screw so much (as described in other posts above), there really is a lot of pressure in the cone of the aluminum caliper. I would say sealing it on the top with less pressure is much better, but i honestly don't know that for sure.
So for safety reasons i do not wan't to suggest the regular bolt for street driving, just for track riding with lot's of space behind corners.

 

[LionZoo]

I thought that a different heat expansion between bleeding screw an caliper might cause the leak. So i tried screws out of stainless steel as well as aluminum. Unfortuntely there wasn't a noticable difference between these materials. So the calipers leak and leak and leak. Just a little, but you notice it in the brake pedal and the car starts pulling a little to one side.
After all i ended up with a regular M10X1mm steel bolt with a copper seal. Now it's sealed on the top and it works great. For brake bleeding i remove the bolts and use the regular bleeders.
It works fine to me for more than a year now. I'd be afraid of tightening the regular bleeding screw so much (as described in other posts above), there really is a lot of pressure in the cone of the aluminum caliper. I would say sealing it on the top with less pressure is much better, but i honestly don't know that for sure.
So for safety reasons i do not wan't to suggest the regular bolt for street driving, just for track riding with lot's of space behind corners.

So you only put in the bleed screws for bleeding? And then when you're done the bolt is inserted into the caliper?