Brake Hose Fittings

[Redd]

Can anyone tell me what fittings are at the end of the brake hardlines at each wheel well? Are they 1/8" NPT Male, or 3AN Male?

[deansbimmer]

They're neither. They're specific brake connections. M10 thread size, ISO inverted bubble flare. 4.75mm pipe.

[Redd]

This link states hoses with 3AN fittings will fit our BMW applications. Are they wrong?

https://www.seemslegitgarage.com/pro...brake-hose-kit

I'm not looking to buy these hoses. I'm actually looking to get a brake residual pressure valve (RPV) to see if it will help with long pedal travel. Trying to determine which fittings I need to get to connect the RPV between the brake flexible hose and the hardline. These are the RPVs I'm looking at:

https://www.tbmbrakes.com/products/r...ressure-valves

The fittings are integrated, so I need to choose them during purchase. To put them between the hardline and flexible brake hose, I'm thinking 3AN Female to 3AN Male.

Hardline > 3AN Female-RPV-3AN Male > Flexible brake hose > caliper

Any advice is welcome.

[Redd]

In retrospect, deansbimmer, you are right. I should get some an RPV that allows custom fittings to be made to fit our brake lines properly. Thanks.

[deansbimmer]

Originally Posted by Redd

This link states hoses with 3AN fittings will fit our BMW applications. Are they wrong?
......

I'm not looking to buy these hoses. I'm actually looking to get a brake residual pressure valve (RPV) to see if it will help with long pedal travel. Trying to determine which fittings I need to get to connect the RPV between the brake flexible hose and the hardline. These are the RPVs I'm looking at:

Any advice is welcome.

I think you're misunderstanding their description. That company isn't saying 3AN hoses fit BMW. They're saying their kit includes adapters from the BMW DIN (ISO) to 3AN so that their generic hose will work:

The brake hose kit uses M10x1 DIN to -3AN adapter fittings on each end. These are compatible with all BMW hard lines and caliper connections. Install the fittings first, then the hose.

Nothing 3AN will fit any BMW without significant modification. Packaging becomes an issue as well. There's nowhere to put an extra 6" of RPV and adapters without cutting out some pipe and installing new flares and fittings...

I'm curious as to why you think a RPV is needed? Residual pressure in a disc brake system is a recipe for problems....Dragging your pads and overheating your discs, glazing rotors, pad deposits, etc. Have you modified your brakes with a BBK? Assuming no air in the system...Excessive pedal travel is an indicator that something in the system is incorrect or mismatched for the application.

[Redd]

I have had Brembo GT bbk for 6 years now. They are great on street but I am getting pad knockback at the track. I explored anti-knockback springs but the GT calipers are not designed to use springs. Only option appeared to be to replace the calipers with a racing setup like AP Pro 5000 R.

Then I read about this brake RPV which some in the VAG community have used to good effect to firm up the brake pedal and reduce knockback. 2 psi residual pressure is small and did not cause pad drag in those applications. They were cheap enough that I thought I would experiment with it before going down the route of new calipers.

[DukeofAlexandria]

Originally Posted by Redd

This link states hoses with 3AN fittings will fit our BMW applications. Are they wrong?

https://www.seemslegitgarage.com/pro...brake-hose-kit

I'm not looking to buy these hoses. I'm actually looking to get a brake residual pressure valve (RPV) to see if it will help with long pedal travel. Trying to determine which fittings I need to get to connect the RPV between the brake flexible hose and the hardline. These are the RPVs I'm looking at:

https://www.tbmbrakes.com/products/r...ressure-valves

The fittings are integrated, so I need to choose them during purchase. To put them between the hardline and flexible brake hose, I'm thinking 3AN Female to 3AN Male.

Hardline > 3AN Female-RPV-3AN Male > Flexible brake hose > caliper

Any advice is welcome.

Oh look, another person trusting/misunderstanding something from that trash shop….who would have thought it?!?!?!

Listen to deansbimmer, that is the correct answer and stop shopping those yahoos.

-Duke

[Redd]

Originally Posted by DukeofAlexandria

Oh look, another person trusting/misunderstanding something from that trash shop….who would have thought it?!?!?!

Listen to deansbimmer, that is the correct answer and stop shopping those yahoos.

-Duke

Read my post again. I'm not buying anything from Seems Legit Garage.

[deansbimmer]

If you're doing more and more track work I would absolutely recommend switching to a better design like the AP RadiCal system by Essex. Brembo look cool and all but are not popular on track cars for lots of reasons. Ratios between MC and caliper piston sizes are one, and will cause long pedal travel (I think that's your root cause). AP would be a great upgrade on several fronts and would save you from hacking up brake pipes and tinkering with RPV's.

I'm not a fan of the idea of adding residual pressure valves. Not only for theory, but in execution- a quality install that won't leak or be a reliability and safety risk will require a specialized effort.

[Redd]

Originally Posted by deansbimmer

If you're doing more and more track work I would absolutely recommend switching to a better design like the AP RadiCal system by Essex. Brembo look cool and all but are not popular on track cars for lots of reasons. Ratios between MC and caliper piston sizes are one, and will cause long pedal travel (I think that's your root cause). AP would be a great upgrade on several fronts and would save you from hacking up brake pipes and tinkering with RPV's.

I'm not a fan of the idea of adding residual pressure valves. Not only for theory, but in execution- a quality install that won't leak or be a reliability and safety risk will require a specialized effort.

Yeah, knowing what I know now, I would definitely not get another Brembo kit. Not only the longer pedal travel as you mentioned, post sales technical support has been difficult for non-race applications. The GT kits seem to be a 'that's just how they are, take it or leave it' kind of deal.

Thanks for the great advice as always deansbimmer. I better start saving up for that AP kit.

[nrubenstein]

One question: Is the amount of pad knockback that you're getting new? Have you investigated whether, say, aged wheel bearings are making it a lot worse?

Also, I can't help but wonder whether AKB springs can be retrofitted, regardless of whether or not Brembo says that they can be? It's just a spring. The stoptech AKB springs are very generic and just require a sliver of open space behind the piston to work.

https://www.zeckhausen.com/catalog/p...ducts_id=22051