Brake question

[PeteWoody]

HI This is my first time navigating this forum so feel free to direct me if needed.
I have a brake question and or issue. I have a MK4 roadster with all the FFR Standard brake assembly.
After driving the go-cart Im not happy with the performance of the brakes. Although it stops the car the pedal isn't solid and won't lock up the wheels.
I have bleed it every which way, used a pressure bleeder, bleed it back to front then right to left. (I have found with the balance bar set up sometimes it likes to be bleed right side rear then front and then left side) It just doesn't get any better.
Im now considering boosting them. Vacuum or hydroboost.
Has anyone else had this issue? how did you fix it?
Any recommendations much appreciated
Regards
Pete

[BornWestUSA]

Are all the bleeder screws facing up? Bleeder bottles attached?

With dual master cylinders and a balance bar Wilwood says to bleed one front and one rear caliper at the same time, or both on the right side, then both on the left.

with "bleeder bottles" you may not even need an assistant.

Good luck!

[edwardb]

Power brakes is an often discussed topic and is a pretty significant change now that you have the Wilwood pedal box installed, all the lines run, etc. I agree now is the time if you choose to go that way. But highly recommend NOT making that decision based on the testing you've done so far. If your pedal isn't solid you don't have all the air out of the lines so it's not reasonable to make a decision yet. Personally, I've done pressure bleeding with all my builds including several times with the Wilwood balance bar setup. First bench bleed the master cylinders. Then I have a pressure cap for the reservoir(s), put 5-6 PSI into the reservoir, and do the usual bleed rotation of right rear, left rear, right front, left front. One at a time. Sometimes takes a few rotations to confirm the air is completely out while constantly monitoring the fluid level and recharging the air pressure as needed. Have always been successful with a hard pedal. With a hard pedal you should get a much better idea of what the brakes are really like. Note also pads take time to break in plus there are multiple options for more aggressive pads.

[egchewy79]

do you have a soft pedal feel or are you just dissatisfied with the braking power?
have you properly bedding in the brakes yet?
I ended up switching to Hawk pads to get a grippier brake feel but they are a bit dustier.

[PeteWoody]

HI Thanks for the reply. I have a soft pedal but I'm convinced the brakes are bleed and there is no air in the system. It also has a lot of pedal travel. The rods at the master cylinders are adjusted to the minimum. but the pedal goes almost to the floor. It feels like its by-passing either in the master or the calipers. Has anyone used non return valves at the caliper? apparently this keeps a couple of pounds of pressure in the caliper. Can someone confirm that when driven the go-cart the pedal is solid and the car will lock up the wheels. I'm not sure if I'm being fussy with manual brakes or is as good as it gets !
Egchewy79 Can you elaborate on the Hawk pads? do you know the part numbers
Appreciate your help

[edwardb]

HI Thanks for the reply. I have a soft pedal but I'm convinced the brakes are bleed and there is no air in the system. It also has a lot of pedal travel. The rods at the master cylinders are adjusted to the minimum. but the pedal goes almost to the floor. It feels like its by-passing either in the master or the calipers. Has anyone used non return valves at the caliper? apparently this keeps a couple of pounds of pressure in the caliper. Can someone confirm that when driven the go-cart the pedal is solid and the car will lock up the wheels. I'm not sure if I'm being fussy with manual brakes or is as good as it gets !
Egchewy79 Can you elaborate on the Hawk pads? do you know the part numbers
Appreciate your help

Assuming everything is assembled properly, the pedal going to the floor is not normal. Any type of special valving, e.g. non-return, also isn't normal. Hundreds (thousands...) of these cars have been built without them. No reason yours should require anything different. If all the air is really out, then you're right, sounds like fluid is bypassing somewhere. Since you mentioned a balance bar, you must have the Wilwood pedal box with the kit supplied Wilwood master cylinders. Some have reported issues with those but I wouldn't assume that first. Maybe post a picture of your pedal box installation. One at rest and the other with the brake pedal pushed down? Manual brakes definitely have a different feel than power. But you should have a rock hard stop after a couple inches of travel and you should be able to hold it there for several minutes at least without anything changing. I personally wouldn't judge anything about the brakes (e.g. not being able to skid the tires...) until you have them working normally as described. I would also caution about just how aggressive a go-kart should be driven (my opinion...) and also without your pads being bedded. Once you get the brakes working properly, I'd recommend saving that evaluation for when the car is finished, licensed, insured, etc. then you can do real testing and try more aggressive pads if necessary.

[Jeff Kleiner]

When the pedal goes to the floor is the balance bar pivoting over to one master or the other? If so the side that's pushing all the way in is the end where your problem lies. Lots of reports lately of Wilwood master cylinders failing (some right out of the box) and bypassing. I suspect that you may be experiencing that.

Jeff

[OB6]

Lots of reports lately of Wilwood master cylinders failing (some right out of the box) and bypassing. I suspect that you may be experiencing that.

Jeff

I experienced this over the weekend. My brake MC's were fine (at least for now), but the clutch MC leaked as soon as I started to bleed it. I removed all three and replaced with Tiltons.

Side note - compared to the Tilton, the Wilwood unit feels like the bore is lined with sandpaper when you turn the threaded rod. The Tilton is very smooth. This was true of all three Wilwood units I have/had. It doesn't appear that Wilwood's quality is where it needs to be, especially for a critical component like a MC.

[ProfessorB]

If you've got that much travel and a soft pedal, you've got a problem somewhere. Not normal.

[RoadRacer]

> I'm convinced the brakes are bleed and there is no air in the system

Been there.. you still might be wrong. I have been. I haven't seen anyone mention this here - but I always start by reverse bleeding, that is push fluid in the caliper and watch the bubbles come out the reservoir. The MC is the highest point and it's hard to push air all the way down to the caliper, much easier the other way. Just try it. Just a real cheap-and-nasty auto parts store tool like this works (https://www.amazon.com/Phoenix-Systems-2104-B-Reverse-Bleeder/dp/B00GRV800S/ref=sr_1_4?crid=2WTU0IMLY8K4G&dib=eyJ2IjoiMSJ9.wFw02GUdtgTgX_Ak69m54s8IAh5G1gh5r P0xZarhkx9LBAVmcLPGwXrXP6cemhAz_BXhnI7KGCIg0RqgGV5 1HzPp_75G2bYUj-7iAXaS9siGLT7BLZNSdNTydI5fVbmxI4MRWHpRJxPd-Vre2iElyjNqJy2eRLK_ZJjbQlywjvwN8aizqBgrvbvZzNWckDN r_vNonUB1byRFY_y4PddJLWhqkE9Qg8twYU-tUerSetPFcoa2QNjlPnRSfeQ9NprlmF0zHQxPEU6J3JFSWR-ax8NkyNwR6F9ufWAIdrBOOtc.HIKhknQdlL-ouKoFqBSQsltkcMX3QbTLgSv9YgsYxJU&dib_tag=se&keywords=reverse+bleeder&qid=1721264710&sprefix=reverse+bleeder%2Caps%2C146&sr=8-4) (mine was $25)

Failing that, the MC inside seal, as Jeff says. Easy and quick to swap that out.

[Ducky2009]

As others have said, a soft pedal is not normal and you probably have air in the line. Also, it does take many miles for the brake pads to brake-in and work at full capacity.
With that being said, I drove my car approx. 500 miles before paint and was never happy with the brakes. Couldn't lock up the wheels. Same as you, Wilwood master cylinders and supplies FFR "stock" calipers. I ended up changing to a regular single master cylinder and vacuum power brakes.

[JMD]

My research led me to believe that the FFR supplied stock floating calipers were designed to be paired with a boosted MC and will never work properly with a manual MC, no matter what size. Yes you can mess with pad compound and get something that works better, but I've learned that the key to building a well performing manual brake setup is the proper pairing of components. If you have some sort of assist than floating calipers will probably work great on this car, but for the additional cost and complexity of doing so I decided instead to go with a matched component unassisted Wilwood system from Gordon Levy. I've heard lots of good things about it...but haven't actually got my chassis rolling yet so take it for what it's worth. ;)