jmason
Go Kart Newbie
- Location
- Frederick, MD
Yes, 272 mm rears still in place.
I don't have the S3 caliper. I installed the Neuspeed 6-piston caliper.
I don't have the S3 caliper. I installed the Neuspeed 6-piston caliper.
fuck sorry getting over cold your the wrong personYes, 272 mm rears still in place.
I don't have the S3 caliper. I installed the Neuspeed 6-piston caliper.
So before my track day last weekend, I went to the shop at the track to throw on some S3 calipers, usp stainless lines,, centric rotors and hawk pads. After installing all of this and bleeding it i noticed the pedal goes practically to the floor. I know it was bled correctly because we went through 2 bottles of rbf-660 trying to get it right. I gave up on them and reinstalled the stock calipers, pads and rotors but left the stainless lines on. With the stainless lines on and stock rear brake components, the pedal still went to the floor. Put the stock rubber lines on going to completely stock rear brakes and it was fine. Im starting to think the lines were the problem but I don't see how new lines could cause this. Also there were no leaks anywhere. Is there a different bleeding procedure I should have done? I did put the rear in "pad lining change mode" through obdeleven. Just wanna hear what you guys think
I have read with interest your posts. I was particularly interested in the results regarding piston retraction. I measured mine and found results similar to those you achieved through your modifications. In my case, the inside half of the caliper showed about 0.005" retraction, while the outside showed less than 0.001" retraction. On the outside, the pads drag on the rotor when the pedal is not pressed. I don't know why there would be a difference inside to outside.
When the engine is not running, the brake pedal is very firm and has a short travel. All good. However, when I start the engine, the pedal travel is longer, and I can push the pedal to the floorboard with what I think is too little effort. If I pump the brake pedal, the travel shortens (not surprising as this action takes up the piston retraction) and the pedal is firmer. It's the change in the firmness of the pedal I don't understand. As an experiment, I went to a VW dealer, sat in a new GTI and, with the engine running, pushed the brake pedal. I could push the pedal to the floorboard only with a lot of effort.
The remediation to this point has been to follow two VW factory brake bleeding procedures, which I have done twice. The procedures are a gravity bleed (in my case using a Schwaben power bleeder set to 20 psi) and a two person bleed. For both procedures: LF, RF, LR, RR order, outer caliper bleed followed by inner caliper bleed for the fronts. Each procedure is followed by a road test that includes a stop that activates the ABS.
There is no evidence of brake fluid leakage. I have not performed an ABS bleed. To my knowledge, the MC reservoir has never run empty allowing air to enter the system.
I have a 2015 Audi A3 2.0 which has the same master as the S3 im pretty sure.what model and year do you have?
what brakes did you change out fronts?
you changed all 4 lines to SS?
your bleeding outter and inner pistons on the front....I got Brembo GT-S no issuesI have a 2015 Audi A3 2.0 which has the same master as the S3 im pretty sure.
I changed out front for ttrs brakes and the pedal feels almost the same as stock honestly.
The only thing that changed pedal feel was changing the rears to S3 brakes and SS lines. I should have tried the S3 brakes with stock lines to make sure its definitely an issue with the lines. The front already had SS lines when I installed the ttrs brakes.
I am not sure which caliper you are using, is it a four or six piston? Do you know the piston diameters? What about the master cylinder piston size? It is possible your caliper to MC piston displacement ratio is to large. Is there a larger MC you can install? Perhaps from the S3 or Golf R/GTI PP?
... remainder deleted for brevity ...
Yeah I bled both bleeders up front. Im not sure why I'm having this issue. I should be able to eliminate the front as the problem cause I was running those brakes for awhile with no problemyour bleeding outter and inner pistons on the front....I got Brembo GT-S no issues
View attachment 193074View attachment 193075
Yeah I bled both bleeders up front. Im not sure why I'm having this issue. I should be able to eliminate the front as the problem cause I was running those brakes for awhile with no problem
On a separate note, your setup is really legit. Im not sure the springrates on kw v3s but I know they're a good damper and the brake kit is gorgeous
I tried to perform the Bleed Front procedure. The security code did not work, nor would the selection activate without a code. Back to the drawing boards.By poking around the VCDS dialog boxes and menus, I did some translation of Bleeding with ABS Hydraulic Unit -N55-Pump into VCDS. I haven't tried this yet, so I can't vouch for its accuracy.
I don't know what the flushing cycles are, if the order is important (it's the order presented in VCDS), or if those four steps all need to be performed. By "Bleed brakes", I assume you just open the caliper bleed valves like doing a gravity bleed.
- Connect VCDS
- Switch the ignition on
- Select Control Modules, 03 – ABS Brakes. Security code is 40168 (don't know when or if this is required)
- Select Basic Settings, Bleed Brakes
- Select one of the following:
- First Flushing Cycle
- Bleed Rear
- Bleed Front
- Second Flushing Cycle
- Select Go!
- Bleed brakes
Thank you for your thorough response. Here are some answers to the questions you posed.
1. Neuspeed 6-piston calipers. I don't know the piston diameters.
2. From my research, the GTI, Golf R, and Audi S3 use the same master cylinder. I seem to recall the bore is about 23 mm.
3. The figures I quoted for piston retraction were measured between the pad and the rotor. During the measuring process, an anti-rattle clip was in place. This clip is designed to move the pad away from the rotor when the brake is not applied, which I could verify as I watched the action of the pads and pistons with someone pressing the brake pedal. When making these measurements, I did not see a gap between the piston and the pad backing plate. While perhaps not as precise as your measurements, I think they are representative.
4. My take-away from your research is that your problem was one of "slack" in the brake pedal, meaning that you had to press the brake pedal down a bit before the brakes engaged. You addressed this with the grease and pressure valves. This is not my situation. In my case, brake engagement is near the top of the pedal travel. However, under heavy braking, the pedal travel is longer than I would like and is somewhat soft; not a firm end point of travel. In fact, I can press the pedal to the floorboard. This is not an issue in actual use as I get full braking action well above the floorboard, verified on-track.