Nismo32

Hey Blakeo, Yeah I have confirmed it is the calliper by testing without the brackets etc. Even Alcon haven't been able to explain that away. They are saying it's normal! To be fair with good pads the car stops fine even on the track. But the pedal feel isn't good. I bet if you did endurance type events they would start to struggle. Who did you buy yours through Blakeo? My lines are secured by a bracket off the stock splitter block point. Has some rubber grommets. I also got custom lines made that are a bit shorter than some of the ones you see.

Hey GTSBoy. What would be the reason for that - if the entire caliper is moving to one side because of the dog bone being flexy - what would actually cause that? If a caliper has no physical flex as the pressure on both sides is even - then why would it move at all? Keen to get thoughts - not having a go. I just cant see the mechanism that would cause the entire caliper to shimy to one side.

Hello, The dog bone wont have much to do with this - the calliper applies a load about the disc - the outside of the calliper is more flexible than the inside by virtue of it not haveing the big torqued down bolts, additional metal structure on the caliper itself, and mostly not being cantilevered. So the outside of the calliper is pushing away as its more bendy and brining the inside with it as an equal pressure on both sides of the caliper looks to cause more flex on the outside - which makes sense. I have done this same thing with the calliper unbolted from the dog bone - same thing happens. Although id have to watch more carefully to see how much more the outside moves than the inside in this case. Im guessing there is a point in the pedals travel where the pressure is not actually increasing in the system - its just volumne displacemnt - and because the outside of the calliper is more flexy, it receives that volume. Have gone back to Alcon again - but beyond a resolution there I would stay clear of this calliper and possibly any of the lighweight type of callipers - especially if you have the smaller 15/16" master cylinder. Cheers.

Nah never got it sorted. I have clamped all the pistons fully back using g-clamps. Pressure bled, vacuum bled, tapped it with a mallet, sung to the gods of deceleration.....no difference. My only real conclusion is the brake pressure from the car is to much for the calliper. So I would definitely not buy these callipers. Endless would be a better option especially if it doesn't have so much lightening done to the calliper by ways of material removal. As a side note the new D2 1 piece calliper does exactly the same thing as the Alcon. So there are other callipers that have the same issue. If anything the D2 was worse.

Thanks for that Komdotkom Does anyone by chance know what the thread is on the end of the hard line of the GTST front brake system before it goes to the braided line - will need to get a fitting to put in there as you say. Could you do this with the caliper on the car? Just get the pistons all the way back with a spacer or even some clamps? Im running a 36mm disc and 18mm pads - the pistons are almost as far back as they can get but i think with some old pads and a wedge I can make sure. Just easier if the caliper is mounted to something.

Agreed. I will do this....although not sure how to bench bleed a caliper. Will have to find some gear or use the little vac pump I have. There are AKB springs in these. Although I feel like they are only on the large piston....although I could be wrong there. So can't push them all the way back.

I do - but have better results with the pressure bleeder. I could try the vac bleeder and see if it gets any other bubbles out. Will see if i can find it.....got relegated a while ago!!

Yep - i went from furthest away to closest to MC - both sides of each caliper - then came back and did it again to make sure.

Good plan. I will do that for sure. havent actually checked to see that all things are happening as they should on each side of the caliper! And yes, i agree, it seems super odd that a caliper can be so bendy. Im just struggling to find an alterante explanation.

This would be the only reason the dogbone would flex - pushing/pulling it based on unequal load. Not sure how to check for this besides putting a gauge on each bleed nipple and giving it the berries to see what pressure it reads.

I did think of this - i unbolted the caliper from the dogbone so it was just resting on the disc and the result was the same - the caliper spread about the disc. Ill do this again and get some video this time. I did also use a digital caliper when fitting the kit - the misalignment of the disc to the caliper was <0.5mm. The shims I have are 0.5mm so i wasnt really able to improve alignment. Seemed pretty good off the bat really. I tell ya - this has me thoroughly confused

To be fair im not sure - i have bled the system a lot of times - the pressure bleeder i use has worked a treat on previous setups on this car. So i would assume its doing the job here also...... I did also bleed with the pedal later on just to be "sure" - didnt make a difference.

Hey GTSBoy - I used a pressure bleeder to bleed the kit - didnt do pedal bleeding at first. Issue was still there. When you push the pedal you get the caliper flex - so the fluid is going to the caliper - its not bypassing within the master itself

Hello SAU, I recently purchased an Alcon TA6 kit through a QLD company who supplies the dog bones/rotors etc. The kit has 356x36mm rotors - aluminium dog bones - TA6 calipers. I used the HEL brake lines I already have. Kit appears to be of high quality.....as much as visually i guess it can be. What I have noticed after install and pressure bleeding (and pedal bleeding) multiple times is that the calliper is flexing a decent amount when the pedal is pushed - enough that i can push the pedal to the floor as the calliper just keeps on flexing. Details: 1. OEM master cylinder @ 15/16" (BM44 - non ABS GTST) 2. OEM everything else on brake system - rear callipers etc. Just braided lines (front/rear) and the TA6 front kit 3. The TA6 calliper has ~2% smaller piston area than the OEM 4 pot sumitomo calliper - so no issue there.....i dont think. TA6 is 27/31.8/38.1 and OEM is 40.4/40.4 4. Have checked the calliper flex with car on (booster assistance) and off - same result just have to push harder with car off 5. Have unbolted calliper from the dog bone so its just resting on the disc and tested again - same thing - so flex of the dog bone doesnt seem to be an issue 6. Tried to measure pedal ratio as best i could - looks to be about 4.8:1 with some margin for error - ignoring the booster with 50kg of leg (beeeefy - but with booster probably fairly achievable) thats about 770psi of brake pressure which doesnt seem super high - but maybe it is?? So 75kg of leg = 1150psi. I guess my question is - is this normal? Alcon distributors over here have been helpful but ultimately have said its normal. I feel like modulation is bad as only the first 30-40% of pedal pressure/travel does anything. After that its a mix of flex....and maybe some extra clamp force. My old setup - Ksport 8 pots with 12 years of track work on them did not have this issue - pedal was solid. Only reason for change was a hub failure caused the disc to tear one of the callipers to bits. Thanks SAU - any thoughts/help would be appreciated. 20240303_124128 (1) (1).mp4

Will take $150