UUC BBK crap braking - No bite

[frantic]

I have an S54 swapped E30 touring and have been to one track day so far earlier this year where I feel the brakes were not up to par, which I sort of felt while having it on the road also. They feel like they have no bite, pedal travel is semi hard but feels like I get almost no response without a good hard push on the brakes. I expected the harder pedal from the 750 MC, but there doesn't seem to be any bit eto the brakes they sort of slowly come on feel worse than OE braking when I jump into my stock 325i I can really notice how bad they are in my touring.

My current setup consists of:

UUC BBK on the front, Hawk DTC-30 pads
Rears OE UUC discs and DTC-30 pads
Braided lines front and rear
MK2 Gold Brake booster (9" - same as Proche 944 / Clio type ones)
750il MC
no ABS
Motul 5.1 Fluid

I've just started adding some brake ducting, however fade isn't my issue (though at one point I almost thought they had abit of fade).

I'm tracking it again in 5 weeks and am trying to figure out how to get the best out of these brakes, had nothing but constant issues with this UUC stuff with the stupid rattle clips and the brakes just feel dead it doesn't add any confidence taking it out onto a track with an S54.

What I'm wanting to do
-Try more track orentated pads (Hawk DTC-60's or Ferrado are the only ones I have come across)
-Go back to an e30 Master Cylinder
-Scrap this stuff and go 5 lug (Which I have weighed up and at this point in time is abit out of reach in the time frame)


And yes I understand the smaller booster and 750i MC is working against me in terms of boost assist and the pedal being alot harder. Just looking for anyone in a similar situation in the past or experience what worked best with a BBK and having to run a smaller booster?

[FredK]

Without knowing what it exactly feels like, I think you're on the right track. The only thing I am uncertain of is

1) Is the booster known-good? and
2) How much vacuum can the S54 honestly pull with that dinky little tubular vacuum reservoir? I'm not sure if it is sized properly. A vacuum canister may help you out. Something like https://www.summitracing.com/parts/cca-5200

I had a 735/750 23.8 mm master cylinder in my car when it was set up with a US S50 (240 hp), paired with a 944 booster and E30 M3 brakes. I hated the lack of boost, and like you, was nervous on the track hauling down from speed. I swapped back to the stock E30 Girling 22.2mm master cylinder, which helped greatly.

Will better pads help? Probably, but I think you'd enjoy maybe 10 - 20% better mu with DTC-60s.

I hope you sort things out!

[frantic]

Yeah I had the booster in there with an M52 before hand, was all good. Changed the entire brake system really with the above for the S54 swap but that's when I ran into the issues.

I've been reading up on these vacuum canisters, they seem to only be a buffer for vacuum rather than allowing it to create more. I'm still reading up on it though and quite curious if something like that is my issue.

I'm not running any of the sucking jet pump system (I just realized now), my booster is run straight off the air balancing rail that's on the ITB's. Maybe this is my issue, as I've read and found that the sucking jet pump helps create more vacuum..

[vitiokas95]

My friend, I have been using UUC for couple year for my track days, and it was OK until I started to do ''wheel to wheel'' racing with my S50 swapped E30. These brakes are garbage. I was blowing seals twice a weekend. What I did now, I contacted Lee at Massive and he built me monster set up, 332mm front brakes with Wilwood calipers and rotors. Now I run PFC01 pads and brakes are just awesome. I would recommend you this set up. It saved me bunch of money as I did not needed to switch to 5 lug set up to find good brakes.

[vitiokas95]

Here is a pic

[vitiokas95]

Another one. Look at the thicknes of that disc and pads 😄

[whodwho]

I went thru a bunch of brake changes recently and experienced this as well

The smaller booster with a larger MC and not the best vacuum source = what you are experiencing.

Go back to a the smaller MC and it will get better

[Smelser]

BRAKES????????

You Mean the WUSSY PEDAL!

[ed94r]

My friend, I have been using UUC for couple year for my track days, and it was OK until I started to do ''wheel to wheel'' racing with my S50 swapped E30. These brakes are garbage. I was blowing seals twice a weekend. What I did now, I contacted Lee at Massive and he built me monster set up, 332mm front brakes with Wilwood calipers and rotors. Now I run PFC01 pads and brakes are just awesome. I would recommend you this set up. It saved me bunch of money as I did not needed to switch to 5 lug set up to find good brakes.

Quoted

[sklbase]

Frantic - I have the same set up - UUC front BBK, an s54 swap and a 944 booster, but with the stock MC and the brakes suck.

I'm still looking for an alternate plan - massive BBK or a 5 lug swap with adapters for e46 m3 front calipers and e36 rears.


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