GAZRNR Posted March 5, 2006 Share Posted March 5, 2006 I have a concern with the brake system I put together on my 78Z. If I am driving normally on the street and have to brake hard for some reason the initial brake "grab" is not that hard bite your get in any average street car, in fact I cannot lock the wheels no matter how hard I hit them, once I get some heat into the brakes they seem to be more to what they should be but no lock up. After driving and using the brakes hard a few times I am surpirsed that they are only warm to the touch, the same test with my integra almost burned the skin off my fingers. Slower controled stops are straight & predictible but longer than they should be. On the street you need that hard bite sometimes to avoid whatever comes up. I am using an 81 master cylinder, Wilwood 4 piston calipers with wilwood street pads, wilwood 1.25 curved vane rotors up front, in the rear I have Modern's rear 240sx brake kit. I am using a wilwood proporting valve for adjusting the rear brake balance and SS lines on all 4 corners. I have blead the system a number of times and I do not have a spongy pedel, the foot pressure is consistent. I did this upgrade expecting an agressive brake system that would not fade out. Any thoughts? Bad vacum brake booster? Need a more agressive pad up front? Thanks, Rusty Quote Link to comment Share on other sites More sharing options...
2003z Posted March 5, 2006 Share Posted March 5, 2006 DO you have the brakes on the wrong side? (bleed valves below the feed line)? Its a common mistake, and you will think they are bled, as you won't get any air out, but they won't be. Quote Link to comment Share on other sites More sharing options...
fastzcars Posted March 5, 2006 Share Posted March 5, 2006 I wouldn't think that you had air in the line. My feeling is that you probably need a different pad in front. I didn't like the wilwood pads on my car. They squeeled like pigs. So I tried the EBC green pads. They are for the street and can take some track use and I like them much better than the wilwood's. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted March 5, 2006 Share Posted March 5, 2006 I would think a different pad as well. Maybe a fresh turn of the rotors, then make sure you bed in the pads properly. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 5, 2006 Share Posted March 5, 2006 Yep, wrong pads seems to be the case. You actually need a LESS aggressive pad, as the more aggressive pad will require more heat before it starts working. Maybe something like a Hawk HPS, or the EBC Green as mentioned before. Quote Link to comment Share on other sites More sharing options...
Clifton Posted March 5, 2006 Share Posted March 5, 2006 Did this just happen or was it after the brake swap? Regardless of the pad you shouldn't have any problem locking up a tire with those brakes, especially if you are running street tires. I have had a bad vacuum booster and I had a hard time stopping, even pushing as hard as I could still wouldn't lock a tire. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 5, 2006 Share Posted March 5, 2006 Regardless of the pad you shouldn't have any problem locking up a tire with those brakes, especially if you are running street tires. That has not been my experience. Aggressive race pads don't do jack until they get some heat in them IME. Quote Link to comment Share on other sites More sharing options...
GAZRNR Posted March 6, 2006 Author Share Posted March 6, 2006 Thanks for all the input. The wilwood NDL calipers have 2 bleeders on each side top & bottom so there are no issues getting the air out and way it is made it doesn't matter what side they go on. The wilwood Q compound pad is supposed to be their recommedned pad for the street. I followed the MFG bedding process and the brakes have been like I described since I installed them. I get no screech or dust, it's like they are not wearing at all. No hard bite and long stops. I am looking into the Hawk HPS (F) compound PN: HB237F-.625 which is their street pad for the caliper I am using. Has anyone tried this pad series and had the results they expected? Could there be an issue with the vacume brake booster? How can you tell if it is worn out or dead? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 6, 2006 Share Posted March 6, 2006 You could disconnect the vacuum line to the booster and drive it down the street, then reconnect and see if there is a difference. Just be aware that you'll have to hit the brakes really hard to stop. Or you could start the car, then turn it off and pump the brakes about 5 times. You should feel the pedal change and get rock hard after about the 4th pump or so. Quote Link to comment Share on other sites More sharing options...
Guest Speedyblue Posted March 6, 2006 Share Posted March 6, 2006 As a continuance of what jmortenson said, after pumping the pedal a few times, hold it down and start the car again. The vacuum should make the pedal go down a little as the booster helps you. Quote Link to comment Share on other sites More sharing options...
bjhines Posted March 6, 2006 Share Posted March 6, 2006 well... no lock???? that is scary... My booster went out on a run down Tail of the Dragon last year.... I could still lock all 4 wheels... I had normal pedal height.. just a lot harder pedal... That was stock rotors with Carbotech XP9 pads in Toyota calipers.. I went to a vented set up soon after that and replaced the booster as well.. the new brakes work fine with no booster as well... cold or hot... I had plugged the vac lines when I was tuning the DCOES... I had no trouble stopping it.. just a harder pedal.. still easy to lock... Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted March 7, 2006 Share Posted March 7, 2006 I tried the HB237-HPS pads and didn't like them very much for either street or autocross. I switched to the HB237-HP-plus and LOVE them. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted March 8, 2006 Share Posted March 8, 2006 I would say, Check brake booster. Check that the brake pedal is fully actuating the master cylinder. Prop. valve facing wrong way? Any fluid leaks? Front /rear master cylinder lines swapped? Quote Link to comment Share on other sites More sharing options...
Phantom Posted March 8, 2006 Share Posted March 8, 2006 I'm running the Modern 240SX/300ZX rear disk brake set-up with their recommended pads and Willwood 12.2" vented rotors with forged superlites in the front with Hawk pads. I also have the '81 master cylinder but have not yet installed the adjustable proportioning vavle. Observations: 1) I have no problem locking them all up. 2) My front wheels are always coated with brake dust. Get the car on a wet parking lot and attempt some lock-up tests. Let's be sure that you aren't trying to do all your braking with the rear. YOu'll know right away on wet pavement if the rear tires are the only ones that lock up. That will require more adjustment on your proportioning valve. Obvious questions - you did remove the stock proportioning valve - correct? You also carefully bled the the master cylinder before it was installed? If it wasn't "bench bled" you may not have a properly operating master cylinder. After all that I would be back to the vacuum booster. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.