Claypoolxx

Hi. I've been a member for a while but don't usually post, just a lot of reading. I could use some guidance however. I have a 90 z51 that I bought on here and is used mainly for autocross. When hitting the brakes hard before and leading into a turn occasionally I lock up one of the front tires. I have hp+ pads all around. Its time to change the rears and I'm thinking I may want something with more bite to help even out the braking. Does that make sense?

Some info about the car. The abs has been disabled and the rear, but not the front has been lowered (by one of the previous owners).

If I had to guess, I think that the front not being lowered as well is preventing enough weight transfer for the front tires to "dig in".

If changing rears pads could help what should I get? If not, any other ideas?

Thanks for any help,

Jared

93Rubie

Stupid question, why NO ABS? Preference?

I don't like the HP+, too grabby.

VERY happy with Ferodo DS2500's but alas no rear pads available. I run HPS out back. Seem to work just fine even on a track day.

The Hawk Street Race pads might be a good one to try. Carbotech sells some nice pads too.

Here is the thing, I'd rather have a front lock than the rear, that might cause funny handling under braking. Speaking of funny handling, the rear being lowered on a C4 is good as the roll center is high compared to the front. However, if you don't have the proper front to rear rake, front lower than rear, they handle funny.

Yes, weight transfer to front is good for turn in.

Claypoolxx

[QUOTE=93Rubie;1590492453]Stupid question, why NO ABS?

I'm not sure if the ABS was actually disabled or its just because the front wheel sensors are bad. I've heard that the ABS no a 90 can be very intrusive though.

93Rubie

[QUOTE=Claypoolxx;1590492890]To the best of my knowledge the system is no different than on my 93. I do not find it intrusive at all. In fact being able to stand on the brakes and turn at the same time seems to be an advantage.

Adam@Amp'dAutosport.com

What tires are you using?

Claypoolxx

315/35/17 nt-01 front and rear on 17x11 rims. Just about 2 degrees of camber front and rear too.

Adam@Amp'dAutosport.com

Your going to need something that works from dead cold I would look at the Carbotech AX6 plenty of bite when cold.

Carbotech™ AX6™

The AX6™ is specifically engineered for Autocross applications. A high torque brake compound delivering reliable and consistent performance over a very wide operating temperature range of 50°F to 1000°F + (10°C to 537°C+). The advanced compound matrix provides an excellent initial bite, high coefficient of friction at lower temperatures along with very progressive brake modulation and release characteristics. Many drivers use the AX6™ for street driving as well, even though Carbotech™ doesn't recommend street driving with AX6™ due to possible elevated levels of dust and noise. AX6™ is NOT recommended as a race compound in most applications.

C5 Hardtop

Without ABS, this sounds normal to me.

Claypoolxx

Can anyone confirm if my assumption that using a rear pad with more bite will help even out the braking?

93Rubie

I don't think it will. I think without ABS the more aggressive rear pads will lead to rear locking. You can always try it and see how it goes. Pads are not stupid expensive.

96GS#007

You need to change the brake bias spring in the master cylinder. Doug Rippie Motorsports created them and sold them for years. Used to be ~$20 and if you're mechanically inclined you can remove the old spring and install the new one in about an hour.

Dramatically improved front end dive due to braking on my '96. It had '90 Z51 springs and sway bars as well as Koni adjustable shocks so yours should react in a similar manner. As an aside, the ABS was not intrusive at all....on my '96 or on my '90 Z51 coupe I had before that.

The spring....

SunnydayDILYSI

Keep in mind that you want your front brakes to lock up just before your rear brakes. If your back end locks up first, you'll do a 180. With your rear end compressed (lowered) but your front end still riding high, you probably have a lot of weight transfer to the front on braking. I would lower the front a bit to balance it out. To directly answer your question, yes, a mix of compounds will change the bias (e.g., Carbotech XP8 in front and XP10 in back). That said, most people go the other direction because 80% of braking is done in front and they don't want to do a 180 (i.e., a lot of folks run XP10 up front and XP8 in the back, I've never seen the opposite).