Need Advice on Brake Upgrade for a 76

[Jcon]

I've gone through a boat load of threads to the point that I'm dizzy. I have a 1976 912E modified. (If you're not familiar with them, It was a one year only car. They took a 911 -Everything- and put a 2.0 in it from a 914 and slightly different gearing. this one is modified. It's light weight - 2300 lbs, 2.6 Liter 180hp. It's a street car only. The brakes just don't feel like they match the rest of the car.
The car gets up and goes quickly ( it's not fast but it's quick). When I hit the gas it goes. the suspension is upgraded and refreshed. It turns on a dime. If I think about turning its happened already.
When I hit the brakes the pedal feels fine, but unless I really mash the pedal , braking is vague. It takes too much effort and time to slow the car, which really feels out of place to the rest of the car. The calipers are rebuilt, all the lines are new, hard lines and rubber. New master cylinder, Pads are new etc etc. all of that was done to refresh the car not to fix an issue. All by the previous owner.

So what's the next move in terms of an upgrade in braking feel. The car stops and its not dangerous or anything. The brakes are working as designed I think, they just feel a step behind the rest of the car. I'd like more aggressive braking feel.

So larger calipers / rotors / MC ? What's the current thinking?

[Bill Verburg]

Originally Posted by Jcon

I've gone through a boat load of threads to the point that I'm dizzy. I have a 1976 912E modified. (If you're not familiar with them, It was a one year only car. They took a 911 -Everything- and put a 2.0 in it from a 914 and slightly different gearing. this one is modified. It's light weight - 2300 lbs, 2.6 Liter 180hp. It's a street car only. The brakes just don't feel like they match the rest of the car.
The car gets up and goes quickly ( it's not fast but it's quick). When I hit the gas it goes. the suspension is upgraded and refreshed. It turns on a dime. If I think about turning its happened already.
When I hit the brakes the pedal feels fine, but unless I really mash the pedal , braking is vague. It takes too much effort and time to slow the car, which really feels out of place to the rest of the car. The calipers are rebuilt, all the lines are new, hard lines and rubber. New master cylinder, Pads are new etc etc. all of that was done to refresh the car not to fix an issue. All by the previous owner.

So what's the next move in terms of an upgrade in braking feel. The car stops and its not dangerous or anything. The brakes are working as designed I think, they just feel a step behind the rest of the car. I'd like more aggressive braking feel.

So larger calipers / rotors / MC ? What's the current thinking?

Sounds like the brakes are working as designed, the early non boosted brakes frequently complained about because of pedal effort from people more used to modern boosted brakes.

You don't need anything more than what you have

except perhaps try some different
pads

pads have different temperature regimes where the operate best and there can be a large different in the initial bits and release character of the different materials used.

I'm not recommending any particular brand but just as an example here are the profiles of some Hawk brand pads

[inaminit]

I am having the same experience as Jcon. My 912E has a stock engine and original suspension, and the brakes require a ridiculous amount of pedal pressure. I have a 76s, also unboosted, and it has much better braking with much less pedal pressure. The 912E rotors are solid, not ventilated and the calipers have a thinner spacer between the halves to work with the thinner rotors. I am wondering if this arrangement is part of the problem.
So I am going to ditch the front rotors and switch to ventilated rotors, with wider calipers and street pads. If that dosen't do the job, then maybe a caliper upgrade? Other users have switched to Alfa calipers with good results. If the front calipers are upgraded, what about the rears? I know that you must maintain a certain ratio betwee the front and rear braking systems.
Thanks in advance for your advice

[Bill Verburg]

Originally Posted by inaminit

I am having the same experience as Jcon. My 912E has a stock engine and original suspension, and the brakes require a ridiculous amount of pedal pressure. I have a 76s, also unboosted, and it has much better braking with much less pedal pressure. The 912E rotors are solid, not ventilated and the calipers have a thinner spacer between the halves to work with the thinner rotors. I am wondering if this arrangement is part of the problem.
So I am going to ditch the front rotors and switch to ventilated rotors, with wider calipers and street pads. If that dosen't do the job, then maybe a caliper upgrade? Other users have switched to Alfa calipers with good results. If the front calipers are upgraded, what about the rears? I know that you must maintain a certain ratio betwee the front and rear braking systems.
Thanks in advance for your advice

If the 912e has solid rotors then by all means upgrade to either 911 2.4/2.7/3.0 20 x 289 or 3.2 24x289 w/ either Sc or 3.2 calipers to match the rotors, you would need 3.5" struts for this,
w/ 3" struts the Alfa caliper and the 3.0 20 x289 rotors

w/ any of the above use 2.4/2.7/3.0 rear M calipers on the matching 20 x290 rotors, don't use the 3.2 24 x290s they will ruin bias for normal usage.

[Duc Hunter]

A pad switch and understanding they are non-assisted brake will be the route. I like the non-assisted feel, and on my 1975 I went to Carrera brakes, ATE 23mm “turbo” master cylinder, and new pads…that did help a fair bit…but it still takes a fair bit of pressure to stop. Again non-assisted brakes. I changed my brakes for different reason, I doubt if you made the change I did you would be happy with the “increased braking power.”

[Bill Verburg]

Originally Posted by Duc Hunter

A pad switch and understanding they are non-assisted brake will be the route. I like the non-assisted feel, and on my 1975 I went to Carrera brakes, ATE 23mm “turbo” master cylinder, and new pads…that did help a fair bit…but it still takes a fair bit of pressure to stop. Again non-assisted brakes. I changed my brakes for different reason, I doubt if you made the change I did you would be happy with the “increased braking power.”

When using A & M calipers the stock non boosted m/c is 19.05mm, this m/c is quite close to the Granny end of the scale and leaves a lot to be desired in terms of feel and control. For part of '69 they used a 20.6mm version that gave better feel at the cost of some extra effort, this m/c is very close to the ideal or sweet spot . The Doctors, Lawyers and Indian Chiefs that were buying the cars objected to the requisite effort so they went to a boosted 20.6 mm used from '77 thru '89.

Some racers do use the 23.8mm non boosted m/c fw/ A & M's for it's exquisite feel and control but the leg effort w/ A & M calipers is quite high

[inaminit]

One last question-Our host offers drilled and slotted rotors-which is best for street use?
Thanks in advance

[kmcteer]

I generally stay away from drilled rotors. The heat stress can lead to cracking and that is too big of a hassle to even consider. Slotted work fine in my experience across vehicles.

With all of that said, to increase braking power you need to create a higher stopping moment. there are several ways to do this but the easiest is increasing the coefficient of friction of the pad. When I did a manual brake conversion in the past on a Scirocco, I jumped up to a EBC yellow stuff pad. It had great initial bite and only got better with heat.

-Kelly

[ToySnakePMC]

Just to chime in -- my 912E was purchased about 6 yrs ago with a 3.0/ 915 swap - and I later learned - the car has SC vented brakes at all corners.

i need to measure my caliper bolt measurement to verify which calipers i have (3 or 3.5") But, the non-assisted brakes are great. I've completed some aggressive mountain rallies in the mtns of VA, TN, and NC - and never ran out of brakes coming down the twisties. I'm easy on brakes - but I definitely was stabbing them hard and often on those weekends.

Here's a photo or 2:

[Bill Verburg]

Originally Posted by inaminit

One last question-Our host offers drilled and slotted rotors-which is best for street use?
Thanks in advance

For street use any of them will do fine, stay away from drilled for track use, they will crack out way before plain or slotted

[Duc Hunter]

Originally Posted by Bill Verburg

When using A & M calipers the stock non boosted m/c is 19.05mm, this m/c is quite close to the Granny end of the scale and leaves a lot to be desired in terms of feel and control. For part of '69 they used a 20.6mm version that gave better feel at the cost of some extra effort, this m/c is very close to the ideal or sweet spot . The Doctors, Lawyers and Indian Chiefs that were buying the cars objected to the requisite effort so they went to a boosted 20.6 mm used from '77 thru '89.

Some racers do use the 23.8mm non boosted m/c fw/ A & M's for it's exquisite feel and control but the leg effort w/ A & M calipers is quite high

Bill, So you're saying that the 23mm 91135501202 that I just put in with my circa 1988 Carrera calipers (all rebuild by PMB, and their pads) was not that best match? I am 6'2", 230lbs and don't miss a leg day in the gym, so I don't find a firm pedal.

[Bill Verburg]

Originally Posted by Duc Hunter

Bill, So you're saying that the 23mm 91135501202 that I just put in with my circa 1988 Carrera calipers (all rebuild by PMB, and their pads) was not that best match? I am 6'2", 230lbs and don't miss a leg day in the gym, so I don't find a firm pedal.

Not at all, just that the 23.8, especially non-boosted, takes way more leg than most drivers will want to have to use.

Track guys love that combination because it gives exquisite control.