Rear brake project
02-16-2007, 07:21 AM
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Rear brake project
I modified my back brakes to go with the front. Using Wilwood Forged Dynalite calipers (4 piston) for the primary rear braking with 12.9" directional vane vented rotors.
Now the interesting part. For parking brakes, I used Wilwood Billet Spot calipers and converted them from hydraulic to mechanical by bolting on the mechanical actuators from the stock rear calipers. It is a tight fit, but everything works with no interferences.
This was a lot of work but I wanted parking/emergency brakes and did not want to use the cheap Wilwood parking brake calipers or the expensive ($250 each) calipers that are available.
Parking/eBrake caliper. Top view. You can see top of the custom mouting bracket (7075 aluminum) and the aluminum spacer that I added to adapt the caliper to fit a 1" thick rotor. The caliper is on a floating mount since it is a single piston.
Parking/eBrake caliper. Front view. The aluminum boss that is sticking out to the left was eventually trimmed back so that it just butts against the main caliper for extra support. The bolts sticking out the face were also eventually ground flush as you can see in the later pictures.
I was able to use the stock eBrake cable bracket and cable. I did a lot of cutting and grinding to get the stock actuator onto the Wilwood caliper.
A better view of the components for the eBrake caliper. You can see the mounting bracket, spacer, front and rear caliper halves, and the 2 main bolts with the floating mount bushings.
I mounted the mechanical actuator to the rear caliper half using four 1/4-20 grade 8 bolts. A steel rod fits into the center hole and is pushed forward by the actuator mechanism when the eBrake is pulled. The steel rod pushes on the Wilwood caliper piston to clamp the caliper.
Top view of stock rear caliper and my creation.
Picture after painting the spacer and actuator then grinding the 2 main bolts. Mounting bracket is not in the picture so you can see the bushings better.
Mounted on left rear. Tight fit with upper ball joint mount. No rubbing anywhere.
I did not take a separate pic of it, but the primary caliper has it's own mounting bracket that is steel. I did not want to risk a brake failure just to save a little weight.
Plenty of clearance to wheel (18" X 10", offset +76). Definitely would not fit under the stock wheels. Hope I don't get any flats because I am sure the spare will not fit over the brakes.
Now the interesting part. For parking brakes, I used Wilwood Billet Spot calipers and converted them from hydraulic to mechanical by bolting on the mechanical actuators from the stock rear calipers. It is a tight fit, but everything works with no interferences.
This was a lot of work but I wanted parking/emergency brakes and did not want to use the cheap Wilwood parking brake calipers or the expensive ($250 each) calipers that are available.
Parking/eBrake caliper. Top view. You can see top of the custom mouting bracket (7075 aluminum) and the aluminum spacer that I added to adapt the caliper to fit a 1" thick rotor. The caliper is on a floating mount since it is a single piston.
Parking/eBrake caliper. Front view. The aluminum boss that is sticking out to the left was eventually trimmed back so that it just butts against the main caliper for extra support. The bolts sticking out the face were also eventually ground flush as you can see in the later pictures.
I was able to use the stock eBrake cable bracket and cable. I did a lot of cutting and grinding to get the stock actuator onto the Wilwood caliper.
A better view of the components for the eBrake caliper. You can see the mounting bracket, spacer, front and rear caliper halves, and the 2 main bolts with the floating mount bushings.
I mounted the mechanical actuator to the rear caliper half using four 1/4-20 grade 8 bolts. A steel rod fits into the center hole and is pushed forward by the actuator mechanism when the eBrake is pulled. The steel rod pushes on the Wilwood caliper piston to clamp the caliper.
Top view of stock rear caliper and my creation.
Picture after painting the spacer and actuator then grinding the 2 main bolts. Mounting bracket is not in the picture so you can see the bushings better.
Mounted on left rear. Tight fit with upper ball joint mount. No rubbing anywhere.
I did not take a separate pic of it, but the primary caliper has it's own mounting bracket that is steel. I did not want to risk a brake failure just to save a little weight.
Plenty of clearance to wheel (18" X 10", offset +76). Definitely would not fit under the stock wheels. Hope I don't get any flats because I am sure the spare will not fit over the brakes.
02-16-2007, 07:24 AM
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OK, I'll be the 1st to admit I can be dumb to certain things.
Is that a second brake? If so, explain why you need it to me please. It does look nice!! The whole setup looks great in fact!
Is that a second brake? If so, explain why you need it to me please. It does look nice!! The whole setup looks great in fact!
02-16-2007, 08:16 AM
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I added the captioning. I tend to post then edit so I don't lose my typing.
The lower mounted caliper is the primary rear brake and the smaller caliper above it is the eBrake.
The lower mounted caliper is the primary rear brake and the smaller caliper above it is the eBrake.
02-16-2007, 09:07 AM
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Rear rotors are 12.9" diameter, 1" thick and directionally vented. Slotted but not drilled. I was afraid drilling might lead to cracks. Also, drilling would add about $80 per rotor.
I now have 12.9" on front and rear. I tried to maintain front/rear brake bias similiar to stock. By my measurements stock bias is about 66/33 front to rear accounting for differences in piston diameters and rotor diameters.
I am using 1.75" diameter pistons on the front and 1.375" diameter on the rear with equal rotor size. I figure my new brake setup gives me about 60/40 front to rear bias. I think I can handle the extra rear braking since I have 285's on the back and the vented rotors should take care of the added heat.
I now have 12.9" on front and rear. I tried to maintain front/rear brake bias similiar to stock. By my measurements stock bias is about 66/33 front to rear accounting for differences in piston diameters and rotor diameters.
I am using 1.75" diameter pistons on the front and 1.375" diameter on the rear with equal rotor size. I figure my new brake setup gives me about 60/40 front to rear bias. I think I can handle the extra rear braking since I have 285's on the back and the vented rotors should take care of the added heat.
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02-16-2007, 04:57 PM
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In answer to your question RBC3: The stock rear caliper is a combination hydraulic brake for primary braking and mechanical for eBrake, and the Wilwood Dynalite caliper is only hydraulic and has no eBrake function (pretty much typical of after market calipers). So when I replaced the stock rear calipers with the Wilwood Dynalites, I lost the eBrakes. I had to add the modified Billet Spot calipers to provide mechanical eBrakes. The pictures did not make much sense until I added the captions and explanation.
For Skip: This was way too much work to do again, so you are on your own if you want a one-off brake set up like this. I probably won't do the Dragon this time but I am seriouly considering the next track day at Talladega.
For Skip: This was way too much work to do again, so you are on your own if you want a one-off brake set up like this. I probably won't do the Dragon this time but I am seriouly considering the next track day at Talladega.
Nice work Terry.