Calipers on the Gen III

[JGK95]

Who can tell me the size of the piston in the Gen III brake calipers both front and back. Already I'm gathering info on braking as I plan to track the car at solo events with the SCCA. The Gen II's rear calipers look like a hand brake by comparison.

Jay K.

 

[Steve-Indy]

From the 2005 Viper Service Manual:

FRONT....44mm and 42mm

REAR.....40mm and 38mm

 

[JGK95]

Thanks Steve! I couldn't believe it that I had over fifty views and not one response. From what I read above, why do the numbers differ? Any idea?

Thanks,

Jay K.

 

[Janni]

Smaller pistons in the rear are used for brake balance.

Smaller pistons within the same caliper are used to even out the clamping force over the brake pad, i.e. so the pad hits the disc flat, not one half the pad first......

 

[JGK95]

Janni,

Thanks, I understood the purpose of the smaller piston in the rear caliper. My question was geared toward the answer in which two front and rear mm sizes were provided. I was left guessing why the fronts are either 44mm OR 42mm and the rear calipers 40mm OR 38mm rather than a single number for the front and a single number for the rear. Why the difference in sizes for the same front calipers?

Alternatively, "Is there a difference in the sizes of the front or rear pistons for the '03 cars to the '05 cars?"

Thanks,

Jay K.

 

[Janni]

Jay,
All Gen III front calipers are the same. All Gen III rear calipers are the same (save for color). Rronts are not the same as rears.

The fronts and rears are 4 piston calipers. With 2 pair of different sized pistons - the piston size is staggered in the caliper to provide a flush force to the brake pad - that's why there are 2 sizes of pistons in each caliper.

I hope this makes sense.

 

[Viper IV]

Jay K
If your interested I have a set of perfect 04 rotors I'd consider selling. Front and Rear
Rob

 

[Tom F&L GoR]

Within a caliper there are two piston sizes. The smaller piston clamps on the leading edge of the pad (in the direction of rotor rotation.) The larger piston provides more clamping downstream because the hot gases escaping from the forward edge of the hot brake pad decrease the contact area as you get to the trailing edge of the brake pad against the rotor. Therefore left and right caliper are not the same, even if you take into account that the bleeder screws can be put on the "other" end; the smaller piston is in the leading position. What Janni said.

Jay, for Solo events, having a total of 16 brake pistons may be overkill. For many events, it's the brake balance front to rear that needs attention; only when you add endurance to the requirement list do you need larger parts, IMO. And you can get better balance for 20% of the cost of a four caliper swap.

 

[JGK95]

Janni AND Tom,

Thank you both for the clarification. I now understand. I had thought that the Caliper housed only one piston instead of two.

Rob,

I need a Gen III to put those rotors on first!

I'm currently in the market and looking around for either a silver or black and will consider red as a last choice.

Come to think of it I'd better verify with the Viper Registry on this site if Silver was a color choice for 2K3.

This is definitely a thread that is going to be marked as a favorite.

Thanks everyone again,

Jay K.

 

[Tom F&L GoR]

Jay, each caliper has four pistons; two on inside, two on outside. SRT really does have total of 16 brake pistons on the car.

 

[JGK95]

Doh!

Dragged, Kicking and screaming I'll learn me yet bout how to count brake pistons!

Thanks again Tom,

Jay K.