I’ll just ramble on here for a while. When fitting a different front brake system to a Sunbeam, I would rate the selection on the following criteria. This is not necessarily in priority order.
· Lighter weight
Lighter weight of the brake assembly improves the ride and handling
· Increased piston area
Under equal hydraulic pressure, the clamping force of the caliper is only increased by increasing piston area.
· Larger disk diameter
Brake torque is a function of the clamping force, the friction coefficient between the pad and the disk and the radius of the pad centroid from the axis. As an example, if you increase the piston area by 20% and the disk diameter by 10% you will increase the braking torque by 32%. The downside is the larger package.
· Vented disk
Although a larger brake pad area is an important criterion, vented disks are more important. Most modern cars have vented front disks that have vastly improved cooling. Because the Tiger is a light vehicle this may not be an important criteria but there must be a performance improvement to give us justification for the modification, right?
· Increased pad area
Brake pad size is not irrelevant. The coefficient of friction of the pad on the disk surface is generally dependent on the pad material and the pad and disk temperature. This is where pad size becomes relevant. Passenger car pad material is selected that has a coefficient of friction that remains consistently high under normal operating conditions so that the driver experiences good braking performance. If the brakes over heat, as when the car is going down unusually steep grades the coefficient of friction reduces drastically so fading occurs. For this reason, larger pads will give better braking because they can absorb more heat before fade.
When racing type pads, usually high metallic, are used, a different phenomenal occurs. When cold, these pads have very low friction and when hot the friction is high. When with these pads are used in a road race car, the temperature stays high while racing so the braking torque stays high, minimizing fade. If used in your normal passenger car, the pads stay relatively cool so high pedal pressures are required to stop the vehicle.
· More pistons
Smaller multiple pistons will fit within the pad area and spread the clamping load out evenly to reduce uneven pressure across the pad.
· Smaller package
If a smaller package were found that would allow the disk and caliper to move outward, the steering arm could move out and allow an improvement in steering Ackerman.
· Low cost of installation
Machining is an expensive proposition if you have to pay someone to do it. Finding parts that can be retrofitted with a minimum of machining would make the modification achievable for more of our members.
· Available new and used parts over a long term
There must be used parts in junkyards that fit. If parts are used from a low production car, it sometimes doesn’t’t take long before the replacement parts cost more than Sunbeam parts. I modified my rear brakes using Mazda 1985 RX7 components because the junkyards were full of good parts. Now they are all gone around here and if parts stores have them they ask a premium price.
· Looks good
When we show these brakes to someone it’s nice to hear “Wow” when they look at them!
· Other
Now, tell me what I forgot to mention.
I’m interested in the ideas that some of you have and I hope you will keep putting them put them in this Forum. For your information, I fitted a 2002 Mustang Cobra caliper with a 10”x 1” vented disk to a Sunbeam spindle. It will fit on either a Tiger or Alpine and have an increased braking torque of 43%. That increase would cause a front to rear brake balance problem. It looked good with the polished Cobra name on it. However, because of the heavy vented disk, the assembly weighs 2.6 lb more then the Sunbeam assembly. I feel this is unacceptable.