upgrading 1" rotors

[MikeB]

My 82 C10 has the light duty front rotors that are 1" thick. If I buy dropped spindles for 1-1/4" rotors, will I need anything other than calipers and rotors for 1-1/4" spindles? I assume at least the inner wheel bearings will also need to be changed, but is there anything else?

Other than the meatier rotors being able to handle more heat, is there any reason the 1" brakes won't stop the truck just as well? I think the pads are identical.

 

[MikeB]

Bump.

 

[theblindchicken]

Can't say for certain, but don't think much else would need to be changed to go to the 1.25" rotor. Maybe the backplate if anything.

Definitely check to make sure that they're the same diameter so you don't have any issues with mounting the new calipers in the same place. May need to verify that the thickness is the same at the mounting surface to the hub. If they are different, then you may need different wheel studs.

Believe that the main reason to go to the 1.25" rotors is for the higher handling of heat which can minimize warping, takes longer before any possible brake fade, and longer wear life.

Take it with a few grains of salt.

 

[chengny]

Other than the meatier rotors being able to handle more heat, is there any reason the 1" brakes won't stop the truck just as well? I think the pads are identical.

Awhile ago, I was interested in the advantages (if any) of increased rotor thickness - so I did some research. Basically what I found agrees exactly with Christian's statement:

Believe that the main reason to go to the 1.25" rotors is for the higher handling of heat which can minimize warping, takes longer before any possible brake fade, and longer wear life.

Under normal circumstances (e.g. not being used on the track and not trailering extremely overweight loads), the only characteristic of a rotor that can reduce braking time/distance is diameter. Thicker rotors (along with other advanced manufacturing techniques like venting/cross drilling/slotting) have only one purpose - to improve heat retention and dissipation rates.

Those rates are the two key factors that prevent "brake fade". Brake fade refers to the loss of friction between the rotor and brake pads.

The reduction of friction - brake fade - is caused when the temperature at the interface of the disc and pad increases until it reaches the "kneepoint".

The kneepoint is that temperature value on the temperature-friction curve where the binding material - the resin used in the manufacturing process of the pads - begins to break down.

As the binding agent decomposes, it starts to "gas off". I searched - a long time - looking for an answer as to for why this condition causes brake fade. But, after a while I gave up - there doesn't seem to be a clear consensus on exactly how the release of the gas causes loss of friction.

Anyway,the bottom line:

Unless you plan on racing your truck on the track or pulling 40' trailers with it, I wouldn't waste my money on 1 1/4" rotors. You should have no concern about your stock brakes ever reaching the knee point.

 

[MikeB]

Believe that the main reason to go to the 1.25" rotors is for the higher handling of heat which can minimize warping, takes longer before any possible brake fade, and longer wear life.

That's what I was thinking. But also more rotating mass to stop. However, I Don't know if that's significant compared to wheel and tire weights and diameters.

Unless you plan on racing your truck on the track or pulling 40' trailers with it, I wouldn't waste my money on 1 1/4" rotors. You should have no concern about your stock brakes ever reaching the knee point.

Mostly what my truck does is carry me and sometime a 200-300 lb load on level highways.

Regarding the statement about rotor diameter being the determining factor for braking time/distance, it's been my experience that forged multi-piston calipers such as Wilwood can also make a noticeable improvement over stock cast calipers by not flexing and by spreading the applied force over more of the pad, instead of just the center.

Thanks for your comments, guys!

 

[theblindchicken]

Torque is all about leverage. Distance from the source of the force (brake pads) to the center point multiplied by the magnitude of the force.

Torque = Force x Distance

Increasing the thickness of the calipers would have no added benefit nor consequence to your braking ability in terms of torque applied. Increasing the rotor diameter will improve your braking ability.

Theoretically, if the total piston area is unchanged, whether it is in a single piston or numerous pistons, the braking ability would be the same.

But, I personally believe that the more uniformly the caliper applies the brakes, the more improved that your brakes will be as well as extending the life of your brake pads. Thus why it seems as though smaller multi-piston calipers are an upgrade over larger single piston calipers such as the stock ones.

 

[CRM]

Do you have standard brakes or power brakes?

 

[MikeB]

Do you have standard brakes or power brakes?

Manual brakes. They actually work pretty well, but I am considering going to power.

Why do you ask?

Thanks.

 

[MikeB]

I personally believe that the more uniformly the caliper applies the brakes, the more improved that your brakes will be as well as extending the life of your brake pads. Thus why it seems as though smaller multi-piston calipers are an upgrade over larger single piston calipers such as the stock ones.

Definitely. I have used Wilwood 4-piston calipers with relatively small piston and pad area, but I also went from 10.4" rotors to 11.75", and of course a different pad compound, so I can't make a true comparison of calipers. That always seems to be the problem with upgrades. We end up changing several things, so we never know which of the parts made the biggest difference!

I'd love to use their D52 two-piston caliper kit on my truck, but it costs around $375 including their excellent BP10 pads.

 

[CRM]

Manual brakes. They actually work pretty well, but I am considering going to power.

Why do you ask?

Thanks.

I was just curious. Would power brakes work better for what your wanting to do without the rotor upgrade?

 

[MikeB]

I was just curious. Would power brakes work better for what your wanting to do without the rotor upgrade?

OE-style power brakes would certainly require less effort, but I don't know if stopping power would be as good. And I'd need to get the master cylinder bore and booster size correct. Also, I don't know if the factory used the same pedal ratio for manual vs. power. On some vehicles, the linkage under the dash is different -- less mechanical leverage and pedal travel for power brakes.

 

[74 Shortbed]

I have one with power brakes and one with manual and both pedals are the same(same year)I'll have to check the donors and see if there's any difference.

 

[MikeB]

I have one with power brakes and one with manual and both pedals are the same(same year)I'll have to check the donors and see if there's any difference.

I'd appreciate that. Maybe the only difference was master cylinder bore size.

Any 15x7 5-on-5 truck rally wheels in your donor inventory?

 

[74 Shortbed]

I'll check on that too, I know I have one set but I'll be using them.

 

[74 Shortbed]

I'd appreciate that. Maybe the only difference was master cylinder bore size.

Any 15x7 5-on-5 truck rally wheels in your donor inventory?

Ok, I have a 78 and 80 donors and the pedals are the same in those as my 74's.. Sorry about the wheels, thought I had another set but they're not rallies..