New front disk brakes on a 76, worth it?

[jasonmcc]

So I have a 76 with stock front brakes and rear drums. I also have 15" rims on 33" tires with MOAB hydroboost and mustang coyote. My question is with the 15" rim I believe the biggest I could go would be the Wilwood 12.19" rotor. Is that worth it or should the conversion only really be considered beneficial if I go to a 17" rim and run 14" rotors like this https://www.wildhorses4x4.com/product/18121/Bronco_Disc_Brake_Kits

 

[toddz69]

Nothing to be gained, in my opinion, with a Wilwood conversion that fits under a 15" rim. You're losing piston area compared to stock and therefore losing clamping force and brake torque.

The larger diameter kits gain a little bit of the brake torque back (longer moment arm), may give you a little more thermal capacity to combat fade (unsure of the rotor mass compared to stock), and give you more pad friction options than stock, I'm sure. They do look sexy though.

Todd Z.

 

[Broncobowsher]

I will agree with Todd on the 15" wheel is limited to a nominal 12" rotor. The overall specs of the base Wilwood kit are a slight step down from stock '76 or the GM conversion. The only way to get more brake is to get a larger wheel.

It is a pretty good engineering trick to fit a 12" rotor into a 15" wheel. 15 years ago I had a car with the factory optional Brembo big brake option. The big brakes were 12" rotors and those required 17" wheels, and special high clearance wheels at that.

 

[Apogee]

X3...I don't have any issue with the Ø12.88 or Ø12.19 Wilwood rotor diameters, however it's the lack of thermal mass that bothers me on their smaller offerings. Both their Forged Narrow Superlite and D8-4 (C3 Corvette caliper) kits have what I would consider to be underweight rotors at 11.5# and 10.5# each respectively, versus 17.4# for the Ø14" disc kit. When the rotor is described as an Ultralite 32 vane rotor, that's not generally conducive to truck/SUV use IMO...which makes sense since they're repurposing rotors originally developed for dirt circle track use on cars that weigh 2000-2500 pounds.

Pad support is better with the multi-piston calipers, but I would expect the pad and rotor temperatures to spike harder and to a greater degree given the lack of thermal mass in the rotors, making pad selection tricky if not impossible for anything other than light-duty use.

Tobin

 

[SteveL]

You could upgrade the stock caliper to the t-bird calipers.

 

[DirtDonk]

I have not heard anyone mention pad size/friction surface area yet, assuming that makes a quantifiable difference (which I think it likely does).
I have not looked up the square-inch size of the pads in question, but if the Wilwoods are enough larger than stock, with the wider support of the 4-pistons in the caliper, there could still be an advantage to them even without the larger diameter rotor.
I wonder if there is a specification for clamping force applied to a rotor? Guessing it's surface area driven, but other than that I have no idea how they would measure to compare.

For substantially less money (like $500 bucks less) you can get the larger and heavier 6-piston Dynapro calipers. They're used with slightly smaller diameter rotors at 11.75 inches, presumably to let the larger caliper still fit inside a 15" wheel, so not sure how that effects the equation. But that gets the thermal mass that was discussed up a notch I would think.

The evenness of the clamping force and the (perhaps) larger pad area of the 6-piston caliper could tip the scales to the benefit side. Unfortunately I see they we don't list them for the '76 and '77 Broncos which is obviously a problem for this discussion.
But in a pinch if you were looking for something like that and didn't mind changing to the earlier knuckles and steering in order to keep the 15" wheels, it's at least an option.
I don't think swapping knuckles has any other advantage unless you're lifted and use the truck off-road and want the early steering linkage anyway, to support the larger tires better.
Or if you happen to have found a perfect set of 15" wheels that have too much backspacing for the '76/'77 knuckles?
Lotta' reach there, but it's all stuff that goes on with Broncos all the time anyway.

Just trying to add some more to the discussion here. I can't say any given Wilwood for a 15" wheel will outperform a stock brake or not, but limiting the discussion to only the Superlite series might not tell the full story.
The larger Ford calipers is always an option as well. But even with the larger piston potentially applying more pressure to the back of the pads, the friction material area is exactly the same as the stock Bronco pad material.

Paul

 

[68ford]

I have had the 6 piston wilwood kit in a 15in wheel for about 4 yrs now. I went from stock 76 77 disc so its a good comparison. Truck has 35 in tires, weighs 5200 pounds and has no power assist. So I was going to feel if there was a change. The wilwood set up requires slightly less pedal effort all the time. But it's a very slight improvement. For some weird reason when I'm in hot desert especially dry climate, they become noticeably easier to stop verses by the beach. No idea why.
Wilwood tech recently told me I could get the same narrow 6 piston caliper with larger pistons that put the surface area just over a t bird caliper. That I would say would make a true noticeable difference over stock and likely the t bird calipers. Another thing that's anoying, is whatever size the rotor is, it could atleast .750 over all larger. Plently of room between the wheel and the caliper. I have 12.875 rotors on the back with 4 piston superlites with the special large pistons. That was a serious improvement over the drums and required major balance bar adjustments to shift pressure bias from rear to up front. Mine have about 30k miles on them and they seem to be wearing really well. Probably good for 75k miles. Put out minimal brake dust.

 

[Broncobowsher]

You can get a noticeable difference in brake feel just by changing the brake pad composition.

 

[bronconut73]

I don't mean to hijack the thread but every couple of years I see a thing on eBay being sold that is a spacer for the master cylinder and a longer rod for your brake pedal. The ideas that gives you greater leverage and makes for easier pedal effort. I always told myself that I can make one of those and I can make a longer brake rod so I don't need to buy it. But you know life being like it is I never did make it and I never did buy it but I was wondering if any of you guys did. It's on eBay again. I'll try to find it. But many of you may already know what I'm talking about and I was just wondering if it really helped when you have manual brakes?

Here it is,

https://www.ebay.com/ulk/itm/223248...d=link&campid=5335857059&toolid=20001&mkevt=1

 

[Broncobowsher]

Simple physics says it does nothing.
The phycology department will tell you that if you spend your hard earned money on something that you think is better, you will convince yourself that it is better.

Pick up a 15/16" bore master cylinder, you will get lower efforts on your manual brakes. That will do more than that kit will do. Unless that kit includes an undersized master cylinder.

 

[DirtDonk]

Didn't read the description, but that's not for increasing anything. It's a factory Ford part for use with "standard" brakes where there is no booster used.
In other words, if you had a '76 or '77 EB with manual brakes, you had one of those on the firewall between it and the booster.

Paul

 

[68ford]

My buddy runs all 76-77 brakes with a wilwood 7/8 master. Made a longer rod to get the pedal a little more off the floor because of the little bit longer stroke required.
He has 35in tires and an automatic that idles high and pushes pretty hard. It stops amazing well. Very little effort. I was very surprised and pleased when I drove it.

 

[76YETI]

Hijack alert . Are the T-bird calipers the same size as the stock 76-77 calipers? I’m running 15” wheels and there isn’t much room.

 

[toddz69]

Hijack alert . Are the T-bird calipers the same size as the stock 76-77 calipers? I’m running 15” wheels and there isn’t much room.

Yes.

Todd Z.