Will I be happy with this disc brake conversion?

[Rick Bollinger]

I am looking at a Willwood conversion. It has a 2 piston willwood calipers, 12 inch drilled and slotted rotors, western chassis 2.5 inch drop spindles. includes bearings & seals. This kit uses the stock ball joints and tie rod ends. I have power drum brakes on my 68 will this master work with this set up? And do I need the proportioning valve with the 2 piston calipers? I know I am asking a lot. I appreciate the feedback.
Thanks
Rick

[Rick Bollinger]

One more thing will my 15x7 truck rallies fit with this kit?

[rpmerf]

I'll add what I can here.

What is the use of this truck? Occasional driver, daily driver, hauling, towing, drag racing, track racing, autocross?

I believe you CAN use a drum / drum master with a disc brake setup, but you have to keep an eye on the fluid as the the front reservoir is a bit small for disc brakes. A disc / drum master will have a larger disc reservoir that will keep up with wear better. You will want to see what size master you should have on there. Stock master for power brakes should be 1-1/8". JB7 brakes form the 80s have a 1-1/4" master.

You will always need a prop valve to balance the braking between the front and rear. It should be designed for a disc / drum pickup. You could get a custom one and go someplace where you can lock the tires to adjust it.

[68Stepbed]

Compared to stock drum brakes, it'll be an improvement, but there's a possibility the master cylinder won't match up to the piston area of the Wilwood calipers.

That said, the stock disc brake calipers have a larger piston area than the Wilwoods and actually offer a higher clamping force than the Wilwoods.

I would actually recommend a kit like this one. --> https://www.earlyclassic.com/node/1213

[Rick Bollinger]

Thanks Matt
It is driven about 9 mos a year mainly for fun. Sometimes to work about 70 miles round trip. I also have a camper that I would like to pull with it on occasion. It's 28 foot with electric brakes. So I would like to do this right the first time.

[GMCPaul]

You do need to use both a disc drum master cylinder and disc / drum prop valve. We recommend this on all our Wildwood caliper disc conversion kits, and our GM caliper disc conversions. The disc brakes will not function correctly without disc drum master and prop valve.
Paul Sr @ GMCPauls

[Rick Bollinger]

With a stock "ish" setup like the one shown with 12"x 1 1/4' rotors and later model calipers which booster would be best? I have stock power brakes with I believe a 11" booster. Is this sufficient or should I be looking at a 9" duel? Don't forget there will be a trailer involved. And what about drilled and slotted even my trailer puller now does not have these.
Rick

[68Stepbed]

Originally Posted by Rick Bollinger

With a stock "ish" setup like the one shown with 12"x 1 1/4' rotors and later model calipers which booster would be best? I have stock power brakes with I believe a 11" booster. Is this sufficient or should I be looking at a 9" duel? Don't forget there will be a trailer involved. And what about drilled and slotted even my trailer puller now does not have these.
Rick

https://www.earlyclassic.com/node/144

As for drilled/slotted, this is a gray area for brakes. Many companies like to advertise the benefits of these rotors, when in fact, they really don't do that much. Slotted rotors actually do more as they allow for gases and dust to be released faster. However, drilled rotors can actually fatigue quicker and crack under stress.

www.youtube.com/watch?reload=9&v=_L_ev1iuGzg

[Rick Bollinger]

I measured my booster today and it is a 9" not a 11" like I thought. I believe it is a single diaphragm. I have around 15-18 inches of vacuum so which is better the 9" or 11"? Here are pictures of what I have. going with stock "ish" conversion kit with GM calipers upgraded ball joints and tie rod ends 71-87.
Thanks Rick

[68Stepbed]

Originally Posted by Rick Bollinger

I measured my booster today and it is a 9" not a 11" like I thought. I believe it is a single diaphragm. I have around 15-18 inches of vacuum so which is better the 9" or 11"? Here are pictures of what I have. going with stock "ish" conversion kit with GM calipers upgraded ball joints and tie rod ends 71-87.
Thanks Rick

With the amount of vacuum you're pulling, you won't see any difference between either size booster. I think you're putting too much emphasis on the booster. The biggest factor will be in the master cylinder bore size.

I actually had this setup on my truck for several years. It always worked great and with aggressive pads, I shocked people with how well it stopped with "stock" brakes. https://www.performanceonline.com/19...e-Booster-Kit/