"One time only" deep discount on Wilwood 4 wheel disc brake system...

[biomedtechguy]

I have a one time only discount available for a 4 wheel disc brake system from Wilwood.
I am going to have the same 17" diameter wheels front and rear on my car, FOREVER, except for the rear wheels when I'm at the quarter mile dragstrip if I find that I have to put drag slicks on the rear to get a handle on 60ft times and not throw away the power I'm going to have.
I want to use these 6 piston front discs:
https://www.summitracing.com/parts/wil-140-10815-dr

12.88" disc, 6 piston fronts
MY QUESTION IS if I use those front discs, I would want to use these for the rear, because these work with a 15" wheel, and I may need a 15" rear wheel for track day slicks:
https://www.summitracing.com/parts/wil-140-7144-dr/

12.19" diameter disc 4 piston rear
ANY PROBLEMS WITH MIXING THESE 2 SIZES AND PISTON COUNT?
Thanks

 

[Jerry Hall]

ANY PROBLEMS WITH MIXING THESE 2 SIZES AND PISTON COUNT?

Install an adjustable proportioning valve and you should be fine.

 

[biomedtechguy]

Install an adjustable proportioning valve and you should be fine.

Everything I need is coming from the one source. Wilwood everything, including the prop valve. I am keeping the system manual brakes, but switching to the Wilwood master cylinder.
I'm excited about having more brakes than I need, but it's a great opportunity to save money, and an attractive, high end brake system goes along with the "theme" I am working towards. Kind of a resto mod, boulevard bruiser, occasional drag strip car. I'm not going with a "modern engine" and I am keeping the 3x2 Holley carbs that I just had modded by Promax, but a 3x2 EFI system may be in the future.
I also have a custom console in the works, a Passon Performance a855 5 speed installed already (it's great) and I put these really cool bucket seats in last September:

I already have a complete new front suspension system from QA1 including the K member I need to get installed, and I am going to have the Gerst or RMS triangulated rear suspension system in the future.

 

[funknut]

Those brakes are top notch as you already know, so I’m sure you’ll love them. My struggle with rear brakes was also making sure they would fit with 15” wheels.

Not all 15” wheels are equal, and 12.2” discs are quite large, plus you factor in caliper clearance and you’re quite likely over 13.2” (remember a 1/2” increase on one side is doubled on the diameter). Whether or not that’s enough for the 15” wheels you want is anyone’s guess and depends on the wheel’s inner profile. Their product page says “may fit some 15” wheels” so just be aware. Maybe if you call they can give you a list of wheels they know to fit that kit?

 

[biomedtechguy]

The rear wheels in question will ONLY be for the quarter mile, so I don't care that much what they look like, as long as they work.
I'm not that experienced, but I'm pretty sure that in order to get a tall, flexible sidewall and a slick or DOT legal slick, likely bias ply vs radial (I have a manual transmission) I have a LOT MORE options with a 15" wheel than the 17" Aluminum Rallye wheels that are on it now.

 

[1967coronet440]

Bio, I run those brakes on the rear of my coronet, the critical measurements are going to be caliper clearance and backspace of the wheel you choose. I run 15” billet specialties street lites, first set I order we’re 15x8 with 5.5” bs and they didn’t clear the caliper! Exchanged for a 4.5” bs and it clears by a hair. There is a step on the barrel of the wheel where it goes down by .5” or so that’s where I was hitting. I run the 6 piston up front with a 17” with no clearance issues whatsoever.

 

[biomedtechguy]

15x8 with 5.5” bs and they didn’t clear the caliper! Exchanged for a 4.5” bs and it clears by a hair.

I have some concerns about the backspacing at 4.5"
My 17"x9" rear Aluminum Rallye wheels are a 5" backspacing, and the 315/35 17" Toyo Proxes TQ drag radials fit perfectly centered with the stock suspension and rear quarter wheelwells. I am a little worried about the 1/2" difference in backspacing offset.
GREAT information though, and I really like the look of those wheels.
There's no other style that is going to outshine the 17" Rallyes, but for track days, pretty wheels are just lagniappe.

 

[1967coronet440]

If I did it over again I would go with the smaller 11” rotor in the rear and not worry about clearance with the 15” wheel. Using the big 6 piston set up in the front IMO you won’t notice any difference running that smaller rotor in the rear.


https://wilwood.com/BrakeKits/BrakeKitSearch?flg=11

 

[1967coronet440]

Do you have a 15” wheel in mind? You could look up the diagram and see how much caliper clearance they come with.

 

[biomedtechguy]

I get that. I was trying not to mismatch too much smaller in the rear vs front, and the 17s are going to be on it except for track days.
I think that I can find a 15" wheel for track only purposes that will work with the 12.19, unless backspacing is going to be a problem.
IMPORTANT QUESTION:
I am likely to get mini tubs in the future, and I'm DEFINITELY going with the 4 link RMS StreetLynx or Gerst triangulated rear suspension. Since the only room I have to go with a wider wheel (10/11/12" wide)(without narrowing the rear axle) is to the inside, how does that affect backspacing? Does going wider towards the differential increase or decrease backspacing?

 

[Jerry Hall]

It increases back spacing.

IMPORTANT QUESTION:
I am likely to get mini tubs in the future, and I'm DEFINITELY going with the 4 link RMS StreetLynx or Gerst triangulated rear suspension. Since the only room I have to go with a wider wheel (10/11/12" wide)(without narrowing the rear axle) is to the inside, how does that affect backspacing? Does going wider towards the differential increase or decrease backspacing

 

[1967coronet440]

You can definitely make it work since I run that set up with a 15” wheel, in my case anything more than a 4.5” bs wouldn’t clear my caliper, plenty other wheels out there that it may work with. going to take some homework and measurements on your end before you make a purchase though! Increasing backspacing brings the wheel in towards the differential.

 

[1967coronet440]

Oh and I run the rms street lynx also.

 

[Jerry Hall]

Don't worry about a smaller rotor on the rear, it's not necessarily a mismatch. You don't need to much brake on the rear. Anytime you have to much brake on the rear and you lock up the brakes and the rears lock before the fronts your car will swap ends. You can go with the smaller rotor as suggested and have all the rear brakes you need with the proper adjustment of the proportioning valve.

 

[biomedtechguy]

Thanks a lot guys.
Really good info.

 

[biomedtechguy]

This is the front disc brake system I am ordering Tuesday:
140-12282-DR (regular price $1,300)
12.88 diameter

The rear set 140-12282-DR (regular price $850) 12.19" swapped to 6 piston (add $300)

A master cylinder like this that is around $280-$360

And a 4 corner brake line kit.
So I'm getting everything for $2,400 and when I added up everything I'm saving around $500
Can't wait for the brakes to come in
The QA1 K-member and front suspension system and the SPC upper control arms are all getting installed with the brakes!

 

[1967coronet440]

Just a thought here, and I totally understand you want what you want. But you could save yourself the $300 bones and just stick with the 4 piston rears. 6 piston is overkill and if you really wanted to upgrade the braking on the rear you’d be better off going with a bigger rotor instead of the caliper.

 

[biomedtechguy]

Just a thought here, and I totally understand you want what you want. But you could save yourself the $300 bones and just stick with the 4 piston rears. 6 piston is overkill and if you really wanted to upgrade the braking on the rear you’d be better off going with a bigger rotor instead of the caliper.

Thanks.
The vendor explained that the 6 piston swap in, on what are normally 4 piston brakes in the rear, is a "trick" they discovered in parts interchangeability.
I like the idea of being one of what I assume will be very few 70 Roadrunners with 6 piston calipers on all 4 wheels!

 

[1967coronet440]

That’s cool, I’m sure it’ll look awesome.

 

[MW 413]

Call Willwood's tech line and ask. They have one older tech that specializes in Mopars.
Don't remember his name. They can give you the kit numbers for the set up you need. Eliminates the guessing.