AR vs Dr Diff 13" front discs 73 up?

-
Rice Nuker

Rice Nuker

Let the Coal Roll!
Joined
Jan 29, 2010
Messages
2,263
Reaction score
53
Location
U.S.A.! Near Jackson CA
Anyone care to discuss the differences in the two kits?

The AR Engineering kit shows 13" discs, cast iron over 1" thick . Viper calipers and new hubs.
No lines, no pads. Special order build. 1495


The Dr Diff shows 13" coated(?) discs. Loaded Cobra calipers and new hubs and stainless lines. Cant tell if they are in stock. 850

Am I missing something crucial here about the kits? One is near double the price and has no brake lines or pads.

Would anyone like to share some wisdom and experience to the specifics of these two kits?

.
 
prices went up at AR, they used to be in the $900 range. I guess the kits are all special order now, I should have upgraded sooner!
btw the AR kit does'nt include calipers
 
Go dr diff, he use parts easily found at an auto parts store (same with the rear kit).
 
1970, so the rotors at dr diff are production like cobra or something ?

I am going to email them and get the details on the rotors. Seems like there is no reason to buy AR unless someone has some astounding revelation about how Dr Diff will totally fall off the car or fail to provide equivalent stopping power.

.
 
One kit has no calipers.
I should talk to Dr Diff because one or more parts are found at Napa.
I can talk directly to Dr Diff.



.
 
Further investigation is revealing that there may be reasons that the kits are different prices. I have not heard any one shed any real technical wisdom as to what the pros and cons of each kit may be.
So what I have gathered so fare is;
Cobra calipers are not as good as viper calipers. The material that the different kit's caliper mounts and hubs are made from is a factor possibly. The composition of the rotor is a factor too.
More to come
 
I am trying to clarify the differences in the two kits in options, components, the details on the components, why one is better or worse and any other kits that any one wants to clearly inform us on.



.
 
Why dont you just call wilwood for a good kit? they are around the same price and their kits come with everything you need
 
Hubs are custom, Dr Diff uses a cut down rotor for the hub, at least he used to. Real PBR calipers are not avail anymore, so now they are a cheaper Asian copy. It's a floating 2 piston caliper typical on many modern cars. The Viper is a fixed 4 piston and very rigid/more expensive unit. I've been running an old Dr Diff kit since 06, and it's a very good setup. It's a cobra setup so the piston sizes work without any special proportioning valve. Personally, I would not run anything from Wilwood. OE style parts make sense and usually work better anyway.
 
Rice - You are comparing two kits that aren't really that comparable. Doctor Diff has a Viper based kit which would be a better comparison. His Viper kit uses a 14 inch SRT rotor though so you need an 18 inch rim. My 13 inch Viper kit is designed to work with Mustang 17x8 rims. But at least the calipers are the same between those two kits.

The Baer 6P kit is a good one comparison against my 13 inch Viper kit. The Baer rotor is thinner, the hub is designed for a Mopar wheel, but the 6P caliper is a good comparison to the Viper caliper. The Mustang calipers aren't really in the same league as the Brembo or Baer designs.

These higher end kits all have significant differences between them. My 13 inch kits are designed to only work with Mustang rims. That is a big difference but I don't see anyone even mentioning it in the thread. When you're shopping for these kits you have to pay attention to wheel size, wheel offset, brake bias, piston size, etc.

Do you have a copy of my B-body book? If not, you should pick up a copy and read it. I covered all of the available brake kits in the book so that is the easiest way to compare the kits.

If you post what your budget is and what you're trying to accomplish I'll give you a recommendation. If your car isn't very fast you might not even need one of these kits. The factory 11.75 setup works pretty well up to 120 mph or so.
 
Cool, thanks all for the informed replies.

I do understand that there are differences, and well, they are both front brake kits, so I was comparing them.
Just doing what most people do, trying to compare the bang for the buck based on material, hardware, performance and longevity.

Andy,

Well, I would say 1k is my limit on an out the door setup. Rotors, calipers, pads, caliper brackets, stainless mesh flex hoses. That's probably enough said but here are some supporting meanderings..

I do very much prefer any brand automotive production hardware or based on production hardware as much as possible, rather than custom parts like calipers, rotors, hubs. Wilwood looks like I will be buying willwood for ever when I need a new part.
I prefer to get the most stopping power and longevity for my buck.
Not interested in power brakes really at all. I would rather just push harder and run a smaller diameter master cylinder, unless the stroke wont fill the calipers before it bottoms out.
I am buying wheels, either 18 or 20. I do like 18 and 20 inch mustang wheel options and if they fit my back spacing needs I will use them being that the aftermarket mustang wheels are cheap. I am essentially going to buy wheels/offset/backspacing once the suspension is in place. Pro touring style car generally.
Car will be 1 - 2 " lower at the most. I still need to clear the tree limbs and rocks when I go Smokey and the Bandit style.
I am going to try hard to keep identical wheel / tire on 4 corners when I buy so I can rotate them and have large traction up front.
Full plan is: Duster. moderate - balanced 440 w/ ported al heads / 727 w tight converter/ 2.76 SG 8-3/4.
Stiffest bars all around. Poly everything. ff uca. boxed lcas. sf conns. boxed up k frame. braces where needed.

So, I need to stop a nose heavy street machine with reasonably large rubber on front and rear. Rear has 11x2.5" or 3" drums so, should be fine, uhm,I guess, or not.

I don't see any point in only going 120. I can do that with a Georgia overdrive, loaded with chickens. At least I could until the dang ICC started checkin' on down the line :)

I plan to get er up the point where it stops pulling in high gear and set the cruise control.
A year ago I bought a new 11.75 setup with exception of the used spindles. Reckon most of that will sit on a shelf.

I am going to look into your book.

Thanks.
 
You aren't going to be able to buy a good brake kit for $1000. My 13 inch Viper kit costs about $2000 for a complete setup. The Baer kits are $2500 to $3000.

Your best bet is the 13 inch Mustang kit from DoctorDiff. It isn't really a high performance brake kit but it would be a bit better than a factory 11.75 setup. But at your price point, that is the best that you'll be able to afford.
 
A 13" brake kit that stopped the Mustang Cobra in a very short distance (110 from 60?) is a pretty darn good kit. I've run this on the track and I'd consider this a pretty serious setup regardless of the bread and butter 2 piston calipers.
 
Thanks AndyF and GMachine for sharing the expertise and application knowledge!

Yep I can only go to a certain level of bitchen when I have a budget cap on various facets of the machine.
 
AndyF said:
Rice -

These higher end kits all have significant differences between them. My 13 inch kits are designed to only work with Mustang rims. That is a big difference but I don't see anyone even mentioning it in the thread. When you're shopping for these kits you have to pay attention to wheel size, wheel offset, brake bias, piston size, etc.
Click to expand...

Does your 13" kit place hub mounting surface of the wheel in the same position as the 73+ factory disc brakes? if not what is the offset?
 
GMachineDartGT said:
A 13" brake kit that stopped the Mustang Cobra in a very short distance (110 from 60?) is a pretty darn good kit. I've run this on the track and I'd consider this a pretty serious setup regardless of the bread and butter 2 piston calipers.
Click to expand...

Sure, the 13 x 1.10 Mustang setup with the two piston slider caliper is better than anything Mopar ever installed back in the day. But you'll notice that the Ford engineers don't use those brakes on any of the serious Mustang models. Anything with some power gets upgraded to a Brembo caliper and a larger, or thicker rotor.

It is all about power, speed and weight. You need more brake mass to haul down a faster car. The Mustang kit is probably good up to 135 mph or so in a Mopar, after that you really need something with some serious mass.

The DoctorDiff kit with the 14 inch SRT rotors should be good up past 150 mph in a Mopar. Those SRT rotors are super heavy so they'll absorb a ton of heat before they cook.
 
I agree, but the tracks that I've been to so far have topped me out around 130. For me the next upgrade may be the brembo caliper. The corvette (reg model) still uses the PBR but with a 1.25 rotor instead of 1.1 ford rotor. I've also used the SRT kit when I built the suspension/brakes on Angrier Daytona with good results.
 
This is the 14"/13" kit Andy is referring to. It works on the A spindle too. Uses SRT8 rotors with Viper calipers up front and Varga calipers in the rear. Another very well matched OE durable system.
 
GMachineDartGT said:
This is the 14"/13" kit Andy is referring to. It works on the A spindle too. Uses SRT8 rotors with Viper calipers up front and Varga calipers in the rear. Another very well matched OE durable system.
Click to expand...

Which spindle? Drum or disc brake?
 
You must log in or register to reply here.
-

Back
Top