Dr. Diff 10 x 2 1/2 inch or 11 x 2 1/2 rear drum brake Assy

[65Vart]

Changing the SBP rear axles on my 68 GTS to BBP
what should I go with , 10 x 2 1/2 inch or 11 x 2 1/2 drums(Dr. diff) ?
Also. are screw in studs a better choice than the press in ?

Thanks

 

[dano]

Why not go disc?

 

[65Vart]

Why not go disc?

I know , good point, but I want to keep it semi period looking.

 

[dano]

I know , good point, but I want to keep it semi period looking.

I thought that too, until I drove my GTS in modern traffic. But I live in a large metro city so that might not be a factor.

 

[4mulas]

My opinion- 10.5" unless you’re running oversized front brakes too. Then maybe consider 11"

 

[340sFastback]

I am going 11 3/4 inch front disc and 10.7 rear disc when I convert mine to big bolt pattern. With 15 inch steel wheels no one can see those brakes. But if you want to run 14 inch wheels I think you have to go drum brakes in the rear.

 

[65Vart]

My opinion- 10.5" unless you’re running oversized front brakes too. Then maybe consider 11"

Running discs up front

 

[PROSTOCKTOM]

It all depends on what size rims you're running and if they are factory rims on what size to choose. Personally I use the 10" x2-1/2"

Tom

 

[340sFastback]

Running discs up front

If your running 11 inch disc up front I would run 10 inch drums.

 

[abodyjoe]

i run the 11" drums out back. easy to get back then so i figured may as well go with the large drums.

 

[burks440]

u get 30% more stopping power with 11''

 

[4mulas]

Running discs up front

I assumed that. There are different diameter discs.

If running big front brakes 11" cordoba size use 11"rear. If using the smaller single piston floating caliper 73+ a body disc brakes use the 10.5

 

[72bluNblu]

I've run the factory 10.95" front disks (DoctorDiff stage I) with 10x2.5" rear drums as well as the 11.75" front disks (DD stage II) and 11x2.5" rear drums. The 11.75" front disk with 11x2.5" rear drum combination is a substantial increase in braking power, and still works with 15" wheels.

I've actually run all of DoctorDiff's front brake options, from Stage I (factory BBP brakes) all the way up to Stage IV, his 13" Viper kit. The 11.75" disk front with 11x2.5" rear drum set up is by far the best bang for the buck, and is honestly very close in performance to the Stage III front kit with 11.7" rear disks. The Stage IV kit with 11.7" is a decent improvement from there, but that requires minimum 17" wheels in the front.

For a street car the 11.75" front disks with 11x2.5" rear drums is a really good set up.

 

[64mopar]

I would say,depends on wheel/tire size.
15" wheels under 10" width.
Tires less than 28" diameter 12" cross section.
10x2.5 should be fine for stopping.
A larger combination, you may need 11x2.5.

 

[72bluNblu]

I would say,depends on wheel/tire size.
15" wheels under 10" width.
Tires less than 28" diameter 12" cross section.
10x2.5 should be fine for stopping.
A larger combination, you may need 11x2.5.

Having run the 11.75"/11x2.5" combination with 225/60/15's, 245/60/15's, 275/40/17's, 275/35/18's and 295/35/18's, I wouldn't keep the 10.95's and 10x2.5's with anything 245 or wider. Will they work? Sure. But with a good tire compound the 275's can push the 11x2.5's to their limits even on the street. Same for the 11.75" front disks with 275's. When I was running 11.75" front disks and 11x2.5" drums with semi-metallic brake compounds on my '72 Challenger you could tell they were working hard to reign in those 17x9's with 275/40/17's, and those tires were much harder than the 200 tread wear stuff I run now.

And again, the 11.75 front disk/11x2.5" rear drum works with 15" rims just fine. Probably pretty close to as big as you can go for brakes with 15" wheels. And they're not crazy with 225/60/15's either, they're still an improvement over 10.95's/10x2.5's.

 

[Super-Cuda]

I've run the factory 10.95" front disks (DoctorDiff stage I) with 10x2.5" rear drums as well as the 11.75" front disks (DD stage II) and 11x2.5" rear drums. The 11.75" front disk with 11x2.5" rear drum combination is a substantial increase in braking power, and still works with 15" wheels.

I've actually run all of DoctorDiff's front brake options, from Stage I (factory BBP brakes) all the way up to Stage IV, his 13" Viper kit. The 11.75" disk front with 11x2.5" rear drum set up is by far the best bang for the buck, and is honestly very close in performance to the Stage III front kit with 11.7" rear disks. The Stage IV kit with 11.7" is a decent improvement from there, but that requires minimum 17" wheels in the front.

For a street car the 11.75" front disks with 11x2.5" rear drums is a really good set up.

11 " disk up front, 11' drums in back what I have and the car stops extremely well!!

Here's some pics of the size difference and the Moser axles I used with threaded studs.

Also, side by side comparison of 10" vs 11 inch drums.

As well, , I used the hand brake cable setup from a 71-72 Demon (Rock Auto) and it installed and worked fine on my 68 Barracuda Fastback.