11 Brakes On Front, 10 The Back.

Has anyone done this before? Seems to make sense. 1 1/8 bore cylinders on front, 7/8 on rear 10 inch.

 

On my first 2a, it had the stock 9x1 3/4 or whatever heel toe brakes. Terrible. Scary. Dangerous.

I put the bendix style 11" drums up front and could lock them up. It went from a scary dangerous vehicle to one that was dramatically safer and more pleasant to drive.

Do it.

 

If you can only find two 11" backing plates, it really is a huge upgrade to throw them in the front.

 

My 70 is 11 drums all around. Dad's 69 is 11" drums up front and stock 10 inch on the rear. I think they both stop the same...as mentioned above, the front brakes do most of the work.

 

Ideally you want to have the fronts and rears lock up at the same time in hard braking. Too-small brakes in the rear will let the fronts lock first and you'll lose steering control in lockup. However, it's worse to have the rears lock first, since that can put you into a spin.

Even with an imbalance, I'd expect it's safer to put the bigger brakes on the front even if you don't have matching brakes for the rear.

 

Let's all just remember that generally speaking the front should have a larger diameter wheel cylinder. Generally 1 1/8" on 11" front. Rear usually 15/16" or 7/8". When ordering parts, a 1974 CJ5 had 11" front and back, is in the middle of the model break and is usually a good reference.

 

My 65 has 11" on the front and stock 9" rear. What an improvement!

 

Isn't that just the opposite? A small brake in the back as compared to a larger set up front with additional brake torque would first create Dive and weight transfer in the chassis , thus moving the CG forward leaving the rear axle with less weight and a much better chance to lock up sooner than the fronts ..................the only way to counter that would be brakes of near equal size and a chassis set up to counter the Anti-Dive effect under braking.

 

AFAIK it's all about the traction difference between rolling and sliding tires. If the rears lock up and you are in a turn, the back end will come around and you're in a spin. If the fronts lock up, you plow in whatever direction you were going. The amount of weight transfer depends on how hard you brake. In a panic stop, the rear end does get very light, and in that case you want less force on the rear tires to avoid lockup. My physical understanding says weight transfer will happen regardless of the design. Kinda think braking dive cannot significantly change the mechanics of stopping. I believe the only way to prevent such weight transfer is to stop less suddenly.

 

On dirt, going downhill, if I brake hard the fronts will slide. Before, with the 9"s in the front it would not slide but dart one way or the other.
You can adjust the 9s in the rear so they are not so aggressive.

 

thank you for all the info.

 

It may not change the mechanics of stopping , but any percent of Dive will change how the vehicle stops by simply moving the COG forward............once the COG moves forward on a Jeep that is already lite over the rear axle the rear will either slide or lock up due to the loss of traction regardless if there is 9 or 11 " brakes there , tire size and weight thereof also plays a major part of the decision to increase the size of the brakes / torque in order to stop.

 

The 11" front brakes are more powerful than the 9".

 

Big upgrade this year will be 11" brakes going in the front , and converting to a split system master cylinder .
It helps I have a brother with his own garage and lift .

 

Cool. That is agood upgrade.

 

I did the 11s on the front at the end of last year. Huge improvements I still have 9s on the rear. I bought the kit from Herm’s to save time and effort sourcing parts.