Posted by Greg Coffin [172.68.3.113] on Tuesday, December 03, 2024 at 18:55:33 :
In Reply to: Dodge 6x6 posted by Don in ohio [172.71.222.97] on Monday, December 02, 2024 at 09:10:34 :
I have not put discs on my 6x6, but if I did I would just do the front axle. The front axle still does the majority of the braking on a 6x6, so I feel that discs on the front is the best return for the investment. The only caveat to that would be if I were regularly carrying a lot of weight in the bed, or doing a lot of heavy towing, then I would consider discs on all 6 wheels. I would also be running a power brake booster and dual master cylinder with disc brakes.
I do have a dual circuit power brake system on my 6x6 (all drum), which works very well. My truck gets very little use, and rarely carries any heavy cargo, so drum brakes are just fine for me. I can lock up all 6 wheels if I want to, but during normal use the system feels very stable.
As for what master cylinder to use on a 6x6, I have had very good performance from a 1-1/4" dual circuit master cylinder. The braking seems very balanced with all drum brakes and no proportioning valve. I did a lot of testing on dirt roads to see when the front and rear axles started to lock up.
There is a lot of debate on which brake circuit to use on which axle (front vs rear). At first I ran the larger reservoir (rear circuit on the master cylinder, closer to the mounting bolts) to the rear brakes due to the increased volume due to brake wear. But I read a compelling article that made the case to run the front circuit to the rear axle and the rear circuit to the front axle. This configuration is also how most light trucks are set up from the factory. So I changed my system to that.
As for fluid volume requirements during braking, I don't think it makes a lot of difference if you have an increased flow to one axle over the other. Consider these points:
- All 4 wheel light trucks with front discs and rear drums have an increased brake fluid flow to the front axle during braking. These vehicles use a dual circuit master cylinder with the same bore for the front and rear brakes (same output per circuit during braking).
- A 6x6 with front discs and rear drums has close to a balanced fluid flow during braking, similar to a 4 wheel truck with drums on both axles.
- A 6x6 with all disc brakes would have an increased fluid flow to the rear brakes during braking.
- A master cylinder for a vehicle with front disc/rear drum brakes has a larger (rear) reservoir to compensate for the increased fluid requirements for the front discs due to brake wear, not during braking.
If you made it this far, I hope this helps. There's more to discuss, but this is enough for now. :)
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