Dual calipers per rotor

[bettonracing17]

Not a secondary caliper for handbrakes/ parking brakes.

This is an idea more for discussion than for implementation.

Car: Circuit racer. 4lb+/hp. Wide slicks all round. Medium downforce. Short wheelbase.

Avg. Track: Low/ medium speed corners after long straights. Occassional stoplight after hwy offramp... jk.

Proposed brake setup: Front wheels only. Custom knuckle. Twin calipers mounted 180deg apart. Single master cylinder for all 4 front calipers (appropriately sized). Adjustable f/r wheel bias bar. Adjustable pedal ratio.

Intended advantages: A wider range of useful calipers and all the resulting advantages (read: cost).

Observed disadvantages: Complexity. More time consuming brake jobs. More parts to fail. Increased unsprung weight. I suspect a reduction in clamping effectiveness of each caliper (compared to a single caliper setup) but overall more brake friction overall and thus
calculations would be slightly more complex.

Assumptions: The designer has required resources to properly size all (6) calipers. The knuckles would be optimized for the proposed setup. The tuner & driver have good enough communication and knowledge to find the [presumably narrowed] f/r bias sweetspot. Adequate brake cooling.

I'm sure if this setup worked favorably, I'd be able to find something on the net or at the tracks. Searches proved fruitless.

If anybody's experimented with similar setups, as well as those of You more educated ones, please educate me.

Note: I may add additional points as I remember them.

Regards,

H. Kurt Betton

 

[patprimmer]

From your OP

Intended advantages: A wider range of useful calipers and all the resulting advantages (read: cost).

I can see no other interpretation.

If you can see no other advantages than the one you just dismissed, and you see several disadvantages, why are you pursuing this.

Why do you change your parameters when the answer does not support your case. Is this work related or are you just wasting our time for your amusement.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[bettonracing17]

Thanks for Your reply.

Intended advantages: A wider range of useful calipers and all the resulting advantages (read: cost).

I can see no other interpretation.

My intended (expected?) interpretation was that cost would be the primary (overall?) advantage but the other advantages of having a wider range of calipers (such as pad options, rotor thicknesses, mounting type, piston arrangement, availability, serviceability, etc) would also be considered in the assessment of the setup.

I apologize if You feel as if Your time was wasted but I was trying to get more educated opinions (& facts) on the setup, which I have attained from the posts of Yourself and others. If I've somehow offended You (or anybody else) by asking for Your opinions on other aspects of the setup, rest assured, that was not my intention.

I'm unable to find where I've changed the parameters as opposed to asking You (and others) to include other parameters that seemed to be ignored in Your recommendations.

I've concluded that the setup is less ideal than initially expected (butter knife to cut bread?), primarily due to the heat rejection issue. For equal performance to a single caliper setup, the heat rejection issue seems to have a counterproductive effect as opposed to an 'advantage reduction' effect. That being said, I rest the case for the "dual calipers".

FTR, this is not for work and is more for 'amusement'. If I've violated the spirit of the forum, please feel free to delete the thread.

Regards,

H. Kurt Betton

 

[bentwings1]

Hi, we just completed a sand rail (kart) which has inboard rear brake (way more than needed) and had single piston caliper front brakes. These were not quite enough so we installed as large of disc as would fit within the wheel. About 2" larger in dia. still using the single caliper. Still not quite enough but much better. Then we found a double piston caliper very slightly larger (bulk) with slightly smaller pistons. Again much improved but still not quite enough. Next step was a smaller bore master cylinder to increase the pressure. This really did the job. The final step was to install a 2# residual valve right at the master cylinder. This reduced the stroke considerably and improved the feel. Over all we added only a few ounces for the larger discs and a couple for the slightly larger calipers. Now the braking on this insanely fast kart is almost as good as its accelleration. Overall cost was very small as we made our own brackets (all modeled on SW), modified stock discs, purchased over the counter stock calipers and pads.
We also looked at heat build up. It isn't really there. Maybe the discs are just too small and the forces are not high enough. 7 guys flogged this little sand rail for an entire day and there were no brake problems. No other problems either. The discs got a little warm..you surely didn't want to touch them and the master cyl was barely warm to the touch.

Call it hit and miss engineering but this little animal is a long way from our first adventure into high performance. We set set some goals as you have and met all of them plus used over the counter parts so replacement is very easy.

99 Dodge CTD dually.