Single piston !!!

[q8charger]

Hello,

I'm looking to convert my drums break to the kit 4 - wheel discs. For my car 1969 charger big block 8 3/4 . I'm using wheel magnums 500 15 in .X 8 in , 5 x 4.5 in .Bolt Circle , 4.5 Backspace. I ask the Doctor diff and they offer me 11.75 ( Stage 2) front brake kit $ 635
10.7 rear disc brak kit $ 600 - 650
Custom parking brake cables $100
Set rear disc lug studs $25
Pair Green bearing $65
Booster 1 1/32  $385
Single piston front and rear
The total will be $ 1,860

I'm not sure if it is good offer or not !! Because i will spend $ 1,860  for  Single piston !! 

[303 Mopar]

To go from drums to 4-disc, yes that is a good price.  And Cass at Dr Diff knows his stuff and will not over sell you.  You can try to go price Wilwood or others, but you will find them more.  Welcome to Mopar parts!

[q8charger]

There are no way to get more than Single pistion

[Kern Dog]

Not sure I understand. Is that a question?

[John_Kunkel]

It seems logical that 4-piston calipers would have more grunt than single-piston calipers but some single-piston calipers actually have more clamping power than a lot of the popular dual-piston calipers.

Doc's offering is the best bang for the buck.

[Brass]

It seems logical that 4-piston calipers would have more grunt than single-piston calipers but some single-piston calipers actually have more clamping power than a lot of the popular dual-piston calipers.

Doc's offering is the best bang for the buck.

x2.  This is what I have come to understand also.  I have Doc's stage II and clamping power is not a problem.

[q8charger]

So it is no matter how many piston will be ?

[MSRacing89]

It seems logical that 4-piston calipers would have more grunt than single-piston calipers but some single-piston calipers actually have more clamping power than a lot of the popular dual-piston calipers.

Doc's offering is the best bang for the buck.

I would generally agree with this, but let's not forget why multi-piston calipers were developed.  The multi-piston calipers allow for a bit more driver and heat control in high performance/ racing situations.  In my experience, single pistons have less of a gap between heavy braking and complete lock up.  But for 99% of the builds out there, these single piston kits are all good. 

[John_Kunkel]

So it is no matter how many piston will be ?

Depends on the size of the pistons, once you go past 4 pistons it's near impossible to equal the clamping power with a single-piston floating caliper. For instance, the popular Wilwood Superlite calipers with 1.75" pistons have less clamping power than the factory 2.95" (75 MM) single-piston caliper but add 2 more pistons and you can't match it with a single-piston caliper. 

[Brass]

So what determines the pedal control of clamping force; the size and number of pistons, the master cylinder bore, or all of the above?  I am using Doc's kit with a Hydratech Hydroboost.  As mentioned, clamping force is no problem but more modulation prior to complete lock up would indeed be nice.  

[MSRacing89]

So what determines the pedal control of clamping force; the size and number of pistons, the master cylinder bore, or all of the above?  I am using Doc's kit with a Hydratech Hydroboost.  As mentioned, clamping force is no problem but more modulation prior to complete lock up would indeed be nice.  

All the above, but what is important with Hydraboost is the master cylinder bore size.  You have the potential to produce much more pedal pressure and not realize it.  Generally we compensate for this with a larger bore Master, like 1 1/8".  If you feel like your system is a bit touchy, go to a larger bore and it will smooth it out for you.

[Brass]

Good to know - thanks.

[q8charger]

Which one is the best Repro Bendix dual diaphragm booster with 1 1/32"   Or   Master booster 1 1/8"  ?

[q8charger]

Any suggestion please?

[Kern Dog]

SINGLE PISTON !!!

[alfaitalia]

It seems logical that 4-piston calipers would have more grunt than single-piston calipers but some single-piston calipers actually have more clamping power than a lot of the popular dual-piston calipers.

Doc's offering is the best bang for the buck.

True.....but why would you need to much clamping power with multi piston calipers??......What you loose in pressure you gain in friction area. Especially if you get pads made for the job. You also get better cooling, more pad leading edges too ( if you go for the really posh ones with separate pads for each piston) which adds to actual braking force, more even pad wear. None of the loses you get if you have horrible sliding calipers either as the slides gets stickier and seizes solid like on my Jeep! There is a reason all cars have multi piston calipers these days....they are better all round. My last two bikes GSXR1000 and Zrx1100 both had SIX piston front calipers on each front discs...so that's 12 in total ....just for the front! Makes to old single piston ones on my classic Yam RD250 feel like drum brakes! Single piston is fine and they will stop you....but wont be better than a multi piston setup IMO.

[bc3j]

FWIW it depends on what type of driving you plan on doing.  I use slider single 2.75" calipers with metallic pads and 11" rear drum brakes and my car stops great. I use a manual 15/16" master cylinder.  Pedal ratio and using the correct distribution valving for disc brakes is important. Pedal feel when braking is a personal thing and I prefer the manual brakes. For me, I am not planning on changing to rear disc brakes.