P-Body brake upgrades - Prop valve and M/C questions

[Shadow24]

Got a question on brake system setup/upgrades: I'm trying to hash out the final parts of my disc upgrade on a 94 shadow (originally a disc/drum car). I currently have planned:


later Van 60mm calipers (for 11" brakes)
11" R/T Rotors
Front Pads: ceramic or other GOOD pads
Rear Pads: probably average semi-metallics or ceramics
Rear solid disc setup (drum ebrake) (10" or 11" - not sure, haven't measured...)




However, my stumbling block at this point is the Prop valve. I have been unable to locate a factory disc/disc valve for a P-Body and am considering going with an adjustable prop valve. The big concerns i have are the only valves I can find that may work only have one out for the rear for a F/R setup. This is quite different from the diagonal RF/LR and LF/RR diagonal split from the factory.


What would switching ot a front/rear adjustable valve have over a factory prop valve, if any?


Also, I'm not sure which M/C I'd need, whether a 24mm, 1" or 1-1/8" due to the caliper sizing?

[turbovanman²]

Any 91+ car/van with the 11" rotors will have the calipers you need. I love the AkeBono ceramics, good stuff. Don't forget you'll need the caliper adapter bracket which from what I've read, will come with some calipers or you can buy it from Rock Auto.

Prop valve, well you can do 2 things, run 2 valves and splice into the rear lines, getting rid off the stocker OR redo the brake lines so you have the fronts on their own circuit and the rear on their own thus you can use one valve.

I would probably match the rears to the front so go rear vented 11" setup.

Use the 24mm master, the larger one works but its a much harder pedal. When mine fails, I am going back to the stock 24mm M/C.

[135sohc]

The stock disc/drum P body uses the SAME prop valve (yellow tag) as the 11" 4 wheel disc brakes. No need to change anything.

[turbovanman²]

The stock disc/drum P body uses the SAME prop valve (yellow tag) as the 11" 4 wheel disc brakes. No need to change anything.

Oh, good info,

[turboshad]

I got my solid rear setup from a LeBaron and I am also using the prop valve from it. I don't remember having to delete or change any of the lines going to the back but it was a while ago that I did it. That just seems like the kind of job I would remember. Either way the whole setup works great.

[Shadow24]

hmmm, thats lucky that it is the same prop valve then. I read rbryant's thread on prop valves, but wasnt sure as his info only called out 14" wheels on the p-body. Guess all i need now is a 24mm M/C

[rbryant]

Let me know if you need front brake pads.

You can also use Neon rear rotors with the 10" backing plates if you use either 1/8" spacers on the hub (behind the rotor) or hubs from a 85-94 rear drum car.
The rear drum hubs are spaced outward ~6mm compared to rear disc hubs. Fortunately the rear drum hubs also use the same axle stub so they are plug and play.

The extra spacing is required because the neon rear rotors have a ~2mm deeper hat than the 89-94 non vented rotors which causes them to bottom out on the 89-94 backing plate but are otherwise basically the same rotors (same diameter, same bolt pattern etc).

The 95-99 neon rotors are also slightly thinner making them only 9lbs. That is 2lbs lighter than the 89-94 non vented rotors and 5lbs lighter than the vented rotor.
The Stratus and SRT4 rotors are thicker than the 95-99 rotors bringing them back up to 11lbs each to match the 89-94 non vented rotors.

I also find that there are higher quality rotors that are still available for the neon for a better price than there are for the 89-94 non vented setup.

If you want more rear braking power then you can upgrade to Intrepid/Concorde rear calipers which are bolt on and increase the caliper piston size from 34->36mm over the 89-94 calipers.

-Rich

[Shadow24]

Hmmmm so lets see if i got this all straight:

the later 60mm van calipers are the same as an 11" r/t's calipers?

also, what is a good brake bias ratio on a p-body? with the 60mm fronts, 24mm m/c and the 36mm rears with good pads, i figured about a 71/29% brake bias front to rear over the near 91/9% stock bias on 54mm fronts, 21mm m/c and 15mm drum cylinders

I have 94 rear drums on the new chassis, so supposedly i wouldnt need a spacer for the neon 11" rear discs? what sub-model were those discs on?

Any particular submodel intrepid to look for the rear calipers on?

also, are the HPS pads semi-metallics or ceramics?

[rbryant]

Hmmmm so lets see if i got this all straight:

the later 60mm van calipers are the same as an 11" r/t's calipers?

Yes, as are the 11" front brake calipers on the 91 and later Lebaron, Daytona, etc. The 89/90 11" brakes are different.

also, what is a good brake bias ratio on a p-body? with the 60mm fronts, 24mm m/c and the 36mm rears with good pads, i figured about a 71/29% brake bias front to rear over the near 91/9% stock bias on 54mm fronts, 21mm m/c and 15mm drum cylinders

Changing the rotor size changes bias, changing pad material changes bias, etc etc so it isn't so straight forward....

Just use this: http://www.tceperformanceproducts.com/bias-calculator/

Typical Brake Options (assuming the same pad compound front and rear):

• 60mm caliper 11.69" fronts with 36mm caliper 10.64 rears is 75.2% (Intrepid)
• 58mm caliper 11.025" fronts with 34mm caliper 10.62 rears is 73.9% (SRT4)
• 60mm caliper 11.11" fronts with 36mm caliper 11.27 rears is 72.6% (11" fronts with vented rears)
• 54mm caliper 10.24" fronts with 34mm caliper 10.62" rears is 66.8% (10" all disc car)
• 54mm caliper 10.12" fronts with 34mm caliper 10.62" rears is 66.1% (Neon with rear discs)
  -
• 60mm caliper 11.11" fronts with 34mm caliper 10.62" rears is 75.2% (not a factory option but it is what I am doing for my lbody)
• 60mm caliper 11.11" fronts with 36mm caliper 10.62" rears is 73.0% (not a factory option but it is my backup plan)
  -
• 60mm caliper 10.24" fronts with 34mm caliper 10.62" rears is 71.3% (Lbody SLH package using caravan calipers and non vented rears)
• 60mm caliper 10.24" fronts with 36mm caliper 11.27" rears is 65.9% (proven bad lbody setup with 60mm calipers and 11" vented rears)
  
  

If I want more rear brake it will be less than an hour of work to change it to use Intrepid calipers but even more interestingly...

OEM brake pads have a coefficient of about .4 and a performance street pad like the HPS pads is more like .45.

Using a stock pad in the rear and HPS pad in the front would change the ratios by about 2% in my setup using a really cheap rear pad (.35 coef) could change things by up to 5% so the pads actually change the bias more than the calipers and rotors making this exercise a bit mute.

I have 94 rear drums on the new chassis, so supposedly i wouldnt need a spacer for the neon 11" rear discs? what sub-model were those discs on?

I think so but I have only verified that my charger drum hubs work.
Unfortunately the part numbers are hard to get because they list them as a drum and hub.

I did look to see that the rear drums hubs use a larger 14.1mm spline wheel stud on both the 87 shelby charger and later cars and the rear disc hub uses a 13.56mm spline stud so they are clearly different on drum cars than disc cars all the way up to 94.

At any rate you have them so you can easily check and test my theory that it is all of the rear drum hubs.

Any particular submodel intrepid to look for the rear calipers on?

The 36mm non vented calipers came on lots of cars:

CHRYSLER 300M (1999 - 2004)
CHRYSLER CONCORDE (1998 - 2004)
CHRYSLER DYNASTY (1991 - 1993)
CHRYSLER IMPERIAL (1991 - 1993)
CHRYSLER LHS (1999 - 2001)
CHRYSLER NEW YORKER (1991 - 1993)
CHRYSLER SEBRING (2001 - 2006)
DODGE DYNASTY (1991 - 1993)
DODGE INTREPID (1998 - 2004)
DODGE STRATUS (2001 - 2006)


Note that vented rear calipers won't work with non vented rotors because they are too wide and the piston would pop out before making contact with the pads.

also, are the HPS pads semi-metallics or ceramics?

They are semi-metallic which offers a bit more bite than their ceramic line (which they never made for the 11" brakes).

-Rich

[Shadow24]

I can try the neon rotor thing, sounds like a nice option for brake rotors. same with the intrepid rear calipers

That was the same bias calculator i was using, I probably had slightly different #s though. (http://www.tceperformanceproducts.com/bias-calculator/)

On the intrepid calipers, do they use the same bracket as the 34mm calipers? or do i need to source brackets for the different rear calipers? (I'm also assuming i still need to use the 89+ disc backing plate as well...)

[rbryant]

I can try the neon rotor thing, sounds like a nice option for brake rotors. same with the intrepid rear calipers

That was the same bias calculator i was using, I probably had slightly different #s though. (http://www.tceperformanceproducts.com/bias-calculator/)

On the intrepid calipers, do they use the same bracket as the 34mm calipers? or do i need to source brackets for the different rear calipers? (I'm also assuming i still need to use the 89+ disc backing plate as well...)

Yea the calculator is all in standard inch sizes so it is somewhat of a pain. There could be a mistake in mine but I tried to do it a couple of times each. The difference was probably in the 11.11" and 10.62" instead of 11" and 10".

On the rear brakes the backing plate and caliper bracket are all one piece.

The Intrepid calipers are basically the same caliper but with a larger bore than the neon. The 1G Neon calipers are the same as the 89+ non vented calipers. The 2G neon calipers are compatible as well but they are 34mm and have a different thread on their banjo bolt.

There are about 4 different non vented rear rotors that can work depending on the hub.

regular 89+ non vented rotors (will work with either the disc or drum hub .47" thick, 11lbs)


95-99 Neon rotors (require extra spacing of the drum hub so they don't bottom out on the backing plate .35" thick, 9lbs)


96-99 Stratus rotors (also require the extra spacing of the drum hub. They are just slightly different from the Neon rotor it doesn't make sense why they made these different)


SRT/PT HO rear rotors (also require the extra spacing of the drum hub and are .47" thick .47 thick, 10lbs)


And here is the vented rear for reference:


Intrepid rotors are a 5x114mm bolt pattern so they don't work.

These are all pictures from Centric. The Neon rears are still available in their premium coated line while the 89 vented are only available in the economy line for about the same price. There are also lots of drilled/slotted/dimpled options for the Neon/Stratus/PT rotors and not that many options for ours.

I have also seen the stratus listed as using a 10lb rotor so who knows but either way it should work.

-Rich

[turbovanman²]

If you want more rear braking power then you can upgrade to Intrepid/Concorde rear calipers which are bolt on and increase the caliper piston size from 34->36mm over the 89-94 calipers.

-Rich

Hmmmmmmmm, I need a bit more rear brake and I don't want to mess with prop valves.

[rbryant]

Hmmmmmmmm, I need a bit more rear brake and I don't want to mess with prop valves.

Vented rear calipers are already 36mm the intrepid calipers are an upgrade for non vented rears to get the larger calipers but without the need for the heavier rotors.

-Rich

[turbovanman²]

Vented rear calipers are already 36mm the intrepid calipers are an upgrade for non vented rears to get the larger calipers but without the need for the heavier rotors.

-Rich

Oh, drat, lol.