LS430 Big Brake Swap

yeah, I have to remember that that is about 1/4 the cost of the original car

You Guy's Bump steer kits are shipping tomorrow.
I made the comment because I know the M030 spindles are GOLD.....
******So basically any Late spindle (non M030) with the LS430 calipers and Boxster S rotors trumps the M030 set-up IMO*******

If you really wanted to break the bank some GT3 Rotors could be modded up.
With the M030 spindles, you would have to upgrade to the 965 Rotors because of the offset or figure some fandangled adapter bracket
However, with Boxster S rotors, you get the best Bang For The Buck.

Its all about the availability of REAL racing pads for me. The Lexus upgrade is great for a DD car.
Thanks for the update.

those things are made out of unobtanium

what is the best racing pad material for car rotors?
Pagid Blue, Orange...what's the diff.?
Like I said, If a large enough pad can be found, It can be machined to go in the Lexus Caliper. I have done this before to Hayabusa 6-pot brakes.

Has anyone ever compared the actual size of the pads between the 951 and ls430?

There's was a pic back on "the old site" comparing the 2 pads. I don't know if its made it over here or not.


I also know (well, its been talked about over on RL) that just about any brake pad company will make a run of pads with whatever material you want. If I remember correctly PBR said they would do a custom run for as little as 10 sets.

They already make street pads for the LS430. All they have to do is cut the racing friction material, and glue it on the metal backer plate instead of the street material.

54mm x 115mm pad face

Does anyone know if a 16 inch wheel will fit over the lexus calipers?

Ok, did a little comparison to answer Eric's Question on what the size difference is between the brake pads on the different caliper options. Here is what I found.

t/area %/diff
Turbo Brake pad width 98mm 5292 100%
928 S4 Brake pad width 132mm 7128 135%
Big Reds 132mm
Lexus S430 115mm x54 6210 117%

(assume all pads are 54mm wide, need to verify)

jimbo93 wrote:Does anyone know if a 16 inch wheel will fit over the lexus calipers?

I would like to know this too. I have 16 inch phone dials that I would like to keep on the car

From dimensions posted earlier of the calipers + 318mm DIA. Boxster S rotors, I get at least 15 1/2" overall, which means a big fat NO.

17" maybe, 18" = mama's baby.

gt1scca wrote:.
17" maybe, 18" = mama's baby.

I have Boxster 17's and they fit but its tight

msmoorenburg wrote:

gt1scca wrote:.
17" maybe, 18" = mama's baby.

I have Boxster 17's and they fit but its tight

Can you post a pic of your setup?

Boxster 17's

msmoorenburg wrote:Boxster 17's

looks awesome

thanks

I've read just about every post on these brakes and I don't remember ever seeing anything about changing the proportioning valve.

With putting such big brakes on the front, even if we upgrade the rears to 951 calipers, wouldn't the rear bias needed to be changed?

I know there are different valves from different porsche models that work on our cars, but has anyone found which one works best with the Lexus upgrade?

(I'm talking for NA cars, of course)

A couple of people have these on the road already. Would be good to know in case I don't like the Tilton Dual MC biasing knob alone...

I do have an update.....I took off the Early Spindle/Hubs that I had cryoed and installed a set of hub/spindles from an 87-S to test my modded RX-7 arms with 944 geometry and recent mod of taking an Early 944 strut and properly modding it to fit LATE spindles. After moving over the control arm adapter bolt holes for the late offset, I used the same Boxster S rotors and Lexus calipers and I confirmed that after you add the billet rotor centering rings, you can put 3/16" washer shims between the LS430 caliper brackets and the 944 LATE spindle tabs. Everything Fits like a glove....

m73m95 wrote:I've read just about every post on these brakes and I don't remember ever seeing anything about changing the proportioning valve.

Porsche Brake Proportioning Valves

5/18 bar
951 355 305 01

5/33 bar
928 355 305 01

5/33 bar
928 355 305 02

5/45 bar
964 355 305 00

5/55 bar
930 355 305 01

5/60 bar
965 355 305 01

m73m95 wrote:With putting such big brakes on the front, even if we upgrade the rears to 951 calipers, wouldn't the rear bias needed to be changed?

If using a single tandem master cylinder, yes. With the Tilton or Wilwood dual MC balance bar, the proportioning valve may not be necessary IF the balance is set correctly.

m73m95 wrote:I know there are different valves from different Porsche models that work on our cars, but has anyone found which one works best with the Lexus upgrade?

As far as I know, no one with the LS430s installed has changed or upgraded the P valve...

m73m95 wrote:(I'm talking for NA cars, of course)

Here's the rest ... of the story:

The 951 and S2 already have a proportioning valve, the 18/5 version. Installing the 33/5 proportioning valve in place of the 18/5 would increase the fluid pressure at which the valve starts reducing pressure on the rear circuit. Instead of starting to reduce pressure at 18 bar, it starts reducing the pressure at 33 bar. More pressure = more braking power.

According to the factory workshop manual, the '5' means the reduction coefficient is 0.46. Once the bleed pressure of 33 bar is reached, pressure to the rear brakes is reduced to 46% of the front.

On a non-ABS car, the bias valve is screwed into the master cylinder and is an easy bolt-on. All 951s use the 18/5 valve. The 928 part is a 33/5, which won't start to limit rear brake pressure until line pressure reaches 33 bar instead of 18. There are also 45 and 55 bar units, but I would not recommend those for street use on a non-ABS car as they will create dangerous rear wheel lockup.

BE WARNED...

With the N/A rear brakes, there is not enough pad or rotor area to properly dissipate the heat generated by a large increase in pressure (i.e. clamping force). This is why the N/A brakes haven’t been mentioned...

I'd rather be strapped to an electric chair on wheels...

Thanks for posting all of that, but I've already gotten all of that information lol.... sorry.

But that's my question. Porsche makes 6 different Prop valves. Which one balances the LS calipers on front with the 4 piston turbo calipers on the rear?

Each valve is $100, so trial and error is expensive.

I guess if someone posts the size of the pistons in both the LS calipers, and the turbo rears, then we compared them to the sizes of the stock pistons (which ever version of 944 you have). Then figured out the difference in clamping forces (based on more/smaller pistons vs one large piston), we could then find what one would balance the system better (still keeping the majority of the braking in the front, of course). IF we keep the same line size, and pedal pressure in all the equations, it shouldn't be too hard to figure out ..... right? "I mean, how hard could it be?" (thanks Top Gear!)

I'm going to keep the stock master cylinder. Either no booster, or the hydroboost. This is obviously not needed for the dual MC setup.

OK, I just read every post in this thread again.....I just need a simple answer to make sure I'm reading everything correctly.

I have an early offset car (85.5).

Is the best solution for the rear going to be 951 REAR calipers, or FRONT calipers?

The way I understand it is, to put the rear late 951 calipers on, all I need are washers to space the calipers away from the rotor.... correct?

Then, to add FRONT 951 calipers to the rear of my car, I need 88 and up 951 calipers AND rear late turbo rotors? Do I still need the washers on the mounting bolts? Will the late rotors fit on my early offset arms and still have the parking brake function properly?

If the turbo fronts will work on the rear of an early car, I feel it would be a much better balance with the big LS calipers up front.

My post above is still in play though. I'd like to balance my pressures as best I can.... though with the bigger front calipers on the rear, a prop valve may not be needed.

The LS430 setup is new...very, like 2-3 months. The only drivable car I know of is Dawgz83944, but he's running the hydroboost. MatthewB (PHB) may be driving his car...no info on his prop valve though.

m73m95 wrote:...how hard could it be?

Not very, it just hasn't been...

This (brake debate) has been a hot one for a while, and there are systems that work well (as should the LS430 / Boxster setup). It hasn't been tested for what you're asking is all.

As far as the stock master cylinder...
Axe that. Takes about 160+ lbs. of pedal pressure to move the piston.
Try the Wilwood 260-7563 tandem master cylinder.
Properly sized, and requires only moderate pedal pressure.

Turbo and LS430 piston sizes are here somewhere...

No - N/A info.

We like to stop.

_______________________________________________________________________________________

Now,

For you're next post...

m73m95 wrote:I have an early offset car (85.5).
Is the best solution for the rear going to be 951 REAR calipers, or FRONT calipers?

FRONT calipers / REAR rotors from 951.

m73m95 wrote:The way I understand it is, to put the rear late 951 calipers on, all I need are washers to space the calipers away from the rotor.... correct?

Correct. Shimming calipers is due to differences in rotor design OR trailing arms from early to late cars.

The closest setup to the LS430 / Boxster is the "Big Reds" / Turbo rear...
5/18 bar valves work well on these systems, and the LS430 piston sizes are close to the Brembos. Boxster rotors are only ~18 mm smaller in diameter.

That being said...

Dump the N/A brakes, and use the 5/18 valve with the Turbo rear / LS430 setup.

Yeah, that was easy...



EDIT: Or, you can install an adjustable valve for about the same price, and balance the system yourself...I have done that on other projects with no trouble.

Thanks for the answers gt1scca!

I don't know if I'm going to do this swap first or my suspension.

The deciding factor will probably be the wheels. If I can find the wheels I want, the I'll replace/add the LS brakes to the front, and the Front 951 calipers and rear 951 rotors with them.

$3k for custom Fikse wheels, or $3k for the elephant racing suspension setup..... hmmmmmmm? I bet there are people out there that would like to have my problems LOL

With the early (23mm) offset, you can have 1.25" adapters made, and bolt on a set of C5 or C6 Corvette wheels.

CHEAP.
$250 / set used all day...

(I have also seen those adapters 5 X 130mm to 5 X 4.75" on eBay)

Here's a set that will work...

(not hub-concentric though...)
Part # LM5/130/475

Thickness 1.25 inches (31.75mm)
Studs Installed 12mm x 1.50 Thread Pitch
Lugs Included 12mm x 1.50 Open End Bulge
Center Bore Diameter 2.878 inches (73.1mm)
Special Orders can be built to include optional
stud sizes and adapter thicknesses from 0.79
inches (20mm) thru 2.0 inches (50.8mm)

lugmanusa.com
Also states they will fab custom orders...hub-concentric should be possible.