Mustang - P63 wheels/brake conversion ?

[hahnej]

Just curious - Have seen Mustangs for sale that list "P-63 wheels/brakes conversion", what does this involve and why is it done?

I know that a lot of Sea Furies have F-102 wheels and brakes replacing the British setup, but haven't heard anything on Mustangs.

Thanks!

[51fixer]

Just curious - Have seen Mustangs for sale that list "P-63 wheels/brakes conversion", what does this involve and why is it done?

I know that a lot of Sea Furies have F-102 wheels and brakes replacing the British setup, but haven't heard anything on Mustangs.

Thanks!

Both P-51 and P-63 used the same axel, tire (27SC) so were the same except for the size and number of stacked rotating and stationary discs that make up the braking part.
P-51 were 7" in dia and IIRC have 9 rotating and 10 stationary discs.
P-63 are 9" and have 7 rotating and 8 stationary discs.
Only other change needed to put P-63 on a P-51 is that there is a plunger in each wheel well that the P-51 brake housing will strike when retracted. This is part of the mechanism that controls a valve to close the inner gear doors during the gear sequence.
Since the P-63 brake housing is larger in dia and different in shape, the striker needs some modification to function properly.
Rich

[Randy Haskin]

What's the advantage of that modification?

[51fixer]

What's the advantage of that modification?

Braking comes down to a few things, pressure, square footage of contact area and torque or the distance from the center the pressure is applied.ie the further out the more effective that force can be applied.
Difference is the square footage, 9 rotating discs in the P-51 vs 7 in the P-63.
Picture of P-63 is found half way down this page-
http://warbirdinformationexchange.org/p ... c&start=45
P-63 was designed for a nosewheel a/c. We are a little leery of them but I have never heard of the brakes tipping P-51 on its nose.
Rich

[RareBear]

It appears that the extra square footage available on the P-63 discs is somewhat negated by the extra discs on the P-51, so the main difference is the greater torque being applied by the P-63 units?

Walt

[hahnej]

Thanks for the info, curiousity satisfied!

[David W3]

While the NAA built Mustangs (and the CA-17s built up from NAA components) delivered to the RAAF had the smaller brakes, the wholly Australian Mustangs built by CAC had the larger brakes as the standard factory fit. From the correspondence about the contract at the time there was some concern about short field performance vs overbraking and tipping on their noses.

The latter does not seem to be a difficulty in practise; I have yet to see a photo of RAAF Mustang on its nose.

HTH
David Muir

Author 'Southern Cross Mustangs'

[famvburg]

A friend of mine who owned a 'D model in the early '70s, had P-63 brakes. He says the big advantage is that they don't get hot like stock Mustang brakes so therefore you get better braking action.

[sdennison]

It appears that the extra square footage available on the P-63 discs is somewhat negated by the extra discs on the P-51, so the main difference is the greater torque being applied by the P-63 units?

Walt

All seems to be "genometry". What is the actual comparison in total swept area of the '51 vs '63 brakes? If the plates are the same dimensions for surface area, then you are correct that more plates mean more braking surface unless you get greater pressure from the P-63 brakes with less area.

Other possiblities, different pad material that is more efficient?

Answer is?

[51fixer]

A few photos of the different wheels-
Inside of P-51 wheel where the rotating discs engage the slots in the wheel.

Same view of the P-63 wheel-

P-51 wheel inside and outside-


P-63 wheel inside and outside view-


One other big difference is the P-51 wheel is solid mag. To mount a tire it isn't any different than getting a tire mounted for your car or pickup. Only the bead on the tire is about 3/4" thick.
The P-63 wheel is a split rim. The wheel has a ring on the outboard side that is held in place by small ring retainer. All parts, including the retainer, are mag. This does make changing a tire pretty easy though.
Rich

[Tom N]

I talked to the guy that "pioneered" the changeover many mustangs went through going to the P-63 brakes. He had a huge inventory of P-63 wheels and brake parts and sold the concept to the operators in the 70's because he had the inventory to sell.

The P-63 setup using the P-51 master cylinders works ok --sometimes requires pumping up the brakes to get full pedal; I've flown both set-ups and don't think there is much functional difference in the stopping capability. The surface area calculates out pretty similarly. One nice thing about the P-63 setup is the wheel is a split rim assembly which allows you to break the bead and remove and replace the tires without a tire machine.

[51fixer]

It appears that the extra square footage available on the P-63 discs is somewhat negated by the extra discs on the P-51, so the main difference is the greater torque being applied by the P-63 units?

Walt

All seems to be "genometry". What is the actual comparison in total swept area of the '51 vs '63 brakes? If the plates are the same dimensions for surface area, then you are correct that more plates mean more braking surface unless you get greater pressure from the P-63 brakes with less area.

Other possiblities, different pad material that is more efficient?

Answer is?

There really isn't a pad. The stationary discs are hard chrome and ground flat. The rotating discs are hot metal sprayed on both sides with a bronze alloy material that is the "pad". This stack gets squeezed by an o-ring in the brake housing and there is threaded steel plate that sets the gap of the stack which is adjustable. All this is the same design, type and material between the -63 and the -51. Only real difference is the dia and number of discs.
Rich

[retroaviation]

Thanks for posting those pictures, Rich. You just helped me identify a P-63 wheel I have here.

Gary

[sdennison]

There really isn't a pad. The stationary discs are hard chrome and ground flat. The rotating discs are hot metal sprayed on both sides with a bronze alloy material that is the "pad". This stack gets squeezed by an o-ring in the brake housing and there is threaded steel plate that sets the gap of the stack which is adjustable. All this is the same design, type and material between the -63 and the -51. Only real difference is the dia and number of discs.
Rich

So what is the advantage to going through this mod? Is there an availability issue with either version, parts wise? Are the friction plates rebuildable?

[Randy Haskin]

Thanks!!

Those photos describe things perfectly.