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Original lining for 33-36 Packard 8s &12s were

Primary - Raybestos 451
Secondary - Hyco DV 1391

Anyone have the specs on these - COF ?

Anyone know which shoe, P or S, got the lower and higher COF.

G'day Packardbarry,
to PackardInfo, and sorry I can't help with your request.

But a request to you, could you please include your Packard in the Packard Owner's Registry here, together with a pic, any known history and how you acquired it?

Can't answer your question, but I wonder how important it really is. When I relined my 34 Eight about 40 years back I used the same molded lining (asbestos of course), both primary and secondary because I couldn't find the OEM materials. Those Bendix 14" mechanicals are superlative when done correctly, I wish I had brakes that good in my other cars. I just checked the linings again this spring at about 35,000 miles and they're good for another 40 years. Don't forget the front left gets narrower linings. If I had to guess, I'd say the higher coefficient of friction goes on the secondary shoe, but that's just a guess.

Not only were they specing out the 1,3/4 wide shoe for the LF they were also specing the RF get 150 lbs more pull (650 lbs for RF & 500 lbs for other 3). Im sure this was to compensate for the TRUNNION making the car steer to the left.

Unless it was for safety (possibility of veering into oncoming traffic when braking hard?) I'm not entirely sure why the LF gets narrower lining and hence less drag, but done to spec and adjusted correctly (see my little blog on it in PAC Projects Forum), the car should stop dead straight, and with very little pedal effort. Initial adjustment after a reline can be timeconsuming with a lot of repetitive adjustment and testing (unless you're lucky) but worth every minute - the 14" Bendix system is terrific, far better than the earlier Bendix-Perrot.

If the alignment is correct, the trunnion doesn't make the car steer to the left - it should steer dead straight if you take you hands off the wheel, with either the brakes applied or not - but perhaps I misunderstand your statement.

Wouldnt it be great if we could find a piece of Packard Lit. that told us what they were thinking with this lesser width LF lining vrs.the others and why the 650lb pull on the RH vrs 500lb on the other 3.
Please SOMEONE FIND THAT PAPER !!!!!!!!!!
Until then all we have are THEORIES.

Heres my theory:
Rear of the RH spring is attached to the frame via a solid spring hanger. Rear of the LH spring is attached to the Trunion which if u look at its design is a swinging hanger with springs. Stopping forward enursha would put rearward force on both springs. Force on the RH would go rearward against the solid mt hanger. Force on the LH spring rearward against the Trunion, which is moveable vrs the RH hanger, pulling the LH side of the axle back, counterclockwise, with it and thus steering the car to the left. This lesser width lining on the LH brake gives u less friction than the wider RH and the more lbs pull on the RH would compensate, pulling the car to the right and thus straighten the car out.

Whether this steering to the left was/is truly a problem was/is debateable. Im thinking Packard saw this as a problem and was just trying to make great greater.

For whatever its worth this is my theory of the lining and the 650lb pull. But IVE BEEN WRONG BEFORE.

Getting back to my orig. question BRAKE LININGS

Can't help at the moment with documentation on the width but seem to recall reading it was because of linkage tolerances, wear, stretch whatever. Being the LF wheel was closest with none of the above to speak of, and normal weight shift during braking that wheel would see pedal first and grab so it's lining had a smaller surface area.

This excerpt from adjusting info might partially answer the why different pull specs.https://www.packardinfo.com/xoops/html/downloads/SC/SL-VOL8NO16.pdf

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From experience...

Yes the smaller left front is because of the trunion block. Several years ago I restored a car for a guy who was simply collecting parts and started a build. Car was real enough but incomplete. At the time not knowing, had gone through litterally days of adjustment, balance, tire measurment, everything to try to stop the car from pulling left when stopped. Turns out the shoes are indeed smaller and (I'd have to go measure one) the drum too may be a tad narrow. Yes it's because of the trunion block design. No amount of adjustment will relieve the left pull if all 4 corners pull equal. Not a theory, a fact. I had no paper at the time, I had Art Brummer. 99 out of 100 times he was right on the money. No matter what, even everything dead on to spec, the car will stop straight, but you'll feel the left side "pull" just a wee bit, not in the wheel, in the car. In a panic stop it will initially pull left then straighten right out. Nature of the beast.

The drum is the same as the other front drum, it's just the lining that's narrower, by 1/2 inch in the Eights and Super Eights, and 5/8 in the Twelves.

In other than light braking situations, the very small amount of movement allowed by the trunion on the front left will allow the spring and axle to move rearwards very slightly, but enough to alter the effective length of the brake-actuating cable, thus increasing the pull on the left front wheel - hence the narrower lining. This is because the forward end of the cable sheath is affixed to the wheel and the rearward end attached to the frame, thus the changing of this dimension actually applies force to the shoes. This explanation received from an outside source who chose not to respond to this thread but shared his understanding with me.

Lining specs for 1934 below, left-hand column in the Eight, center is the Super 8, right is the Twelve.

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