Early C1 Disc Brakes? SR1 or Sebring

[Tom W.]

Re: Early C1 Disc Brakes? SR1 or Sebring

Hi Loren,
Are you aware of any brake test that was done with the Model 2934 "SR" Corvette disc brake as specified in AIM dated 2/15/56 work order #19399?
Tom

[Loren L.]

Re: Early C1 Disc Brakes? SR1 or Sebring

Hi Loren,
Are you aware of any brake test that was done with the Model 2934 "SR" Corvette disc brake as specified in AIM dated 2/15/56 work order #19399?
Tom

On January 21 & 22 1956, there was evaluation testing on HALIBRAND SPOT DISC BRAKES, including some variations using a Hydrovac booster - letter reports by ZAD and, I believe, Paul King, reflected dismal results. The underlying causes for failure seemed to be excess weight.

[Tom W.]

Re: Early C1 Disc Brakes? SR1 or Sebring

On my copy of the AIM there is no reference to the brake illustrated having any affiliation with Halibrand. Every component of the brake package has GM part numbers assigned.
I have not been able to find a single part number or manufacturers casting identification on the physical parts themselves. The only thing to date has been Halibrand Eng on one of the spinner nuts. The other one has no markings, but is essentially the same.
I have also had the Halibrand Brake identified as both a "SPOT" brake and a "SPORT" brake. I've tried to research the Halibrand brake on the internet but have had no luck to date.
I'd like to compare it to mine.
How can I get a copy of the brake testing reports you mentioned?
Thanks,
Tom

[Loren L.]

Re: Early C1 Disc Brakes? SR1 or Sebring

"...my copy of the AIM..." - Is this referring to the two sheets John H. furnished? Because I think he's absolutely correct that they were prepared in advance IF the decision went that way....and it did not.
Remember that at this point, Sebring was two months away.

The first order was on Dec 29, 1955 for "...one set of Magnesium wheels and Hubs plus one set of spot disc brakes...." at an estimated cost of $1100, to be shipped by air freight.

Russ Sanders on Jan 9, 1956 includes:
"2. Halibrand Spot Disc Brakes and Associated Equipment"
with six other items that have to be built on the 25 cars that Chevrolet
"must release for production".

A number of internal documents published by Neas/Robinson in their "Holy Grail" series still refer to Halibrand wheels AND brakes.

Frank Burrell's 1/11/56 six page letter detailing the cars' equipment still refers to spot discs.

On 1/12/56, GM orders "...three (3) sets of Magnesium wheels. Front hubs, rear axle shafts and Spot disc brakes and necessary attaching parts
per verbal instructions from Mr. Paul King.".

The presence of Chevrolet part #s is required to be believable to the sanctioning body - buried somewhere in the files is the bulletin to the effect of Halibrand wheel #2211 is assigned part #_____________.

[Tom W.]

Re: Early C1 Disc Brakes? SR1 or Sebring

Loren,
Thanks again, I'll take my magnifying glass and start looking for numbers. There may be some on the non-machined surfaces of the castings. The cap screws that hold the disc on the hubs have all been safety wired in pairs. That's one of the reasons that I can't remove the disc without destroying those wires.
John Neas has asked me to call him so I plan to do that tonight. Yes, the information I have came from an AIM provided by John H.
As you may appreciate...with each email my head spins a little more.
"Holy Grail", Spot Discs,Russ Sanders,Frank Burrell. I guess these are all documents and engineers responsible for the SR development program?
Tom

[Terry M.]

Re: Early C1 Disc Brakes? SR1 or Sebring

The "Holy Grail" series Loren refers to was a series of Corvette Restorer articles published while I was editor. My guess would be 1999 and/or 2000, but my references are at home.

[Tom W.]

Re: Early C1 Disc Brakes? SR1 or Sebring

Thanks Terry.
Since I've been a member since about 1975 I'm sure I have these articles somewhere. ( Pack Rat) It may take me longer to find the articles than it takes to solve this wheel/hub/disc mystery!
I wonder if it would be on the CD's that I got last Christmas? Would there be a key word that unlocks the SR Corvettes or the Holy Grail?
Tom

[Terry M.]

[Tom W.]

Re: Early C1 Disc Brakes? SR1 or Sebring

Thanks Terry,
I just had a wonderful phone conversation with John Neas.

I'm going to look at a few things he told me to check.
I'm getting closer on the wheels. Loren Lundberg's note said the wheel number refernces Halibrand 2211. I checked my wheels and they are W.H. 2011. There's also a code on them that says N 184.

Perhaps someone knows the Halibrand wheel codes if there is any record or relationship to dates or job numbers.

[John N.]

Re: Early C1 Disc Brakes? SR1 or Sebring

Thanks Terry,
I just had a wonderful phone conversation with John Neas.

I'm going to look at a few things he told me to check.
I'm getting closer on the wheels. Loren Lundberg's note said the wheel number refernces Halibrand 2211. I checked my wheels and they are W.H. 2011. There's also a code on them that says N 184.

Perhaps someone knows the Halibrand wheel codes if there is any record or relationship to dates or job numbers.

Just checked what I believe to be a 56 Sebring race wheel. WH 2011
15 x650 Halibrand Eng. Co. Culver City Calif. plus a keystone looking item. I looked at what is probably is a wheel from the 56 St Louis production SR car and can not see anything yet. Layers of dust, using a flashlight and a decade of Chicago winter corrosion on magnesium has made anything left hard to read. Hope to have better luck in the future on other wheels. The production SR wheel has a stronger spoke design and the 56 Sebring wheel had the wheel weights on screws which were equally spaced around the circumference of the rim. The heads of the phillips screws (bolts) were in the bead area.
Regards

[Tom W.]

Re: Early C1 Disc Brakes? SR1 or Sebring

Thanks John,
Since we've all learned that production line and racing situations can drift from the "gospel according to GM", in your opinion, would it be a fair assumption that these wheels and the related hubs may have been the prototype dicussed in the 2/15/56 AIM for 2934 SR Corvette?
There was mention in an earlier blog that said " the presence of Chevrolet part numbers is required to be believable to the sanctioning body". That would presume that all racing and experimental parts, machined or otherwise would have a GM part number cast/stamped into them. If that is so, then certainly production parts with plans to produce thousands of examples would most certainly have the GM part number on them.
Beside my desk was a box of misc Corvette parts that I neglected to take to my shop. I thought I'd test the part number theory by going through them to find the part numbers. I didn't even select a particular vintage.
All of these original GM Corvette parts have no identifying part number.
You'll recognize most of them as "run of the mill" common parts. ( C1 56-7 front emblem bezel, C2 upper radiator support, C3 interior trim moulding,C2 lower shift boot) From this example a strong case exists that whether a part is cast, stamped, or moulded, part numbers do not exist on all Chevrolet parts. Furthermore, my theory is that racing and experimental parts may be even more difficult to identify, and certainly deem "authentic" ,based on practices that bypassed corporate protocol and in the case of racing development, authority. The need to fulfill urgent deadlines for performance situations would necessitate a reasonable degree of latitude resulting in exceptions. You know what they say "if it walks like a duck, quacks like a duck, and looks like a duck....it probably is a duck".
Comments?

[Jimmy B.]

Re: Early C1 Disc Brakes? SR1 or Sebring

John,

The regular HALIBRAND production wheel of 56 SR # 2823 had that 2011 number on it.

Jim Blakely

also rear wheel cylinders were 7/8" bore had "XP" and a 4 digit number stamped into it if memory serves me correctly.

[Loren L.]

Re: Early C1 Disc Brakes? SR1 or Sebring

[quote=Tom Westbrook (1232);456392]Thanks John,
Since we've all learned that production line and racing situations can drift from the "gospel according to GM", in your opinion, would it be a fair assumption that these wheels and the related hubs may have been the prototype dicussed in the 2/15/56 AIM for 2934 SR Corvette?
There was mention in an earlier blog that said " the presence of Chevrolet part numbers is required to be believable to the sanctioning body". That would presume that all racing and experimental parts, machined or otherwise would have a GM part number cast/stamped into them. If that is so, then certainly production parts with plans to produce thousands of examples would most certainly have the GM part number on them.
Beside my desk was a box of misc Corvette parts that I neglected to take to my shop. I thought I'd test the part number theory by going through them to find the part numbers. I didn't even select a particular vintage.
All of these original GM Corvette parts have no identifying part number.


The previous paragraph may represent quantum leap in illogical reasoning.
Having a part # assigned to a part is LIGHT YEARS away from having a part number PHYSICALLY ON the part.
We are all aware of hundreds of parts that do not have part #s, but DO have casting #s and millions more that bear neither part or casting #.

As an example(used because I had to find it recently for another question), we'll go to Engineering Change Recommendation 42590, initiated 12/5/61 with get-it-done-date of Dec 31,1961. The ECR covered 1> aux. frt stabilizer bar (mounted beneath the A-arms), 2>brake drums, etc., including forward self-adjusters, 3>37 gallon fuel tank, and 4>Release of Halibrand wheels, hubs, axle shafts and spinner nuts. It was noted "(This unit existed in 1956 but was cancelled in 1957.").

Sheet 4 of the ECR then lists a "Wheel unit - knock off" and assigns part #3823250 to it, ie, the UNIT; the wheel itself is assigned 3823159; LH nuts are 3734855; RH nuts are 3734856; LH front hub is 3823155; RH front hub is 3823156; LR axle shaft is 3823157; RR axle shaft is 3823158; and the KO Instruction sheet is 3823160.

On the next 11 lines, we find an explanation for the code E used in the above lines:

"E: List Drwg - This Number issued to
cover an Equivalent to the
Halibrand Engr Co Product and
the Release Notice the Part Number.
"D: Halibrand Engr Co Part # H-838-L
and H-838-R.
"C: Halibrand Engr Co Part # H-838-L
and H-818-R.
"B: Halibrand Engr Co Part # H-326-FL
and H-326-FR.
"A: Halibrand Engr Co Part # H-2011."

[Tyler T.]

Re: Early C1 Disc Brakes? SR1 or Sebring

The no part numbers on installed parts continued into 1988 at least. My 88 ZR 1 prototype calipers have no markings on them but I have a PAD with part numbers on it. I also have other ZR 1 specific body suspension items with paper tags on them and no markings. These tags correspond to the engineering numbers in the PAD drawings.

Tyler

John Neas for NCRS man of the year!!!

[Tom W.]

Re: Early C1 Disc Brakes? SR1 or Sebring

Hi Loren,
I understand your point. I disagree that it's "light years away from having the part # on the part". I don't know the actual percentage of parts that have been cast with the initial part # assigned by GM, but I'm sure it's considerable. The rationale was that there may be a means of absolute authentication if the part itself bore the number illustrated in the AIM. For those of us that do not have the extensive documentation that you have, it's probably the most used path of logic to identify parts. I think what I'm trying to say is, Part Numbers were assigned to 2/15/56 AIM 2934 SR Corvette components and I hoped to be able to match those to my parts.
Now, since there are no part numbers visible on any of the components except the wheels, and that number is not a GM part number, what is the mechanism that best validates the authenticity of a part or assembly in the absence of any identifying marks?
Your Code "A" Halibrand part number H-2011 certainly indicates the part number and Corvette is synonymous. Is that sufficent normally?
As you know two others that have documented SR cars have found similar markings on their wheels. I'm interpreting your submittal as another piece of information that assists in the absolute identification of at least the wheels.
Also the language "believeable to the sancioning body" would indicate that some one or some group of individuals, making up a sanctioning body, has the authority to render an opinion on the authenticity of my parts.
Does "sanctioning body" refer to the NCRS? Who is that body specifically? From your experience,what more is needed to accept this assembly as authentic as it relates to 2934 SR Corvette?
Thanks,
Tom