Author Topic: Rear Brake Standard Diameter  (Read 4566 times)

69Z28-RS

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Re: Rear Brake Standard Diameter
« Reply #30 on: February 12, 2014, 03:59:42 AM »
Section 5 in the Specifications at the back had (or would have had) some additional data, including torques and nominal dimensions of the brake drums and shoes...  It seems the '68 SM had a glitch (either in the initial release or ??)..
Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55-'56-'57 Nomads, '55-'57 B/A Sedan

lakeholme

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Re: Rear Brake Standard Diameter
« Reply #31 on: February 12, 2014, 06:03:15 PM »
Section 5 in the Specifications at the back had (or would have had) some additional data, including torques and nominal dimensions of the brake drums and shoes...  It seems the '68 SM had a glitch (either in the initial release or ??)..

Gary, it would be good to have the charts that are in the 67 and 69 for quick reference, especially the torque chart.  I compared page 5-21 that Steve mentions in the 68 SM, and it is virtually the same as 5-22 in the 67 SM.

Think maybe the same guy that decided we didn't need options listed on the cowl tag in 68 was in charge of the SM?  ??? ;D ???
Phillip
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69Z28-RS

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Re: Rear Brake Standard Diameter
« Reply #32 on: February 12, 2014, 06:11:26 PM »
Section 5 in the Specifications at the back had (or would have had) some additional data, including torques and nominal dimensions of the brake drums and shoes...  It seems the '68 SM had a glitch (either in the initial release or ??)..

Gary, it would be good to have the charts that are in the 67 and 69 for quick reference, especially the torque chart.  I compared page 5-21 that Steve mentions in the 68 SM, and it is virtually the same as 5-22 in the 67 SM.

Think maybe the same guy that decided we didn't need options listed on the cowl tag in 68 was in charge of the SM?  ??? ;D ???

I've already returned my manuals to their 'basement' storage spot.. :) , but I recall that the 'brake drum' information in the main Section 5 was the same information in the '67 and '69 manuals.   In the Specifications (at the back of the SM), the '67 manual contained separate charts for 'Torque Settings' and 'Brakes', but the '69 manual combined this information into a single chart (which I scanned and posted on an earlier post).   A quick review of those two charts did not indicate any differences in the information, just that the two charts were combined into ONE for the '69 manual.   I think from this you'd be safe to rely on information from either the '67 or '69 SMs to obtain data for your '68.   If you really want the two charts from the '67 manual page, let me know and I will retrieve that manual page and scan/post it.. :)
Going back thru the messages I see that Pete had already posted the two charts from the '67 manual, so you have access to the Specs section for Brakes from both the '67 and '69 manuals.   I'm suspecting that the '68 manuals that some of you have simply had an error for that page to be missing in the specs section (but it should contain the same information as either of the other manuals, unless the '68 was unique and different, which i don't think would be true).

PS.  In an earlier reply in this thread, I posted these comments:
"The drum itself will have a specification stamped into it; how much it can be turned down is generally stamped into the back edge of the drum.   
There is also a angle cut on the back inner edge of the brake surface, which can be used as a quick indication of how much it could be turned down..."
On further reflection this might be incorrect:  I was citing data from my front disk rotor, which was the item I most recently had turned.   It's been so long since I turned a rear drum, that I have to renege on that comment above, as I have no idea if diameter/spec data were ever stamped into drums.  Maybe someone else can clarify that issue?
Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55-'56-'57 Nomads, '55-'57 B/A Sedan

Steve68

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Re: Rear Brake Standard Diameter
« Reply #33 on: February 12, 2014, 07:38:22 PM »
Quote
I'm suspecting that the '68 manuals that some of you have simply had an error for that page to be missing in the specs section (but it should contain the same information as either of the other manuals, unless the '68 was unique and different, which i don't think would be true).

I ordered my service and overhaul manuals using the form in the back of the warranty book right after I brought my car home from the dealer.  June build so I would have thought if there was a missing section that Helm would have known by then and fixed it.

Steve

69Z28-RS

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Re: Rear Brake Standard Diameter
« Reply #34 on: February 12, 2014, 07:53:53 PM »
Steve,

Have you found that same information (from the Torque/Brake) section of the Specifications at the rear, to be located elsewhere within the '68 manual?   If not, then what other conclusion could you draw other than:
1) all you fellas with '68 manuals "lost" that page somehow?
or 2) Chevy/Helm accidentally left it out?

It doesn't do one much good to know he can 'cut' a drum by either 0.020" or 0.060" from std, IF he can't verify what the Std size was...?
Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55-'56-'57 Nomads, '55-'57 B/A Sedan

68Zproject

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Re: Rear Brake Standard Diameter
« Reply #35 on: February 12, 2014, 08:03:36 PM »
I have a chassis service manual (68) and it has section 5 (brakes).
...a section 5 under Specifications?
Please post it....

Not under specifications.  Just under the sections.  Paul, mine is dated 67.
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Steve68

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Re: Rear Brake Standard Diameter
« Reply #36 on: February 12, 2014, 08:30:24 PM »
Quote
It doesn't do one much good to know he can 'cut' a drum by either 0.020" or 0.060" from std, IF he can't verify what the Std size was...?

9 1/2 inches

69Z28-RS

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Re: Rear Brake Standard Diameter
« Reply #37 on: February 12, 2014, 09:53:52 PM »
Quote
It doesn't do one much good to know he can 'cut' a drum by either 0.020" or 0.060" from std, IF he can't verify what the Std size was...?

9 1/2 inches

The only location I found that dimension was in the specification section (5) which was missing in the '68 SM..
Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55-'56-'57 Nomads, '55-'57 B/A Sedan

1968RSZ28

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Re: Rear Brake Standard Diameter
« Reply #38 on: February 12, 2014, 10:48:47 PM »
Quote
It doesn't do one much good to know he can 'cut' a drum by either 0.020" or 0.060" from std, IF he can't verify what the Std size was...?

9 1/2 inches

The only location I found that dimension was in the specification section (5) which was missing in the '68 SM..

It's called extrapolating.  Let's see, the '67 service manual says 9.5" and the '69 service manual says 9.5", I'll bet the '68s are 9.5" too!   ;)

Paul

Steve68

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Re: Rear Brake Standard Diameter
« Reply #39 on: February 12, 2014, 10:55:28 PM »
Quote
It doesn't do one much good to know he can 'cut' a drum by either 0.020" or 0.060" from std, IF he can't verify what the Std size was...?

9 1/2 inches

The only location I found that dimension was in the specification section (5) which was missing in the '68 SM..

The 1968 "AMA specifications-Passenger Car" provides the information.  See page 19, drum, diameter, front, standard 9.5 and disk 11.0, rear 9.5.

Steve
« Last Edit: February 12, 2014, 11:35:21 PM by Steve68 »

Camarocards

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Re: Rear Brake Standard Diameter
« Reply #40 on: February 13, 2014, 01:19:04 AM »
Many thanks to all who have contributed to this thread. I never thought it would have turned out the way it did. I was just looking for an answer that I thought would be easy to provide................if you have a manual that lists it!,  ;D ;D ;D

Thanks again!

Bob
Bob
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