Believe suspension on my 64FI is the F40. Rear Spring is 7 leaf with top two flat, front stabilizer is 15/16, however the front spring tag just fell off. Tag is labeled ED p.n. 3851100 not the expected ED pm 3832518. A look at GM parts catalof has a note next to 3832518 "(dark green)" while note for 3851100 is "(part No. on spring). Is there any way to verify what spring I have? Is number really stamped on the 3851100 and where? Could the tag be wrong, should it be ED for the F40? A search of past info found a Posting on 10Oct99 by Midkiff Re;Part No. 385110 (Front Spring) that appears to say ED was the F40, however the NCRS 3rd Judging Guide says the opposite, ie the EA is the F40. Have owned the car since 1966 and doubt the suspension went through changes. Hope I've kept all these numbers clear and thanks in advance for any help.
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Re: C2 1964 F40 suspension identification help
The Z-06/F-40/F-41 550 lb/in front spring has a wire diameter of .680" versus .552" for the base '63 spring. (The '64 front variable rate base spring may be different, but is probably smaller than .680")
This information is in my 1963 AMA specs that were included in the GM "restoration package", and the 1964 version should also include spring dimension data.
IIRC Z-06/F-40/F-41 also has a "heavy duty" lower rear shock/strut rod mount, but I don't know the visual differences.
Also in the AMA specs, the original Z-06/F-40/F-41 rear shocks have a 1.375" diameter piston rod versus 1.0" for base. Front shock piston rod diameter is 1.0" for both base and Z-06/F-40/F-41.
Duke -
Re:OK its a F40, but why tag of ED ?
Measured spring (thanks Duke) and now all components meet the F40 spec (not shocks since they left a long time ago). NOW why is spring label marked ED pn 3851100, that green tag with black letters that just fell off spring? Would like to order a new tag, but which one - ED or EA. Is this an error in the NCRS Judging Guide page 138?
My next quest will be for the 1964 J56 or J65 option on my car, but that's tomorrow when the lights better and I can find pn and measure brake pad size - thanks all. Have seen some past posting on this problem, so I need to get some facts before asking.
Q for Duke - How does one get the AMA specs in the GM restoration package?Comment
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Re:OK its a F40, but why tag of ED ?
Call GM customer service 800-222-1020 and tell them you own a '64 and would like the "restoration package". They will want the VIN and there is no charge.
J-65 brakes consist of segmented metallic linings, drums with a finer friction surface finish using the same casting numbers as base drums, and special high temperature springs that might be a different color than the base brake springs. Everything else was identical to base brakes.
Unfortunately, if J-65 linings were replaced with conventional organic linings virtually all J-65 evidence is erased. The good news is that J-65 linings will easily last 100K+ miles, but many were replaced due to their somewhat cantakerous nature in daily driving.
I have advised several with original J-65 linings that still had plenty of material to overhaul the brake system - rebuild or replace master and wheel cylinders and drums as required, but just cleanup and reuse the J-65 linings if they are satisfied with their normal everyday performance. Though they can be cranky in normal driving they are impossible to fade - even on a race track!
J-56 HD brakes are easily IDed by the finned drum, vented backing plates, and dual circuit master cylinder. Very rare and "neat" but they don't work well either on the street or track and are VERY expensive if you need any new parts.
BTW if you have either base of J-65 brakes I'd like to get the drum numbers. Also, are the numbers "cast in" or stamped, and do the drums have "max dia. 11.090"? Stamped? Or cast in?
This will help determine if your drums are original or replacements, and the replacement era.
Not too many of us are interested in the nuances of J-65, and since they can only be positively IDed if the drums are removed, they are not mentioned in the JG, but I am trying to collect as much info on them as possible.
DukeComment
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Re Why tag of ED ? & its a J-65 brake
Duke, thanks for info on next question and tele number, changed subject to make search quicker.
My brakes are the J-65, segmented metallic linings. The non finned drum has the casting number 3828688 along the outside angled edge and also a W3 marking, these appear to be cast in. The shoes have casting # 5461962 on all.
Replaced rear in the 80's(??) since they rusted together and GM had drums and shoes still. The numbers are from the old parts that I still have. Unable to find the "max dia. . . ." anywhere on drum - let me known where to look.
The brakes were always great after first stop and still have more life in them (the front) and rear are still new. Yes springs are special and unique colors.Comment
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Re: Re Why tag of ED ? & its a J-65 brake
I believe the 688 is an original drum casting. One of my original SWC rear drums is a 688, and the other is 3752623. I can't discern any visual differences between the two.
Beginning as early as 1/1/68 a new FMVSS required the maximum diameter to be permanently marked on drums. I've seen some where it appears to be die stamped, and I believe this was a "rework" of existing stock. The replacement drums you bought in the eighties should have the max. dia. as part of the mold and the castings numbers would be different.
Can't be of any assistance on the spring tag issue.
DukeComment
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Re: J-65 brake replacement drum
Duke - just pulled rear wheel off to get pn of drum. PN is 3868538 and the W 11 is also on the drum, however the max dia is not on the drum.Comment
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Re: J-65 brake replacement drum
That's probably the original drum. You might want to measure them. Though the J-65 linings are very long lived - easily over 100K miles of normal driving, they're relatively hard on drums compared to conventional linings and once the metallic linings are worn, the drums may be worn near the limit, too.
The maximum diameter established for these drums is 11.090".
DukeComment
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3868538 is not a 64 J65 drum *NM*
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Double check the number
My original J-65 drums casting numbers are:
Front: 3828671
Rear: one 3828688 and one 3752623
None show a value for max diameter since they were manufactured long before the requirement was in place.
The replacement drums casting numbers I bought circa 1977 - part numbers specifically called out for metallic brakes are:
Front: 3869532 (has max dia. in casting)
Rear: one 3969538 (no max diameter), one 3985945 (has max dia. in casting)
Check the numbers again and see if the eights might be nines.
DukeComment
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Correction
3969538 SHOULD BE 3869538!
I'm sure the fourth digit on mine is 9. The fact that this casting does not have an embedded max diameter indicates that it was manufactured prior to the FMVSS for max diameter, which I believe went into effect on 1/1/69, so this number may have been originally installed on drum brake Corvettes in production, but I'm not sure.
Base and J-65 drums were machined from the same castings. The only difference is a 20 microinch finish on J-65 drums, so they had differnet end item part numbers from base drums. A 20 microinch finish is a near polish.
DukeComment
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Re: Correction
Yes the 9 is an 8. These were replacement drums, still have originals of correct pn that I may check and pur back on. Posting was to let Duke know the pn for the replacements since he has an interest of collecting data for the J-65.Comment
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Re: Correction
What are the casting numbers of your originals?
DukeComment
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