1966/67 BB radiator support bracket question

[Matt L.]

Re: 1966/67 BB radiator support bracket question

Hi Matt<

Thank you for taking the photos and for posting them. This really helps - my car is configured the same as yours. My car was built March 25th (VIN 17534) Also an AOS.

hi Kurt,
sure thing. glad it helped you out. let me know if you need anymore pics and i would be happy to share. thats what these original cars are for and i am very grateful to own it.

take care,
matt

[R N.]

Re: 1966/67 BB radiator support bracket question

My thick washers measure 1.370" OD x .175" thick, with an ID of .460" I'm not 100% sure they are original, but they do look the part of being 47 years old. The thinner washers measure 1.240" OD x .100" thick with an ID of .335"

BTW, the bolts measure 5/16" - 18 x 1-5/8" long with head marking of RSC with 7/8" thread length.

[Ralph B.]

Re: 1966/67 BB radiator support bracket question

My thick washers measure 1.370" OD x .175" thick, with an ID of .460" I'm not 100% sure they are original, but they do look the part of being 47 years old. The thinner washers measure 1.240" OD x .100" thick with an ID of .335"

BTW, the bolts measure 5/16" - 18 x 1-5/8" long with head marking of RSC with 7/8" thread length.

Regarding the "thinner" washers, they appear to be the washer currently specified in the AIM; P/N 3688003 which specs out @ 1.25 OD X 11/32 ID X 3/32 thick and is long since been obsoleted per Joe.

If interested; Midwest makes a cad plated washer that has a slightly larger OD and is .116 thick, unfortunately the ID is much larger @ .43; however this will be covered nicely by the lock washer --- you will just have to keep it centered, or, find a thin wall washer/bushing to reduce it down closer to the bolt size. These are METRIC FENDER WASHERS and are carried by True Value Hardware. Note: I believe all True Value stores carry Midwest fasteners; however, not all of them will stock the metric fender washers. They are not perfect but 1000 times more accurate (and fuctional) than what you will find from the Corvette suppliers which only seem to carry very skinny reproductions around .062 thick which could allow the support to be easily crushed. ------ Best I could find so far !!!

Ralph

[Joseph T.]

Re: 1966/67 BB radiator support bracket question

Here is a picture of an unrestored 1966 L72 (St Louis Body) June car and the washers seem to be the same diameter and similar thickness.photo.jpg

[Ronald L.]

Re: 1966/67 BB radiator support bracket question

Kurt RSC was the only bolt used in that are into the early C3. Sounds like you have the correct washers, not in the snow belt right now to measure sets of originals.

[Alan D.]

Re: 1966/67 BB radiator support bracket question

Interesting thread - It appears the thin washer has part number 3688003 and know dimensions.

Knowing that GM production typically used what was available to fix a problem I don't think it is unreasonable to postulate that the thick washer existed some place in the factory so just used on the Corvette.
The thick washer used on various Harmonic Balance Bolts was pn 3864814 So if somebody has the dimensions for that pn it may turn out it was used as the thick washer everyone is seeing.

A little more support for this idea - the 78-80 Cadillac used this thick washer for the "radiator support mounting" Just a guess.

[Ralph B.]

Re: 1966/67 BB radiator support bracket question

[QUOTE=Alan Drake (43261);654252]Interesting thread - It appears the thin washer has part number 3688003 and know dimensions.

Knowing that GM production typically used what was available to fix a problem I don't think it is unreasonable to postulate that the thick washer existed some place in the factory so just used on the Corvette.
The thick washer used on various Harmonic Balance Bolts was pn 3864814 So if somebody has the dimensions for that pn it may turn out it was used as the thick washer everyone is seeing.

Alan,
Very well could be it, ID is a bit large but still works. looks like it's still available as well (see listing below).
Ralph

3864814 - WASHER

	GM PART # 3864814 CATEGORY: All PACK QTY: 2 CORE CHARGE: $0.00	List Price: $13.89 Price: $8.08 You Save: $5.81 (42%)
DESCRIPTION: WASHERCrankshaft (bolt) washer2.06"O.D.x0.52"I.D.x0.28"thick washer for crankshaft bolt, big-block.

[Ralph B.]

Re: 1966/67 BB radiator support bracket question

[QUOTE=Ralph Benedetti (49275);654300]

Interesting thread - It appears the thin washer has part number 3688003 and know dimensions.

Knowing that GM production typically used what was available to fix a problem I don't think it is unreasonable to postulate that the thick washer existed some place in the factory so just used on the Corvette.
The thick washer used on various Harmonic Balance Bolts was pn 3864814 So if somebody has the dimensions for that pn it may turn out it was used as the thick washer everyone is seeing.

Alan,
Very well could be it, ID is a bit large but still works. looks like it's still available as well (see listing below).
Ralph

3864814 - WASHER

	GM PART # 3864814 CATEGORY: All PACK QTY: 2 CORE CHARGE: $0.00	List Price: $13.89 Price: $8.08 You Save: $5.81 (42%)
DESCRIPTION: WASHERCrankshaft (bolt) washer2.06"O.D.x0.52"I.D.x0.28"thick washer for crankshaft bolt, big-block.

I just realized the OD is too big @ 2.06", so may not be "thick" washer in question.

[Ralph B.]

Re: 1966/67 BB radiator support bracket question

My thick washers measure 1.370" OD x .175" thick, with an ID of .460" I'm not 100% sure they are original, but they do look the part of being 47 years old. The thinner washers measure 1.240" OD x .100" thick with an ID of .335"

BTW, the bolts measure 5/16" - 18 x 1-5/8" long with head marking of RSC with 7/8" thread length.

Kurt,
Based on the assumption that the RSC head bolt you described is GM 454872 specified in AIM @ 1-5/8" long then the addition of the "thick" washer would be critical "or" the bolt would hit/damage the radiator, however, not an issue on the (2) center bolts that secure the shroud where we only see the single "thinner" washer 3688003 and lock washer 103320 used which complies with the AIM. ------- If this is the case then the AIM call out would be incorrect and the factory adjusted for the error by simply adding the "thick" washers in the (4) locations?
Ralph