Caliper orange paint markings, late 65 --- mystery solved

[Wayne M.]

Back in January of this year, I asked about orange paint dabs on the inboard halves of my rear calipers. Others also reported this (early '66s).

The definitive answer was right under my nose. In the Spring 2004 RESTORER, Brian Futo submitted a Tech Service bulletin # DR 763, dated Aug 20th 1965. Subject: Disc Brake Squeal, 1965 Corvette. " .... Effective June 15th, (St.Louis) began using a shoe and lining assembly with reduced lining pad size to minimize this condition. All 1965 vehicles with this new lining assembly will be identified with orange paint on the back side of the caliper housing or on the front wheel hub and rear wheel spindle. .... For existing 1965 Corvettes, complaints of brake squeal prior to this change should have the brake shoe lining modified per (dwg. attached) ..."

Involves 3 cuts of lining with hacksaw; a triangular section at each end of shoe, and widening the center gap considerably. IMO, this mod. removes approx. 25% of the total lining surface.

Here's the link to earlier thread (shows pics). Anybody else have these orange markings or ever seen a modified brake shoe ?

https://www.forums.ncrs.org/showthread.php?t=66915&highlight=orange+paint&uid=5437

[Ronald L.]

Re: Caliper orange paint markings, late 65 --- mystery solved

Wayne and or perhaps Joe has the document...how long was the orange paint daub process in place??

In other words, how far into 66 production did this occur?

Wayne, I found a very very nice surviving example of the orange daub on the outside and what appears to be a black swab on the inner caliper.

[Joe L.]

Re: Caliper orange paint markings, late 65 --- mystery solved

Back in January of this year, I asked about orange paint dabs on the inboard halves of my rear calipers. Others also reported this (early '66s).

The definitive answer was right under my nose. In the Spring 2004 RESTORER, Brian Futo submitted a Tech Service bulletin # DR 763, dated Aug 20th 1965. Subject: Disc Brake Squeal, 1965 Corvette. " .... Effective June 15th, (St.Louis) began using a shoe and lining assembly with reduced lining pad size to minimize this condition. All 1965 vehicles with this new lining assembly will be identified with orange paint on the back side of the caliper housing or on the front wheel hub and rear wheel spindle. .... For existing 1965 Corvettes, complaints of brake squeal prior to this change should have the brake shoe lining modified per (dwg. attached) ..."

Involves 3 cuts of lining with hacksaw; a triangular section at each end of shoe, and widening the center gap considerably. IMO, this mod. removes approx. 25% of the total lining surface.

Here's the link to earlier thread (shows pics). Anybody else have these orange markings or ever seen a modified brake shoe ?

https://www.forums.ncrs.org/showthre...paint&uid=5437

Wayne------

Various modifications of the pad friction component configuration are used to this day to minimize brake noise.

For example, many OEM brake pads for GM cars have both ends of the friction surface tapered. This is done to reduce brake noise. However, just as you note in the case of the Corvette pads with the "cuts", this reduces the brake pad effective surface area (at least, until the pad is worn down to a point in which the taper is gone). Aftermarket type brake pads, including aftermarket-quality Delco pads, usually do not have the taper.

As in many other cases, I suppose the difference in brake pad configuration for OEM pads has a lot to do with the fact that the OEM pads, although also available in SERVICE, are used in PRODUCTION on new cars. So, everything necessary and possible is going to be done to minimize brake noise so that the customer does not get the "wrong idea" on that all-important test drive when he or she is shopping for a car.

[Ronald L.]

Re: Caliper orange paint markings, late 65 --- mystery solved

Joe - We solve this simpler these days, there is an Asian supplier that has a patent on the pads that don't squeak.

How long did the orange paint operation last into the 1966 model year???

[Tony S.]

Re: Caliper orange paint markings, late 65 --- mystery solved

Wayne. Interersting stuff. My late July L78 car had those orange daubs in the center of the inner halves of the rear calipers. Also, on both sides of the same rear halves, there were heavy white paint daubs. The paint order was: white/orange/white. This paint arrangement was on both rear inner calipers, but there were no such paint daubs on the original fronts.

I wonder what the white paint daubs signified?

Interesting stuff.

Tony

[Joe L.]

Re: Caliper orange paint markings, late 65 --- mystery solved

Joe -

How long did the orange paint operation last into the 1966 model year???

Ron-----


I have no idea.

[Wayne M.]

Re: Caliper orange paint markings, late 65 --- mystery solved

.....My late July L78 car had those orange daubs in the center of the inner halves of the rear calipers. Also, on both sides of the same rear halves, there were heavy white paint daubs. The paint order was: white/orange/white. This paint arrangement was on both rear inner calipers, but there were no such paint daubs on the original fronts.

I wonder what the white paint daubs signified? ....

Tony --- both my inboards have white (on one piston hump / orange in the center / white on the 2nd piston hump). As far as the fronts, the TSB says "identified by orange paint on the back side of the caliper housing or on the front wheel hub and rear wheel spindle.".

My theory is that the white was some kind of torque check at St. Louis, because the same white paint was on the inboard yoke of one of my BB shot-peened half-shafts (see big pic below, left only -- the other is from a '64).

[Tony S.]

Re: Caliper orange paint markings, late 65 --- mystery solved

Great photo Wayne. My July 29th car had the same white paint daubs. Of course, our cars were built only 3 days apart.

Tony

[Ronald L.]

Re: Caliper orange paint markings, late 65 --- mystery solved

Does anyone (MH) have the Dealer service bulletins for 65 or 66?


Would that not give us a general idea how long this lasted.

[Wayne M.]

Re: Caliper orange paint markings, late 65 --- mystery solved

Does anyone (MH) have the Dealer service bulletins for 65 or 66?


Would that not give us a general idea how long this lasted.

Ron -- my '65 and '66 TSB's have already been cherry-picked, so I haven't got complete sets. I would doubt that they would have waited until the end of this pad modification to include both start and stop dates in the TSB. I suspect it would have been until earlier design "squeaky" brake pads were exhausted.

This 2/15/66 Tech Info bulletin (reprinted in Vette Vues) may be the 'end' date of the orange paint, although I can't imagine that they would continue make the cuts on the pad material for 6 months.

Subject: Riveted Brake Pads, 1966 Corvette [quote] "In production, riveted brake pads have replaced bonded pads on the 1966 Corvette. Also, service replacement parts will be of the riveted type. The riveted brake pads entered production on the front brakes only, with Serial No. S109343, and on both the front and rear brakes, with Serial No. S109688. To exhaust parts stock, 51 units built between Serial Nos. S110379 and S110459 had bonded pads installed in the rear brakes" [end quote].

Here's an eBay pic of really rare no-rivet pads, #5467291, found on 1965 Corvettes and '66s up to the dates mentioned above. Parts history says to replace with 5452513 as of 7-66, in service.

The first 400 or so 1965 Corvettes had their calipers replaced due to a design problem. Recall notices state that all but 2 had this done at the dealers, before release to the public.

[Ronald L.]

Re: Caliper orange paint markings, late 65 --- mystery solved

Wayne,
I agree, it seems odd such a latent TSB from the start of a problem, but then perhaps there were interim pads that did not get all the way there. After all this was early in the use of disc brakes, and we still have to tweak them to this day on new models.

Tony, Wayne and any one that has the white and orange daubs - can you detect if there is any of the white on top of the orange?

That would help substantiate that Chevrolet Warren where these were bolted to the wheel ends was doing a paint marking operation to verify torque.

Now did that correlate to the drive shaft? Not really, given the drive shaft was St Louis installed and the calipers Chevy Warren.

It also seems funny there was a delay until July to get them in service, why would they want to use up old stock on a problematic part???

[Wayne M.]

Re: Caliper orange paint markings, late 65 --- mystery solved

.....Tony, Wayne and any one that has the white and orange daubs - can you detect if there is any of the white on top of the orange?

That would help substantiate that Chevrolet Warren where these were bolted to the wheel ends was doing a paint marking operation to verify torque. .......

Ron -- here's close-ups of my 2 rear inboard calipers. On the first pic, I'd say white over orange [note coarse bristle marks on the white]. But on the 2nd pic, seems to be a toss-up.

If we assume the white was added after the orange [hence at St.Louis], it could also be a sign of verification of the inboard bleeder and brake line tube connection. I can't say for sure that the color of white on my inboard half shaft yoke is the same shade as on the caliper.

[Ronald L.]

Re: Caliper orange paint markings, late 65 --- mystery solved

Wayne,

Thanks for posting, yes its clear white over orange.

My thinking is this, orange was for the rework, but as far as what the white was for...?...it could be at Warren when they drove the fasteners and then certified the fasteners were torqued. Those would be a safety type of item.

Perhaps John knows what paint marking activities occurred at St Louis.

[Joe L.]

Re: Caliper orange paint markings, late 65 --- mystery solved

Ron -- here's close-ups of my 2 rear inboard calipers. On the first pic, I'd say white over orange [note coarse bristle marks on the white]. But on the 2nd pic, seems to be a toss-up.

If we assume the white was added after the orange [hence at St.Louis], it could also be a sign of verification of the inboard bleeder and brake line tube connection. I can't say for sure that the color of white on my inboard half shaft yoke is the same shade as on the caliper.

Wayne-----


I greatly doubt that any paint inspection marks were placed on the calipers at St. Louis. I expect that all such "daubs" were placed at some sub-assembly point before the parts even got to St. Louis.

[John H.]

Re: Caliper orange paint markings, late 65 --- mystery solved

Perhaps John knows what paint marking activities occurred at St Louis.

Ron -

There were no paint-marking activities at St. Louis except occasional much smaller marks on or adjacent to critical safety fasteners they torqued, only on random-sample daily quality audit vehicles. There's a lot of "graffiti" on some restored cars whose owners think every bolt got a paint mark.