CHEVELLE TECH is a regular column intended as a guide to assist members with questions they have regarding 1964-72 Chevelles. We'll publish as many letters and responses per issue as space permits.
Sorry, but no personal responses can be made.
Address your questions to:
CHEVELLE TECH, A.C.E.S.,
4636 Lebanon Pike, Suite 195,
Nashville, TN 37076-1316.
Gary Payne, Weaverville, NC
A:
Disc brakes were first offered as a Chevelle option
in 1967. Four piston calipers and two-piece rotors were used
during the '67-8 model years, while a single piston caliper design
was used on '69 and up versions. As far as interchangeability,
Gary, you can use a disc setup from any '67-'72 GM "A"
body (Cutlass, Skylark, Tempest) by swapping everything from
the spindles on out. You should also try to swap all the attendant
brake booster/master cylinder/proportioning valve assemblies from
the donor car, as well as all the hard lines. Naturally, you'll
want to turn the rotors, rebuild the calipers, and replace all
rubber hoses, too.
Two problems make the early ('67-'72) disc setups a bit more difficult to live with: leaking caliper pistons, and difficult-to-find two-piece rotors. Although some folks claim that the four-piston calipers provide better stopping power than the later ('69-'72) single piston design, those small gains are more than offset with the reliability and parts availability of the single piston design. Four piston calipers can be sleeved with stainless steel liners, however, making them much more leak resistant. Unless you're restoring your '67 Chevelle, Gary, and need the four piston calipers to make your conversion correct, we recommend staying with the single piston configuration.
Searching your local junkyards should turn up all the pieces you need, Gary. But, in case you come up empty-handed, try contacting the folks at Master Power Brakes (254-1 Rolling Hills Road, Mooresville, NC 28115 (704) 664-8866) to order one of their complete kits. All the parts are new or reconditioned, and they'll take all the guesswork out of your conversion.
As for the rearend in your Chevelle, our manuals tell us that the '67 uses a rearend measuring 54.25 inches from axle tube flange to axle tube flange, and 12-bolt rearends fitting that spec were used only from '65 through '67. Minor differences in spring seats shouldn't present any big problems. On '68-'72 models, the rearends measure approximately one inch wider for axle tube flange to axle tube flange and the spring seats were aactually moved slightly inboard compared to the '65-7 versions. Gearsets shouldn't present any problems in the ratios you've indicated, especially if you shop for after market pieces. You will, however, need the correct posi carrier for the gearset, and in the event that a GM unit is difficult to locate, try ordering a Brute Strength unit from Moroso (P.O. Box 1470, Guilford, CT 06437-0570 (203) 453-6571).
I'm hoping you can answer a few questions concerning my '69 Chevelle 2dr sport coupe. With the info currently available to me, it is an SS396, 4speed (verified by the floorpan stamping), and a 4.10 posi (8 7/8 " 12'bolt, stamped KK0603B). The engine and trans are not original, and no build sheets were found.
VIN: 136379B353672.
ST 69 13637 BAL 206061 BDY
TR791 52E PNT
02C B L 131654
The interior needs to be restored to the original parchment color. Which items remain black? I've rebuilt and installed a Muncie 4-speed stamped P8D25. Is this April '68 trans acceptable for a February '69 car, from a collector's standpoint? What 396 was most likely installed in this car? 325, 350, or 375 hp version? Is there a company similar to Pontiac historical services that can give me more specific info by the VIN?
I'm hoping you can help me with my restoration, and I'm looking forward to being a member of ACES.
David Williams, Seaford, VA
A:
Items remaining black in your otherwise Parchment
interior, David include the dash housing and pad, steering column
and wheel, carpet, windshield pillars, and rear package tray.
There's some difference of opinion on the headliner and visors,
but most folks I've discussed this with seem to feel that they,
too, should be black. Any feedback from the membership on this?
From a collector's standpoint, it's doubtful that the Muncie you've installed could be considered "correct" because of the date coding. Generally, the dated components should fall within a 4-8 week window prior to the build date of the vehicle. Other than the date code, the Muncie trans is "correct" in that it is the same type transmission installed at the factory.
The engine most likely installed in your Chevelle would have to be the 325-horse version, David. We're making a "best guess" estimate here, based simply on the fact that the L35 engine was the most prolific of the three 396 variants. In case you're interested, there were 59,786 325-horse engines installed in '69 Chevelle Super Sports, while the 350 and 375-horse versions numbered 17,358 and 9,486 units respectively.
As for any information brokers on Chevelles, there are none that we know of. Unfortunately, Chevrolet didn't keep as specific records on their production as Pontiac did, and information such as you've requested has been rumored to exist, we've never seen anything to substantiate those rumors. One of our future projects, Dave, is to try and decipher cowl tag accessory codes using a relational data base comprised of information provide by our members. Specifically, we'll be asking for cowl tag data and build sheets on member's cars. That way, we'll be sure that options appearing on the care are, in fact, assembly line installed, and not added on later. Unfortunatley, That project won't get off the ground until we have a larger member base to provide reasonably accurate sampling. Try to hang in there with us, and we'll all learn more about our Chevelles as time goes on.
I'm requesting any information on a Warranty Service Bulletin for a leak under the dash on the passenger side of '66 Chevelles. This would be greatly appreciated since I am finishing up the body work on my car, and believe this would be an ideal time to address the problem.
Whenever it rains, I find water under the carpet on the front passenger floorboard. I assumed the leak was from the windshield and have taken the dash out of the car to cut out and seal any rust holes under the dash. I still have the leak.
I met a lady at a party who told me I had a leak on the passenger side before I even told her about it. It turns out that she was a factory GM mechanic back in the Sixties, and remembered a Warranty Service Bulletin for a leak on the passenger side of my car. She said she seemed to remember it was a body seal problem. I have tried to locate this service bulletin without luck. Thanks for any help you can offer.
Hans Yeager, Austin, TX
A:
At this time, Hans, we are in poor shape with regards
to Service Bulletins. Perhaps one of the members can provide
us with some insight into your problem, or even better yet, a
copy of the Service Bulletin you refer to so we can add it to
our archives. We also own a '66, and while we haven't encountered
any leaks such as you've described, we're interested in the repair
anyway. How 'bout it, members?
