Any 71 BB owners know about ground straps?

[Lynn H.]

Re: Any 71 BB owners know about ground straps?

As a follow up to yesterdays post I checked my 71 #16798 which is radio equiped. No ground strap(s) on the front body mount(s). There is a 3/16" pilot hole on the front flange of the frame bracket. No pilot hole in the passenger side frame bracket. 71 #21467 is exactly the same.

Dave,
Interesting to say the least.....I personally have never seen one of these grounds on the passenger side of the car, I have only seen them on the drivers side.
Lynn

[Dave S.]

Re: Any 71 BB owners know about ground straps?

Dave,
Interesting to say the least.....I personally have never seen one of these grounds on the passenger side of the car, I have only seen them on the drivers side.
Lynn

The pilot holes are in the drivers side on both cars. Sorry if I was not clear on that. They are 3/16" but have never been taped with a bolt.

[Paul C.]

Re: Any 71 BB owners know about ground straps?

Maybe it depends on whether you car was built on Monday AM or Friday PM--not a good time. My January 28, 1971 LT-1 has a set of rims all dated February 29, 1970 (K10 2 29 AZ) unfortunately there was no February 29th in 1970. I think anything is possible on a car coming off the line. Just my 2 cents.
Paul

[Paul O.]

Re: Any 71 BB owners know about ground straps?

Upon further investigation S/N 6473 71 LT-1 no grounding strap but does have the mounting holes. Can't check my S/N 1914 since I sold it several years ago and have no photos of that area. Paul 18046

[John H.]

Re: Any 71 BB owners know about ground straps?

Dunno about C3's, but it's always been my belief that the strap on midyears is unrelated to the presence/absence of a radio, and is erroneously shown in the U69 (radio) section of the Assembly Manual.

Everything inside a midyear is grounded to the birdcage, and everything from the doors back (including the dome light, tail/stop/turn/backup and license lamps, fuel tank sending unit, coupe rear blower, etc.) are grounded through one little black wire that runs forward through the main body harness and instrument panel harness to the radio connector, where a pigtail from that cavity with an eyelet on it screws to the bottom of the lower instrument panel brace piece of the birdcage.

That strap from the front edge of the birdcage sill to the #1 body mount bracket on the frame is the ONLY ground path from the birdcage back to the battery, except on convertibles where the #2 body mount bolts tie the birdcage sill directly to the frame with no insulator.

[Thomas H.]

Re: Any 71 BB owners know about ground straps?

My 71 LS5, S/N 1632 (early Sept 70 build) does not have the ground strap, but it does have the hole in the bracket. The hole has never been threaded.

I do have the ground straps from the exhaust to the frame as expected for an AM/FM car.

I second the sentiment from an earlier post... The garage floor is really cold!

Tom

PS: I can't wait for spring!!!!!!

[Joseph M.]

Re: Any 71 BB owners know about ground straps?

My 70 has the driver side ground strap. I personally took it off while disassembling the car for restoration.

[Sal C.]

Re: Any 71 BB owners know about ground straps?

Another curve ball! Granted its an early car, but according to the AIM and our judging guide, the 71s and 72s shouldn't have the exhaust ground straps.

[Chuck S.]

Re: Any 71 BB owners know about ground straps?

Dunno about C3's, but it's always been my belief that the strap on midyears is unrelated to the presence/absence of a radio, and is erroneously shown in the U69 (radio) section of the Assembly Manual.

Everything inside a midyear is grounded to the birdcage, and everything from the doors back (including the dome light, tail/stop/turn/backup and license lamps, fuel tank sending unit, coupe rear blower, etc.) are grounded through one little black wire that runs forward through the main body harness and instrument panel harness to the radio connector, where a pigtail from that cavity with an eyelet on it screws to the bottom of the lower instrument panel brace piece of the birdcage.

That strap from the front edge of the birdcage sill to the #1 body mount bracket on the frame is the ONLY ground path from the birdcage back to the battery, except on convertibles where the #2 body mount bolts tie the birdcage sill directly to the frame with no insulator.

I agree that the purpose of the ground strap may have changed over the years. It may have begun as a necessity for the radios (Sheet A8 also shows braided straps on both exhaust pipes to the frame) and as more grounds were added to the bird cage, the straps became necessary for electrical continuity. My thought is...if you're still claiming your car has ground straps after apparent discontinuance in 70, then where are your exhaust pipe ground straps?

On thing to remember on 70-72 is that the body mounts had solid aluminum biscuits and steel shims that should have provided an electrical path from frame to birdcage without the need for the ground strap to the bird cage. In 73, when they went back to a soft body mount, I might be convinced that a ground strap had to be reimplemented, but I have a real hard time believeing that these ground straps were being installed on the line by GM employees, and they're NOT SHOWN in the AIMs somewhere.

[Thomas H.]

Re: Any 71 BB owners know about ground straps?

Another curve ball! Granted its an early car, but according to the AIM and our judging guide, the 71s and 72s shouldn't have the exhaust ground straps.

Sal,

My car being a low serial number (1632) and early 71 build (Sept, 70) has a mixture of 70 and 71 parts on it which is why I probably have the exhaust ground straps as they were used in 1970. I am not the original owner of my car so I can't be sure they were not added on sometime over the years, but why?

My car also has the yellow emissions label even though the TIMJG has them listed as being used in 71 up to "at least" S/N 1455. I'm 1632.

Fun stuff.

Tom

[Terry M.]

Re: Any 71 BB owners know about ground straps?

Sal,

My car being a low serial number (1632) and early 71 build (Sept, 70) has a mixture of 70 and 71 parts on it which is why I probably have the exhaust ground straps as they were used in 1970. I am not the original owner of my car so I can't be sure they were not added on sometime over the years, but why?

My car also has the yellow emissions label even though the TIMJG has them listed as being used in 71 up to "at least" S/N 1455. I'm 1632.

Fun stuff.

Tom

Tom,
To "at least" 1455 does NOT exclude your 1632. In fact it would include it. Find a few more 1971s around your s/n and we can move that number in the next revision -- if I can talk the others into it.

The exhaust system ground straps were supposed to stop during 1970 production when the 1971 style distributor shielding and the RFI shield came into use. That was, I think around 12000 or so in 1970. But I would agree the exhaust system grounds seem like an unlikely owner inspired addition.

[Paul O.]

Re: Any 71 BB owners know about ground straps?

Tom my old S/N 1914 had the additional yellow vapor canister label hope that will be added to the next 70-72 update. I was second owner in 1974 till 2007 also never had the exhaust ground straps on the car our cars were build just a few days apart. Paul 18046

[Thomas H.]

Re: Any 71 BB owners know about ground straps?

Ok, here is a picture of the ground straps from my 71. Do they look like the factory ones? If not then I can conclude that someone added them to the car at some point in it's life.

The one end that came off of the exhaust clamp is chewed up, but the frame ends are intact.

Tom