Battery Cable Replacement (C3 Positive)

[Lee S.]

What I have long thought to be a "hot soak" condition on my 1974 Coupe w/454 is turning out to be something more basic. The positive cable at the starter solenoid end has evidence of a prior repair (tape wrapped) and visible white corrosion within the wire strands of the cable. The smaller posts on the solenoid are loose and the solenoid is of unknown orgin. My intent is to replace the solenoid and cable.

Is there a service replacement process to replace the cable? It comes out of the battery box behind the drivers seat and is attahed to the LS driveshaft tunnel by a couple clips. It crosses over the top of the driveshaft and travels the length of the RS driveshaft tunnel under the transmission insulation blanket and is secured by four or five clips... I can't see the last one yet estimated to be at the center position. I have the other clips out... about four hours work. It appears some will be impossible to re-attach. Unless you haven't seen this, you can't imagine how difficult this is.

What perverse mind designed this? It makes me want to buy a Nova. What is the experience and best practices of others here?

Details... 1974 Coupe, 454, THM400.

As usual, I will post results for everyone's benefit. Thanks to all.

[William C.]

Re: Battery Cable Replacement (C3 Positive)

Remember to check the ground side of the system also where it attaches to the frame below the battery box. One of the problems is in this era GM used "copper clad aluminum" battery cable, (the words are printed on the outer jacket of the battery cable) and both positiva and negative connections are subject to corrosion at the junction of the cable and the terminal over the 30+ years since the car was built.

[Lee S.]

Re: Battery Cable Replacement (C3 Positive)

Thanks Bill, I should have elaborated in the first message. I replaced both negative cables this past spring... the one below the battery box and the one from the frame to the engine block. The frame to engine block cable was in particularly nasty condition. This bought some time for awhile. Increased resistance in the positive cable is now the weak link. The battery is also new.

[Jim T.]

Re: Battery Cable Replacement (C3 Positive)

Lee I have not replaced the positive battery cable on my 70 with turbo 400, but have replaced the positive battery cable on my 68 4-speed. I have experienced your frustration of disconnecting all the clips holding the positive cable. The one clip that was more difficult than the others was the one underneath the tunnel insulation at the rear of the transmission. I had to pull down the tunnel insulation to find it and working from the end of the transmission between the fiberglass tunnel and the tunnel insulation was able to complete the job. I put it all back together with the original clips holding the new cable. Having the car on my lift was helpful. Since your car is a turbo you do have a removable transmission frame crossmember. You could lower the transmission a couple inches safely using a floor jack under the crossmember for more room. Unlock the distributor cap since it will move towards the firewall. Looking forward to your completion post and how the new cable solves your no hot start problem.

[Lee S.]

Re: Battery Cable Replacement (C3 Positive)

Thanks - I thought about the transmission mount in the shower this morning. I'm glad you mentioned this.

It appears I may have to remove the RS exhaust forward of the crossmember also. I think it will be tough to get the joint apart where the pipes join at this point. I think I'll be able to get my hands in there easier if the exhaust pipe is removed. The car is on jackstands, not a hoist... not that fortunate yet. I should also say that the starter heat shield was on the car.

Its really hard to say this was hot soak. Condition just recently started. End result is different as car doesn't start hot or cold if battery is not absolute optimum charge.

[Mike E.]

Re: Battery Cable Replacement (C3 Positive)

What I like about my 62's is the lack of this sort of thing--park it on the hill, pop the clutch, and away you go. Battery cables in plain sight--cable ends mount within about 18 inches of each other on the car--one clip total.
Solid axles are simple mechanically, and I'm a simple mechanic---it's a great fit!

[Lee S.]

Re: Battery Cable Replacement (C3 Positive)

I'll think of you very fondly tonight as I struggle further.

[mike cobine]

Re: Battery Cable Replacement (C3 Positive)

What perverse mind designed this? It makes me want to buy a Nova. What is the experience and best practices of others here?

ROFL. I have said a lot of things about some of those who designed these cars I'm addicted to, and so have many others no doubt.

Basically, it is as if they tried with each year to make it impossible to service the car. Each new year brought a more fiendish plot against anyone trying to work on it.

Remember, they were built in the days when you were supposed to trade every year or every two at the most. GM was just helping you make up your mind to trade that old car that needed work.

[Lee S.]

Battery Cable Replacement (C3 Positive) UPDATE

Following the guidance suggested here, I removed the front exhaust pipes and lowered the transmission crossmember last night. This has provided much greater accessability and replacement of the cable should proceed with ease now. It appears this will also be a great time to replace the transmission tunnel insulation which is in poor condition.

BUBBA VISITS AGAIN - Last spring I overhauled the rear suspension and found the rear shocks top mounting bolts installed backwards. They had to be cutoff with a die grinder. Last night I found the same condition with the upper bolts on the transmission crossmember. Installed backwards, they hit the seat well/floor area and cannot be removed. This car had a frame off restoration (?) in about 1990 in the Chicago area. I was able to remove them with brute force. I small fiberglass repair will be necessary on the RS. Bubba, I'm gonna find you some day!

Further updates to follow on the cable installation.

[Lee S.]

Battery Cable Replacement (C3 Positive) QUESTION

Well, the old cable and transmission tunnel insulation came out last night. The new cable is in position but not tightened down. I'm going to put the starter in tonight and make sure the cable is positioned with enough slack to attach to the solenoid. The new transmission tunnel insulation will be installed soon. I made a cut in the old one that I'll use as a template to go around the shift cable and other parts. I'll take some photos of the whole process so others may benefit from this experience.

The old cable is very clearly corroded at the solenoid end, and well into the cable. This was covered by Bubba's electrical tape.

The new cable has an additional pigtail at the battery end (red, about 12" long, #10 gauge - est) with a loop connector. I guess the cable has other applications not required in my car (1974). What do I do with this? I can't leave a hot wire loose in the battery compartment. My guess is to wrap the cable with splicing tape from the battery connector past the loop. This will at least appear to be one cable.

Any thoughts?

[Harmon C.]

Re: Battery Cable Replacement (C3 Positive) QUESTI

If you plan on having your car judged get the correct cable now you don't want to do this job again. The cable you have is for a newer year.

[Dick W.]

Re: Battery Cable Replacement (C3 Positive)

"What I like about my 62's is the lack of this sort of thing--park it on the hill, pop the clutch, and away you go. Battery cables in plain sight--cable ends mount within about 18 inches of each other on the car--one clip total.
Solid axles are simple mechanically, and I'm a simple mechanic---it's a great fit!"

But Reverend, no A/C. If I remember correctly you are quite a bit taller than I am. No head room in the '62. One has to be careful getting in and out lest you bang your knee caps on the door jamb. Seats that have 1" less than no padding, etc. My first two Corvettes were 1961's so I remember all this

[Patrick H.]

Re: Battery Cable Replacement (C3 Positive) QUESTI

Agreed. You have a quasi-generic replacement cable. You need to get the correct one without that pigtail.

In addition, make sure the new tunnel insulation you purchase is not hard and stiff like cardboard. Doc Rebuild gave me a lesson in tunnel insulation at Carlisle, and it turns out there there is a stiff repro and a pliable (and therefore more correct and far easier to use) repro. You want the pliable one. I believe Paragon makes it, so that should be easy to get.

Patrick