[Sirrotica]

Originally Posted by Geoff

Nope.
You are assuming that the frame resistance is only 7 times the CSA of a copper grd cable, when in reality, the CSA is much more than 7 times. If the frame was 14 times the CSA of an equivalent copper cable. the frame resistance would be half that of a copper cable, with a corresponding reduction in the voltage drop [ loss ]. The connecting lugs are nearly all copper, but tin plated. There are numerous resistance points in the starter cct, both on the neg & pos side which add to the total res in the cct.
If you had a copper cable for the grd from the battery in the trunk, it will heat up from the current draw during cranking. Because copper is a good conductor of heat, it heats up very quickly...& it's resistance increases....& causes more voltage drop. Using the steel frame as the grd, it heats up much more slowly because it is a poorer heat conductor than copper & will have less voltage drop than the copper cable. It is the sum of all the voltage drops in the cct that reduces the final voltage that the starter sees.

You sound like every engineer I've ever dealt with, you quote books written by other engineers. You think every application has ideal conditions at all times. When their fixes don't work, they blame something else.

I've done the exact same thing with a 1973 455 T/A, and tried every way I could to use the frame for a ground. I welded the ground bolt to the trunk floor and used heavy ground straps to the engine. When hot, the engine did the exact same thing he describes. What solved the problem? Running a dedicated ground cable to the bellhousing bolt, never a problem after that dedicated ground was connected. Please explain what the books say about that phenomenon.

In real world cases most starter motor powered accessories on a vehicle have a dedicated ground to the accessory from the battery. Why would someone do that if they simply could use the body/frame for half the path of current? Does your book cover that?

He already has the system you're touting, and has problems with it, but you say that he can't have. If you thinks steel is such a wonderful conductor, you obviously have never had to deal with a melted shift cable when someone forgot to re install the ground and tried to crank the starter. It gets red hot and melts the jacket into a burned mess. I'm sure you have a technical response to cover that situation too.

When it comes to real world problems the books aren't always correct in real world applications. Problems such as poor welds, corroded welds, rust, aren't taken into the equation. Maybe you've never looked at GM frame with the body removed. The welds look like chicken scratch many times, and many times over years they actually fail at welded joints. Spot welds use very little area and are susceptible to hidden corrosion. You're assuming all these joints will carry the electric load needed to crank a hot engine.

While you're on the topic of heated copper not carrying the needed electric load, the starter pinned in between the exhaust, and engine block does build resistance the more it's heated. You know what isn't getting heated? The dedicated ground cable, it's likely around ambient air temperature.

As I said the OP can choose to deal with resolving his problem whichever way he chooses. With a dedicated ground he will be sure that the system has full volts and amps with only 2 connections. The cars and trucks I've used dedicated ground cable to wire starter motors or starter motor powered accessories on are still functioning decades later. He has the frame ground system, and it's failing.

I'll use real world experience Geoff, and you can discuss theory, have a nice day.

[Geoff]

Sirrotica,
I am quoting from real world experience, started when I rebuilt my first engine in 1965.......& am still doing it today.
Anybody who doesn't read books to enhance their knowledge base is a fool.
I studied electirical engineering for a total of 6 yrears at a technical college.

Getting back to the frame issue.

Using the frame for grd return is a good idea, has lower resistance PROVIDED the cable connections at each end are clean & have good surface area contact.

Here is something else not mentioned. Starter cable is made of stranded copper wire. Many strands. There is an air gap between each strand. I couldn't find any battery cable for this comparison, so I used domestic power cable. It was stranded, 7 strands; I stripped the insulation off & measured the od with a micrometer: 0.102". Measured the OD of a strand, calculated the area & multiplied by 7. Combined area came to 0.073". A big drop from 102. The same principle applies to batt cable. you might strip the insulation & measure it at 5/16". But it would have the SAME resistrance as a piece of solid copper of a much smaller OD. Steel frame is solid, no air gaps, whsat you see is what you get....

[Sirrotica]

Originally Posted by Geoff

Sirrotica,
I am quoting from real world experience, started when I rebuilt my first engine in 1965.......& am still doing it today.
Anybody who doesn't read books to enhance their knowledge base is a fool.
I studied electirical engineering for a total of 6 yrears at a technical college.

Getting back to the frame issue.

Using the frame for grd return is a good idea, has lower resistance PROVIDED the cable connections at each end are clean & have good surface area contact.

Here is something else not mentioned. Starter cable is made of stranded copper wire. Many strands. There is an air gap between each strand. I couldn't find any battery cable for this comparison, so I used domestic power cable. It was stranded, 7 strands; I stripped the insulation off & measured the od with a micrometer: 0.102". Measured the OD of a strand, calculated the area & multiplied by 7. Combined area came to 0.073". A big drop from 102. The same principle applies to batt cable. you might strip the insulation & measure it at 5/16". But it would have the SAME resistrance as a piece of solid copper of a much smaller OD. Steel frame is solid, no air gaps, whsat you see is what you get....

Spoken like a true engineer, how did I predict that was your background? Simply by your attitude. I bet you love Lucas electrical systems too. The Brits do have a way to make wiring in an automobile as frustrating as it could possibly be.

There's a joke that goes along with Lucas electrical systems. Why do the British drink warm beer? Because they have Lucas refrigerators...............LOL

As I said previously you want to make something simple hard, and you ASSUME it's going to work out in real life just the way it's laid out in a classroom, or in a technical manual.

I went round and round with an engineer about an overheating 4-53 Detroit, did all his suggestions, and listened to his calculations. I told him my opinion was the transmission cooler in the radiator was overcoming the heat rejection ability of the radiator, causing the overheating of the engine coolant. I suggested an auxiliary transmission cooler. I got the same answer you gave me "NOPE". A year later after installing the largest custom made radiator that would physically fit in the machine, reversing the fan pitch, ruining the rings in the engine from continual overheating, and having to have the engine rebuilt under warranty, they tried an auxiliary transmission cooler, and it solved the overheating problem, the first thing I suggested to the engineer a year earlier. By this time the customer was disgusted, bought another machine that didn't overheat and the Gradall company lost their ass in wasted money because their engineer said on paper. "it can't overheat".

We have different weather in the US than you have, we have a lot of corrosion problems with wiring and electrical systems, the OP said that 20 some years ago the car worked with a frame ground, but now it doesn't. Your answer was maybe his engine is to tight, really that's your summation of his problem, and how he should solve it?

Believe me when I tell you that I tried your way in my own car, and until I ran a dedicated ground the engine would spin slowly when everything is heat soaked. It didn't work for me, and there have been numerous people on this board that have had the same problem when relocating a battery to the rear.

I did some due diligence about remote batteries, yes it required reading so you can retract your comment about reading.

Seems there are people split roughly 50/50 about using frames versus dedicated grounds. Some interesting facts that I found, that even though a frame/body ground will work without a dedicated ground, 2 drawbacks show up. The motor components have a reduced life with frame grounds, and there is electronic interference with onboard electronics. ECMs and stereo systems were among the most mentioned systems not getting along with frame grounds with remote batteries. While some people were able to get adequate function from a frame ground, the motors ran hotter, and gave up sooner than with a dedicated ground.

One thing you mentioned previously was tinning all the connection points. You intend to get under the car and tin each connection point where the cables attach to the frame, you must have way more time to screw with an electrical system than most people do. Would you be doing this to prove your frame grounds work. or just to save $50 on buying a ground cable?

Electric winch manufacturers used to ground their units through the winch cases, but due to the high amp draw stopped using a frame ground in favor of a dedicated ground cable. Warn was one of the manufactures that now supply's ground cables to reach the battery terminals, before they just supplied ground straps. An electric recovery winch also draws huge amounts of current, in case you're not familiar with them. The winches draw is likely equivalent to a heat soaked Pontiac starter. The winch draw is around 450 amps on average loaded heavily.

To sum it all up you can make all your tinned connections and screw with short ground straps connected to the frame, or spend $50 for some cable for a dedicated ground with 2 connections, and extend the starter motor life. You'll also be safeguarding any electronics that may not play well with frame ground connections. It's the OPs choice how he'd like to attack and solve his problem.

I suspect you'll have a laundry list tomorrow of why the frame ground is superior, engineers have a lot of pride and tenacity, but I've said my peace.

I'm going to get some sleep Geoff, it's 2:30 AM in Ohio.

[Scarebird]

Both recent builds I have done were trunk batteries.

First was a Trans Am with a LS3, had a separate ground cable and large battery - no issues,

Second was the Lemans, L84 (Gen V 5.3). Smaller primary cable and battery, with no ground cable running full length. No starting issues.

Both had heat shields fabricated as experience with Pontiac and Olds V8's showed this as a must when hot. Both have engine, frame and body grounded at every opportunity.

I think the asbestos is causing more issues than solving.

[Jimbobeast]

"or spend $50 for some cable for a dedicated ground"

00 cable is $6.50 per foot.

[johnta1]

Inflation!



So around $60/$75 now.
(in a couple weeks probably double that)

[Sirrotica]

As far as shielding, I've never used a insulated type shield. I've used a factory style tin, or just made one out of a piece of tin with a 90 degree bend and secured it to the outer starter bolt, either work in my experience.

I would guess the insulation would hold heat in as well as shield it. With a tin shield the air can still carry away some heat as well as shield the motor from the exhaust radiant heat.

[Sirrotica]

Originally Posted by Jimbobeast

"or spend $50 for some cable for a dedicated ground"

00 cable is $6.50 per foot.

I haven't priced it in awhile, but you're correct it has nearly doubled.

I believe I used #2 when I ran mine, but the car was sold about 6 years ago, so I can't verify what size I used. You might want to look at used welding cables through Marketplace on a ground the insulation having some nicks is irrelevant. Sometimes people sell welding cable on there pretty reasonably. Inoperative stick welder would be another possibility to find some bargain leads.

I've also heard of people buying 20 ft HD jumper cables, and cutting the clamps off, might save some money there.

Geoff is adamant that steel is best, I guess 1 inch rebar would be a whole lot cheaper................. Tough to bend though.

I'm thinking that next set of jumper cables I buy should be solid steel wire rope, like a cable excavator uses, instead of copper wire.

[HWYSTR455]

Not all battery cables are created the same, and some can perform less than another even among the same gauge.

Age also effects stranded cable, it just won't last forever, and the longer the run, the shorter the life span.

Use SGT or SGX cable for batteries and you will avoid a lot of that.

Welding cable is easier to run, easier to bend, but it won't last as long as SGT or SGX cable. SGX cable has near the same flexibility as welding cable but will last longer.

There's a resistance difference too. In general, you can use one or two sizes smaller SGT/SGX cable as compared to welding cable. (Depending on brand and quality).

SGT/SGX is a standard, 'welding' cable needs to be EPDM to equal SGT/SGX (nearly).

I've made my own battery wires for like 20+ years, remember to use quality connectors, it makes a big difference.

I don't use the typical clamp-style battery connectors anymore, only use ring/eyelet ends on cables. You can buy marine clamp-style if you want, makes it easier to swap out the ends and not have to muck with the cables. Otherwise, just use batteries that have marine type posts or side posts.

When doing grounds to a frame, use a thread-sert or riv-nuts. They crush to the frame and make a solid contact the entire circumference. It helps seal out moisture too. Star washers suffer from not making a full/good contact.

.

[Jimbobeast]

Originally Posted by gto4ben

Which mini starter are you using?
I installed a Jegs 1.4kW (~1.9hp) rated denso style starter for my 455 and it struggles when warm I suspect it may need need new solenoid contacts after 14 years of use but it wasn't that great when new. I'm considering getting a 2kW (~2.7hp) upgrade in the same style but would like to know your type first.

I have an IMI hi-torque mini starter rated at 1.2kw that is 20 years old. An upgrade to a 2.0 kw seems wise.

[Jimbobeast]

OK, first of all thank you to everyone for giving sound advice, and probably everyone is at least partially correct.
Let's remember that this battery system was installed in 1997. That's 28 years ago for the math challenged among us. No doubt corrosion has set in and a cleaning renewal of all contact points (pos and ground)seems the first order of business. I also have a battery disconnect switch in the trunk (helps on a vehicle that is not driven everyday) but this is undoubtedly another source of resistance and power loss. I will clean this as well and if no improvement, try removing it from the circuit.
The pos and ground cables all look fairly clean, but again, more that a quarter century has passed. If no improvement, a metal heat shield will replace the asbestos blanket currently in place. Following that a new 2.0kw starter will replace the old 1.2kw IMI mini-starter.
And finally, if all the above do not correct the hot start problem, I will run a dedicated ground to the bellhousing.
Does this sound like a logical, problem directed course of action?
I took photos today but they have not yet uploaded from my phone.

[Shiny]

I think you are wise to not assume the cause for your symptoms and even wiser to revisit the basics (clean all the connections).

The VAST majority of electrical failures are connection failures.

You spelled it out well - corrosion is difficult to prevent. Even a well-clamped connection can loosen up from corrosion and thermal cycling. Connecting to/between highly corrosive materials (steel, zinc, tin are examples) will be more likely to fail than clamped joints between copper, nickel, and noble metals.

The best approach to solving any problem is to define it. If it were me, I'd be measuring voltage drops along the circuit before spending money on new parts...

For example, measure the voltage across that disconnect switch while cranking the starter so you can make an informed decision.

[HWYSTR455]

Run the ground to the frame directly across from the run to the ENGINE. Or visa-versa. Leave the existing batt to frame in place, and at same connection point make the run to the front.

Paint on the bellhousing-block etc may be a drain point.

I think there's a combo of issues going on, age of parts/wires/etc. Inspect everything front to back/back to front. Wouldn't hurt too much to redo the whole thing.

Wirebarn.com runs sales all the time on wire at very reasonable prices.

The eyelets are what they are, copper/tin, at $6-$8 a pop, it's worth it for as long as it lasts. The materials are 85% of the cost.

$25 for a decent battery terminal crimper, should have one in your toolbox anyway.

https://www.amazon.com/IWISS-Termina...1zcF9hdGY&th=1

SGX 2awg is plenty for the run front to back with quality wire. 10 feet is less than $40.

https://www.wirebarn.com/2-AWG-SGX-S...ED-_p_610.html

Eyelet, good, thick adhesive shrink tubing and you are good.

Do it right, do it once. You can spend more $ and time by chopping away at a piece at a time, just bite the bullet and cut to the chase. Then you will KNOW it's right and not have to worry about it.

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[HWYSTR455]

Riv-nut tool kit:

https://www.amazon.com/HARDELL-Metri...0&sr=8-10&th=1


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[Geoff]

Sirrotica,
I am not an engineer & never claimed to be one.....
Because a person has an intimate understanding of how something works....does not mean they are an engineer. It just means they understand the problems & the fixes...

[Sirrotica]

Originally Posted by Geoff

Sirrotica,
I am not an engineer & never claimed to be one.....
Because a person has an intimate understanding of how something works....does not mean they are an engineer. It just means they understand the problems & the fixes...

I'm well aware of what an engineer is, and how they interact with people that don't have a degree. Very dismissive of what anyone says that doesn't agree with their analysis of a problem.

The OP has made his decision, so he took the advisements given, and deduced what fits his situation. No one can ask any more than that...........hope the facts stated, help him fix his situation long term.

[Jimbobeast]

HWYSTR455, I don't understand this:
Run the ground to the frame directly across from the run to the ENGINE. Or visa-versa. Leave the existing batt to frame in place, and at same connection point make the run to the front.

[HWYSTR455]

Originally Posted by Jimbobeast

HWYSTR455, I don't understand this:
Run the ground to the frame directly across from the run to the ENGINE. Or visa-versa. Leave the existing batt to frame in place, and at same connection point make the run to the front.

I was suggesting to double up on the ground. Batt is trunk is grounded to frame back there, correct? Connect a dedicated ground wire to the same point in the trunk and run it forward to another ground point on the frame close to the engine. Then from that point run it to the engine block.

But, if you're going to go over the entire circuit, you can try using riv-nuts at those two points first, and just replace the cables. That would save the money of the ground cable run from front to back.


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[HWYSTR455]

Here is a pic of my batt-frame-block ground point. It has a riv-nut in the frame.

My batt is in the front, but the principle for the circuit for a batt in trunk is the same.



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[HWYSTR455]

I have a high amp ALT, so at the block junction I run a ground to the case of the ALT as well.



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