The Reenmachine DOHC '67 Shelby Clone Convertible Progress
- Thread starter reenmachine
- Start date
SN65
Member
Hi All,reenmachine said:
This is the type of thing that I have a lot of trouble understanding.
What is the difference between the two methods? I thought that the major consideration (as far as grounds go) was to attain a good contact patch at the ground point.....
As long as you are not restricting the flow of electrons, does it really make any difference as to the path that they take to ground? I was always of the opinion that running the ground to chassis ASAP was always the best approch. Also, if this were an issue (running two full length cables from the battery) wouldn't the people supplying the battery relocation kits jump all over this? I imagine that they would love the opportunity to bump the price of their kits by offering the two cable system as an upgrade.
Bob
Route666
Active Member
I think what would matter is if you have a lot of systems connected in between the power source and your EFI components that dump into the earth or positive at varying times and with varying current - this could cause the negative to be not quite as negative as it was, or the same with the positive. I think a good analogy would be having the EFI on a four-lane freeway all by itself compared to it encountering lots of traffic on the on-ramps, thus having to slow down (or endure lower or higher voltage).
That's kind of the idea. The car would probably run fine if I just grounded the battery in the trunk, but it's not ideal, and there may be a slight improvement grounding to the engine.Route666 said:
Each of the myriad sensors on the engine has a voltage difference across it with a value that varies depending on the property it's measuring. The computer looks at all these values to make its decision about how to run the engine. For the best accuracy, all of these signals need to be compared to the exact same reference, or as close as possible to it.
For example, you know that two pieces of identical wire of different lengths will have different resistance values. Similarly, if two different sensors have to find your main ground by different paths through the car, each path will have a slightly different resistance, and the resultant sensor signals thus will have been compared to different references, changing their relationship ever so slightly.
I would guess that battery relocation kits don't address this because 99% of their customers run carbureted cars. If you look at the late-model aftermarket, however, you'll find numerous "earthing" kits designed to ground the living crap out of everything to even out the reference point.
reenmachine said:Here's what's been keeping me busy lately -- and bringing in a new crop of grey hair! I'm completely custom wiring the 4.6. I totally understand it at this point, which is the culmination of about 10 months of research...
As someone who's wired a car or two in my day I can say you have quite a job cut out for you there!
Installing a good, neat wiring job is one of the most fulfilling parts of the build. Turning that key and watching everything come to life is a fantastic feeling.
reenmachine said:
Hmmm, got me thinking, this one, not sure I fully agree. You won't get a better ground than off the body (all things being equal - no corrosion, and grounding to the body tub rather than fenders etc.) as you have so many parallel paths through the body. Every time you put a resistance in parallel you reduce the total resistance to less than the lowest resistance in the circuit:
1 1 1 1
- = - + - + - ...etc
RT R1 R2 R3
But, I think I might be a little pedantic here, 'cos a truck load of copper is going to have a pretty low resistance...
I love what you're doing, I wish I had the either the skills to do it myself, or the cash to buy (and ship, and pay the VAT & duty...) it.
Something more to add to this mix
Every time you turn off a coil or motor, the back emf dumps into the ground circuit. Depending on the size of that coil or motor the back emf can be a very large spike. Look at the sampling frequency of late model ECU's and it is understandable why so many people put grounds everywhere. A cleaner way to "fix" this is to add simple diodes into all relays, coils and motor circuits. I've scoped out some pretty complex systems and found this to be a very good way to go (but that is just my experience).
So for the layman technician who will be working on this car 5 years down the road, I aggree with reenmachine that running accessory grounds along with the full cable, positive and negative, is a good way to keep it simple.
There's an old saying I heard years ago. "if all else fails, add another ground".
With the ECU 10' away from the signals, it will be very important to keep everything as clean and neat as possible. There is little room for problems. I'm sure he is also looking carefully at isolating the stereo cables and at a minumum, twisting the wires. He's probably going to run shielded cables for all the sensors.
Of course when done, the best test is to find a nice gradual long uphill grade and throw on some "Snoop-Doggy-Poop" rap at about a billion decibels. If you make it to the top without ripping the stereo out of the dash or throwing every code in the book, You've got a good clean electrical system, and total hearing loss
Scott
Every time you turn off a coil or motor, the back emf dumps into the ground circuit. Depending on the size of that coil or motor the back emf can be a very large spike. Look at the sampling frequency of late model ECU's and it is understandable why so many people put grounds everywhere. A cleaner way to "fix" this is to add simple diodes into all relays, coils and motor circuits. I've scoped out some pretty complex systems and found this to be a very good way to go (but that is just my experience).
So for the layman technician who will be working on this car 5 years down the road, I aggree with reenmachine that running accessory grounds along with the full cable, positive and negative, is a good way to keep it simple.
There's an old saying I heard years ago. "if all else fails, add another ground".
With the ECU 10' away from the signals, it will be very important to keep everything as clean and neat as possible. There is little room for problems. I'm sure he is also looking carefully at isolating the stereo cables and at a minumum, twisting the wires. He's probably going to run shielded cables for all the sensors.
Of course when done, the best test is to find a nice gradual long uphill grade and throw on some "Snoop-Doggy-Poop" rap at about a billion decibels. If you make it to the top without ripping the stereo out of the dash or throwing every code in the book, You've got a good clean electrical system, and total hearing loss
Scott
SN65
Member
Hi Scott,66Runt said:Every time you turn off a coil or motor, the back emf dumps into the ground circuit. Depending on the size of that coil or motor the back emf can be a very large spike. Look at the sampling frequency of late model ECU's and it is understandable why so many people put grounds everywhere. A cleaner way to "fix" this is to add simple diodes into all relays, coils and motor circuits. I've scoped out some pretty complex systems and found this to be a very good way to go (but that is just my experience).
So for the layman technician who will be working on this car 5 years down the road, I aggree with reenmachine that running accessory grounds along with the full cable, positive and negative, is a good way to keep it simple.
There's an old saying I heard years ago. "if all else fails, add another ground".
With the ECU 10' away from the signals, it will be very important to keep everything as clean and neat as possible. There is little room for problems. I'm sure he is also looking carefully at isolating the stereo cables and at a minumum, twisting the wires. He's probably going to run shielded cables for all the sensors.
Of course when done, the best test is to find a nice gradual long uphill grade and throw on some "Snoop-Doggy-Poop" rap at about a billion decibels. If you make it to the top without ripping the stereo out of the dash or throwing every code in the book, You've got a good clean electrical system, and total hearing loss
Scott
Sounds like you (as well as reen) know a bit more than I in regard to electrical design and theory.
On the 03 Cobra the only "engine to chassis" ground I can find is a 1/4" strap on the drivers side. I was going to beef that up a bit. As far as everything else goes, I think I will use your "factory approved electrical testing procedure". I am afraid I will have to alter the specs somewhat in that I will be swapping out the "Snoop-Doggy-Poop rap" with some "Montrose".
Anyone remember them???
Bob
Yes about the stereo stuff, and a partial yes on the shielding. The only sensor leads that are really sensitive are the crank position and cam position sensors. They are fully shielded and carry their own solid strand ground with them within the shielding.66Runt said:
My back was getting sore bending over the engine compartment and trunk all day doing wiring, so I put it up on the lift to plumb up the fuel system. I'll probably be able to post some pics of that tonight.
I plumbed up most of the fuel system today. I just have to decide exactly where to mount the regulator, and I'm missing a couple of fittings. Plenty of other stuff to do though -- back to the electrical system...
SN65
Member
Hi TS,tomstir said:
Yep, I am going to crank out some "Rock Candy" once I get the system operational. Hope I don't blow out a window.
Bob
Be careful out there...
I've been GLUED!
I had the car up on the hoist yesterday finishing up the parking brake mechanism, and was using a big-ass Snap-On 1/2" drive ratchet to tighten a large bolt. It was kind of in an awkward position, and under max torque it popped off of the bolt head and whalloped me square in the forehead! It was like getting cracked in the head with a hammer. The edge of the ratchet gave me a nice clean gash, so I headed up to the ER to get stitched up. They glued me instead! I guess it's fairly common these days -- it's a cyanoacrylate glue pretty much just like regular super glue, but medical grade. They said it'll leave much less of a scar that way. I thought it was pretty cool.
Of course you get almost daily scrapes and bruises out in the shop, but this was the first ER trip from this car in about a year of building it, and now I'll have a cool scar to remember it by.
My dad says that's probably why Boyd has his giant beard and always wears a hat after so many years of doing this stuff...
I'll be in LA for my brother's wedding for a few days, so I'll check in with you cats next week. Cheers!
I've been GLUED!
I had the car up on the hoist yesterday finishing up the parking brake mechanism, and was using a big-ass Snap-On 1/2" drive ratchet to tighten a large bolt. It was kind of in an awkward position, and under max torque it popped off of the bolt head and whalloped me square in the forehead! It was like getting cracked in the head with a hammer. The edge of the ratchet gave me a nice clean gash, so I headed up to the ER to get stitched up. They glued me instead! I guess it's fairly common these days -- it's a cyanoacrylate glue pretty much just like regular super glue, but medical grade. They said it'll leave much less of a scar that way. I thought it was pretty cool.
Of course you get almost daily scrapes and bruises out in the shop, but this was the first ER trip from this car in about a year of building it, and now I'll have a cool scar to remember it by.
My dad says that's probably why Boyd has his giant beard and always wears a hat after so many years of doing this stuff...I'll be in LA for my brother's wedding for a few days, so I'll check in with you cats next week. Cheers!
CochinoFilipino
Founding Member
67MustangManiac
New Member
- Aug 5, 2004
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reenmachine said:
Now ya see, it's just sad that the BOTTOM of someone else's car looks better than ANY PLACE on mine!
Maniac!
70vert
New Member
Heidt's now available from Mustang Depot
http://mustangdepot.com/OnLineCatalog/Suspension/heidts-irs.htm
I have to say, these guys seem to be doing a good job of keeping abreast of the Restomod trends. I noticed that in the kit, though, they mention the forward struts coming with the kit, but where the heck are you supposed to connect them?
Reen, you mentioned you had to do a few custom things to get this to fit and be braced correctly, so it seems a little fishy that Mustang Depot is selling it as a kit that is just supposed to work. I know you added that crossbar in the front, but what else was necessary?
Obviously, I'm thinking seriously about the Heidt's, after my front brakes get sorted that is. It actually seems to be a relative bargain in IRS, (hah!) what with the brakes being included. The reason I'm fussing about it now, though, is that I'm getting floor pans and subframe connectors done and I would really like something the Heidt's forward struts will link into, a la Reenmachine. Imitation is the sincerest form of flattery! If I lived near K.A.R., I would have you guys do it!
http://mustangdepot.com/OnLineCatalog/Suspension/heidts-irs.htm
I have to say, these guys seem to be doing a good job of keeping abreast of the Restomod trends. I noticed that in the kit, though, they mention the forward struts coming with the kit, but where the heck are you supposed to connect them?
Reen, you mentioned you had to do a few custom things to get this to fit and be braced correctly, so it seems a little fishy that Mustang Depot is selling it as a kit that is just supposed to work. I know you added that crossbar in the front, but what else was necessary?
Obviously, I'm thinking seriously about the Heidt's, after my front brakes get sorted that is. It actually seems to be a relative bargain in IRS, (hah!) what with the brakes being included. The reason I'm fussing about it now, though, is that I'm getting floor pans and subframe connectors done and I would really like something the Heidt's forward struts will link into, a la Reenmachine. Imitation is the sincerest form of flattery! If I lived near K.A.R., I would have you guys do it!
It's a pretty big job to put this in a Mustang if you want everything to be absolutely bomber. There's lots of fabrication work involved and if you make the smallest mistake lining everything up you'll never be able to align it. Parts of the original car need to be modified, parts need to be fabricated and added to the car, and parts of the Heidt's kit need to be modified. It is not for the weak of constitution.
I find it interesting that they're selling it with no mention of compatibility with the Mustang. Have they put one in? mdjay?
I find it interesting that they're selling it with no mention of compatibility with the Mustang. Have they put one in? mdjay?
Don't know that I'd be interested. In fact, I don't know that I'll do another. I think I prefer the Cobra IRS.65mistress said:If they haven't then maybe you can contract with them to do the installations for them.
