Battery Box Replacement
12-26-2005, 10:41 AM
#1
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Battery Box Replacement
WEll, the While you're in there bug has hit as usual. 
The fuel tank is out as it had a nice big crack in it, and I was doing my usual clean up and inspection on everything else, and what do you know, I check the bottom of the battery box, and it's so corroded that you can stick your finger right through the bottom!
So, a leak of the tank has induced - fuel line rebuild, tank replacement, powdercoating parts and now battery box replacement!!! Damn!!!!!!!!!!
Ok, next question since I've got to replace the box, can I graft in a later model?(87 and up) I've looked at the later models and it looks like the bottom is shallower and smaller which enabled the later model cars to have the true duel exhaust that snaked behind the trasaxle. I'm assuming I'd have to go with a later model battery and make mods to the + terminal line and the - battery cable as well.
If I can remember right I think someone has done this before. If I'm wrong, I'll just go with an identical box and it will be a cut out, weld in swap.
Bottom line is I've got to make a decision while I"m waiting on parts so I can get this project rolling. Thanks.
The fuel tank is out as it had a nice big crack in it, and I was doing my usual clean up and inspection on everything else, and what do you know, I check the bottom of the battery box, and it's so corroded that you can stick your finger right through the bottom!
So, a leak of the tank has induced - fuel line rebuild, tank replacement, powdercoating parts and now battery box replacement!!! Damn!!!!!!!!!!
Ok, next question since I've got to replace the box, can I graft in a later model?(87 and up) I've looked at the later models and it looks like the bottom is shallower and smaller which enabled the later model cars to have the true duel exhaust that snaked behind the trasaxle. I'm assuming I'd have to go with a later model battery and make mods to the + terminal line and the - battery cable as well.
If I can remember right I think someone has done this before. If I'm wrong, I'll just go with an identical box and it will be a cut out, weld in swap. Bottom line is I've got to make a decision while I"m waiting on parts so I can get this project rolling. Thanks.
12-26-2005, 11:01 AM
#2
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Chuck,
You have to go with the 84 as I have it in stock
The later ones ar like rocking horse s**t to find.
Just kidding.
You have to go with the 84 as I have it in stock
The later ones ar like rocking horse s**t to find.
Just kidding.
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
12-26-2005, 02:18 PM
#4
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Carl Fausett(sp?) took his early box and cat a huge hunk off the rear to save weight. Would that approach work for you, or is yours corroded at the front?
12-26-2005, 02:26 PM
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Dave,
It's corroded mostly at the front (paper thin-pushed my finger through it) and getting bad in the back. It's only on the bottom, the rest of the box is solid.
It's corroded mostly at the front (paper thin-pushed my finger through it) and getting bad in the back. It's only on the bottom, the rest of the box is solid.
12-26-2005, 02:36 PM
#6
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Is yours welded in or bolted to the transaxle? If the former, you're in for some work regardless. If the latter, There are a number of people who have removed theirs for various reasons. I think Hacker is one, there are bound to be others. It might not be as hard as you think to find one...
12-26-2005, 02:59 PM
#7
Chuck,
Since that puppy is going under the knife...
1. If possible, use a double line -if you aren't sober yet- , thats two(2) parallel cut lines.
If available use a high speed die grinder with a very thin cutting disc. Very fast and easy to control.
High-speed Air Grinders are going for about $22.00 out the door -get rid of the shield-. Downside
is that you do need an air supply.
2. No matter what you choose to make your cut with make sure you leave enough of the original box
to lap the new piece in. You may have to notch the new piece in at the corners, notch the new
piece not the original for in metalwork the rule of thumb is; you attach to existing structure to
include the way you mount hardware.
3. If you are going to use rivets...you should be able to find some in the appropriate size (4/32 aka
#4's, or 1/8" should) with locking collars on the pins. Straight line, or, eyeball your rivet line
around the box, fit the box close to final location to make sure you won't drill into something
expensive and the fastener, both, won't chaff thru something expensive/block some other fastener
on another component and that the rivet gun, or for bolts/ self tappers (latter not recommended)
screwdriver/ratchet can fit where you need it.
4. Mark location of holes accordingly, pre-drill the replacement piece off the car, -see #5 below- line
it up and drill. If using rivets dip them in the silicone then fasten as you go.
5. Run a light bead of silicone house caulking (outdoor, door/window trim type) to the lip of either
the replacement piece or original. I recommend putting it on the correct side.
6. Ignore all of the above -except laping- if you plan on brazing or welding it in place.
7. No matter what you really need to silicone seal the lap sides -inside and out- to give you a nice
equal width, tape line finish as well as to prevent corrosion of any sort on the two long running
exposed cut surfaces -paint alone is not sufficient-.
8. Most important! With tank and batt.box out you can now clean previously unseen areas of your
sHARk. Think of it as cleaning your belly button -Inny's only- something you don't often do but while
you are in there........ why not. Check for cracks on the heat shield while you are at it.
9. Should this task frustrate you beyond normal human endurance I'll buy that OB of off you for a
couple hundred bucks - I just want the interior-.
This repair will be inspected at the next 3rd Coast for Quality Cherman Craftsmanship
Since that puppy is going under the knife...
1. If possible, use a double line -if you aren't sober yet- , thats two(2) parallel cut lines.
If available use a high speed die grinder with a very thin cutting disc. Very fast and easy to control.
High-speed Air Grinders are going for about $22.00 out the door -get rid of the shield-. Downside
is that you do need an air supply.
2. No matter what you choose to make your cut with make sure you leave enough of the original box
to lap the new piece in. You may have to notch the new piece in at the corners, notch the new
piece not the original for in metalwork the rule of thumb is; you attach to existing structure to
include the way you mount hardware.
3. If you are going to use rivets...you should be able to find some in the appropriate size (4/32 aka
#4's, or 1/8" should) with locking collars on the pins. Straight line, or, eyeball your rivet line
around the box, fit the box close to final location to make sure you won't drill into something
expensive and the fastener, both, won't chaff thru something expensive/block some other fastener
on another component and that the rivet gun, or for bolts/ self tappers (latter not recommended)
screwdriver/ratchet can fit where you need it.
4. Mark location of holes accordingly, pre-drill the replacement piece off the car, -see #5 below- line
it up and drill. If using rivets dip them in the silicone then fasten as you go.
5. Run a light bead of silicone house caulking (outdoor, door/window trim type) to the lip of either
the replacement piece or original. I recommend putting it on the correct side.
6. Ignore all of the above -except laping- if you plan on brazing or welding it in place.
7. No matter what you really need to silicone seal the lap sides -inside and out- to give you a nice
equal width, tape line finish as well as to prevent corrosion of any sort on the two long running
exposed cut surfaces -paint alone is not sufficient-.
8. Most important! With tank and batt.box out you can now clean previously unseen areas of your
sHARk. Think of it as cleaning your belly button -Inny's only- something you don't often do but while
you are in there........ why not. Check for cracks on the heat shield while you are at it.
9. Should this task frustrate you beyond normal human endurance I'll buy that OB of off you for a
couple hundred bucks - I just want the interior-.
This repair will be inspected at the next 3rd Coast for Quality Cherman Craftsmanship
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12-26-2005, 03:17 PM
#8
I'd just get a small battery to make it work inside the main area for the spare tire well. That battery box is huge and heavy.
12-27-2005, 09:56 AM
#9
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Dave,
The bolted in box stopped after your model year. So everything 79 and up is welded. I think that the 86.5 or 87s and up used a smaller box as they were able to add duel exhaust and have it snake between the box and the back of the transaxle.
John, thanks for the details, I plan on welding it into place. Roger has a box in good condition off his parts car so I may go that route (stock) or if I get a wild hair graft a later model box in so I would be able to go to the true duel setup. Sounds good in theory but just leads me down the road of more $$$$$s! BTW, I thought I'd sell her to you for $300 when I'm done, sound fair?? Find me a dead 89 and up with black sport seats and a good interior and I may take you up on your interior offer! 
Branden,
Again if I can use an 87 box, that will be the idea. I agree, that friggin battery is way too big!
The bolted in box stopped after your model year. So everything 79 and up is welded. I think that the 86.5 or 87s and up used a smaller box as they were able to add duel exhaust and have it snake between the box and the back of the transaxle.
John, thanks for the details, I plan on welding it into place. Roger has a box in good condition off his parts car so I may go that route (stock) or if I get a wild hair graft a later model box in so I would be able to go to the true duel setup. Sounds good in theory but just leads me down the road of more $$$$$s!
BTW, I thought I'd sell her to you for $300 when I'm done, sound fair?? Find me a dead 89 and up with black sport seats and a good interior and I may take you up on your interior offer! Branden,
Again if I can use an 87 box, that will be the idea. I agree, that friggin battery is way too big!
12-27-2005, 01:47 PM
#10
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Yeah, I know it was supposed to be bolted in on 78 cars only, but I figured there was a slight chance that some early 79 cars were built that way too...
12-27-2005, 03:55 PM
#11
Im my 1984 model, I cut the old box out and welded in a S4 type so that I could run a true dual exhaust. That was successful. However the heat shielding is another matter, around the battery box, no problem but the shielding for the second muffler is not so straight forward, I haven't solved that problem yet.
Cheers Greg
Cheers Greg
12-27-2005, 04:57 PM
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Greg,
I think I remember you telling me you pulled this off, but I've slept since then. Ok, does the battery box of the later cars graft directly to the area the earlier models are welded to. In other words, is the top of the box identical, and then it just tapers and is shallower? (I think I have a line on a later model box) Would I have them cut out just above were the weld is or way up by the door to the battery box? Also, is the door and floorpan area the same. Maybe I'm making this harder than it needs to be, but I want to be sure before I pull the trigger and get knee deep into the job.
Also, I'm guessing you mean the heat sheild for the pass. side muffler? Do you really need it? Do the mufflers get that much hotter than the pipes themselves. Details man, I need em!!!
Thanks!
I think I remember you telling me you pulled this off, but I've slept since then. Ok, does the battery box of the later cars graft directly to the area the earlier models are welded to. In other words, is the top of the box identical, and then it just tapers and is shallower? (I think I have a line on a later model box) Would I have them cut out just above were the weld is or way up by the door to the battery box? Also, is the door and floorpan area the same. Maybe I'm making this harder than it needs to be, but I want to be sure before I pull the trigger and get knee deep into the job.
Also, I'm guessing you mean the heat sheild for the pass. side muffler? Do you really need it? Do the mufflers get that much hotter than the pipes themselves. Details man, I need em!!!
Thanks!
12-27-2005, 11:36 PM
#13
Hey Chuck hope your going good and all the best to you in the new year, the battery box is a straight forward replacement on the model I described, I don't know about yours though if yours bolts in, I would then suspect not.
But in my case the battery box is exactly the same size at the top where it is welded in. Just go slowly and have the correct tools to remove the spots welds and you will have no trouble at all. I then miged the new box back in using plenty of anti corrosion compound to ensure no rust. Don't use a rust convertor or anything like that.
As to the exhaust the shielding that I describe that is a PITA is the muffler shieding. There is a number of problems, battery cable and other pipes, all can be solved but time consuming. If you want to know more just let me know.
Cheers Greg
But in my case the battery box is exactly the same size at the top where it is welded in. Just go slowly and have the correct tools to remove the spots welds and you will have no trouble at all. I then miged the new box back in using plenty of anti corrosion compound to ensure no rust. Don't use a rust convertor or anything like that.
As to the exhaust the shielding that I describe that is a PITA is the muffler shieding. There is a number of problems, battery cable and other pipes, all can be solved but time consuming. If you want to know more just let me know.
Cheers Greg
12-28-2005, 05:53 AM
#14
Chuck,
FWIW
Those crafty Deutchlanders put those heat shields on for a reason...
There was a crack in the shield back by the big 'bathtub rear muffler on Pattycakes that I didn't find
or notice for that matter until I tried to resolve a left rear sidelamp/marker light issue.
Light kept burning out and I thought ot was a short due to all the lamps & fuses I was replacing.
while cleaning the socket one day some of the dicolored wire crumbled away. I figured it was dirt and age. Replaced the wire and everything worked well... for a while then the problem returned.
Turned out it was a serperating seam on the rear muffler, heat was pressure forced thru the seam then a crack in the shield and onto the lamp socket holder.
IMO when we go to larger diameter exhaust pipe which run closer to the shields invariably there's going to be more heat and a significantly larger concentration of heat as the larger pipes radiate and hold more heat in a given area. While moving this might not be an issue but at idle or at/after shut down might become a problem. when I do my annual TT, TT clamp, exhaust inspection I always drop the exhaust looking for corrosion, cracks ect, and I drop the shields looking for cracks , particularly around the mount ears and points. As well as to see if a critter or two hasn't taken up residence.
Gee, I don't know if want to spend a whle $300.00 on a interior
.
FWIW
Those crafty Deutchlanders put those heat shields on for a reason...
There was a crack in the shield back by the big 'bathtub rear muffler on Pattycakes that I didn't find
or notice for that matter until I tried to resolve a left rear sidelamp/marker light issue.
Light kept burning out and I thought ot was a short due to all the lamps & fuses I was replacing.
while cleaning the socket one day some of the dicolored wire crumbled away. I figured it was dirt and age. Replaced the wire and everything worked well... for a while then the problem returned.
Turned out it was a serperating seam on the rear muffler, heat was pressure forced thru the seam then a crack in the shield and onto the lamp socket holder.
IMO when we go to larger diameter exhaust pipe which run closer to the shields invariably there's going to be more heat and a significantly larger concentration of heat as the larger pipes radiate and hold more heat in a given area. While moving this might not be an issue but at idle or at/after shut down might become a problem. when I do my annual TT, TT clamp, exhaust inspection I always drop the exhaust looking for corrosion, cracks ect, and I drop the shields looking for cracks , particularly around the mount ears and points. As well as to see if a critter or two hasn't taken up residence.
Gee, I don't know if want to spend a whle $300.00 on a interior
.
12-28-2005, 10:30 AM
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Greg,
I will Pm you later today if I can, I've got one day of work during the holidays here that I've got to take care of. Hope you are having a good holiday as well.
John, thanks for the feedback, definately something to consider. I guess if I move down the road fast enough, I may not have to worry too much!! Hope you're doing good and Maybe if you find me some sport seats, we can bring that $300 down a bit!
I will Pm you later today if I can, I've got one day of work during the holidays here that I've got to take care of. Hope you are having a good holiday as well.
John, thanks for the feedback, definately something to consider. I guess if I move down the road fast enough, I may not have to worry too much!! Hope you're doing good and Maybe if you find me some sport seats, we can bring that $300 down a bit!