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90+ Amp upgrade for L-body (How-To)

Electrical 
12K views 22 replies 10 participants last post by  GLHS0325 
#1 ·
If you are tired of removing the AC compressor and struggling to remove your factory 60/78 amp Chrysler alternator, headlights that dim when you turn on the AC, engines that surge under boost with headlights and wipers turned on and loss of performance/engine stuttering when the AC cycles in your L-body, then you might want to consider the following Nippondenso alternator and charging harness upgrade.

Why? The nippon is more powerful, more reliable, smaller, and more easily serviced, also a lot more plentiful and cheaper in the salvage yard, easier to find in good working condition, uses the same accessory belt, and is soooo much easier to R&R if needed.

In brief, all you need to do is source some parts from other Chrysler models and exchange them for your OEM L-body components. There is no cutting, fabrication, welding, or bending required for this upgrade. It will take about 1-2 hours to perform once you have all the needed parts.

Here is what you need to perform this upgrade:

1 Nippondenso alternator from any Chrysler product from this period (87-92). They come in 90, 120 and 160 amp configurations. You need one that has the same pulley on it with the same number of grooves. Some will have a pulley with more grooves, those wont fit your L-body unless you swap the pulley using a press. The wider pulley will interfere with other drive belts. The first picture below show the difference in size as well as the different arrangement of the adjusting bracket. These alternators are plentiful in the salvage yard as well as over the parts counter.

1 Non L-body alternator adjusting bracket Mopar# 4323 295. They are commonly found on anything built in the 86-89 range, I have found them most commonly on the Lancer, not so much on the Daytona. The second picture below shows this bracket, one that has been quickly refinished. They are not hard to find in the salvage yard.

1 P-body/Shadow negative charge harness set. Just find about any Dodge Shadow and pull the front charge harness off of it...connectors and all. Choose one that is in the best possible condition and that the small sensor wires are still pliable on if you have several to choose from. All you are really after is the negative portion, the cables and wires that run from the back of the alternator to the battery negative terminal. Some of the wires are factory spliced and there is no need to cut them, just grab the whole thing and swap it over to the harness you already have. The third and fourth picture below shows the differences in the gauge of the wire. It is important to use the proper gauge wire. The 60/78 amp cable is not rated to carry a 90 amp load sustained. That is important!


The process to upgrade is very straight forward:


STEP 1: Get your parts ready, clean them up as needed

Begin by disconnecting the battery terminals and removing the AC compressor if you have one. It is also a good idea to confirm the charging system is already working w/a VOM across the battery terminals w/the car running. It should read 14+ volts. Of course if you are doing this upgrade because your 60/78 amp Chrysler unit has failed, this will not be necessary.

STEP 2: Remove the old alternator and front charge harness
STEP 3: Transfer the negative portion of the 90 amp charge harness over to your 60/78 amp harness. You might find it easier to cut and splice the two green field coil wires, solder them properly and use shrink wrap or a quality electrical tape (3M is good stuff). One wire will need to be removed from the plastic end connector and moved to the old harness connector. On the plastic end connector, use a small flat tool to remove the needed wire so that you can slip the same wire in from the 90 amp. Tape up the upgraded charge harness with old school electrical friction tape, self fusing 'Tommy Tape' or (last choice) good quality electrical tape.
STEP 4: Attach the charge harness to the new/used Nippondenso 90+ amp alternator
STEP 5: Attach the new adjusting strap to the alternator and finger tighten the pinch bolt, leave it just loose enough to be able to adjust it once installed. Run the adjusting bolt down to the point where it is in approximately the 1/2 way up/down position.
STEP 6: install the alternator, put the large pivot bolt in place and tighten it down.
STEP 7: Crawl under the car and attach the lower adjusting bracket bolt to the water pump housing, tighten it.
STEP 8: Install the accessory belt, adjust it and tighten the adjusting bracket pinch bolt.
STEP 9:(optional) Reinstal AC compressor if you still have one
STEP 10: Attach the negative battery cable to the battery and tighten
STEP 11: Start the car to test and confirm you have a charge, a VOM across the battery w/engine running should show 14+ volts.
 

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#2 ·
There are two brackets pictured here:
http://www.turbododge.com/forums/at...78-90-amp-upgrade-l-body-how-alt-update-5.jpg

The one on the left is the one you are looking for and that is documented in the how to. The one on the right is the one that came on most L-body cars. The one in the how to, that is pictured in this link, puts the adjuster right where it should have been to begin with and you don't have to notch the radiator support like with the other non-L-body brackets that were used on the Nippondenso alt. I run this bracket on all my L-body cars and it's great. I even have an extra one if you are having trouble finding the correct one.
 
#4 · (Edited)
My 85 T1 Charger, both my 86 GLHS Omnis and my 87 GLHS Charger all had the original huge 60-78 amp Cryco alternators and the crappy, can't see the adjuster bolt head three piece adjusters. I'm sure that they were all original cars as far as the alternators goes. As I've said, the bracket I use is the one piece unit available from 84 through 85, 86 and 87 and was installed on 2.2 cars with the 90-100 amp alternators, Bosh, but they also fit the nippondenso 90 or 120. I've seen countless other Omnis and Chargers from 86 down with the same crappy three piece setup in the salvage yards. In 87 a better crappy three piece was introduced, it was apparently also used on the Cryco alternator units. I'm not sure when the change over actually was...

2.2 cars from 88-92 got the new 2 piece unit with the large rubber hockey puck absorber that cracks up. It mounts the Bosh 90-100 alternator, the large Cryco unit doesn't seem to be used after 87.

The 2 piece that bolts to the water pump housing and has a separate piece with a large rubber insert on it, I've seen that a lot and used on many cars in the yard. It WONT fit an L-body unless you notch the front radiator support, but it does help bring the adjusting nut up where it can actually be seen.

The bracket I use is typically found on Lancers and Acclaims and LeBarons, Daytonas, etc...with the 90-100 amp nippondenso. I've never found one on a Daytona or a Shadow though in the yards. It's always been a Lancer or Acclaim.

This is the one that works best and fits the nippon on an L-body, and it brings the belt tension adjuster bult head right up where it can be seen and easily turned with a 13mm socket and a longer extension, about 18"+. It also leaves plenty of clearance for the radiator support. It's the best fit with the nippon on an L-body:


The years available and other brackets look like this:

 
#5 ·
Here is a parts list of doing this same conversion using only Chrysler parts and the larger Bosch style alternator.

Alt. #5233718
spacer between horns #4273289
bolt #6501659
bolt #6501595
washer #6100878

Bracket to water pump#4323295
bolt #6500775
wire harness #4331112

Alt belt gates poly z belt 410, but use 405 or 400

I give credit for this list to Mark A Thies, thanks for sharing.
 
#6 ·
Great info.
It seems the 1990 L-bodies have the NipponDenso alternator from the factory. I believe my Horizon probably has the 90amp.
I wonder if the 120amp would help at idle. It seems my lights dim and my blower slows a bit.
Would this be a direct swap 90A- 120A with no ill effects?
Also, maybe some of the 90 L-body parts could be used for the Denso swap?
 
#7 ·
I had this mod done to GLHS #0956 and I have to say it's THE Most important non-performance upgrade you can do.
Everything worked better. A/C, Lights, Defroster, everything!
A very inexpensive upgrade and servicing the Alt. afterward is a ton easier.
I Would suggest not going past the 90A spec because I'm not sure the wiring harness's inside the car can handle the 120A current.
Yes, the ground wire and the positive wire from Alternator to Battery is fine, and the green field regulator wires aren't affected, but the body harness, both in the dash and in the engine bay might not handle 120 amps.
That 90A. Alt. was what they should have put in from the factory from the beginning.
 
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#10 ·
Got mine upgrade installed later night. As mentioned, very easy install. To me the hardest part was wrangling the old huge alternator out. I was not sure if any of the a/c bracket bolts went into water jackets so that was in the way. If that could have came off it would have been easier.

Only issue I have is now now hazard lights. I checked security of the electrical connector off tha battery, but that was as far as I got before I went to bed. I am sure its simple as it worked before the upgrade. Most likely an electrical conne tor jist not fully seated.
 
#11 ·
That hazard light connection is the one I repaired.
It's behind the battery and has a single orange wire that comes out of the positive battery harness.
Mine was hanging on by a few threads.
I clipped it, cleaned the terminal, and soldered it back on.
Credit to 4 L-bodies for the heads up on where that wire goes.
 
#13 ·
Got it all installed and wondered if it was ok to cut off the new P-body alternator harness mounting tab that is circled in red? It appears it is only for mounting the harness to the alternator and nothing to do with the operation.

I ask as you can see in the photo, the two mounting tabs for the harness to alternator do not sign up with the mounting studs. The left mounting tab lines up along with the two mounting tabs in the center, but not the far right one. It also appears that the far left one was actually part of the system (metal exposed under the nut) so cutting that was not an option. Anyhow, this was how I installed it and it all works, just wondered if I could clean that up a little by cutting that far right ear off.

FWIW this is a new AC Delco Alternator.

BTW, I have read where people recommended replacing the alternator mount bushings with poly bushings. Anyone have a source or part number for the poly bushing?

Thanks!

Automotive tire Motor vehicle Gas Auto part Coil
 
#15 ·
Got it all installed and wondered if it was ok to cut off the new P-body alternator harness mounting tab that is circled in red? It appears it is only for mounting the harness to the alternator and nothing to do with the operation.

I ask as you can see in the photo, the two mounting tabs for the harness to alternator do not sign up with the mounting studs. The left mounting tab lines up along with the two mounting tabs in the center, but not the far right one. It also appears that the far left one was actually part of the system (metal exposed under the nut) so cutting that was not an option. Anyhow, this was how I installed it and it all works, just wondered if I could clean that up a little by cutting that far right ear off.

FWIW this is a new AC Delco Alternator.

BTW, I have read where people recommended replacing the alternator mount bushings with poly bushings. Anyone have a source or part number for the poly bushing?

Thanks!
View attachment 275141
Rather than cutting it off, why don't you just make a small tab of metal linking the two together? That way the harness still has its structural support from this post. That's what I would do anyway.
With the poly bushings from Johnny make sure you order the correct ones for your alternator bracket. They're two different sized bushings used based on the year of your bracket. IIRC, the early bushings got the larger OD bushing, while the newer brackets used a smaller bushing.
 
#16 ·
A word of caution when swapping to 90 amp alternators, the fusible link will blow if you ever get to a situation where the alternator goes to full charge.
I left the lights on for a while in my old GLHS and then got it started and headed out in the rain at night with the AC on and it trying to charge the battery. Cooked the fusible link and I got stuck in Philadelphia.
 
#17 ·
A word of caution when swapping to 90 amp alternators, the fusible link will blow if you ever get to a situation where the alternator goes to full charge.
I left the lights on for a while in my old GLHS and then got it started and headed out in the rain at night with the AC on and it trying to charge the battery. Cooked the fusible link and I got stuck in Philadelphia.
Which fusible link blew?
 
#20 ·
Many, many years ago, I had Cliff Ramsdell do this mod.
It's one of the best things you can for an L-body.
Everything electrical worked better after the swap.
 
#23 ·
A current meter clamped on it with all accessories running will tell what the current draw is.
The question is, what accessories are fed by that fusible link.
If we know which, we can check all fuses in the drivers side panel and get the total current draw.
 
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