The images of the 100A and 130A Denso alternators were taken at a McGrath Lexus in Chicago.

You are certainly welcome to visit your local Lexus dealer and see for yourself that both alternators connectors are the same, that pulley diameters are the same and mounting centers are the same...the only physical difference is the third mounting ear...whose mounting hole aligns with an existing front engine bolt hole....requiring you use a different bolt (stud)..and nut. From an LS430...

Denso apparently achieved improved power output by changing winding configuration and wire profile (more square and less round)

Upgrades to be found for our LS400 by looking in the LS430 parts bin.

Whether you are a pessimist or an optimistic, is of course your choice

Meanwhile, here is a link to a LS400 upgrade taken from the Lexus LS430 parts bin.

https://www.clublexus.com/forums/ls-1st-and-2nd-gen-1990-2000/802539-ls430-water-inlet-housing-in-ls400.html

 

I'm optimistic about the possibility! The Arizona heat eats batteries for breakfast. You are lucky to get 2 years out of one and they always die in the summer. I realize a higher output alternator may not solve the issue but if I can have a happier and healthier charging system by simply swapping a part I'm in!

I found the extra nut ( 9008017242 ) required on LS430 part diagrams but the alternator diagram does not show the stud. Do you happen to know the part number? This info may also help pmarr and his mechanic accomplish this...

 

So just confirming simply here ... nobody has confirmed having actually done this yet, right?

 

Lexus did it...1UZ-FE and 3UZ-FE have identical engine block externals...and component mounting points so the upgraded alternator is bolt on, plug-and-play propsition...

So to accommodate the third alternator ear, instead of using a bolt, I believe Lexus used a longer stud with threaded end (as depicted in posted image of LS 430 block) from an existing tapped hole, and capped off with a nut.

I will order these parts from Lexus and present images to the array.

I might locate a used 130A alternator from a pick and pull just to present fitment...

I have not yet changed over because I have an almost brand new (not rebuilt) 100A OEM alternator...and because I have been sorting out suppliers to produce replacement negative grounding cables...for those interested..

What I am advocating is if replacing your failed alternator then upgrade to the improved design as did Lexus.

I have been promoting Lexus options so the question of why the factory didn't do it does not arise.....and here on a Lexus forum, it still does..

Magic

 

Yes, that's right.
But there is a way if the battery is not too old. I have done many different experiments to revive those failed batteries and I made an equipment.
My home made equipment makes it possible to reduce the internal impedance of a fully discharged battery. It is a kind of a desulfator. Most of desufators use an oscillator and a switching FET but those are not quite effective for a fully discharged battery. Mine is totally different from those. I'm wondering I should start a new thread about it or not.

The ECU capacitor issue is now the biggest thread on a LS400 forum. May be I should start another interesting thread since there are many people who suffer their failed alternators and the fully discharged batteries.

 

...also consider wiring and connector age related issues such as main negative battery cable, secondary engine to chassis grounds (perhaps adding a chassis to transmission ground?), how to replace connector shells and contacts (available from Lexus) without hacking and splicing the wiring harness...

 

how to replace connector shells and contacts (available from Lexus) without hacking and splicing the wiring harness...

/\/\/\/\/\/\/\/\/\/\ THIS ! /\/\/\/\/\/\/\/\/\/\/\

 

For those who don't know about how to order the connectors:

Connector part numbers always start with 90980. The last 5 digits are molded on the connector itself, usually near the retainer clip on the back of the connector.

 

Priced the whole shebang, aftermarket Denso Alternator and P/S Pump replacement $800 and change. To do OE Parts $1550. Went with aftermarket parts on a car with 229,000 miles, which is my daughter's that I paid 2 grand for so I do not feel bad. Assuming 8-10,000 miles per year I could reasonably expect to get 6-10 years out of this repair. Needless to say TB/WP in 30-40K miles so who knows. All I know is we have a solid, reliable LS for several more years which is some piece of mind.

 

Following is a list of mounting hardware for LS430 and LS400 alternators..remember the LS430 uses improved Denso 130A with third mounting ear.. (anyone care to speculate on why the third mounting ear...my guess is improved mounting stability and noise/vibration damping...

LS430

1.) 9017910144

2a.).9017908153 ; 9017908135; 9017908203; 90179-08203; 90179-08135 nut for alternator midpoint mounting ear

2b.) 9010908298 bolt for midpoint mounting ear

3.).90119A0280 ; 9011910791

LS400

1.) 9017910144

2a.) No midpoint alternator mounting ear

2b.) No midpoint alternator mounting ear

3.) 9011910791

Same hardware P.N.s for top and bottom LS400 and LS430 alternator mounting ears.Some show no longer available, but are superseded...bolt 90109-08298 is available...

LS430 oil pump bolts..bolt #3 (90109-08298) is the special bolt with studed hex head for affixing 130A alternator third mounting ear...
This Lexus parts diagram depicts LS400 oil pump bolts...notice bolt #3 as compared to LS430 bolt does not have a stud protruding from the head...not necessary because LS400 100A alternator does not possess a third mounting ear.

 

It's interesting that an LS430 alternator fits on an LS400 with some hardware from Lexus. What I'm failing to see if the point of it all. The 100A alternator is totally suitable for an LS400. Saying the 130A is 'improved' because the engineers realized something after the LS400 isn't plausible at all to me. It's my opinion that the LS430 has a higher capacity unit because of the increased electrical draw the LS430 has over the LS400, ESPECIALLY the Ultra Luxury Package. It's my opinion that the larger capacity alternator has absolutely zero to do with engineers finding that it's better for the battery. They were making 130A alternators back then. It's just not at all required for an LS400.

Now, if you're running a large aftermarket stereo and have increased electrical draw from stock then I say this is a very worthy upgrade in that case.

 

I think it's more than the additional output. The plot of it's output indicates it has higher output at lower RPM's, which is all that really matters for us. On my stock '98 alternator when coming to a stop (low RPM's) I can see my headlights dim a bit when I hit the brakes so additional charging current can only help. Even revving the engine from idle you can see the lights change, so there is definately NOT full charging current at low RPMs.

I also wonder if using the 3rd bolt is really neccesary. Remember we're still using the stock wiring and stock fusing (and assuming stock electrical system) so the alternator should never see it's full 130A output, and associated torque on it's mounts.

 

The whole idea was hatched when running heater, defogger (A.C. compressor), fog lamps, headlamps, rear window defogger, radio...no question the alternator was not keeping up at idle or above idle tp 1,000 RPM...the heater blower RPM would drop appreciably at idle..the battery reserve was not fully covering for it.

A lot of higher amperage audiophile aftermarket alternators cheated by using smaller alternator pulleys so they would spin faster (read accelerated bearing wear and more noise) necessitating a shorter serpentine belt.

Several higher amperage alternator options did not start producing power until 800 - 850 RPM....a problem in stop and go traffic with the AC running...

(I believe the reason Toyota terminated the main negative battery cable at the A.C. compressor was to insure the magnetic clutch received full power..to increase life...aside from slight pulley bearing wear, mine has performed reliably for 18 years...)

(The 130A alternator was an improved design (winding configuration) and.... from the Toyota parts bin and otherwise met my criteria.

Thie random aftermarket stuff was not an engineered solution because it did not improve power production at low RPM

I imagine all other systems such as ignition and all onboard ECU's are deprived as well when the alternator is overtaxed...

So the investigation led to the improved LS430 alternator..

The third bolt may be profiled to fit behind the 130A alternators mounting ear vs the standard bolt head.....besides it is only a couple of dollars.

Lexus reconfigured the housing for a reason...I believe for improved mounting rigidity and vibration sound damping

 

If the housing is very similar, why even use the third bolt? Wouldn't two keep it secure enough? It's not like the alternator is going to rotate and shear either of the two bolts or stress them any more than it would on the 100A alternator.

 

I understand both sides of the 3rd bolt argument. If the 400 alt is fine with 2 shouldn't the 430 alt mount safely with 2 as well? But for less than $5, assuming the hole for the stud is there as YODA says, why WOULDN"T you go ahead and use the 3rd bolt? Piece of mind rarely comes that cheap...