Has anyone rebuilt an NSX Alternator?

Seems like a bearing is going and I'm getting this whirring noise. I see where you can buy replacement bearings from Honda but has anyone done this themselves? I've looked and don't see any mention. Thanks in advance.

BATMANs said:

https://www.google.com/search?q=reb...j0&sourceid=chrome&espv=210&es_sm=93&ie=UTF-8

Click to expand...

Thanks BATMANs but I meant has anyone on Prime done this? I was hoping I could do this myself.

just buy another one. I bought a newly rebuilt one off of ebay for around 100-130 shipped. Worked great for the last two years.

Valhalla said:

Thanks BATMANs but I meant has anyone on Prime done this? I was hoping I could do this myself.

Click to expand...

alternators are really not special. certainly nothing for the NSX.

Years ago when I had the FD I had the alternator rebuilt (didn't need to but wanted to double the power output for stereo system) and had the housing powder coated while it was apart.

Yeah I know it's not that expensive to just replace. I have a used one but just thought I could replace the bearings myself. Just trying not to add to the landfills. And I do enjoy working on my car. I will probably polish what ever alternator I do stick back in the car.

Hi, Valhalla.
Please refer to the following link for some of the photos that I took while doing this.

• ACG, alternator OH

After the software update on the NSXCB site, the photo size and layout changed but I hope you can see them.

As others mentioned, nothing special and probably easier (or possibly even cheaper if you are going to replace other parts at the same time) to get hold of re-manufactured one but since you have the spare one, why not try it....

Good luck.

Kaz

Thanks kaz, I'll check them out when I get home.

Alright, making progress. Got this from Kaz;

Re: Alternator repair

Hi, JC.

Both bearings are pressed in but if you apply the force evenly/parallel, the one close to the brush will come out together with the rotor shaft.

It’s fairly tight fit around the rotor shaft so you need to slowly separate the two housings.
Just use plastic hammer to create tiny gap between the two and use it as a leverage point to evenly widen the gap and in parallel.

Once they are separated, you may need miniature puller but you can create your own method if you have thin craw on the universal puller or similar device and if you can pull it in parallel without scratching the rotor.

The bearing behind the pulley is held at the housing by the bearing cover disc.
If you pull the rotor, the shaft will slide out after removing the pulley.
You can punch out this bearing once the rotor is out.

On installation, you may struggle to press in the large bearing.
Keep the bearing away from the housing and just use the heater gun to warm the housing up.
The bearing should slide in now.

There are several different methods in overhauling the ACG so you may find it different when you overhaul your ACG but pretty much all of the ACG will follow the same procedure especially if it is from Denso.

Kaz

So I now have the alternator apart. I used a small puller for battery cables and was able to free the back bearing. Once separated I was able to punch the front bearing out. Will pull the back bearing with a bigger puller tomorrow. Clean everything up, polish, grease and install the bearings and I should be ready to reinstall. I love this forum. Thanks Kaz.

Job is finished and the alternator never looked better (or cleaner). It felt good to do it but I certainly understand why someone would pay the ~$125 for a replacement. Not too hard once you have the proper tools but it was time consuming.

Valhalla said:

Alright, making progress. Got this from Kaz;

Re: Alternator repair

Hi, JC.

Both bearings are pressed in but if you apply the force evenly/parallel, the one close to the brush will come out together with the rotor shaft.

It’s fairly tight fit around the rotor shaft so you need to slowly separate the two housings.
Just use plastic hammer to create tiny gap between the two and use it as a leverage point to evenly widen the gap and in parallel.

Once they are separated, you may need miniature puller but you can create your own method if you have thin craw on the universal puller or similar device and if you can pull it in parallel without scratching the rotor.

The bearing behind the pulley is held at the housing by the bearing cover disc.
If you pull the rotor, the shaft will slide out after removing the pulley.
You can punch out this bearing once the rotor is out.

On installation, you may struggle to press in the large bearing.
Keep the bearing away from the housing and just use the heater gun to warm the housing up.
The bearing should slide in now.

There are several different methods in overhauling the ACG so you may find it different when you overhaul your ACG but pretty much all of the ACG will follow the same procedure especially if it is from Denso.

Kaz

So I now have the alternator apart. I used a small puller for battery cables and was able to free the back bearing. Once separated I was able to punch the front bearing out. Will pull the back bearing with a bigger puller tomorrow. Clean everything up, polish, grease and install the bearings and I should be ready to reinstall. I love this forum. Thanks Kaz.

Job is finished and the alternator never looked better (or cleaner). It felt good to do it but I certainly understand why someone would pay the ~$125 for a replacement. Not too hard once you have the proper tools but it was time consuming.

Click to expand...

Maybe a dumb question, but how did you tighten the alternator pulley nut? The wisdom of the internets says to hit it a few times with an impact gun but this horrifies me.

This was a long time ago. i think I tightened it as much as i could while off the car. Then when I installed it back on the car with belt, the belt gave enough resistance that I was able to finish the tightening with a touch of Loctite to make sure it wasn't going anywhere. That worked.

My alt is whining...not sure what is going on, so looking for parts, found this:

https://www.maniacelectricmotors.com/alternator-repair-for-1991-1994-acura-nsx.html


has parts interchange, quick paste
Alternator Denso 100211-6190

Bearing WBDb(10-2021-4) 15mm ID x 35mm OD x 13mm W - 15x35x13 53514
Bearing WBD 17x52x16mm for Denso Alternators 949100-3330, -4370, -5010 -55222 55222

Brush Holder w/Brushes for Nippondenso Denso IR/IF Alternators 021620-2720 27370-42010 - 74909203 74909203
Brushes Nippondenso (2 Pack) 4.8-5mm Tall x 7mm Wide x 15/14mm Long x 48mm Long Lead - 7390901 7390901
110A Rectifier, 8 Diodes, Replacing Denso 021580-3750, 021580-3990, 021580-4040, 021580-4100, 021580-4430 - 77904015 77904015

(Armature) Denso Alternators 12 Volt, 100-125 Amp, 6.1" / 155mm L - 7090655 7090655
Stator for Nippondenso Alternator OD 130mm / 5.118in - 72908503 72908503
Rotor Slip Ring for Denso Alternators - 7190904a 7190904a

Alternator NSX (101211-7570)
120A Rectifier Diode Assembly Lexus LS400 SC400 GS400 - 77904016 77904016

drew said:

My alt is whining...not sure what is going on, so looking for parts, found this:

https://www.maniacelectricmotors.com/alternator-repair-for-1991-1994-acura-nsx.html


has parts interchange, quick paste
Alternator Denso 100211-6190

Bearing (10-2021-4) 15mm ID x 35mm OD x 13mm W - 53514 53514
Bearing WBD 17x52x16mm for Denso Alternators Ref 949100-3330, -4370, -5010 -55222 55222

Brush Holder w/Brushes for Nippondenso Denso IR/IF Alternators 021620-2720 27370-42010 - 74909203 74909203
Brushes Nippondenso (2 Pack) 4.8-5mm Tall x 7mm Wide x 15/14mm Long x 48mm Long Lead - 7390901 7390901
110A Rectifier, 8 Diodes, Replacing Denso 021580-3750, 021580-3990, 021580-4040, 021580-4100, 021580-4430 - 77904015 77904015


(Armature) Denso Alternators 12 Volt, 100-125 Amp, 6.1" / 155mm L - 7090655 7090655
Stator for Nippondenso Alternator OD 130mm / 5.118in - 72908503 72908503
Rotor Slip Ring for Denso Alternators - 7190904a 7190904a

Alternator NSX (101211-7570)
120A Rectifier Diode Assembly Lexus LS400 SC400 GS400 - 77904016 77904016

Click to expand...

My '91 also whining and has recently gotten even worse pretty sure the bearings are probably shot car has about 160kms or about 90k miles on it. I cannot seem to find the Denso Reman 210-0225 not sure if its discontinued I checked here seems to be unavailable at the moment Denso 210-0225.

I would be interested in rebuilding mine if I can source the correct parts and find the correct method to remove the bearings etc. Kaz gives some good information on DIY

How did you make out with yours did you manage to rebuild it?

from my alternator journey 2 years ago there were no easy new replacements, I got a very low mileage example from a friend.
I did learn that most regions have a local rebuild small business that your dealer may know of...

Still on the project list. All the bearings were available on eBay for nominal costs.

My alternator failed to charge the battery and I had a local place rebuild mine, it ended up being around 100 or 125 I believe

My alternator bearing is singing away. I ordered a rebuilt which supposedly fits, but it did not. I have ordered the bearings and plan to rebuild myself.
Paul

JPS Europa said:

My alternator bearing is singing away. I ordered a rebuilt which supposedly fits, but it did not. I have ordered the bearings and plan to rebuild myself.
Paul

Click to expand...

Let us know how it goes!

Most of the alternator parts are still available from Honda Japan.

All done. Easy peasy...I do have a press and all kinds of pullers though.
Paul

To replace bearings: just need a small 2-jaw puller to get the small bearing side apart. The puller gracefully separates the casing halves.

I tried to use hand tools to remove the pulley and failed. The shaft hex and nut are difficult to get access too. So I used a impact gun and the nut loosened without issue. I also used the impact wrench to tighen the nut, so hopefully I didn't make more difficult for my future self.

I was trying to fix a whine, the existing bearings felt good, but went for the bearing change because I had them. Didn't fix, but everything is much cleaner now and the amount of carbon from the brushes was remarkable. If you are going to take apart the alternator, you might as well replace the brushes too.

Turns out the rectifier was no good, see attached picture. Note the bubbling of the epoxy paint on the right unit, this is the bad whining unit.

There are some NOS units on eBay for a few hundred dollars and AliExpress has some knockoffs (now OEM?) for a few dozen dollars.

The latest version of the rectifier assembly 31127-PR7-A02 is NLA. This p/n has no interchange references.

The previous version 31127-PR7-A01 has some interchange information



https://www.maniacelectricmotors.com/77904015.html

Rectifier Specs​

113mm OD, M8 x 1.25 x 48mm Battery Terminal, 8-40A press-fit diodes, Welded diode terminations, Without mtg. hole for ground strap, Denso 90-120A IR/IF Alternators w/ 130mm OD Stator

Replaces​

OEM: Denso 021580-3750, 021580-3990, 021580-4040, 021580-4100, 021580-4430,

Honda 31127-PR7-A01,

Toyota 27357-50030, 27357-50060, 27357-75060,

Other: WAI New INR732P, 31-8213, AIM AT-07125, AT-07125R, AT-07166, AT-0775, Barsanco 211-231, Cargo 137874,

Denso 021580-3750, 021580-3990, 021580-4040, 021580-4100, 021580-4430, 021580-4690, Honda,

Acura 31127-PR7-A01,

J & N 172-52020, 172-52019,

Just Parts NP1-1245, NP1-1248, MPA 102-0216, Real 21132007, Regitar RN-11, Renard 11226, 11227, SWS NR112009, Toyota 27357-50030, 27357-50060, 27357-75060, TSA ADND-4015, Unipoint REC-614, Wagner W065-126, Wilson 11-29-1291

Application​

Acura (1991-1994) Jaguar (2000-2004)

John Deere (1988-1998)

Lexus (1990-1992)

Toyota (1990-1992)

Unit #s​

Acura 31100-PR7-A01, 31100-PR7-A02, 31100-PR7-A03;

Chrysler 38522267F;

Delco 10459495;

Denso 100211-6020, 100211-6030, 100211-6031, 100211-6040, 100211-6050, 100211-6051, 100211-6060, 100211-6100, 100211-6110, 100211-6120, 100211-6130, 100211-6131, 100211-6140, 100211-6150, 100211-6190, 100211-6350, 100211-8410, 100213-2391, 100213-2530, 101211-7892, 102211-0512, 102211-0980, 102211-0981, TN102211-0980, TN102211-0981;

Ford XR83-10300-BC, XR83-10300-BD32, XR83-10300-CC; Ford Engineering 2R83-AB, XR83-BC, XR83-CC;

Jaguar 2R83-10300-AA, 2R83-10300-AB, XR8-42452, XR8-42453, XR8-8577, XR817076, XR8310300BA, XR837164, XR88578;

John Deere RE36246, RE37201, RE42123, RE44140, RE51921, RE51922, TY6684;

Land Rover ERR6999;

Lexus 27060-50010, 27060-50011, 27060-50011-84, 27060-50011-84;

Toyota 27060-17030, 27060-17040, 27060-42021, 27060-42042, 27060-42080, 27060-61100, 27060-61100-84, 27060-74180, 27060-74180-84;

Valeo 437826

Other: 11092, 11199, 12066, 13384, 13385, 13386, 13388, 13562, 13908, 21369, 23079, 23271

This is old information, but there might be some NOS units or old documentation laying around
Interchange Part Numbers
BBB Industries 13714
CARQUEST 13714A
NASTRA A2042
USA Industries A2042
Vision-OE 13714
Machinery Components N13714
WILSON AUTO ELECTRIC 90-29-5231
ACURA 31100-PR7-J01
LESTER 13714
NIPPONDENSO 101211-7570
DENSO 1012117570
BOSCH AL1278X
ACDelco 3341274
AutoZone AL1278X
HONDA 31100-PR7-J01
HONDA CLG18
DENSO 210-0203
BECK/ARNLEY 186-0907
HOLLANDER 58668
AUTOTECH ENGINEERING 13714
AUTOTECH ENGINEERING V13714

Testing alternator components.

replacing the actual diodes in the rectifier

The ultimate backyard DIY

FWIW an alternator is an amazing complex device. Took until 1965 for them to be commonplace in vehicles.

Also, if somebody is looking to build an alternator from parts, the alternator front casing from the Honda 3.5L engine might be a good start. The case clocking and pulley size appear very close. The rear case is completely different.

Valhalla said:

Alright, making progress. Got this from Kaz;

Re: Alternator repair

Hi, JC.

Both bearings are pressed in but if you apply the force evenly/parallel, the one close to the brush will come out together with the rotor shaft.

It’s fairly tight fit around the rotor shaft so you need to slowly separate the two housings.
Just use plastic hammer to create tiny gap between the two and use it as a leverage point to evenly widen the gap and in parallel.

Once they are separated, you may need miniature puller but you can create your own method if you have thin craw on the universal puller or similar device and if you can pull it in parallel without scratching the rotor.

The bearing behind the pulley is held at the housing by the bearing cover disc.
If you pull the rotor, the shaft will slide out after removing the pulley.
You can punch out this bearing once the rotor is out.

On installation, you may struggle to press in the large bearing.
Keep the bearing away from the housing and just use the heater gun to warm the housing up.
The bearing should slide in now.

There are several different methods in overhauling the ACG so you may find it different when you overhaul your ACG but pretty much all of the ACG will follow the same procedure especially if it is from Denso.

Kaz

So I now have the alternator apart. I used a small puller for battery cables and was able to free the back bearing. Once separated I was able to punch the front bearing out. Will pull the back bearing with a bigger puller tomorrow. Clean everything up, polish, grease and install the bearings and I should be ready to reinstall. I love this forum. Thanks Kaz.

Job is finished and the alternator never looked better (or cleaner). It felt good to do it but I certainly understand why someone would pay the ~$125 for a replacement. Not too hard once you have the proper tools but it was time consuming.

Click to expand...

Hiya Kaz, whats the part number for the voltage regulator please and where did you buy it?

drew said:

To replace bearings: just need a small 2-jaw puller to get the small bearing side apart. The puller gracefully separates the casing halves.

I tried to use hand tools to remove the pulley and failed. The shaft hex and nut are difficult to get access too. So I used a impact gun and the nut loosened without issue. I also used the impact wrench to tighen the nut, so hopefully I didn't make more difficult for my future self.

I was trying to fix a whine, the existing bearings felt good, but went for the bearing change because I had them. Didn't fix, but everything is much cleaner now and the amount of carbon from the brushes was remarkable. If you are going to take apart the alternator, you might as well replace the brushes too.

Turns out the rectifier was no good, see attached picture. Note the bubbling of the epoxy paint on the right unit, this is the bad whining unit.

There are some NOS units on eBay for a few hundred dollars and AliExpress has some knockoffs (now OEM?) for a few dozen dollars.

The latest version of the rectifier assembly 31127-PR7-A02 is NLA. This p/n has no interchange references.

The previous version 31127-PR7-A01 has some interchange information

Rectifier

Denso 90-120A 12V IR/IF Alternators

www.aspwholesale.com

Manufacturer:	Transpo
Condition:	New
Voltage:	12
Replaces:	Denso 021580-3750, 021580-3990, 021580-4040, 021580-4100, 021580-4430 Honda 31127-PR7-A01 Toyota 27357-50030, 27357-50060, 27357-75060
Unit Part Numbers:	Acura 31100-PR7-A01, 31100-PR7-A02, 31100-PR7-A03 Chrysler 38522267F Delco 10459495 Denso 100211-6020, 100211-6030, 100211-6031, 100211-6040, 100211-6050, 100211-6051, 100211-6060, 100211-6100, 100211-6110, 100211-6120, 100211-6130, 100211-6131, 100211-6140, 100211-6150, 100211-6190, 100211-6350, 100211-8410, 100213-2391, 100213-2530, 101211-7892, 102211-0512, 102211-0980, 102211-0981, TN102211-0980, TN102211-0981 Ford XR83-10300-BC, XR83-10300-BD32, XR83-10300-CC Ford Engineering 2R83-AB, XR83-BC, XR83-CC Jaguar 2R83-10300-AA, 2R83-10300-AB, XR8-42452, XR8-42453, XR8-8577, XR817076, XR8310300BA, XR837164, XR88578 John Deere RE36246, RE37201, RE42123, RE44140, RE51921, RE51922, TY6684 Lexus 27060-50010, 27060-50011, 27060-50011-84, 27060-50011-84 Toyota 27060-17030, 27060-17040, 27060-42021, 27060-42042, 27060-42080, 27060-61100, 27060-61100-84, 27060-74180, 27060-74180-84 Valeo 437826
Lester:	11092, 11199, 12066, 13384, 13385, 13386, 13388, 13562, 13908

https://www.maniacelectricmotors.com/77904015.html

Rectifier Specs​

113mm OD, M8 x 1.25 x 48mm Battery Terminal, 8-40A press-fit diodes, Welded diode terminations, Without mtg. hole for ground strap, Denso 90-120A IR/IF Alternators w/ 130mm OD Stator

Replaces​

OEM: Denso 021580-3750, 021580-3990, 021580-4040, 021580-4100, 021580-4430,

Honda 31127-PR7-A01,

Toyota 27357-50030, 27357-50060, 27357-75060,

Other: WAI New INR732P, 31-8213, AIM AT-07125, AT-07125R, AT-07166, AT-0775, Barsanco 211-231, Cargo 137874,

Denso 021580-3750, 021580-3990, 021580-4040, 021580-4100, 021580-4430, 021580-4690, Honda,

Acura 31127-PR7-A01,

J & N 172-52020, 172-52019,

Just Parts NP1-1245, NP1-1248, MPA 102-0216, Real 21132007, Regitar RN-11, Renard 11226, 11227, SWS NR112009, Toyota 27357-50030, 27357-50060, 27357-75060, TSA ADND-4015, Unipoint REC-614, Wagner W065-126, Wilson 11-29-1291

Application​

Acura (1991-1994) Jaguar (2000-2004)

John Deere (1988-1998)

Lexus (1990-1992)

Toyota (1990-1992)

Unit #s​

Acura 31100-PR7-A01, 31100-PR7-A02, 31100-PR7-A03;

Chrysler 38522267F;

Delco 10459495;

Denso 100211-6020, 100211-6030, 100211-6031, 100211-6040, 100211-6050, 100211-6051, 100211-6060, 100211-6100, 100211-6110, 100211-6120, 100211-6130, 100211-6131, 100211-6140, 100211-6150, 100211-6190, 100211-6350, 100211-8410, 100213-2391, 100213-2530, 101211-7892, 102211-0512, 102211-0980, 102211-0981, TN102211-0980, TN102211-0981;

Ford XR83-10300-BC, XR83-10300-BD32, XR83-10300-CC; Ford Engineering 2R83-AB, XR83-BC, XR83-CC;

Jaguar 2R83-10300-AA, 2R83-10300-AB, XR8-42452, XR8-42453, XR8-8577, XR817076, XR8310300BA, XR837164, XR88578;

John Deere RE36246, RE37201, RE42123, RE44140, RE51921, RE51922, TY6684;

Land Rover ERR6999;

Lexus 27060-50010, 27060-50011, 27060-50011-84, 27060-50011-84;

Toyota 27060-17030, 27060-17040, 27060-42021, 27060-42042, 27060-42080, 27060-61100, 27060-61100-84, 27060-74180, 27060-74180-84;

Valeo 437826

Other: 11092, 11199, 12066, 13384, 13385, 13386, 13388, 13562, 13908, 21369, 23079, 23271

Click to expand...

Which rectifier did you end up purchasing? Is there a denso brand alternate? I see some oem still for sale but for a premium at $250. I want to rebuild mine with all quality parts. I was able to source the oem bearings, brush, and regulator. But not the rectifier.

Any tips on the rebuild? Seems like the hardest part is separating the bearings….

The $20 AliExpress rectifier package version is good quality. It appears to be the same one that was available on Amazon for $12. There is no reason the rectifier should cost more, it is simple enough.

This rectifier seems to be used in many alternators, so nothing specific to the NSX.

Once you separate the alternator body halves, it pretty much just falls apart in your hands. I used a brush to clean the electronic parts and engine cleaner on the aluminum body parts.

Maniac sells parts, but you can get Maniac parts cheaper on their Amazon Store if they have them.

The NA2 voltage regulator 31150-PR7-J01 is still available from Honda and has a higher amp rating, which works just fine in the NA1.

Alternate (heh) part numbers: 31150-PD6-004; 31150-PD6-014; 31150-PD6-024; 31150-PR7-A01; 31150PD6024; 31150PR7A01; 31150PR7J01

web paste https://www.delcoribo.com/p/vrt1514...tor-31150-pd6-004,31150-pd6-014,31150-ph3-013

DENSO is OEM actual pn

I have found that Denso p/n: 126000-1060 should work just fine.

VRT1514　HONDA Voltage Regulators

A-Circuit
Voitage Set Point 14.5V
63.5mm Mounting
132645
IN226
(Ref# 35-8213-3)
Regulator
12 Volt, A-Circuit, S-FR-IG-L Terminals, 14.4 Vset
For: Nippondenso IR/IF Alternators
Used On: (1995-85) Acura, Honda
Replaces: Honda 31150-PD6-004, 31150-PD6-014, 31150-PH3-013, 31150-PR7-A01, 31150PD6004, 31150PD6014, 31150PH3013, 31150PR7A01 Nippondenso 126000-0540, 126000-1170, 126000-1060, 126000-0540, 1260000540, 1260001170, 1260001060, 1260000540 MOBILETRON VR-H2005-9A, NEW ERA IVR-513J, USI 71-30004
Unit Nos: Nippondenso 100211-201, 100211-615, 100211-617, 100211-724, 100211-2010, 100211-2011, 100211-2130, 100211-2140, 100211-2550, 100211-3310, 100211-3311, 100211-6150, 100211-6160, 100211201, 100211615, 100211617, 100211724, 1002112010, 1002112011, 1002112130, 1002112140, 1002112550, 1002113310, 1002113311, 1002116150, 1002116160
Lester Nos: 13386, 13387, 14680
WAI Ref. Nos: 1-1008-01ND, 1-1410-01ND, 1-1411-01ND
Dim: 63.5mm Mtg. Length
Note: L-terminal is an output terminal.

TRI226 Repair Circuit
ACDelco E657, E629A
ALANKO 700364
AS-PL ARE6006, ARE6024
CASCO CRE40124AS
ERA 215655
HITACHI 132941
LAUBER CQ1010261
MAGNETI MARELLI 940016084500
MESSMER 215655
MOBILETRON VR-H2005-9A VRH20059A
New-Era IVR-513J
PowerMax 1111506, 81111506
SANDO SRE40124.0 SRE401240
STANDARD VR438
WAIglobal IN226
AIRTEX / WELLS 1V1021
ASHUKI 1536-3004 15363004
PARTS-MALL PXPBF-017 PXPBF017

HONDA ACCORD III (CA) 1985/11 - 1989/12
HONDA LEGEND I Coupe (KA3) 1987/10 - 1991/03
HONDA LEGEND I (HS, KA) 1986/01 - 1991/03
HONDA PRELUDE III (BA) 1986/04 - 1992/01
HONDA ACCORD III Aerodeck (CA) 1985/11 - 1989/12

***

And $32 for a IN226