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.
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Has anyone rebuilt an NSX Alternator?
- Thread starter Valhalla
- Start date
Thanks BATMANs but I meant has anyone on Prime done this? I was hoping I could do this myself.
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.
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
Please refer to the following link for some of the photos that I took while doing this.
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.
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.
Last edited:
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
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
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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?
Still on the project list. All the bearings were available on eBay for nominal costs.
- Joined
- 4 August 2020
- Messages
- 40
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
Paul
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
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
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
John Deere (1988-1998)
Lexus (1990-1992)
Toyota (1990-1992)
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
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
| 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 StatorReplaces
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
Attachments
Last edited:
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.
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.
Last edited:
Hiya Kaz, whats the part number for the voltage regulator please and where did you buy it?
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.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
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, 27357-75060Unit 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 437826Lester: 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
Any tips on the rebuild? Seems like the hardest part is separating the bearings….
The $20 AliExpress version is really good quality.
It appears the same one that was available on Amazon for $12
There is no reason the rectifier should cost more. Also the rectifier seems to be used in a lot of 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.
FYI, Maniac sells parts, but you can get Maniac parts cheaper on their Amazon Store if they have them.
I have yet to find a quality voltage regulator.
It appears the same one that was available on Amazon for $12
There is no reason the rectifier should cost more. Also the rectifier seems to be used in a lot of 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.
FYI, Maniac sells parts, but you can get Maniac parts cheaper on their Amazon Store if they have them.
I have yet to find a quality voltage regulator.
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