Alternator ring terminal stud (1 Viewer)

[alia176]

I am wondering if I may have buggered up the main stud where the large ring terminal is landed. I recall tightening the nut but it never felt tight so I may have kept tightening it w/o realizing that the actual stud may be spinning. Does anyone know how the stud connects to the component inside the alternator? Could I've severed or damaged this connection?

One symptom I was experiencing is low alt output 12 volts and the CHG light is coming on. None of this was present until the Alt was removed for brush replacement.

Thanks.

 

[Ruadhrigh]

Another symptom is that terminal gets freakin hot!!!

 

[alia176]

BTT

 

[TrickyT]

Hot's not good. High resistance + high current = hot. You've got to get a better/tighter connection between the ring lug and the internal wiring in the alternator. And do it before the heat causes the copper wires to oxidize where the ring lug attaches - then you've got a bigger problem. (Rory knows about this.) As to what keeps the stud from spinning, I don't know about Toyota alternators specifically, but the generic solution is square shoulders or square head on the bolt and these fit into a recess in the insulating washer that keeps the stud from contacting the metal case. Sounds to me like you've got to pull the alternator apart. When you're putting everything back together clean the stud, lug, metal washers, and nut(s) with a wire brush to remove any layer of oxide that may be present.

 

[alia176]

Tom

I concur, heat is bad. It'd help if someone has rebuilt their alternator lately who can shed some light on the internals.

I believe that the heat is not being caused by the location where the outside ring lug attaches to the stud; rather, the connection where the stud connects to the regulator/rectifier deal inside the alternator. It is this area, I'm curious about.

Anyway, I'll find out on Friday exactly happened inside the alternator.

Thanks.

 

[Photoman]

I gave my stock 80 amp alternator to another member so I don’t have it to look at for you. I took the back off a 130 amp and hopefully it is similar to the 80 amp. In the picture that stud is just bolted through the plate. The head on the bolt is square. I don’t know if there is a square shoulder on the stud or not. It can be seen there is a nut on the other side of the spacer to tighten the stud down. If this is loose and/or there is a shoulder that is rounded then the stud can spin. This poor contact could then result in the stud getting hot. HTH.

Bill

 

[alia176]

Thanks Bill for the photo. Rory did confirm that the stud got VERY hot and charred the insulation on both white wires that use the ring term. The copper is oxidized as well I'm sure. I'm not sure what may have caused this except that I didn't tighten the stud nut AND the top mounting bolt (to the bracket) all the way. Evidently, I was in a hurry during this phase of the HG project and now I'm paying the price.

We'll be replacing the charred section of the two wires and test out the ALT in the next few days (once I get home from PA!). I wouldn't be surprised if the ALT is fine even though the POS post got blazing hot.

As an aside, this *may* have been the cause of a less than perfect idle the engine was experiencing after the HG project. There was a subtle hesitation in the idle that we couldn't solve and we checked just about every device and ran all sorts of tests! Otherwise, she ran well and pulled hard under load.

Thanks.