Right on... an understandable dilemma which I've also thought of. If you want to score the cheap roller on eBay just for the collar and bushing, it's totally understandable. My selling point here would be:Two reasons I haven't bit the bullet on this yet.
1) for $75, I can buy the big bearing version of the plastic roller (for the hub) and a metal roller from Amazon for less
I can weigh it for you somehow if you're curious, that'll be no issue. I do have some spare 410 stainless sitting here if you want me to make one from that - no worries about that not being heavy enough.2) don't know the mass difference between the two
Due to the stock roller being 3.075" in diameter, and 3.25/3.5" roundstock being substantially more expensive than 3.00" roundstock, I've been making the aluminum ones from 3" and cleaning up the OD, which brings it to about 2.985." Making a smaller OD (70mm/2.755" as you suggested) will be no problem.I may still buy one off you with a reduced diameter since I'm running a larger alternator pulley, thus belt tension is higher.
I guess you're suggesting that I move the bearing further "right" in the pulley in order for the pulley to ride closer to the rod. That's something I've also looked at, and it's not really feasible to change the design. As you can see from this drawing, there is only 1mm difference between the rod land and the edge of the pulley as it is. This dimension is determined by the thickness of the press-fit sleeve that goes over the 17mm bushing.Each and every roller I've seen has the belt riding right up on the outer edge. If the mount for the bearing, which you have @ 0.2638 or 6.7 mm was at 8 mm, this would be fixed.
I've had a spare 6203 aluminum pulley sitting on my desk for several months. Send me a PM if you want it and I'll cut you a deal.Our other B4 needs some parts so I’m looking around for alternates again. If you have a 17mm hub and want a full metal pulley for its inertial properties, then this guy might work for you since it is a mass produced part:
At 74 mm diameter, and assumed 90° of contact with the serpentine belt, it’ll have a little less tension as the belt will get ~0.2 more “slack”. Amazon is selling it for about $36 shipped. It is also a 2 bearing pulley.
If you have an A4 clutched pulley, you loose about 0.4” inches of belt length from the added diameter. This pulley would drop that delta to loosing only about 0.2” of belt length.
Less belt length in the path is greater tension and vice versa, more belt length is less tension.
Edit, so far my custom one is running beautifully.
I'd guess you forgot to install/lost the spacer on the front of the rotor, unless the two halves aren't seated together. The rotor is supposed to be pulled forward by the pulley and held forward. If the spacer is missing, it'll slide too far forward and the slip rings won't line up, or if the two halves aren't seated together enough, there will be too much space between, and it won't line up either.Bumping an old thread….
Disassembled the alt from Rotbox, to install on the pick up. Bearings were noisy and I figures I’d replace them and clean up the alt.
The only thing replaced were the bearings. I ordered Koyo and SKF. Everything that came out of this alt went back in. I did not touch the slip rings, since they looked decent. The issue I’m having is, the regulator brushes are not lining up with the wear marks on the slip rings.
- If I push the rotor to the rear to make the brushes line up with the wear marks, the rear fan is contacting the housing to the point that it locks up.
- If I push the rotor to the front to avoid fan to housing contact, a portion of both brushes are no longer in contact with the slip rings. I also notice the rear bearing is not fully seated in the plastic shim/cup, when I do this.
Any ideas? The only thing I can think of is, when I pressed the front shaft washer onto the shaft, I supported the rotor by the slip ring… I did some light research and I didn’t see anything saying not to do this.
The only thing I can think of is, when I pressed the front shaft washer onto the shaft, I supported the rotor by the slip ring…
Good you figured out the issue! Make sure you still have continuity between the two slip rings. It shouldn't have broken the wire in there, but you'll probably want to make sure of that. I've not really had that specific issue before, as I generally am replacing the slip ring when I rebuild an alternator.Started taking apart another 120A alt, for comparison. Disassembled the 90A, reassembled the 90A, measured some parts, stared at some parts, etc.. Everything checked out, as it should. For a very brief second, I thought about leaving it alone and running it. For another brief second I thought about grinding down the mounting posts for the regulator, to lower the brushes… couldn’t bring myself to do either.
The slip rings did not look like what was on the 120A rotor, or the spare alt. Everything inside was replaced with aftermarket parts. I took a measurement from the inner race to the top of the slip rings, on the 120A and compared it to the 90A.
1.6mm less than expected…. so, the slip rings did slip!
From the above pic, you can see I was already digging in there with screwdrivers. I was lightly levering on the outer race and Robert Bosch called me, and told me to stop. Better do this the right(?) way, before I ruin something.
A couple nuts and washers to support the outer race, some prybar action, and it instantly popped.
If I moved it another .5mm, it’d be perfect, but I decided to leave it alone, before I ruined something. The brushes are fully landing on the slip rings, but not exactly where they were previously riding. Good enough for me….
I need to disassemble it again, because one of the threaded case holes washed out. If I’m installing thread coils in one, I may as well do all…. I’ll probably spray the rear cover satin black, since the nameplate markings look like crap.
Takeaways… don’t do what I did.
This should have been easy. My mistakes cost me at least 4 extra hours.
- Don’t use a press to press the front washer (Bosch calls it a spacer) onto the shaft. Use the pulley, washer and nut to press It on.
- Don’t use a tie rod/pitman arm puller to remove the rear bearing. This probably didn’t cause the issue, but I can’t guarantee it.
I don't measure it, as as long as one brush is touching each slip ring, it doesn't matter too much if it's exactly centered, as there's no groove to line up. I press them down until they touch the step.I do have continuity. That’s something I did glean from the many videos, when I was trying to figure this out.
Being that you’ve replaced slip rings, are you taking before and after height measurements, to ensure they line up with the brushes?
I did assemble the 120A, tonight. I assembled the front half as usual, but did not crimp the stator leads to the rectifier.… makes everything much easier to see. Bolted the halves together and the slip rings were low, again… I’m two for two!. This time, I carefully cut the base of the slip rings with a hacksaw, to form a ledge for the pry bars to grab. A few trial and errors, and the height was perfect.
This one was assembled much faster. I’d estimate 2.5 hours, including set up and clean up.… I’m working a bit slower, so I’m not scratching the refreshed parts.
I realized the slip rings have an open top. Using the puller to remove the rear bearing, couldn’t have caused these issues, since the puller is pushing directly off the rotor shaft. On both alts, the rear bearing does not entirely seat in the plastic spacer cup. Learning new stuff..,,
Sounds like the original one you have is a 13.8v set point regulator. The ones I sell are 14.2 volt set point.Hi there, im new here and im glad i found this thread as i am having issues with my 120 amp alternator and couldn't find much info on them!
I had to replace the regulator a few months back as the brushes quit on me with a 150 mile drive to go! I did manage to get home because i have about 180aH of leisure battery and that kept the headlights on!
now i have replaced the regulator with this one
but i never see much more that 13.6 on my volt meter, although i did just put my multimeter directly on the battery and it was showing 13.8v, but i would still like to see it more like 14.something, also the first time i start the van every day i need to blip the throttle to get the alternator to start charging, that didnt happen with the old regulator, any ideas why?
I did find this adjustable regulator that would be perfect because i think with the leisure battery i could do with the extra voltage to help charge it fully,
you have to scroll down a bit to see the internal adjustable regulator which to me looks like it would fit fine, but i emailed the guy and he said it wouldnt work, i gave him the bosch part number 0123-515-020
anyone know if this would work or have any alternative ideas?
I know i need to check for things like voltage drop across cables and such, and i may take the alternator off again and check i did a good enough job of cleaning the slip rings.
anyway sorry for the long essay!!
cheers for any help!
almost forgot, i got myself a clamp meter in the post today and it read 40amps at idle revs on the cable between the starter and the battery, which i didnt think was too bad at idle rpm, but the voltage is still lower than i would like.
Ahhh thanks for clearing that up, makes sense now!Sounds like the original one you have is a 13.8v set point regulator. The ones I sell are 14.2 volt set point.
The reason that the one from the Volvo guy won't work is that it's for the alternator with a 28mm slip ring, the VW one has a 14mm slip ring.
Where are you located?