Another Alternator Belt Tensioner - 3VX belts?

[82vdub]

It would just be nice to get something designed and installed that will automatically tension itself. That would reduce the amount of time messing around with re-adjusting the belts all the time.

[MagicBus]

I'm sure the back bend on the belt and it's lifespan has to do with the radius of the roller that's bending the belt. Mower decks to bend the belt backwards, but they seem to have 4"+ size pullys on them. Hard to get another 4" diameter pully in the belt setup under the hood of a VW.

Agree... the radius and amount of wrap.

This does not appear too extreme and it's on the slack-side, but again, time will tell...


I got my modded rig out of winter storage, so I'll resume updates on its performance.

I don't think I have much more backbend going on than you do. It's hard for me to take a picture from the same angle thanks to my heavy-duty Home Depot Motorsports intake. Again, I'll continue to monitor, update, tweak and share as necessary.

[littlematt]

I was intrigued by the homebrew idler solution and so I picked up the bits from Grainger. (Hope mentioning them isn't verbotten.)

How are folks preventing the bearings from spinning on the bolt (instead of spinning themselves as they're designed)?

Has anyone sourced this hardware in stainless? I trust a rusty German bolt to unscrew X years from now, but I don't feel so comfy about these Chinese ones.

-lilmatt

[MagicBus]

I was intrigued by the homebrew idler solution and so I picked up the bits from Grainger. (Hope mentioning them isn't verbotten.)

Can't see how it would be. Heck, it's free advertising for them.

How are folks preventing the bearings from spinning on the bolt (instead of spinning themselves as they're designed)?

The nut(s) holding it all together keeps the bearing stationary, suspended between the washers. Even if it did spin against the bolt, I can't imagine that would be much of a problem aside from noise.

Has anyone sourced this hardware in stainless? I trust a rusty German bolt to unscrew X years from now, but I don't feel so comfy about these Chinese ones.
-lilmatt

Not that I know of. If it worries you, a little anti-seize compound should do the trick.

[TylerDurden]

I got a PM reply from Vdub-bub... his belt lasted more than a year, compared to a belt on a stock setup that failed in a shorter time.

My belt is still going at 1000+miles so far; but it was a bit slack, so I gave it a minor tightening (3/8" deflection with moderate one-finger pressure).


I'll post at each fill-up or any belt-related event.

[MagicBus]

Good to know. My car's been sidelined since Wednesday night (severely toasted wheel bearing, not the belt). Will update progress when the car's back on the road.

[coke]

Them wheel bearings are a pain. Do yourself a favor and if you can get your hands on them, get the german brand wheel bearings. They come in a kit with new nuts, bolts, and circlips.

I put napa wheel bearings in my 91 and they lasted 20k miles. Put german ones in the 2nd trip around Biggest pain is taking the knuckle off to get them pressed in.

[MagicBus]

I got the cheapest bearings I could quickly (it is a kit with new hardware). I've decided to sell the car and just wanted to get it roadworthy. Ordered last night. I've gone into it in depth on the vwvortex forums, but this car has been too needy for a daily driver. I already have a needy weekend car (Vanagon) and a needy project (Mercedes 220D). I need a more reliable daily driver than this has been.

Of course, I'll continue to update you all on the belt as long as I have the car.

As for the bearing job, I did the front bearings on a Subaru last year, which is logistically similar. I have the press, bearing drivers and bearing puller already in my garage and ready to go.

[Fatmobile]

Once you get the old bearing pressed out,
you might want to grind the edge and use it to press the new one in.
Grind a ways down on the leading edge so it doesn't get stuck/pressed into the bore too.

You don't want to use the center of the bearing to press the outside edge into the hub.

Also, never set the car down without having the axle bolt snugged-up and holding the 2 halves of the bearing together.

Weight on the wheel can split the bearing,.. I think Hagar said it pushes the end seals out of place.
When you bolt the axle in; it will push it back together,.. but the seal will still be out of place.
I'm not sure if that is the cause of bearing failure with a loose axle nut,..
but I know rolling a car without it tight will shorten the life of that bearing.

[surfcam]

I suspect improper installation for wheel bearings is one cause of them not lasting. I had a local shop press bearings in for me and they only lasted 8 months. One only when 3 weeks. The next time they had no problem after I gave them some instructions. Using the same bearings which have lasted three years so far. One has to be doubly careful not to press the inner race of the bearings. When that happens maybe a ball bearings get's marked, seal goes out of place or cage gets bent.

[MagicBus]

Well, I sold the car on Saturday morning, so I'll no longer be able to update this thread with my experience with the belt. The wheel bearings aren't in yet, but when they are, I'm mailing them to the new owner.

Thanks for all the help, and best of luck to anyone else that tries this fix.

[TylerDurden]

Thanks for your input, MagicBus. Maybe the new owner would be willing to continue the updates?


I neglected to record the exact odometer reading when I did the mod last fall... I'll just say it was at 191,000mi.

So, now the first belt (installed at the mod) has about 1200mi.

[TylerDurden]

Now at 193,000, so 2K mi on the belt & bearings.

I noticed the tach lagging and a light chirp noise when the engine/belts were cold... time for some testing.

I used the high-beams and ventilation-fan as test loads. The tach drops out at 13V and kicks back in at 14V; so maybe we can presume if a stock tach is droopy or slow to report, that alternator output is low (despite no idiot light).

So, I tightened the AC belt as much as the Alt; both were installed at the same time. After the first re-tension, voltage with full loading (high beams and blower) was still low (13V) at idle and a faint chirping sound... I stopped the engine and felt the alt pulley and stock idler: both were hot, indicating slipping.

I re-tensioned the alternator belt to the point where I could not turn the alternator fan with heavy one-finger pressure. Voltage at idle came up to 14V (tach was responsive through its normal range).

Maybe y'all can post if you can move your alternator fan when tensioned to your liking?

I'll keep y'all posted.


ps. My recently installed Bosch re-manufactured alternator is making the same knocking/rattling as the old one I replaced. Hrmmm.... it may be that the alternator's rear-bearing plastic spacer (near the brushes) has wallered out. I'll check that as soon as time permits.

[wolfsburged]

Just read through all of this. I'm fighting alternator belt tension problems on my '84 Jetta 1.6TD. The Mk1 style is similar with AC below and Alt above, but does not have any form of tensioner. Only adjustments are the upper bolt and bracket from the head. I keep loosing tension every few days, and if I tighten up as hard as possible it chirps. Still looking for a solution...

[TylerDurden]

Just read through all of this. I'm fighting alternator belt tension problems on my '84 Jetta 1.6TD. The Mk1 style is similar with AC below and Alt above, but does not have any form of tensioner. Only adjustments are the upper bolt and bracket from the head. I keep loosing tension every few days, and if I tighten up as hard as possible it chirps. Still looking for a solution...

A separate topic might be the best place to explore options. We can link from this topic to that one. Pictures of the setup would be helpful. I'm confident numerous others will have suggestions.