ThickLizzyVetteswerv

So the rear bearing in my stock (replacement) CS130 alternator took a trump on me and was making all kinds of clangy noise. Check out the damage. The convoluted plastic tubing around the battery charge wire was also decently melted.





Now I'm well down the rabbit hole of the infamous C4 alternator heat issues and determined to ensure this doesn't happen again. So the cs130 is out. The CS144 seems to be a fairly straightforward solution and it's tempting, as the only modifications needed are a new rear brace and maybe the milling down of the upper mounting ear.

But then I discovered the AD244 that replaced the CS144 and learned that its output at low RPM is way better and that it's better designed to survive in high temp environments so now that's what I want.

I just happened to have a DR44 on hand, which is actually what succeeded the AD244 but has similar external dimensions (but a different plug setup than what a C4 has) so I've dropped it into the car to see how it fits.

Well, it fits but only kinda. It mates perfectly with the lower mounting setup and the pulley lines right up--though it will need a slightly longer belt--but the problem is that the upper mount is both in the wrong place and too wide to use the stock C4 aluminum upper brace. So I'm trying to decide if the tech upgrade is worth the hassle of creating a new upper brace.

You can see from this picture that the mounting holes on the alternator's upper ear are much closer to the base of the C4 upper brace and would therefore require a much shorter brace. The new brace would be a significant change to the geometry as well, changing from a force tangential to the centerline of the alt to almost straight at its center. I don't know if this matters much, though.

There's no provision for a rear brace like on the stock setup but the double wide mounting ears appear to be designed to obviate the need for that so I'll say no worries there.

I should also note that the alt can also be clocked 180 with the top ear in this pic used as the base but this then puts the other top ear way down the side of the alt to the outside, which would require a really long curved brace that wrapped around the curvature of the alternator. This seems like a worse way to go.

So... anyone got any feedback/input/suggestions? If I came up with a custom brace design that field tested out well, maybe I could do more if others had an interest in this upgrade?

ThickLizzyVetteswerv

Upon further reflection, an adapter piece that allows the use of the stock upper brace seems like a reasonable direction to go for starters.

Here's a sketch of a piece that would attach to the alternators upper mount and lie across its body, to end in a vertical tab that simulates the upper tab of the stock alternator. I don't know how well this would work to stabilize the overall forces it would experience without the rear brace but limiting the analysis to the rear elevation view here, where the force at the pulley is roughly horizontal (from the belt), it seems that the geometry of the two braces would work.

ThickLizzyVetteswerv

I've added a supplemental bracket to halt the rotation the torque on the pulley is imparting to the assembly. This would remove that duty from the previous combination of stock and new brackets and limit their duty to pure compression. Well, probably not pure but much closer to it.

ajp01

I suggest you take a look at using that open mount hole on the bottom of the smog pump instead. The force would be directed tangentially to the pulley center of compression/​​​​tension and it would have more leverage. Just a thought.

ThickLizzyVetteswerv

Yeah, that's a good call. That hole is closer to coplanar with the hole on the alt and with the short lateral distance, it would be easy to incorporate that bracket into the original main adapter bracket and make it one solid thing. In fact, it might actually make more sense to go with my first idea, which was to eliminate the stock upper brace entirely and replace it with something that simply bolts to the new alternator hole location directly.

ajp01

I was thinking a bit simpler and more direct, with no other linkages besides the one I've illustrated here in red. That's such a short run, with the right material it could be stiff enough to avoid vibration and hold quite well.



If it works, let me call dibs on the second bracket that you fabricate for when I'll need to replace mine with the newer alternator eh?

ULTM8Z

It absolutely is. I did the swap on my '71 Camaro with thirdgen Camaro serpentine system and the AD244 runs circles around the old CS130.

Electric fans, EFI, stereo system, and everything else powered on, the alternator maintains 14.2V even at idle.

ThickLizzyVetteswerv

I've been looking for alternative case shapes but have not found anything yet. They're all the same 100 degree or so separation.

ThickLizzyVetteswerv

Well dudes, history is about to be made here. I took the plunge and bought an AD244 this morning and then stopped off for $1.60 worth of scrap steel. Now is the hard part.

I'm still evaluating different bracket strategies and they all have issues but I'm comfortable that I'll reach a good solution without too terribly much struggle.

Frankly, I could probably get away with simply stuffing a wooden wedge between the alternator and the air pump and calling it a day but since this isn't the Flight of the Phoenix, there's no call for such primitive measures. Not yet, anyway...

I made the pleasant discovery that the original belt works just fine with this new arrangement so I won't have to buy a longer one after all.





Here is the AD244 in place. I've sketched in the forces its experiencing, as I understand them. The red shows the tilted axis about which the torque at the pulley from the belt is attempting to rotate the assembly. The line goes from the bottom mounting tab up through the pulley centerline. So my fabricated upper bracket should help oppose this torque. The frame on the AD244 is quite robust at the mounts and the bottom one seems like it could probably handle it on its own if it had to but still, it shouldn't have to.

The yellow curve shows how the belt pulling roughly horizontally on the pulley is also trying to rotate the whole assembly around the established bottom mount. For this reason, I don't think the simple red tab ajp01 propoesd above would be adequate. It would be subjected to some weird forces, pushing really hard down on the air pump side mount while trying to force the alternator upwards.

What I've shown in green is a bracket that could use the existing air pump body bolt locations (green) and maybe even add in the stock upper bracket mount (blue) for extra strength. I prefer the idea of using the intended factory load points to improvising my own, wherever possible.

The big issue with the bracket ideas shown below is that all the bolt locations are at different levels so the brackets would be anything but flat plate. I'd have to add a bunch of double bends in them to get them to lie flat in direct contact with each hole. This would be rather annoying.

For starters, I'll cut out some cardboard mockups to get a feel for things.

ajp01

I like it.

Hit Man X

Interesting! I was eyeballing my LT1 Fleetwood about a month back and wondered if fit my L98 as 140A I believe versus the 105A on the L98. I have a few Gen 3 alts floating about...a 105, 130, and 145A currently.

In for data.

WVZR-1

A CS144 is nearly a direct bolt on for nearly all C4 applications.

ThickLizzyVetteswerv

Here's the final update before I start showing actual metal being shaped.

I've settled on this arrangement. An adapter bracket in yellow to mate with the stock upper brace. A second Z-shaped bar in green to resist the twisting of the alt body. The two bolt holes it uses are virtually coplanar, in that the rear face of the alt mount hole is pretty much the same plane as the front of that unused air pump hole. So I'm going to make the green piece separate from the yellow bracket and add it on the outside of that bracket. So it will need the Z to traverse two thicknesses of steel. I think I can manage this bend in my vise.

The bend I'm more concerned with is the loop at the end of the yellow bracket, through which the stock bolt is to run. Not sure if I'll be able to wrap this 3/16" plate into a tight loop like that but it seems easier to tune the width of that looped plate than it would be to stack multiple little tabs together and weld them onto the base and get them to the precise width to fit snugly in the stock upper arm. I reckon I'll screw with that BEFORE I weld that piece to the other piece running across the alt at the mounting ear.

Oh--one last issue. That unused hole in the air pump is in a good spot but it's not without problems. It's very close to the adjacent hole that IS used and the bolt head there is very close to the unused hole. So close, in fact, that there isn't currently room to accommodate a new bolt head or nut. So I'll try getting two allen head bolts to use in these spots and hope they leave room for one another.




As for the CS144 being an easier install, that is true! But from what I've gleaned from other forums, the AD244 is a considerably better performer and, in my opinion at this point (the very beginning of the tricky part), worth the extra effort.

What I found elsewhere is that a CS144 will put out 65A at idle whereas the AD244 will go 85-89A. Moreover, the AD244 is built to handle/dissipate heat better, which is actually my primary concern here. I don't want to ever worry about sitting in traffic and having my alternator bearings melt on me again. My Corvette is my daily driver.

Finally, this isn't an expensive upgrade. The price of the AD244 was $120. The only additional cost for like tripling the fortitude of my alternator situation is the $50 core charge, since they wouldn't take my piece of trump CS130 carcass. And the $1.60 in steel and probably $6 for the AD244 style pigtail I almost bought but didn't because I wanted one of the premade adapters they sell online for $30 and then changed my mind about spending $30 on such a stupid little part that I can easily accomplish myself with my own soldering iron and some shrink wrap. So $57.60 above the cost of a replacement CS130.

I'LL BUY THAT FOR A DOLLAR

ThickLizzyVetteswerv

Fabrication underway!

ThickLizzyVetteswerv

Some updates.

She ugly but she work.

ThickLizzyVetteswerv

Well, I made a disappointing and embarrassing discovery today, having spent the weekend farting around with this bracket.

Turns out the bracket was a non-starter from the beginning, only I didn't know it because I waited until now to confirm that there's clearance under the hood. And there isn't!

This photo shows my last ditch attempt to reposition things and make space but closing the hood on this pushes it all down 'til it's "sitting on its stops."




So Plan B is something I came up with earlier on and decided against because I wanted to use the stock bracket. I call it, "Little Green Nasty." And I'm not sure if an engineer would love or hate it but it is the embodiment of two desirable philosophies: simplicity and efficiency.

I'll modify what I've already created by welding a simple little leg on the opposite side of the current one. This new leg will torque against the front face of the air pump and the main body of the bracket is just going to rest against the body of the air pump. Yes, that's right--no upper bolts at all! The tension of the serpentine belt will pull the alternator against the air pump and hold it secure laterally and the little torque arm will stop it from twisting and breaking the lower alt mount. I think...

ajp01

Sorry about the hood clearance. I was going to ask when I saw your finished bracket if it cleared the hood, but thought that was already sorted.

On your tab, I'm concerned about pressing from that finger slightly deforming the soft alu of that air pump housing if the force is concentrated on a small area. Those cases deform really easily; the older ones used to have a marking cast into the housing that said "Do not clamp in vise" or something like that.

Wouldn't it be easy to extend that ear further upward to the mounting boss already cast into the air pump housing (the one that the bolt is on the rear plate) and just drill a hole in the front of that boss, tap it or helicoil it, and use a bolt to solidly mount your extended ear and keep the alternator stable?

ThickLizzyVetteswerv

That is a valid concern. I've created a couple of tiny, high pressure contact points here. I don't think getting up to that boss is really very feasible but I can certainly add a vertical element to my torque arm to spread the load out a bit more.

The contact between the main bracket and the air pump body is also a single point, which isn't ideal. I've been thinking about how to address that. Some kind of hardening plastic putty/resin material I could build a form for and fill the entire void between the two bodies?

ajp01

Yes, but I still have concerns with any solution that doesn't use at least one solid bolted mount point to that alternator ear.

The alternator and smog pump are going to be subjected to different vibration, torque, tension, and compression loads in different axes. So when those shock loads are distributed through the serpentine belt through A/C clutch, RPM changes, and resonance forces at different speeds, the thing is going to shift/vibrate front-back, side-to-side, etc.

I'd still try to bolt it somewhere if at all possible, otherwise it's going to notch and twist its way to something failing.

ThickLizzyVetteswerv

I too would like a solidly bolted mount. I'll keep working on it. I do have a curved plate I made to sit against the back of the air pump. You can see the two studs I replaced the existing bolts with in previous pics. I didn't figure out a good way to implement it so I had abandoned that route but maybe I'll keep working on that.