Alternator bracket

[John Staddon]

The alternator belt on my C-V8 (383 engine) squeals when it is cold and in cold weather will go on squealing for a long time. I have tried tightening the belt but even using the full extent of the alternator bracket I am unable to tighten it to 'book spec'. Belt dressing doesn't cure the problem. I have tried a belt that is 25 mm shorter than the one fitted, 1125 mm and not 1150mm, but that is too short and won't go over the pulleys, Taking the alternator off the engine allows the belt to be put on the pulleys but then the alternator won't go back on the engine, the shorter belt won't allow me to align the alternator mounting bolt, the long top bolt the alternator pivots on, with the engine. A 25 mm reduction in belt length is only 12.5 mm on each side of the belt and I don't understand why there is so little adjustment. The alternator bracket appears to be standard Mopar, curved with a small offset where it attaches to the mounting plate on the engine. Photo attached (sorry, besr I can do as the radiator is in the way).

20240906_142630.jpg (269.75 KiB) Viewed 227 times

The belt(s) are V belts so toothed. I have been advised that a toothless belt may be better but can't find one.

Has anyone else had this problem?

What sort of bracket do other people use?

Is the short straight link between curved bracket and alternator perhaps too short?

What sort of belt do other people use, and what length?

John

[slotcarone]

Your car should have a single belt groove on the alternator pulley. Does it line up with the others? The double groove pulley is for a later car with an AC compressor. Are you sure your car does not take the wider belt? That belt would not fit in the alternator pulley though. Can you post some pictures of the rest of the belts/pulleys?

[DPP]

Looks like its had a Mitsubishi alternator upgrade and that was a popular cheat to extend the bracket. As a quick fix you could make a longer piece to replace the short straight bar giving more adjustment. The cog style belts are AVX belts and the smooth ones are SPZ belts.

If you have applied belt dressing I would advise getting it completely off all pulleys and belts with some brake cleaner as it only makes things worse. Oh and dont do what one owner did to sort his squeaky belt he applied WD40

[John Staddon]

Thanks Dave and Slotcarone

I can't photograph the complete alternator assembly, the poor shot I posted is as good a view as you can get as there is very little space between alternator and the fans behind the rad. But the brackets appear to be the standard Mopar offering that lots of places sell.

The alternator is an aftermarket one, it has been on the car for years. There is no makers data on it so I don't know the make but it has an integral regulator and it was fitted because remote regulators used to regularly fail when I first got the car. This alternator has been trouble free, except that the integral regulator needed replacing a few years ago, but after that was done it has been trouble free again. It works fine with the engine pulleys as long as you use the inner groove on the alternator pulley.

I have noticed, since posting and after searching the net for answers to the problem, that the curved alternator bracket on my car is mounted on the radiator side of the engine mounting plate when it should be mounted on the engine side, or on the back face of the mounting plate not the front, that is obviously why there is an offset in the bracket as the offset brings the alternator bracket forward again and exactly in line with the mounting plate. Whether a few millimetres makes much difference I don't now but I will attach it correctly and find out.

I will also try a belt with a length of 1137mm as even 6.5 mm less on each side of the belt may give me enough margin to get the correct tension on the belt (and SPZ one, which are easy to find once you know what they are called).

John

[johnw]

John, I too went through a few poor external regulators in the late 1990s until I found a decent one (by pure luck). Those were early electronic replacement for the electro mechanical regulators that were fitted up to the Mk2 Interceptor. If you took them apart you could sometimes see the faults, insulation problems etc. It didn't seem to be a problem with the car. I bet an electro mechanical one would have worked.

[John Staddon]

Back to the original subject. I fitted an SPZ section belt, smooth not cogged, 1137 mm inside measurement so 13 mm shorter than the old one. On first start up of the engine it was great, no noise, but yesterday, after 100 miles, it turned itself inside out and started to shred, as well as stretching as it got very hot. Obviously that left me with no charging but I got home on the battery. I cleaned everything up today and refitted the old 1150 mm belt but that squeals just as badly as before. I did check pulley alignment and the alternator pully is behind the water pump pulley by 1.5-2 mm and I can correct that easily enough so will try that. But there is also a deeper, chiming noise, like a bell, as well as the squeal. Does anyone have any idea what causes that?

John