When a hobbyist opens the hood of his or her vintage vehicle, the alternator generally isn’t what’s admired most. In fact, short of a charging system issue that forces action, the belt-driven voltage generator is so reliable that it can operate inconspicuously for years without maintenance. Nothing underhood is truly maintenance-free, however, and our Pontiac’s alternator proved just that. It wasn’t a charging issue that drew our attention. Instead, a persistent chatter at idle speed indicated something was amiss. A cursory check revealed that an internal bearing was beginning to fail, and without swift action it could leave us stranded.
Our ’76 Firebird was originally equipped with a 10SI (or System Integrated)-series alternator developed and produced by GM’s Delco-Remy division in a variety of sizes and output ratings. While remanufactured 10SI alternators are typically stocked at local parts stores, we find originality important and decided to completely disassemble our Firebird’s original 80-amp unit and replace its shaft bushings. That then afforded us the opportunity to replace the internal electronics, essentially resulting in a complete alternator rebuild. Follow along to see how we did it.
My new fan belt arrived on Saturday morning but the weather was bit a rubbish, so I began work on the Alternator today. After finding more bad workmanship around the pulley alignment I eventually got everything in place, but to my disappointment I found that the standard Model A fan belt is a few inches too long meaning that it will rub the radiator hose. So the search for a belt goes on….
As mentioned in my previous Alternator post I called Nu Rex in the States and they were very friendly and helpful.
They advised that I’d have to split the Alternator to be able to tighten the belt pulley which in turn locks the fan pulley in place. It’s apparently very rare for one of the pulleys to come loose. I’m wondering if the clearly incorrect fan belt was part of the issue?
Nu Rex advised that the centre of the belt pulley should not be shiny if the belt is the correct item or not worn out, as you can see we were wide of the mark on both counts!
I was also advised that the standard Model A Fan Belt is the correct item, and also to re black the pulley with a marker, which once it becomes shiny again will indicate belt change time.
Popped up to Simon’s and both he and his Dad gave me a hand to tighten the pulley and also lent me a piece of welding rod to lock the brushes in place to allow reassembly of the unit.
So it begins, out with the old and in with the new(er)
Started with removing the dynamo (strangely enough:-))
Please note that the dynamo may foul the distributor.
Got around this by loosening it off and turning it away from the dynamo.
Be sure to mark the position of the dynamo before loosening so as not too put the timing too far out.
I put a small felt tip pen mark on an HT lead to line up with the LT lead of the distributor.
The dynamo was then removed.
Tried a few test fits of the altenator with the various parts of the existing dynamo bracket.
It would appear the best way to do this is to remove all the existing bolts etc (including the large one in the alternator and dynamo picture above) and replace them with two different size bolts and a large amount of washers to ensure all the pulleys line up.
The Herald fan belt will also now be too short, I’ll pick up an new one when I get the bolts.