Thread: Alternator swap

Originally Posted by circlework

You might get something out of the following thread ....

http://www.aulro.com/afvb/isuzu-land...lt-pulley.html

Daryl, yes I did see that post when I was hunting for a solution. Seems like you've been through the same exercise. But the post came to an abrupt end when you decided to throw away the car and keep the alternator . Did you come up with any magic solution or are you still running the 16mm belt on the inside groove of the twin 10mm pulley?

Originally Posted by captainslow

Did you come up with any magic solution or are you still running the 16mm belt on the inside groove of the twin 10mm pulley?

Pete ... sold the wife ... kept the car!
Magic solution was that Bearman (Brian) had a spare pulley.
If you can't find a single belt pulley, then another option is to get the double, turned down on a lathe to accept the larger belt.
See pic - courtesy 08Bender (Tristan).







Cheers.

Originally Posted by circlework

If you can't find a single belt pulley, then another option is to get the double, turned down on a lathe to accept the larger belt.

Yep, that's exactly where I'm heading. I spent half a day bouncing from one shop to the next trying to find a replacement with no luck at all. And this includes all the nationals like Deering, Ashdown Ingram and JAS. I did however get a 3 pin connector from JAS so it wasn't totally wasted. Got lots of sympathy but no pulley.

So its back in with the old one and I'll find someone with a lathe to modify the existing pulley.

Could be a while till I get back onto it - there are plenty of other jobs to work on - but I'll post up the replacement series when I get there.

Thanks again all
Pete

You've probably read it elsewhere, but the truck engines had 2 different styles of alternator bracket, a low one like the Stage1, and a higher mount one that I think was used for clearance when running an aircon compressor.
The high mount one definitely has the narrower foot spacing that suits your new alternator.
That's what I've fitted (but currently still running the original 40Aone with a spacer in the foot), but I think others have cut the original bracket length down to allow the narrower foot to bolt up.

Steve

Originally Posted by steveG

You've probably read it elsewhere, but the truck engines had 2 different styles of alternator bracket, a low one like the Stage1, and a higher mount one that I think was used for clearance when running an aircon compressor.

Steve, yes I think I'll go down the "cut the bracket" route. This is the bracket (below) that I've got which is around 100mm foot spacing. I plan to cut the difference off the rear of the mount.

In the mean time the hoses to the vacuum pump are all stuffed so thats another trip to the shops. Nothing is ever easy is it?

Originally Posted by captainslow

Steve, yes I think I'll go down the "cut the bracket" route. This is the bracket (below) that I've got which is around 100mm foot spacing. I plan to cut the difference off the rear of the mount.

In the mean time the hoses to the vacuum pump are all stuffed so thats another trip to the shops. Nothing is ever easy is it?

If you're talking about the oil feed line to the vac pump, I ended up buying genuine after trying to have one made up with normal industrial fittings. Industrial fittings (from Pirtek IIRC) just weren't a good fit and I wasn't happy with them. Think the genuine hose was around $100, but considering the old one was was probably original (so lasted 25+ years) I was happy to pay the money for a good fit and peace of mind. Think the Pirtek one was still around the $70 mark anyway.

Steve

I finally managed to get a 1B pulley for the 70A alternator and have installed it successfully. Thought I'd put up some notes just in case it helps anyone else going through the same process.

To recap, this is replacing the standard Denso 40A alternator on a NA 4BD1 with a 70A LR170-401. The 70A alternator has an internal regulator compared to the external regulator of the 40A.

The parts I needed to purchase were:-
LR170-401 Alternator from Discount Starter& Alternator in the US for $135. Had a business contact in the states who shipped it to me for free
You'll see from the above posts it came with a dual pulley. Finally found a 1B pulley at a Deering outlet (tried lots) for $20
Electrical connector from JAS for $13
11/32 brake vacuum hose at $15/metre from a brake shop
The oil feed and return hoses fit fine onto the 70A but the vacuum outlet needed to be replaced with the hose.

First job is to cut the alternator mount down to 82mm from 100mm.




But before doing that - drill and tap the end to be cut - this was a tip from Bearman on another post - thanks! The thread is 10mm x 1.5



Then it's out with the hacksaw and files to remove the tail end of the mount.





The pulley didn't quite line up with the fan pulley so I had to add a 3mm washer behind the pulley to get it perfectly alligned.



Next comes the electrics. I wanted to keep loom changes to a minimum so instead of adding a relay to drive the charge lamp I used the relay that is in the external regulator used by the 40A. This means shuffling a couple of wires - but no new wires required - easy!
Here is an outline of the old to the new:-


At the alternator end I removed the wires from the 40A alternator connector and re-plumbed them into the 70A. This required an earth terminal to be added on the 70A (there was already a threaded, named, hole for it. The sense line (red from the 70A connector) was connected directly to the alternator output. Theoretically this sense line should go all the way back to the battery - but the output of the alternator goes straight to the starter motor then via a large feed cable to the battery, so there isn't much of a volt drop between the battery and the sense line. In practice this worked fine.





At the Regulator end its a matter of shuffling the Ignition wires (white), reconnecting the yellow wire to one of the removed white wires. It's a bit hard to explain but here are some before and after shots...





And, it's all done! The internal regulator regulates much better than the old external unit - and I can now charge the batteries even with the lights on (bonus - the old 40A was getting a bit tired).

Hope this helps out someone who is thinking of doing the same thing.

Cheers
Pete

I was wondering why you needed to drill and tap a new thread for alt mount bolt-isn't it already originally threaded?