150A Alternator Upgrade

I decided to upgrade the alternator on my Jimny, after a bit of research into sizes and mount styles I decided on the 150A unit fitted to the Suzuki SX4 as this had a 2 wire plug also and the pivot setup was similar with how it mounted.

So......

I purchased a unit from a reputable eBay trader, here it is with the standard 70A unit fitted to my Jimny.



I sat it in place and started working out exactly what I needed to do to get it in.

The pulley was the clutch type and 6PK instead of 4, this is nothing major as the 4PK belt will fit into the 6PK grooves but I wanted a shoulder either side of the belt. Here is the standard pulley and the clutch pulley, the shaft sizes are totally different.



So I purchased a solid 4PK pulley, just slightly bigger in size than the standard to increase surface area for the belt to wrap round, in the correct bore size as I needed. Technically this changes the power curve of the alternator as it slows the core speed down at base idle but it won't be an issue for me. The rear mount was too close to the front of the vehicle, I needed it to be further back If I wanted to use it, so I checked the hole spacings and rotating it 180 degrees was giving me clearance to allow me to start sizing it up while keeping the pivot hole on the same axis. Using threaded rod I worked out the front to back spacing to ensure the belt lined up, shimming it up with washers to get it sitting just where I needed it. I got a base line of where it was going to sit and got my sizes. The rear mount needed a boss to act as a stop. Here it is sitting normally as you would see it in the vehicle.



And here it is with the boss welded in place ready for fitting



I could have used the front mount with some spacers welded to it but its quite thick and I wanted to run an idler pulley to again increase the surface area of the belt by wrapping it round a little more as it came up front the crank pulley, so I copied the mount onto a bit of 6mm flat bar. Simply by drilling the 10mm hole in the steel and clamping it down, then 1 of the 8mm holes and clamping it again. This gave me the exact shape I needed and out the grinder came.



By saving a few mm in thickness it set the idler back slightly just enough to where I wanted it to sit. This also needed a couple of boss's to get it sitting just right so it fully clamped the alternator bracket when fitted. Note the small mount I ground away on the front of the engine, this is to make space for the belt to run in its new position.



I already knew the top tensioner mount wouldn't work, it was too vertical with the standard Jimny tensioner point, so a small push rod was made and a boss used to space it. I decided to have the rod at the rear of the mount as it allowed me to fit everything up easier.



Once it was all sitting in place I measured it up for a belt, a 4PK900 was what I needed. Grabbed one from the local motor factors and that allowed me to eye through the belt to see if my measurements were correct. They were.

First fit everything was spaced with washers as I said already, so when I pulled it out to make the boss's I set about the wiring. The standard Jimny 3 terminal plug was cut off and the relevant plug for my alternator was fitted. I grabbed one from a Pug 208 in my local breakers yard, they're a really common plug on those. Think I chopped it off a fuel pump or something. Pic of the socket.



I sat the alternator on the bench and span it up with an impact gun with doing some checks, located the exciter connection, I gave this a 12v feed from a booster pack with the neg clamp on the alternator case, and you get an output at the main terminal. So that was the plug wiring worked out. A new 35mm cable was ran from the alternator to an automotive circuit breaker on the bulkhead, then from there to the battery. The old cabling was made redundant and heat shrunk then tied up out the way.



With that done and the boss's fitted to the mounts etc I fitted the assembly to the jeep adding in a nice long 10mm bolt for the pivot, obviously I had taken the radiator, fan etc out to access the alternator so I had plenty room for all this. Chucked on a new power steering belt and reassembled the cooling system.

Here's some pictures of the alternator in place and fully plumbed in.







Ideally I would like a larger diameter idler that is nearer the width of my belt, but the one thats on it will do for now. Everything works as it should, power to the winch is obviously increased by just over 200% in theory. Theres always someone in the vehicle when the winch is used so lifting the idle a little isn't an issue to reach peak power output. I'll probably fit a choke style lever and cable to act as a rev lifter, bit like the PTO on lorries etc, just to make the job easier. Teamed up with the optima redtop battery its probably the best single mod I've done in terms of how it improves the winch.

Thanks for taking the time to do a write up. Provides an additional option for those considering a higher output alternator.

Good job and write up mate, thanks for sharing.