1200 Alternator Direct Swap Upgrade

[mike.lovell127]

16 hours ago, datsunfreak said:

Here is the most recent one, not the best pic, but...

 

I appreciate the photo, and sorry if my post had a bad tone to it. I was frustrated at the time, but I have a couple questions about the swap. 

 

How did you mount the bottom of the alternator? With the top mounted on the same tab that you have it in your photo, it doesn't seem to line up to the original bracket on the bottom regardless of how the top is adjusted. Also do you use the original size belt or switch it for a bigger one? TIA and sorry for coming off as an a**hole if I did. 

[datsunfreak]

6 hours ago, mike.lovell127 said:

How did you mount the bottom of the alternator? With the top mounted on the same tab that you have it in your photo, it doesn't seem to line up to the original bracket on the bottom regardless of how the top is adjusted. Also do you use the original size belt or switch it for a bigger one? 

 

In my experience, the lower mounting tab (the thicker, non-threaded tab), bolts onto the radiator side of the stock mount fine. Then, on the upper end, you have to flip the stock bracket around to attach to the upper tab (thinner, threaded tab) from the back side. That is visible in the above photo. 

 

Did you attach the upper slider bracket to the back of the alternator, or to the front? 

 

I have used the original belt every time I have done this swap on a running/driving car. But at least half the time, it's been on a fresh build that needs a new belt anyway, so tougher to say on those. I usually just measure it out and buy the belt I need, rather than getting hung up on using the "correct" belt. Make sense? 

 

7 hours ago, mike.lovell127 said:

sorry if my post had a bad tone to it. I was frustrated at the time... TIA and sorry for coming off as an a**hole if I did. 

 

You kinda did, but it's cool.  😁

 

I will do whatever I can to help talk you through it. I can take some better photos tonight, if need be. Just let me know. 

[datsunfreak]

Also, you did loosen the bolt that holds the slider bracket to the timing cover, right? 

 

Side note, it's a good idea (once you have it mounted) to run a new fat wire from the output post on the alternator to either the battery cable connection on the starter or the battery itself, in addition to the stock output wire. I always go to the starter because I often move the battery to the trunk. But if you're battery is in the stock spot, then that works best. 

[mike.lovell127]

On 10/2/2024 at 5:47 AM, datsunfreak said:

 

In my experience, the lower mounting tab (the thicker, non-threaded tab), bolts onto the radiator side of the stock mount fine. Then, on the upper end, you have to flip the stock bracket around to attach to the upper tab (thinner, threaded tab) from the back side. That is visible in the above photo. 

 

Did you attach the upper slider bracket to the back of the alternator, or to the front? 

 

I have used the original belt every time I have done this swap on a running/driving car. But at least half the time, it's been on a fresh build that needs a new belt anyway, so tougher to say on those. I usually just measure it out and buy the belt I need, rather than getting hung up on using the "correct" belt. Make sense? 

 

 

You kinda did, but it's cool.  😁

 

I will do whatever I can to help talk you through it. I can take some better photos tonight, if need be. Just let me know. 

I really appreciate that.

 

From the picture/response you shared I realized why I may have been having trouble with the mounting. I have a 78' 620 pickup, and there is a compressor mounted directly above the alternator and next to the battery for AC. Your mounting tab with the slider up top seems to be slightly different than mine. Mine seems to be one solid piece with the mounting bracket for my compressor (as far as I could tell), so taking it off and flipping it and/or loosening it to adjust the placement wasn't an option. Since it was too high up I mounted the top of the alternator to my slider bracket, and using a 3/8, 2in x 2in plate I bridged the gap to the alternator's bottom mount to bolt it to the original alternator mount. It took a lot of time figuring out spacers, grinding the plate and the top alternator tab to make sure the belt pulleys lined up and were at the correct angles, but I have it mounted and lined up now. I measured for a new belt and now all that is left to do is install the new belt and run a wire. 

 

I am planning on using 10 gauge wire and connecting it directly to the battery. Since It will only take around 3ft or less of wire to do so I figured it would be okay. Would you recommend using a fatter wire than 10 gauge?

 

Lastly, since this alternator is internally regulated is there anything I need to do as far as how the stock alternator was set up, or is it good to go once the new alternator is wired in?

 

Thanks again.

[datsunfreak]

On 10/4/2024 at 7:11 PM, mike.lovell127 said:

From the picture/response you shared I realized why I may have been having trouble with the mounting. I have a 78' 620 pickup, and there is a compressor mounted directly above the alternator and next to the battery for AC. Your mounting tab with the slider up top seems to be slightly different than mine. Mine seems to be one solid piece with the mounting bracket for my compressor (as far as I could tell)

 

Aha! The dreaded aftermarket AC compressor bracket that screws everything up! 😄

 

On 10/4/2024 at 7:11 PM, mike.lovell127 said:

I am planning on using 10 gauge wire and connecting it directly to the battery. Since It will only take around 3ft or less of wire to do so I figured it would be okay. Would you recommend using a fatter wire than 10 gauge?

 

10 gauge will be fine. I think the stock wire from the alternator to the fusebox is 10 gauge, and this will be a MUCH shorter run. And that's what I have always used with good success. 

 

On 10/4/2024 at 7:11 PM, mike.lovell127 said:

Lastly, since this alternator is internally regulated is there anything I need to do as far as how the stock alternator was set up, or is it good to go once the new alternator is wired in?

 

If your truck came with an internally regulated alternator (and it should have), you should be just fine. If it has an external regulator, you just need to unplug it and take it out. There are 3 wires to your stock alternator, main power feed, and two small wires in a T plug. Hook up the main power feed but not the other two wires. 

[ggzilla]

The original pics are no longer available ... but I'm guessing those marine alternators are Hitachi LR units. Good to know that the 90A version fits the same as the LT150 that came in B210, 610, etc. Starting in 1978 most USA Datsuns came with factory LR 50A alternators

 

Datsun 1200 came from the factory with a RL alternator -- the Hitachi LR135 from october 1981. Aside from the connector wiring, it is a direct bolt-in for the original 1971-up LT135 alternator used by the Datsun 510 and (early) Datsun 620. Plus it is internally regulated they as inexpensive as $49 at RockAuto or do like I did and get a spare from Pick-n-Pull for cheap. So inexpensive got two of them -- one to swap into my 1200, the second for a backup

 

The 50A LR are about $100 at RockAuto

 

70A LR170 starts at $94 at RockAuto. Same price for the 80A. 90A is $125. For all these need to swap the belt pulley

 

CONNECTOR

The LR connector is slightly different, but the LT connector fits into an LR alternator

 

TWO PHYSICAL SIZES

The 620, 510 and 1200 used the smaller LT135/LR135 for which the larger 50-90A ones may or may not fit. On a 1200 the bigger units fit with a slightly longer belt and the newer adjuster (early adjuster don't have enough range for the 1" bigger diameter alternator). More details at Hitachi LR Alternator

 

WIRING

For externally regulated Datsuns, disconnect the regulator and jumper the connector as previously outlined. Here are some graphics

 

 

store-bought adapter which does the same thing