WTB L-16 Lower Alternator mount

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farmer_fred
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WTB L-16 Lower Alternator mount

Postby farmer_fred » 10 Jul 2017 09:04

We are dropping a fresh L-16 into my wife's 72 510, replacing a tired L-18 of unknown build. I cannot lay my hands on the original alternator bracket and the L-18 version is very different.

Anyone have one they'd part with?

Thanks,

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RMS
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Re: WTB L-16 Lower Alternator mount

Postby RMS » 10 Jul 2017 09:51

I have many. whats your location ?
two_68_510s wrote:I guess our donkeys are quicker then your sled dogs!

farmer_fred
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Re: WTB L-16 Lower Alternator mount

Postby farmer_fred » 10 Jul 2017 09:54

Sorry! Knoxville, TN 37917

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RMS
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Re: WTB L-16 Lower Alternator mount

Postby RMS » 10 Jul 2017 10:05

be $16+ in shipping from v6v1l6..... if no one closer has one I got ya covered
two_68_510s wrote:I guess our donkeys are quicker then your sled dogs!

farmer_fred
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Re: WTB L-16 Lower Alternator mount

Postby farmer_fred » 11 Jul 2017 04:19

I "think" my wife has found one stateside via some other social media platform. Thank you for checking.

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Re: WTB L-16 Lower Alternator mount

Postby farmer_fred » 15 Jul 2017 06:21

Well, the bracket my wife found via FB arrived. It has two holes and appears to mate to the threaded holes in the L-16 block, but the holes in the bracket appear to be for 10mm bolts like the L-18 bracket and block, where the threads in the l-16 block are 8mm:

Image

Seems pretty sloppily aligned with the 8mm bolts. Is this a standard L-16 part?

Thanks!

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Byron510
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Re: WTB L-16 Lower Alternator mount

Postby Byron510 » 15 Jul 2017 07:24

The later L16 blocks did upgrade to the 10mm bolt size and this continued right through production to the end of the L series engines.
If the holes in your alternator accept a 10mm bolt, I would suggest drilling and tapping these to the larger size as well. Another good trick I've done is drill the mount right through and use a single bolt. Nissan eventuallly did this as on all mount as it allows a proper locking nut to be installed so that these bolts don't loosen off - which they have a tendency to do.

Just a few thoughts from a guy whose fought with these in the past. My rally cars were especially hard on these mounts and mounting configurations.

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okayfine
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Re: WTB L-16 Lower Alternator mount

Postby okayfine » 15 Jul 2017 07:34

Definitely drill the mount to accept a 10mm through-bolt for the alternator. The stock 8mm bolt is well known to snap from the loads.

The OP appears to be saying that the mount he has takes 10mm bolts to the block, however. I don't recall this being on L20Bs I've had more recently, but then it's been a while.
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Re: WTB L-16 Lower Alternator mount

Postby farmer_fred » 15 Jul 2017 11:33

Yes, I am talking about the bolts that fasten the alternator mount to the block.

On the L-18 we pulled out, there are three 10mm bolts holding on the alternator mount. The L-16 block has two 8mm threaded holes, but the two-holed mount above has the same sized holes (for 10mm bolts) that the L-18 three-hole mount has. Seems a little loosely aligned but I supposed we could sleeve the holes to keep the bolts centered.

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Re: WTB L-16 Lower Alternator mount

Postby datzenmike » 15 Jul 2017 15:51

Imagine sitting in a stool with two legs. It tends to rock around a line drawn through where the two legs touch the ground. The L16 alternator mount is the same way. I know all L20B (and maybe the L18?) Have three bolts. A tripod is the most stable stool there is..
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

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Re: WTB L-16 Lower Alternator mount

Postby farmer_fred » 16 Jul 2017 05:52

datzenmike wrote:Imagine sitting in a stool with two legs. It tends to rock around a line drawn through where the two legs touch the ground. The L16 alternator mount is the same way. I know all L20B (and maybe the L18?) Have three bolts. A tripod is the most stable stool there is..


Totally understood. But as I used to tell the tire-shop guys when they put tires on my Le Car and asked "You trust that thing going down the road with only 3 lug nuts?"

"Since there's no way to add a fourth, yes." I don't have a way to add a third mounting hole to my L-16 block.

I did find this in my parts book. #37 looks very different from either of the mounts I have here:

Image

Current plan is to figure out sleeves for the 10mm holes in the mount and use higher quality 8mm bolts.

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Byron510
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Re: WTB L-16 Lower Alternator mount

Postby Byron510 » 16 Jul 2017 08:27

As noted in your drawing above, there are a few oddball exceptions.

The three bolt mount to the block started on late L16 block, but I have seen early L18 blocks with only the 2x 10mm mount configuration (still better than the 2x 8mm used on most L13/16 blocks).
I have also seen the 2x 8mm fabricated steel mount shown above on an L16 once, but I can not recall the year or origin of that application (may have been a crate motor).

In most cases, broken bolts on either the bracket to block or alt to bracket mount are due to bolts first loosening off, then breaking due to twisting. I even once saw the cast lug on the block broken away on an L16 due to the bracket coming loose and twisting under load.

My suggestion is to use the 2 bolt mount you have to the block, but make sure the fasteners you use fully enguage the full depth of the block threads and have a sufficiently thick flat and lock washer in place. Another thought is to use exhaust manifold studs lock tighed into the block, and then using nuts and lock washers. Bushing up the holes certainly assists in the integrity of the mount fixation and helps with alignment.

Regarding the alt to bracket mounting, drilling a through hole and using a quality grade shanked bolt with proper flat and lock washers with a self locking nut is the best route from my experience from a reliability point of view. That said I have not had a 2x 10mm mount ever fail on me. (I have however had more than 1 2x 8mm fixation fail in my youth, but it may have been due to the reasons I'll cover below). However drilling this long hole is a bit of a pain, and the mount should be mounted to an angle plate on a drill press at minimum to complete the drilling in order to maintain good alignment. Otherwise, I suggest as above for the block mount, good quality bolts with full enguagement (the threaded holes are quite deep, use it all) with thick flat washers and a new quality lock washer. Also as noted in your bracket, take note of the size of the holes in your alternator mount, it's a good chance that they are larger than the bolts you are using if it's not an OEM unit, and may also need bushing down. Again this is a detail that many overlook, and I feel this is often the reason for failure of bolts at this location.

Just a couple thoughts, who'd have thunk bolting on an alternator would be such a PITA!

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farmer_fred
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Re: WTB L-16 Lower Alternator mount

Postby farmer_fred » 17 Jul 2017 04:15

Well, amazingly, we now have three different versions here. Here's the 8mm-hole two-bolt version next to the 10mm-hole two-bolt version (same 8mm bolt in both):

Image

I guess we'll go with this one for now, after attending to the bolts that attach the alternator. Thanks for all the advice!


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