Need to find out the size of the U20 Lower Alternator Bolt

[Dan Magliari]

Murphy Struck!

So don't you just love it when something fails - minor but major.

This evening when I was working on my roadster gauges at a friends house, we noticed that the alternator was conspiciously loose (Hmmm, it shouldn't be bouncing around like this - should it?) . The upper bracket & Bolt were clearly secure, but upon inspection, we found that the lower bolt - that affixes to the motor mount, I discovered that the bolt was missing (oh oh!).

After removing the alterator from my U20, I discovered that the bolt failed (Looks like a bit of metal fatigue struck), and only the upper bolt was holding the alternator in place (yea, not optimal) (Just happy no disaster, only that I had to abandon the car in place till I can address this).

The bolt that failed was the lower alternator bolt - the larger of the two, that bolts into the motor mount.

Question of the hour: Does anyone know what the size of this bolt is? I will have to try to use an "easy-out" on the broken bolt, and hopefully, I will be able to just obtain a replacement bolt to replace the missing item with.

Feedback appreciated.

Dan

[70MTroadster]

I believe it is a 10mm and I cannot remember the pitch but 1.25 sounds right. I had done the GM alternator swap and moved it over to the cool side but my lashup(s) never worked well and I finally broke one of the long bolts off in the block. So.........I decided to move the 63 amp GM alt over to the original location. It barely clears the block and steering U joint but it works and has lived there for a while now. I used a grade 5 bolt too. Good luck.

Scott

[Dan Magliari]

Ahhh,

Now off to OSH I go. Think I'll stock up on a number of variations to avoid burning repeat trips for one stinking bolt

Hopefully I can extract the remains of the original w/o too much grief. (NOTE TO SELF: Better bring sufficient beer to bribe my friends who are helping). (Beautiful Sat. Tool bad I'm laid up )


BUT HEEEYYYY! I now think I've got working Temp, Amp, Oil ANNNND Fuel Gauges (Yea, we'll see if that fuel gauge really works after I burn some gas (Just because it's reading full (with a full tank) doesn't mean the job's done). Lets see in 50 miles when I should see some movement (hope hope hope!)

Thanks again.

Dan
Soon to be a happy 69 roadster running again with a happier Rebello 2.1L! (Fun while it runs!).

[Dan Magliari]

Indeed, this was a 10mm .125 pitch 70 length.

Drilling out the old bolt proved to be suprisingly easy
After removing the radiator hose, the alternator and the belt, there was sufficent room to get at the broken bolt with an angle drill to drill thru.

Very Scarrrry bolt. Don't know what the heck type of hardware the previous owner used (I expected grief in encountering Grade 5 or better steel), but the drill cut thru the bolt like it was butter (Upside though, it made for easy removal). After inspecting the broken bolt, we found a casting-void in the remaining bolt material surface that was where the break occurred (Yikes). Like I said, don't know the source of the original bolt, but quite cheap quality. Thank god this didn't fail on my way up to Shasta is all I can say at this point!

On the road now with a working Temp Gauge & a non-functioning fuel gauge. Sooo, feeling a lot better.

Progress!

Think I'll take myself for a ride for fathers day!

Thanks again.

Dan

[SLOroadster]

Dan, beleve it or not, the bolt is still in inventory from Nissan. I have a brand new one waiting to go in my car. Currently I am running a piece of all thread that is double nutted on both ends, using nylocks. It seems to work as its been in there for the better part of 2 years. I had the same issue when I was at shasta 2 years ago (what a trip )

Will