can't fix stupid

ScottNC · Mar 7, 2018

While rebuilding my DB885's starter I managed to lose the nut that goes on the small stud exiting the case. Me thinks it could be a less than common metric thread pitch. Might be inch but given it's a Lucas...

Of course I stuck the starter back on the tractor before finding it wasn't going to be as simple as digging though my stash of nuts. Any guess what diameter and thread pitch replacement nut I am looking for? I hate working over gravel.

Brokengun · Mar 7, 2018

Is the nut brass or steel? If its steel get yourself a big magnet on a stick and go nut fishing.

oldproudvet · Mar 7, 2018

Definitely not metric, and to new to be British whitworth, so you just may be in luck...........

joestewart · Mar 7, 2018

Pretty sure its 3/8" national coarse

ScottNC · Mar 8, 2018

(quoted from post at 18:30:44 03/07/18) Pretty sure its 3/8" national coarse

Nope, at least not this one. Fine thread, smaller than 3/8". First thought was 5/16" NF but it wasn't close. Tried what I believe was a fine 8mm (.75?), it screwed on maybe a third the way before binding making me think it might be one of those one-off thread pitch deals. Have seen them before, guns mostly. Didn't want to force the issue to the point of making a mess of the stud. Looks like the starter has never been off the engine prior to last week so I feel it is as Lucas made it. To provide balance to the stud nut there is at least one odd size nut that Lucas put on the solenoid that no wrench seems to fit. Original nut looked like copper. It disappeared while washed parts with a syphon gun and gas on a gravel pad with the expected results.

Guess I need to see if a caliper will fit in there to measure the stud or pull the starter and measure it like I should have to begin with.

ScottNC · Mar 8, 2018

(quoted from post at 16:53:10 03/07/18) Definitely not metric, and to new to be British whitworth, so you just may be in luck...........

Ooooo, Whitworth. What you said. Need to look into that just to be sure, too new or not.

fixerupper · Mar 8, 2018

I had a 1970 Triumph motorcycle that was whitworth but that’s as far as I can go with information.

Determined · Mar 8, 2018

Do you have a tap and die set?

joestewart · Mar 8, 2018

I'll check my 885 on Saturday. Just to be clear, we are talking about the studs / bolts that hold the starter to the clutch housing, right?

gusbratz · Mar 9, 2018

I had a triumph that was whitworth in highschool and have played with the lister diesels as well. I think the whitworth thread is a not a 60* V like the metric or NC which is what caused the problem. most of the the pitch and diameter are the same as NC. you measure it and then think ok I got that and it won't screw on. a lot of old stuff is so worn that an NC nut will go right on and you never notice. I would just chase it with a die.

PartsMan79 · Mar 9, 2018

The parts book says.
"NUT, 5/16 BSF, special, solenoid terminals. (885 gasoline)"

I am guessing that BSF means British Standard Fine.
Sorry!

ScottNC · Mar 9, 2018

(quoted from post at 16:12:41 03/08/18) I'll check my 885 on Saturday. Just to be clear, we are talking about the studs / bolts that hold the starter to the clutch housing, right?

No. This is the stud that the wire from the solenoid attaches to on the body of the starter. It supplies battery voltage to the starter when the solenoid is activated. On the old style GM starter it was a flat tab that stuck up right under the rear of the solenoid, a screw passed through it. Lucas uses a short length of heavy gauge wire for the same thing, the stud being offset slightly to the block side of the starter.

I'll have time tomorrow to see if the stud can be reached with a caliper, if not I'll take it off and not put it on without a suitable replacement nut. Don't have a metric thread pitch gauge but I might before the weekend's out!

ScottNC · Mar 9, 2018

(quoted from post at 09:12:00 03/09/18) The parts book says.
"NUT, 5/16 BSF, special, solenoid terminals. (885 gasoline)"

I am guessing that BSF means British Standard Fine.
Sorry!

It's a diesel but I seriously doubt that matters. Does that mean a 55 degree thread pitch and one off threads per inch? Rats.

Just Googled it, yes it does mean 55 degree and 22TPI to boot. Think I'll call a starter/alternator rebuilder or two.

L.Fure · Mar 9, 2018

That nut didn't leave the planet, and it didn't burn up on reentry either. It has to be somewhere between where you worked on the starter and the tractor. You'll just have to genuflect before the lost parts Gods until it shows up.

ScottNC · Mar 10, 2018

(quoted from post at 17:13:41 03/09/18)
That nut didn't leave the planet, and it didn't burn up on reentry either. It has to be somewhere between where you worked on the starter and the tractor. You'll just have to genuflect before the lost parts Gods until it shows up.

While I appreciate that it is still there, laying, likely in full view amid the gravel of my driveway, until the L.P. Gods see fit to acquiesce, I think I'll visit the Lexington, NC starter/alternator rebuilder this morning. He said he's familiar with Lucas, David Brown tractors and has the nut in question.

Might eat some BBQ while I'm in town.

Thanks to all for the help.

kenbob · Mar 10, 2018

make an offering of Gojo or wd40

can't fix stupid

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