Damaged threads in shifter set screw hole

[rmaynard 15,608]

I started to disassemble the transmission on my Commando 8 in preparation for sand blasting and found that the dog-point set screw that holds the shifter was loose. Not only loose, but wobbling. After removing it, I found the problem. Apparently someone in the past had attempted to drill out a broken set screw and used too large of a bit, as well as drilling off center. This leaves me with a hole that is slightly out of round and threads too weak to properly hold the set screw.

Unless someone has an alternate suggestion on a repair, I am going to attempt a repair by installing 1/4-20 Helicoil.

Any other suggestions are welcomed.

[VinsRJ 723]

Bob, I would say that is your best bet. If the hole is off center that may be the biggest issue (getting centered).

I have welded up the holes before and re-drilled with a fresh No. 7 drill bit.

[rmaynard 15,608]

The original threads are still there, but they are very thin on the upper right portion of the hole. I think I can center the tap though without a problem.

[TT-(Moderator) 1,145]

I've seen quite a few "opened up" to 5/16-18

As long as the point of the set screw fits in the hole on the shifter ball, the thread size doesn't matter.

[AMC RULES 37,134]

Any other suggestions are welcomed.

Umm...how 'bout a bagel and schmear Bob? :ychain:

[rmaynard 15,608]

I've seen quite a few "opened up" to 5/16-18

As long as the point of the set screw fits in the hole on the shifter ball, the thread size doesn't matter.

I thought about a 5/16" but the bottom edge of the locking nut would hit the case. I could grind a little of the case off it necessary.

[Fun Engineer 859]

So will you make a new set screw? Do you think you'll need to use a grade 5 or 8 for this? The reason I ask is my spare Commando Trans had a broken set screw and I'm thinking I should replace it but didn't know if I could get a WH replacement. Times a ticken away Bob. Are you bringing the Commando to the PA show? Any new pictures?

[rmaynard 15,608]

So will you make a new set screw? Do you think you'll need to use a grade 5 or 8 for this? The reason I ask is my spare Commando Trans had a broken set screw and I'm thinking I should replace it but didn't know if I could get a WH replacement. Times a ticken away Bob. Are you bringing the Commando to the PA show? Any new pictures?

If the tractor gods are willing, I will be there with the Commando. If you got your broken set screw out, Toro still sells replacements, and your can get them from McMaster & Carr.

I think they are just grade 5.

I am going to go the route of using a helicoil. Then I can put the good set screw that was already in the hole back in.

[bowtiebutler956 650]

I personally like helicoils, they got me out of alot of jams, and work well when installed properly.

Matt :flags-texas:

[rmaynard 15,608]

I've used them on spark plug holes in aluminum heads, but never in cast iron. First time for everything.

[Martin 2,133]

just a fyi on the dog point set screws.

the ones that you get from toro dont look the same as the oem. when i did my last trans i got the mcmaster carr crew which is the same exact screw dimension wise.

heres the posts from the trans build regarding the set screws.......

just thought id add another p/n

the dog point set screws for the shifter are available through mcmaster carr

95289A347 but they come in a pack of 25 for $10.60. would be nicer if they were sold in a smaller qty but i figure ive used three already for what i have here, and toro want $4.25 for just one.

i think id rather buy 25 of them and have them laying around, they look identical to the one i took out and im sure i will use them up eventually...........(maybe)....

Martin, I could really use about 5 of those set screws if you want to lose a few. Willing to buy them or trade next time I see you.

I've seen Denny's shop...you could eat off the floor.

You guys have a great Christmas and a Happy New Year as well.

just thought id add another p/n

the dog point set screws for the shifter are available through mcmaster carr

95289A347 but they come in a pack of 25 for $10.60. would be nicer if they were sold in a smaller qty but i figure ive used three already for what i have here, and toro want $4.25 for just one.

i think id rather buy 25 of them and have them laying around, they look identical to the one i took out and im sure i will use them up eventually...........(maybe)....

Plus the ones from MCMaster are the right length. The last ones I got from toro were way to long and not the long dog point. Mike

heres a pic of the mcmaster one installed. because ive used a thicker flange nut not as many threads stick out from the end of the nut.....

bob, i think the helicoil is probably the right way to go. at least you can use the correct size set screw for the job. once its all said and done you wont know the difference anyway, im sure the lock nut will cover the repair.........

[bowtiebutler956 650]

Bob I've used them in cast iron many times with no problems whatsoever. I've been an automotive mechanic now for almost 20yrs, and they have saved my bacon on many occasions. I wouldn't recommend it, but once many years ago I had to stack a couple on top of one another for a head bolt thread on an old Cub Cadet Lo Boy. I was still running great when I got rid of it. Like I said though, I wouldn't recommend it, but it was that or replace the block.

Matt :flags-texas:

[can whlvr 993]

ive done the larger dog screw many years ago on my 308 and it worked great and is still working great,heres some pics of the repair

[rmaynard 15,608]

Follow-up...

I picked up a 1/4" Heli-coil kit today. After drilling the hole to 17/64", I tapped it, and inserted the Heli-coil.

All is well.

Thanks for all the suggestions.

[bowtiebutler956 650]

That's good news Bob.

Matt :flags-texas:

[Anglo Traction 761]

Nice work Bob ! , that's another damage limitation repair job ticked off the list. Gives you that warm feeling that you can't be beaten by the 'Bodgers'

[SousaKerry 501]

I personally hate helicoils I use Keenserts they work much better and are much stronger. At work we install them on new equipment on purpose especially on aluminum parts that are removed frequently like die sets