T-20 mounting bolt hole repair

[Rusty-Gunn]

Several months ago two bottom righthand-side mounting bolts broke off the T-20 while drivinf our Max IV , leaving their broken shafts stuck inside their bolt holes.
In an effort to exract these studs I buggered up the holes ugly. UGLY.
I decided to drill these out to half-inch and insert a steel plug in each hole. I chose half-inch because this size would clean up the ugly bolt holes. These holes were threaded first, then the plugs glued in with JB Weld and torqued in tightly. Plugs were actually carriage bolts. I cut the heads off flush to create the plugs.
These plugs were then drilled out to use a 3/8" bolt.
I made a wooded jig to be sure the new 3/8" holes would be drilled correctly.
I did the drilling freehanded, as my drill press is not tall enough for the T-20 to fit in.
Overall I am satisfied with my efforts to fix my T-20 mounting bolt holes.
Pics are in my gallery here: http://www.6x6world.com/gallery/g138...le-repair.html

[Canadian_Zuk]

Looks good!

[Rusty-Gunn]

Thank you Canadian Zuk. I do appreciate it.
A few notes regarding this repair...
I drilled out the buggered-up holes to 27/64", which is suitable for half-inch threads. Once the holes were drilled I cut 12"-13 threads. Due to the tapered tap it would not cut threads well enough deep within each hole. So I carefully ground off most of the taper so the tap can go deeper and cut threads more better. I wanted maximum amount if threads for the best possible repair. I also measured the depth of the holes to match the factory holes, so as not to drill into the plunger bores.
I then used JB Weld to glue in the steel plugs (carriage bolts) and torqued them in tightly. I chose carriage bolts because they are stronger than aluminum but soft enough to drill out.
Next I cut the heads off of the carriage bolts with a hacksaw, and filed them flush with the casing.
I made a wooden jig to properly locate where the new 3/8" holes needed to be. I used a center punch to create a dimple, then drilled a pilot hole.
Note in pic above that the dimple appears off-set. This dimple is actually where it needed to be, its the plug that is off-set to clean out the buggered- up holes. Odd appearence though.
I then drilled 5/16" holes in the plugs, then threaded them to take a 3/8"-16 bolt.
I am satisfied with how this whole thing worked out. I got the idea from Max Rules (Brandon, if I remember correctly). I seen one of his videos recently.
My next step is to fabricate a bracket to assist in holding the T-20 on the frame. The rear top holes (bolts) on the T-20 do not fasten to the frame, as does the front top bolts. I will use Amphibious Drew's idea and make a bolt-on bracket.

[msafi65]

Good job Don. Those that have broken drills and extractors can be a nightmare. One other thought for others trying this. I've had to use a 9/16" hole saw to "core drill" out the hard broken stuff. This will break through on the rear bolts and usually has to have the insert welded in. With the price of a case and gaskets a repair is always worth the try.

[Rusty-Gunn]

Its worth a try. I was unable to use my drill press since its sits too short. I expect to change out that two-inch tube to one at least three feet long, thus allowing for drilling into taller things. All my efforts were freehanded.
Not 100% accurate, but the T-20 fits in.

The wife and I began to fabricate upside down "L" brackets to fasten the top rear transmission bolts to the rear frame area. These brackets are bolt-in style, so the T-20 can still be removed (the fronts are welded at the factory). Amphibious Drew warned about the bottom bolts can break off, and using rear framing to assist in keeping the T-20 immobile can prevent these bolts from breaking off. Had I done this mod last summer those darn bolts would not have caused me the trouble they already have.
All this is fun though. I enjoy working on things.

[Rusty-Gunn]

Update... We got the T-20 mounted in, as well as the rear frame brackets. It took us three days to do this, a work. nd I am happy to report the Max runs fine. We took it out for a ride on a seven mile dirt road. Ran smooth.
After having it sit for two months needing it's repair it was indeed fun to drive it again.
We are planning to ride tomorrow down the coast line. This will ne fun.
Repairing buggered up mounting bolt holes could have been prevented if I had not procrastenated and done the rear brackets last summer (I had said I would do them this summer) as Amphibious Drew recommended everyone do to their Max IV's. Live and learn. Or is that ignore and learn?