blocking locations to support a 420

[Ray III]

I went to Fred's toy store on Tuesday. That guy is awesome. He did show me and my friend his collection. Has a nice little museum in a classic old barn too.

He actually just posted here about the Lindeman clutch housing. Might be because I mentioned the site to him.

[Paul Buhler]

Ray:
I hope he had what you needed. I'll be stopping by to visit Fred for a few things soon. We spoke on Saturday an he said he has what I need. He said you had visited.

Our small world gets closer.

BTW, My tracks are at the pressman, and he'll be working on them as time allows. Paul

[Ray III]

Yeah, my front idlers are good to go. He has at least one left. I picked up some other goodies as well.

Thanks for telling me about him.

[Paul Buhler]

The story continues, but I need some advice. I have the track frames off and I'm replacing two bad rolls and cleaning up and repairing the frames and rock guards.

My question is what do people do to re-attach the rolls when the holes are stripped? There is not enough room in some places to use a nut, so I'm thinking to fill the hole with weld and re-drill and tap for a 1/2" fine thread bolt. Is there an easier good solution? Thanks in advance. Pictures below. Paul

[JimAnderson]

Paul,
There may been easier ways but what you suggest is what I've
done in the past.I take a counter-sink and vee out the hole first.
This makes it easier ,for me at least, to weld up the hole.I don't
try to close the hole but rather put enough metal in for good threads.
I grind the weld flush with the surface and bolt the roller back on
to establish the correct location of the repaired hole.I keep a Dremel
tool handy or a die grinder to round out the hole before drilling the
tap drill size.Hope this makes sense.Luck,JimAnderson

[Paul Buhler]

Thanks Jim. As always, you share good ideas. Can you be specific as to the drill and tap sizes? Torque to use? Thanks.

Some more pictures of the undercarriage rebuild below. Note the dirt piling (sp?) up. The fill is free, and the Town is happy to have a place to dump it where they (usually) don't have to move it, or worry about getting stuck; they promised not to bury the crawler - with one of those strange smiles.

[JimAnderson]

Paul,
Don't get her too pretty.Just kidding, nice looking machine.
I would recommend 1/2-20 threads.The 1/2-13 doesn't leave
many threads for the metal in the frame.It is only about 3/8"
thick.The tap drill size for 1/2-20 is 29/64.This gives 75% thread.
The easiest way to fix this problem involves a cutting torch
and nut.I have seen it done but would never recommend it.
Luck,JimAnderson

[JimAnderson]

Paul,
In answer to your question about torque values I'm afraid I
don't have an answer.The shop manual doesn't seem to specify
the torque values for the bolts holding the rollers in place.I can't
find them at least.Any generic charts are based on bolt grades,
grade 5 ,grade 8 etc.The track frames are mild steel and thread
engagement is not optimum for any generic torque values.Any
values I could give would be seat of the pants guess.With that
said maybe 45 to 50 foot pounds.Luck,JimAnderson

[Paul Buhler]

Jim:
Thank you.
My manual didn't have torque values either, but I did notice that they show lock washers being used. My machine has some and others are missing. I'll work up to the torque you suggest and see how it feels; don't want to pull any new threads out.

I think that using the fill welding and re- tap is as easy as welding in a nut, plus the alignment will be better; best of all, I found that I already have both the recommended bit and tap from some prior project. I only need to do about 4 holes this way.

Happily, I only need to work on one side. The other one has good rolls. I might have some reinforcement refitting, welding, filling, and grinding to do, but it should go relatively quick - famous last words.

As for the paint - it hides a multitude of worn parts, repairs, and mismatches. On the plus side it shows that I have a pretty tight machine - no significant leaks are evident.

And it does make the machine look pretty. Paul

[JimAnderson]

Paul,
you have the general idea.I would put a new lock washer under
the bolt.The bolt in my world would have never seize on it.A new lock washer would the keep bolt secure and the never seize would allow
the bolt be removed without breaking.The rollers have some support from the frame.Luck and best wishes JimAnderson

[Ray III]

I would also fill and redrill the hole. If thickness is a concern you can build up a large weld puddle on the other side to create a boss.

[Paul Buhler]

Hi: Here's an update on the track rebuild.

[Paul Buhler]

and some more:



So far I'm happy with the track rebuild. The price was much better than what I was being quoted elsewhere, and the work is of a good quality. Note how much less snake there is in my tracks now - I suspect they'll be quite a bit shorter too.

I had my 420 tracks rebuilt by Dan Moore in Ludlow, VT

email:danbarkerfarm@aol.com

He says that he is willing to work with others interested in having their tracks re-pinned and bushed. Contact him directly to make your arrangements. He has a lot of old equipment that he's restored/rebuilt and tools to help manipulate/handle tracks to get the job done.

To protect myself, caveat emptor: I'll say that I'm a satisfied customer based on my tracks, their needs and my timeline. You'll have to work out your own arrangements with Dan, and your situation may be different than mine. Good luck. Paul

[Dave T]

Have you thought about just opening the bottem roller mounting holes to 9/16 fine thread ? No worry about loosing the location of the taped holes, no welding, grinding or other dirty work. I did this on my 440 IC and it worked out well for me. Don't forget the new clearance in the roller mounting holes.

[Paul Buhler]

Paul,
The later Berco rollers(the ones you can get now) use 9/16"
bolts.In fact they even spec a very spendy bushing for use with
1/2"bolts.I see no reason that you couldn't use the 9/16 bolt.
You could always weld up the holes later if you wanted.I'd just
make sure you can get the bolts before tapping the frame rail.
I know they make them but finding them might be a problem.
Luck,JimAnderson

Dave: Thanks for the idea. Jim had shared the idea with me as well.

I've chosen to use 1/2" x 2" x 20 grade 8 bolts with lock washers and nuts. My 5 roll frame is boxed, and at some prior point, someone has cut access holes to most of the roll bolts. I like the idea of being able to torque new threads to new threads and make a solid sandwich. My middle rolls are fine and are bolted already so this repair is consistent with the rest of my undercarriage. I have to shorten/invert the bolts behind the track springs to give appropriate room.
I've learned that a 4 roll frame is not boxed and some don't have rock guard/stiffeners either, so I think that the boxing on mine, even with the access holes is stiff enough - it seems to have worked ok so far.

Thanks again for your thoughts - I always appreciate other people sharing their knowledge, skill, and experience - It gives me good options to ponder. Paul