SM420 - Grinding the case, advice needed....

[brooklyn]

Installing a SM420 in a FJ40 and it looks like the front drive shaft is going to rub on the case. I know some people grind the case to make it fit or grind the flange, but is there any other way to make this work? I am using a NOS Military SM420 and it is replacing a non-military SM420 that was grinded by the P/O.

I have researched this and have seen many discussions about the sm420, but nothing regarding a possible work around.

[Pin_Head]

You can use the Extreme Bends plate adaptor and no grinding will be necessary. If you are replacing a tranny that was ground, chances are you don't have an EB plate. Just grind the new case about 1/8 inch. The flanges must be ground to minimum diameter first. What's the big deal?

[brooklyn]

Well, I have read that the grinding can result in putting a hole in the side of the case, which can't be welded and then you're working with epoxy and all that fun stuff.

If think I will call Extreme Bends and see what they have.

I just wish the dollar as was doing better against the Canadian dollar...

[e rock]

Originally Posted by brooklyn

Well, I have read that the grinding can result in putting a hole in the side of the case

The case is about 1/2" thick there (or more?).

Even though I just can't see anyone actually grinding all the way through the case there, I suppose you could use a cutting wheel and make a little cut 1/8" deep through the middle of the section to be removed. Then when you're grinding the area flat, just stop when you get to the bottom of the cut.

You're worrying too much about this.

[Pin_Head]

The case is approx 3/8 thick. You have the one that is already ground as a back up if you go too far.
Just make sure that the flanges are ground down first and then check for fit often.

[Tankota]

Friend of mine ground down the ribs on his 420 then just did about 1/16 more. He used a 3sp flange etc on the driveline cause they are a bit smaller. Never had a prob with it.

[brew8]

Just remember that extreem bends clocks the case down to clear the 420 case so you will loose a coupla of inches of ground clearance.

[high country cruiser]

o.k. i have the miliaty sm420 2 a 3 speed case w/danny wardens 1" adaptor plate and you'll need a pre 73 u-joint which has the clips on the out side all others have them on the inside....pre 73 joints are smaller.driveline slip yokes are the same grind the bolt flange down to almost nothing, real close......also grind the hump that sticks out on the sm420 only enough to clear dont go through......check quite often and take your time don't be in a hurry....while your there you should clearance your driveshaft with the angles on your cups (hold oneway till it touches mark and grind out with a round bit) e-mail me @ cruisernut.rick@yahoo.com and i'll send you pics....it will be easier to understand i always thought with it so thin that would be my weakest link so i built a spare,but it works well......

[brooklyn]

Talked to the guys at extreme bends and yes you're correct I will lose about an inch of clearance. It looks like a minor adjustment to the linkage, and drilling some new holes in the rear cross member. It will be clocked about 11 degrees. I think the drive shafts should be okay - I am hoping as they are both new!

As I am a coward and don't want to risk messing this up... the cost of the new plate and a little loss of ground sounds like the best path for me.

If anyone is looking for a used SM420 adapter plate, I will have one available within the next few weeks. I will also have a complete SM420 - older style with the slinger setup.

(from my six year old)