idler/intermediate arm replacement & endplay reduction

[ashyers]

We've started playing with the truck again after a summer of driving it around. Did about 1500mi and averaged around 7MPG. The only issue was a brake pressure switch that failed to ground. Overall I'm pretty happy. I've never driven a vehicle that has received so many comments and so much attention. I really like the little kids reactions, they seem to be drawn to the thing and just smile and point (guess that's how I ended up w/ it...).

The new students "intro" to the truck is replacing the idler/intermediate arm and pin. I've read the following thread (http://www.g741.org/PHPBB/viewtopic.php ... arm#p29917) and noticed Charles at M-series had some suggestions about eliminating endplay in the idler/intermediate arm. There is not a ton on endplay, but I was wondering if anyone had success using shims or something similar to reduce it as far as possible. I'm not prepared to weld on the link to build it up and was thinking hardened shims may do the trick, our possibly a bushing with a shoulder. Any suggestions?

Andy

[52 M-42]

Andy, I'm not a automotive engineer (I play with large commercial aircraft), but I've always been told not to tighten up the steering too much because if you do, when you are off road bouncing around and you catch a pothole just right you risk getting a nasty twist to you arms and wrists when that steering wheel spins around on you. Not sloppy loose steering but not race car tight either.

This may or may not be something to consider when working on the steering. It could just be another urban myth too.

[w30bob]

I doubt it's an urban myth. I used to take my Dad's 68 F250 4x4 off road with it's manual steering. More than a few times I caught a hole or log and the steering wheel snapped in one direction or the other. If I wasn't holding on tight it would have broken my hand for sure. I'd suggest Andy make it tight enough to prevent wander on the street, and hang on tight if you go off road or don't hit curbs straight on when leaving the road. When that steering wheel jumps out of your hands it will scare the crap out of ya. I bet most younger folks these days don't even know what manual steering feels like.

regards,
bob

[52 M-42]

Well, that is why I was always told to leave it a little loose for "bump steer". Another compromise between on road and off.

[MSeriesRebuild]

The issue that idler arm end play causes is wandering all over the road when driving in a straight ahead position. The arm slides back and forth on the pin, in turn you find yourself fighting the steering wheel constantly in an attempt to hold the truck straight. I've tried shimming in the past, never could get enough shims in there to help the cause. This is because of "out-of-square" wear on the bracket, it prevents enough shims from being inserted. Even a brand new NOS arm/bracket assembly is usually not tight enough to fully correct the issue. This component just never got the attention it should have by Chrysler to make handling characteristics the best they can be.

It is a more involved process to fix the issue than just building up the end OD on the idler arm bore as I described. Some get confused and think that a simple build up and true surface grind takes care of it; it doesn't. The first step is to build up to the point you are sure you have added enough meat to cover all the machining I'm about to mention. The next step is to true the bracket contact surfaces. This requires the removal of said bracket from the frame. Our machinist has made a specialized cutter to true the bracket surface on both sides. Once that is straight and true; then he proceeds to grind the built up area on the arm until it correctly fits the bracket. Either a new or good condition pin/bushing fit is an imperative part of the process so it all comes together correctly. We have tried it all; never have had any luck with a short cut repair that is less than what I've described here. Once this repair is done 100%, your truck will handle like a new Mercedes; unless you have other problems going on within the system in addition to the idler arm issue. If you think you have done it all with repairing your steering system; yet it still wanders and you are constantly fighting the wheel, most likely what I've described will finish the job for you.

[ashyers]

We replaced the arm/bushing/pin and it made a significant change. There's still a little endplay in the system, but not more than a few thousandths. I thought we'd replace the parts and see where we ended up before committing to reworking the assembly.

What we did find, and what is likely responsible for minor wandering remaining in the system, is that the front most left spring bushing/pin is toast. When we were testing things out after the replacement of the idler arm we found we had a bit of "axle steer"! This will get sorted next week as I picked up some bearing stock yesterday and now have a nice weekend project for the old South Bend . Pins should be here Monday.

Andy

[PoW]

It seems to me, that if one drives it a bit after tightening things up, the steering will loosen up to a point and stay that way for a long time.

Don't overthink the old beast....


DG

[ashyers]

I fear the truck has been loosening up since '51!!!

[just me]

Whenever I think my M is 'loose', I drive my International. It is more like herding it than steering it.