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Did some measuring today...

From rear of cab crossmember face to front of trunnion stand crossmember face

left side 89 1/2" right side 89 7/16"

Bolt center cab crossmember to front trunnion (square bracket)

left side AND right side 66 1/4"

Square

Measured a point on top of frame rail x distance from cab crossmember (used a square) to

point on top of frame in line with front trunnion bracket bolts (used plumb bob)

1st diagonal 77 1/8 2nd diagonal 77 3/8

Measured from front axle to front rear diagonally...

1st diagonal 139" 2nd diagonal 139 1/2" BUT...

The axles housing on drivers side seems to be back almost 1/2" in relation to the spring end...that would also explain why the front of the drive housing is over towards the drivers side more than others have measured...

Anyhow, I lools like the frame may be out of square by 1/4" or less...dont know if this a lot or a little?

I guess my plans are to find/build/modify a crossmember to stiffen the frame where the frame was spliced, and maybe retro fit some shocks to the front axle...

also try to figure out why the front axle is canted..and the sliding joint on the driveshaft is definitely not sliding, will check if it is bottomed out...

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Did some measuring today...

From rear of cab crossmember face to front of trunnion stand crossmember face

left side 89 1/2" right side 89 7/16"

Bolt center cab crossmember to front trunnion (square bracket)

left side AND right side 66 1/4"

Square

Measured a point on top of frame rail x distance from cab crossmember (used a square) to

point on top of frame in line with front trunnion bracket bolts (used plumb bob)

1st diagonal 77 1/8 2nd diagonal 77 3/8

Measured from front axle to front rear diagonally...

1st diagonal 139" 2nd diagonal 139 1/2" BUT...

The axles housing on drivers side seems to be back almost 1/2" in relation to the spring end...that would also explain why the front of the drive housing is over towards the drivers side more than others have measured...

Anyhow, I lools like the frame may be out of square by 1/4" or less...dont know if this a lot or a little?

I guess my plans are to find/build/modify a crossmember to stiffen the frame where the frame was spliced, and maybe retro fit some shocks to the front axle...

also try to figure out why the front axle is canted..and the sliding joint on the driveshaft is definitely not sliding, will check if it is bottomed out...

Dead on square is best but +/- 1/32" is alright to me. You are about eight times that. Frame squareness is where everything begins. When a frame is out of square, (and lets say left side more forward than right side) the drive axles through the trunion bushings are loading heavily on the left side trying to keep the axles parallel the the imaginary centerline of thrust angle. This puts abnormal pressure upon the trunion bushings/bearings and as these trunion bushings wear, abnormal side loading is absorbed by the "elephant pads" at the ends of the springs. A combination of excess wear in these two sets of bushings are allowing the actual actual axle centerline to shift. What you have here is a lot of worn parts necessatating replacement to be within tolerance.

The first thing to do in my opinion is to get that frame square. I would find a set of holes on each side of the frame rails prior to the splicing and check for squarness there before cutting the truck apart. If you have a "diamond" condition starting further forward, this must be straighted also.

Rob

Dog.jpg.487f03da076af0150d2376dbd16843ed.jpgPlodding along with no job nor practical application for my existence, but still trying to fix what's broke.

 

 

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So, I should be able to see this by video-ing a nice closeup that shows the inner part of the tire and the frame, after moving forward, backing up should produce a noticable movement as the axles try to track to the other side right?

Guess I will have to drop plumb lines on all major componenets to the ground to measure like I would when rigging an airplane!

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So, I should be able to see this by video-ing a nice closeup that shows the inner part of the tire and the frame, after moving forward, backing up should produce a noticable movement as the axles try to track to the other side right?

Guess I will have to drop plumb lines on all major componenets to the ground to measure like I would when rigging an airplane!

Put a block between the tires on one side of the truck, and ease both forward and backward and you should see things move as the blocked side binds against the block.

Rob

Dog.jpg.487f03da076af0150d2376dbd16843ed.jpgPlodding along with no job nor practical application for my existence, but still trying to fix what's broke.

 

 

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Always wondered if they shortened the frame why there were two welds in the inner frame, looked a short section was added...I knew it started life as a tractor and at some point was converted to a dump...

looked back at my Mack paperwork and see that it was special ordered at 146" wheelbase. it is now 165"...that explains it, they lengthened it!

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Always wondered if they shortened the frame why there were two welds in the inner frame, looked a short section was added...I knew it started life as a tractor and at some point was converted to a dump...

looked back at my Mack paperwork and see that it was special ordered at 146" wheelbase. it is now 165"...that explains it, they lengthened it!

That was my unknowing assumption all along. Never gave a thought to being shortened.

Rob

Dog.jpg.487f03da076af0150d2376dbd16843ed.jpgPlodding along with no job nor practical application for my existence, but still trying to fix what's broke.

 

 

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Always knew you had some kind of extra sensory perspiration! :notworthy:

Yes, and of all the things I've lost, I miss my BALLS!!!, Without a doubt, I miss my balls the most.

Rob

Dog.jpg.487f03da076af0150d2376dbd16843ed.jpgPlodding along with no job nor practical application for my existence, but still trying to fix what's broke.

 

 

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It would be interesting to see this truck going down the road and look for "doglegging".

There would have to be some if ever so slight. New trucks do it also due to production type alignments.

Rob

Dog.jpg.487f03da076af0150d2376dbd16843ed.jpgPlodding along with no job nor practical application for my existence, but still trying to fix what's broke.

 

 

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  • 2 weeks later...

what does your caps look like on the trunnion. does it have a rubber bushing or a cap with with a zerk fitting. post a picture. Those trunnion stands sometimes crack laterally up the center behind the springs. Check for cracks there too. As for the welding of the bottom of your stand goes, if it were done properly it should hold up fine. check those for cracks in the weld.It could be letting the trunnion beam "service spindle" walk or move causing the shake. also check the center bolts, check the bushing caps are drawn up good on the bushing rubber or bronze

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