Adjusting the truss rod

[ChuckR]

How do you adjust the truss rod on the rear axle of early Franklins properly?  Wheels on the ground? Off the ground? 

[ak]

I'd like to know myself.  It would seem to me the differential suspended by a jack while drawing up on the truss rods, but how to determine the pre-adjustment sag and progress?  

[PFitz]

I can't find anything about the truss rods for the early cars in the service charts, so I would imagine it's like the later truss rods. Rear axle up on axle stands under the spring chairs. The wheels have to come off with the later rods because they have a nut on the end of the rod in behind the wheels. The charts say the rod should be kept "tight". I snug the nut up finger tight then wrench-tight two more turns. Then I tap the rod with the wrench to hear if it sounds loose.  

 

Paul 

[ChuckR]

Thanks, Paul.  I found some instructions in a Burn's column in an early ACN.

[PFitz]

Good find, Chuck,

 

Yeah, that procedure to slightly push up the differential  is different from the later cars likely because the rod ends bend upward to their attachment points instead of a straight-line pull like the later rods with a nut to tighten them. 

 

Paul

[f147pu]

On 5/23/2019 at 8:42 PM, PFitz said:

Good find, Chuck,

 

Yeah, that procedure to slightly push up the differential  is different from the later cars likely because the rod ends bend upward to their attachment points instead of a straight-line pull like the later rods with a nut to tighten them. 

 

Paul

Paul,  My 1930 the rod goes under the diff and upwards to the attachments, could the 32-34s be different?

Gordon

[PFitz]

Gordan,  No the later cars use the same basic rear axle design as your Ser. 14.

 

By "straight-line pull" I mean that after the rod curves under the differential the ends go straight through a hole in the bottom edge of the axle tube end casting and are held in tension with a castellated nut and cotter pin on each end.   

 

Early, or late series, all the truss rods go under the differential and angle upward toward the end castings on the axle tube. However, with the earlier cars, once the rod ends reach the axle tube end castings they take an almost right turn upward to their attachment points.

 

Paul 

Edited May 26, 2019 by PFitz (see edit history)

[f147pu]

Oh, ok, thanks, that clears it up for me.