101 Overdrive linkage - rear end

The following are shots of the operating mechanism at the overdrive end.
The additional steel is 1" box section, which is much too strong for the job!
Click on the small photos for a large-size version.

 

 
N/S end of linkage, showing end pivot From the rear, showing down-angle of operating lever. From the rear, showing extension to the O/S to get the lever ratios correct. From directly underneath, showing forward angle of lever and the two pivots. From the N/S, showing (if you can see it) the connection to the cable.  

 

Description:

There is a cross-piece fixed to a plate bolted on top of the inspection panel, on top of the overdrive unit. This goes well to the O/S of the unit - just about as far as it is possible to get without fouling the chassis. The cable outer passes through the O/S end of this and is bolted to it.

A short piece of steel runs rearward from the N/S end of the fixed cross piece, and has the moving operating lever is attached to this by means of a pivot pin (which looks remarkably like a ht steel bolt!)

Another pivot arrangement runs forward from the operating lever to the piston on the overdrive and is bolted to it.

 

The two main setup difficulties are:

  1. the vertical clearance is very tight - the gearbox doesn't move much, but it does move up and down a bit, so you need to leave clearance above your linkage.
  2. it's quite difficult to get the leverage ratios correct (ie the distance from the end pivot to the cable, and the distance from the end pivot to the piston). If you get these wrong, there won't be enough movement at the control lever to make the o/d engage properly, or you'll be heaving on the lever too much and will strain the cable. I made the operating lever on the overdrive as long as possible, just clearing the chassis - that seemed to work OK.