Adjusting 308 Dog Bone After Replacing Bushings

Adjust the distance to the rear mount with shims between it and the rear bulkhead. I used some washers, but there is an official Ferrari shim for this. Ricambi America has them for less than $3 a pop. They call them a "washer." Parts 5 and 6 on the drawing.

You were on the right track.
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When I replaced my motor mounts I had to re-shim the dog bone. A friend with a GT4 had his dog-bone bushings replaced and it needed re-shimming as well. I'd guess it is pretty common when messing with any of them.

 

I had no idea Tirante de Riazione translated into "Dog Bone".

I always thought it meant torque bar.

Doug

 

If you want to get creative then just cut the dog bone in half and thread each side . One side with right hand thread and the other with left hand thread. Get a double threaded nut from a hardware store and install and adjust. Or you could just use shims.

 

same thing happen to me when I removed & replaced the engine

I had to jack up the bottom of the tranny, slacken all engine mount bolts
then put the bone back in the cage !

engine will settle down once restarted & give it some revving up back to normal

c if this helps

j

 

Rob,

How did you get the old bushings out and the new ones in?

 

When removing my dog bone I found the old one was under tension. Inserted a pry bar and pushed on dog bone rearward to relieve tension so I could move bolt in rear body mount. Reversed process after installing new bushings.
I also have an X1/9 which has the same dog bone set up. There is no shim adjustment like on the GT4. What I noticed was the tension on each was appx the same. Had to utilize the pry bar method for removal.
Believe that if there isn't the tension to start with and if with the bolts can be removed easily there exists too much free play in the system and too much movement results. Pre loading I think is good. Can't prove it though with figures but the tension eliminates the other components having to deal with the stresses of rocking back and forth induced by the engine rotational torque.
The amount of resistance isn't enough to deform the rubber but enough you can't pull the bolt out without releasing the tension.

If you really want to tighten the mounting up try this. For the X I took 2 hemi joints and a turn buckle which may a solid mount system. Increases vibration felt, dampening greatly reduce. It also isn't light as there is a fair amount of metal making up this torsion bar. I also doubt the GT4 was designed for such undampened loads.

How I remove the bushings is to burn out the rubber guts, hack saw the outer bushing shell ,try not to cut the dog bone. then beats out easily. Powder coated the dog bone and pressed in the new bushings easily enough using a vise and appropriate sized socket.

Cal

 

i have some spare carb front-to-back linkage bits that could be used..

 

I had to shim mine when I put my engine back in recently - and I know I put the same engine mounts back in the same places with the same spacers underneath.

In relation to the weight of the engine (and therefore the forces it will exert if it moves around on its mountings) the bushes in the dog bone thing seem pretty soft. I couldn't see a reason to want to have them permanently under tension so I shimmed it at the back till the bolts just slid through.

Perhaps one of the pros would be good enough to clear this one up? Should the thing be under tension (or compression?) or should it be shimmed till there is neither tension nor compression?