Video of New 109 Block Being Machined for Girdle

[Bryan Weber]

yes very true. where is this load all being placed? at the motor mounts. this is just about as far forward and as narrow on the block as you can get. very bad for load distribution. all that torque and twisting force is transmitted through the entire block with the motor mounts holding it with the least amount of leverage. That is why we developed the Rear Motor Brace or "RMB" It acts as a mid plate placing all of the torsional load of the motor on the rear of the motor and as wide as you can get so it has the most leverage. This changes it from the worst scenario to the best with one simple bolt on part.

take a look
RMB

Absolutely! That bolt on can help save a lot of blocks. Taking the load off of that engine mount reduces much stress on the block for sure. There is also tremendous stresses on the block from 1,000 + psi and 1,000 + degrees in each cylinder hitting 50 times per second trying to push the crank out of the bottom of the block. All of these stresses can't be duplicated but with RJC's brace they can be minimized.

 

[turboclam]

Would you use the RJC brace and poly mounts?

 

[Race Jace]

yes the poly mounts are a must.

the RMB like any mid plate only takes care of the rotational load placed on the motor. This is a very destructive load placed on the block. The motor mounts secure the motor in the chassis. One thing people never think about is how hard the motor is being pushed toward the rear of the car on launch. the motor/trans is a pretty heavy object and you are throwing the chassis forward on launch HARD and the motor wants to remain at rest. that is why both are a must have.

 

[turbodave231]

Machining cast iron typically doesn't require any coolant. We bore and deck cast iron blocks with no coolant. Cast Iron has alot of graphite in the metal which acts like its own source of lubricant. Now coolant on the front cover is another story!! but for the small amount of aluminum being machined, I wouldn't bother.

A replacement cover could always be machined to size on a mill with an angle plate. I've done 2 that way so far.

Jace, I wasn't throwing rocks and I understand your position. I just felt that the girdle needed to be much closer to .000 before I bolted it to a dead flat surface. I didn't want to introduce any un-necessary stress into the block.

I'm not using any shims between the cap and girdle.......I'm leaving the caps .002 to .003 above the pan rail. This accomplishes the same preload with NO shims. You can see why I want the girdle flat.

A friend in the Tool and Die business helped me develop a gage block that spans the oil pan rails and allows me to measure from the freshly machined pan rail down to the main register (or top of the cap). This allows me to mill the caps to the right height. Maybe I'm over-thinking the whole thing, but it seems to work for me.

Dave

 

[turboclam]

So is the brace just really needed for the track, for launching purposes?