Chassis - Tubular Engine Cradle

 

Andy Bujtas

Here Im test fitting the 406 CID engine with IFGs engine cradle. After the fit, it was determined that the motor mounts had to be removed and switched in order to allow the engine with the low-mounted A/C and Alternator to fit properly.

 

This is another view of the engine cradle after I removed it from the chassis. Upon closer inspection, I found some problems with it which required repairs or modifications. For example, there seemed to be a problem with the action (movement) of the rear control arms. Also, the attachment point for the control arm did not appear strong enough.
It is obvious that the quality of the workmanship was not very good. Not only were the bushing tubes ground to practically nothing, but they are not even aligned with each other thus, the problem with their action. My control arms are currently at the weld shop for repairs. New tubes will be added and the welds refurbished - mainly the burning-out of the voids and porosity. Nit-picky you say? There is always the question of safety to be considered.

The rear upper control arms are a real problem. The design, as received, allows the pivot motion and suspension load to be placed on the retaining bolt threads.

I redeigned the arm to use a bushing tube and a threaded rod to slide through this tube. Motion and friction is on the rod, not a bolt. In addition, the shock bracket had to be fixed as well. And as with the lower control arms, the welds had to be repaired.

Rear Engine Cradle Tab - (Inside of chassis area facing outward)


I reinforced the rear engine cradle tab by welding the back side. As received, the tabs were only welded on 3 sides. I added a forth and cleaned and blended the weld so that it appears as part of the frame.

Engine Cradle Forward Attachment Point


This will be my "Before" picture of the engine cradle forward attachment point. This is where the engine cradle links up with the old Fiero cradle mounts. This may be adequate for 300 HP 350 TPI engines, but for motors with 450+ HP, I think it needs some more meet on it.

Modified Engine Cradle Mounting point


I beefed-up the engine cradle mounting point to the chassis. Flanges were fabricated and welded to the forward cradle attachment point.

It is now a solid piece of steel.

Engine Cradle Work


This is a view of one of the working positions when welding/modifying the cradle. Note in the background my welding unit and rolling tool box. The welder is a Clarke 100E. Not a bad unit for $300 - does a nice job.

Engine Cradle Torque Bar Bracket

The tube chassis comes with torque bars that (probably) help prevent the Fiero cradle mounts from being ripped-off the Fiero frame. However, the bar is attached to only 1 flange. I decided to add another flange to strengthen the torque bar assembly. The torque bars, themselves, were also capped at the ends so that they look nicer.

Torque Bar Bracket and Coil Mount
This is another view of the new torque bar bracket flanges. I also welded a piece of angle iron that will serve as a mounting point for my ignition coil mounting plate. The plate is a 14-gauge flat plate with the holes drilled for a Mallory PROMASTER coil and Ballast Resistor. The plate will be welded on the rear flat-side of this angle piece. A drawing of this plate is provided for downloading as a jpg file or bmp file.

Final Engine Cradle Torque Bars
With the cradle back in place, I installed the torque bars to see how they fit - perfect! As seen, the torque bar ends were capped and ground smooth.

 

 

Craig Nadeau

This was a lot of welding! I designed it a bit shorter so the cradle won't stick out the back so much. I machined the poly bushings myself for everything except the A-arms. It was actually pretty easy.
If I didn't keep changing things this cradle might get finished one day. I have now finished building the 3rd set of upper a arms for this just to get them perfect. Nice Alden Eagle shocks.

 

 

Links:
http://www.specificmotors.com/ - Dave Held makes engine cradles with small block chevy and Porsche or Audi 5000 transmission setups. They are availible in 7" or 11" stretch mainly for lambo kits.

 

 
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Although my information comes from various builders and sources, if you want any information contact me. The photographs used on this site are used with permission, if you want to use any, contact them through the various links on this site. I did and you can see the results!