Suspension Console & Ear Repairs - Need Help, Expert insight and Recommendations V8 street/track car Options

[ajracer]

Greetings 914 Friends:

Originally posted in Paddock, but limited reply, comments or options, so re-posting here. Thinking better option was to post my inquiry in Paddock, so because these members are the ones that go over and above the norm when resolving engineering and performance challenges, especially with heavy or extreme use. The search function and trying to locate prior post and solutions of others, has been a big challenge to try and locate after scanning through 50+ pages of posts with little success; so here is my situation.

So the Teener is a 1974 with LS6 Chev motor mated to Audi 6 speed transaxle. Car is highly modified for aggressive street use and limited time trail track events. However since 2005 the car only had a 300 HP motor, which was then replaced in 2015 with the current 500 HP motor and drive train, which includes a structural steel drive-line cradle that provides significant support in the rear section of the vehicle.

Background on the vehicle which was mainly built by prior owner that installed a Roll bar cage setup without any front interior "front" roll cage bar nor any bars to the front suspension. The main roll bar ties together the Floor (longs) -and Upward to top seat belt mounts; forward angled to front of door jambs. Rearward the roll bars are tied into the sheet metal sections of the rear spring/shock mounts.

Since I took over the project (2004) to re-engineer and complete building the street / track vehicle I had installed both the interior re-enforcement kits (3 pcs. left, rear & rights side of longs. In addition welded in the exterior long re-enforcement kit which ran from the front of longs, including the extension into the rear suspension mounts (where 3 bolts secure trailing arms) Additionally all the seams of the suspension console and inner ear were seam welded for additional support; plus the engine to chassis mounts are also seam welded and re-enforced.

PROBLEM: for which looking for some insight and help from 914 members:

1/ As noted in the attached Photo of the outer suspension console rust and fatigue can be seen near the arm mounting bolts

2. The light sheet metal support on the bottom of the long (inside engine bay) shows some cracking near the Engine mounting bar support to chassis.

Comment: based upon a recent inspection by a 914 friend he indicated because of the serious strength of the drive-line cradle, I t would be excellent idea to build custom brackets to secure the Inner ears to the cradle to minimize additional flexing of the rear section of car. He also mentioned good idea to cut out and re-enforce the structural cross brace which supports the rear of the drive line cradle, thus addition of steel channel support full width (inside trunk) will provide stiffness to reduce possibility of further structural cracking and metal fatigue in the vehicle

Very interested to hear from members on how or what type of approach they have successfully taken to resolve and repair a similar problem to the one indicated here. Apologize for the long post, however the more details provided gives a clearer picture for the serious car guys to respond. Thanks kindly, and Happy New Year to all that read the entire post and provide some guidance. Cheers,

Allan
Toronto, Ontario

[ajracer]

Well after being away from my 914Home for several days, and reading some of the posts, thought it might be helpful to add or restate some details regarding this suspension, engine cradle and motor mounts. ALL the seams of the suspension console and inner ear were seam welded for additional support; plus the engine (motor mounts) and ALL chassis mounts were also seam welded and re-enforced when the car was built. In additional ALL the rear tranny mounts and upper support to trunk was also seam welded.

Not sure if it is clear from the partial photo that shows the front corner of the "engine cradle" but the cradle is thick wall 1.75" tubing that fully supports the drive-line and bolts into the re-enforces rear tranny mounts. In addition we are currently working to re-enforce with a structural cross brace (1"x3") steel tubing which supports the rear tranny mounts, goes full width (inside trunk) to also provide additional stiffness to reduce possibility of flexing and fatigue in the rear end.

Not Shown in the photos is custom (aluminum) structural brackets that will be secured to the inner suspension ear AND the Engine cradle; it is believed this will provide excellent rigidity to the suspension console, especially after the outer area of the suspension console is replaced, seam welded and added steel re-enforcement. Since the vehicle was only getting other upgrades during our "cold winter" there has not been any plans to actually remove the drive-line again this year.

So my solution at this time:
1/ Repair the new found rust in suspension;
2/ Add additional ear to cradle supports,
3/ Custom fabricate the rear structural support in the trunk and
4/ Add special mounting plates to the trunk support for the mounting of a GT-Racing Predator 60" race wing. The wing mounts above the trunk floor will be mainly structural aluminium to reduce weight; as well some carbon fiber pieces will be custom fabricated in order to achieve a "removable wing for track use only" .

Welcome further comments and opinions, as well other options that may not have been previously recommended. Thanks again guys, Allan