So I was checking to see how much rust was in the back trunk after striping down most of the paint I noticed these cracks.. Are these common ? Before i start laying down primer and paint in the trunk is there any stiffening or any bars that I should weld in if so please show some examples..

Those vertical marks aren't cracks, just marks from the forming process. The shock towers don't need reinforcement, BTW. They're not a weak point.

Hey Onthegrind,

I don't know how common the cracks you found are, but want to share that the rear shock towers are 2 layers and can be welded to repair. For extra strength, you could weld in another layer.

I'm running the extra weight of a Chevy smallblock with 450 lb/in rear springs and made it a project to weld the inner to the outer layers. With no extra strengthening, my car has be fine for several years with NO cracking.

Best of luck,
Terry

I'd be more concerned about that rear trunk floor "patch". You might want to get a good look from underneath as that repair certainly did not use a stock replacement panel ...

I did have a look at that rear panel when ia seen it in thought it was gonna be a hack job.. But it is actually pretty solid and nice looking from the bottom. As for the marks I wasn't sure if they where in fact cracks as they where both straight marks I grinder on them a bit with a 3m pad.. I have seen guys running bars in the back does anyone recommend running those ? So no seem welding or anything is needed In the trunk.?

Other question a have when doing the gt stiffening kit should I have door bars on the car and where should I support the car ?

Nobody ?

What engine are you going to run in that car?

Bob

high comp,heads and cammed 2.2

Whenever you weld along the backbone of the car (longs) you need to reinforce the doors or else you are inviting a twist into the chassis. Many of us have learned this one thought unfortunate experience. Once the twist is in, it is hard to get back out again.

Zach

Do you recommend I brace after I get the floors and mcmarks rolls
Cage in the car ? And pics if reenforcing the doors?

The rear shock tower supports tie one solid area (your shock towers) into another solid area (your transmission ladder mount).

Do you need it? Will you be racing at a semi-professional level or is this just a street car? The cool thing about 914s as street cars is all of the space in the twin trunks. So... Your car. Your call.

Totally unnecessary. The towers see little to no stress in the truck side. Check on the inside of the engine bay where the inner rails meet the tower.

I want that loader!

I have some tubing and plates on there way I am going to tie the shock towers in like most of the Patrick cars run... It will be at the track a few times are year and alot of miles on the twisty around my ranch in napa valley so I want a solid chasis setup...

Lol I don't know how I put the photo up there its a good running rig as long as you don't need to find parts for it. Mf parts are pretty hard to come by these days.. A case
850 should be arriving soon i am curious about running a tractor with tracks.

These cars twist in the middle. In the passenger compartment. They don't really flex anywhere else. I agree with Eric that gusseting the shock towers just adds weight and removes storage space.

(I'd suggest taking a look at your suspension ears, though. They're probably cracking...)

I dont think I will risk it anymore. ill put door bars on anything im welding up. when you do a hell hole and cut out the inner wheel house(battery wall), it popps open like the sheer panel is under load.
GT kits: I have seen 5-6 cars now that were GT'd up and cracked in teh rear. these cars were not seam welded. the GT kit is a scab plate design that once its stiff you can see where it transfers teh movement.
the 914 chassis is layered like an onion. you MUST strengthen the inner onion FIRST, before adding outer stiffeners. the other issue that I have noticed is that the scab plates only stiffen the face of a box beam system. I have started to make my GT kit so that it wraps around teh corners of teh "box" section
I observe that the shock towers separate at the base where they connect to the lower longitudinal. the regular gt kit adds a plate there but stopps short of connecting the base of the shock tower. I also like to extend my lower longitudinal plate. after seam welding the 3 layers tht tie in at the base of teh shock tower, I run a gusset there. that stiffener plate goes from teh suspension pick up to the base of teh tower.

one major observation I wish to share that seems to affect everything:
the spot welds get erroded/corroded around their diameter and slowly let go. once enough of them get weak, the joining panels move opposite eachother. this is most obvious failure mode seen in teh right inner suspension pick up

in summary i recommend:
door bar, square, level
seam weld/spot weld
then GT it up

all teh cars I am talking about had fat stickies and track time

I'm not a fan of the bracing in the rear trunk for most cars.

I'll second that.

I promised some door bar pics. the turn buckle is weak so the second bar slides inside those hoops. ugly but stiff. I "C "clamp them once I like where the car is.

I attach to the lower front A pillar because I only want to influence teh B pillar to longitudinal positioning. if you attach to the upper door hinge it limits your ability to control teh A pillar to long and includes teh B pillar to the long. I have another bar that stacks over teh seat belt upper bolt attachment for this.
the 10jreen has A pillar movement but this is rare compared to the B pillar to long common weakness

Brace for the door gaps can be made out of most anything that is laying around from other projects as long as it's made adjustable and remains set.

Sean, Good example.

I like the triangle idea of going to the base of the a pillar and then also to the upper hinge point from the upper seat belt mount. I can't think of anything easier than turnbuckles to make them adjustable though. I also like the side support to support the turnbuckle.