shock tower clearancing for 944 spring plates

[zen]

here are pics (one of inboard, one of outboard) of the 944 spring plate up against a stock shock tower. now to decide how to cut the least amount to allow fit and clearance.

thoughts? (because i bet this has been done many different ways)

doing this safely is my biggest concern since there will be some stress on there with this car.

[Superman]

You have to clearance about 2mm from the Beetle's chassis frame in the area behind the Porsche's eccentric bolt back. Unfortuately, the only way to do this is with the spring plates off the car.

[LOAF]

Zen, I am most curious too..

I am doing 78 vert, and have to wait for the weather to heat up a little.. but once it does I am sending my torsion bar housing to get dismantled by a local porshe guy, so that I a can transplant.. I figure I can do the ones on the car with the right tools..

When I do the swap I know I will encounter the same.. BTW are you using early or late rear trailing arms.. on yours. I can't remember but I have been following you build up..
Sincerely
Alex



You have to clearance about 2mm from the Beetle's chassis frame in the area behind the Porsche's eccentric bolt back. Unfortuately, the only way to do this is with the spring plates off the car.

[boygenius]

Here's what I did.

There is enough room to turn the eccentric nut so I can raise and lower my suspension. I welded the front bolt to the inner plate so I don't have to hold the backside of the spring plate to adjust my suspension. Any possible weakening of the shock tower should be compensated by the kafer cup brace and the roll cage.

[zen]

super, is the 2mm you recommend just surfacing on the shock tower? seems like that is the way to go with the e-bolt. the forward bolt looks like it will go through the webbing as genius did. i was hoping to only follow the bolt path, but that is pretty surgical cutting.

loaf, they are early arms.

genius, thanks for the pics again. i have the tools to do it now and was hoping for last minute reassurance on what cuts everyone has done. tomorrow i start cutting.

btw, what has everyone done for the bump stop? i was thinking of hunting down a stop that has the bolt molded in and drilling the top stop for it and bolting it from the top.

[boygenius]

I'm going to cut the stock bump stop off my original trailing arms and drill a hole through it. Then I'm going to thread the top of my aluminum trailing arm and bolt it on. I'll take some pics when I get to that. Still have to put another coat of POR-15 on the bottom of my chassis. :)

[Superman]

super, is the 2mm you recommend just surfacing on the shock tower?

Yes.

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[zen]

here is what i came up with on clearancing (see attached). cutting to the outside of the marks. i widened the marks so they would show up better in the pics.

genius, did you check full travel to the top stop? because my measurements go much higher than yours on the e-bolt.

also, when looking at the spring plate i have mounted to an uncut shock tower, when the bolts start touching the shock tower there is about 8mm between the inside of the spring plate and the outside of the shock tower (measured at the trailing edge of the shock tower at the top of the spring plate). so is it correct to assume that since only needing to clearance 2mm that the spring plate to shock tower clearance at final mounting has 6mm gap? i assume this is set only by how much the torsion tube bushing pushes outboard on the spring plate after the torsion housing is buttoned down all of the way.

[boygenius]

[QUOTE=zen]
genius, did you check full travel to the top stop? because my measurements go much higher than yours on the e-bolt.

QUOTE]


Zen. With the top of the spring plate resting on the top spring plate stop the e-bolt has about 2mm of clearance. Don't forget your future bump stops will be there to stop those part from touching. :)

Cut off the metal in little steps to figure out exactly you need to remove and then make a cordboard cutout to transfer the design to the other side. :)

[NO_H2O]

Remember to round over all the edges you make but cutting, there sould be no sharp or unrounded edges when you are done. An part with an unrounded edge will crack much sooner than one with a rounded edge.

[zen]

well, no cutting today. home depot nor lowe's had the abor i needed for the angle grinder. :mad:

[zen]

bump on this part...

...also, when looking at the spring plate i have mounted to an uncut shock tower, when the bolts start touching the shock tower there is about 8mm between the inside of the spring plate and the outside of the shock tower (measured at the trailing edge of the shock tower at the top of the spring plate). so is it correct to assume that since only needing to clearance 2mm that the spring plate to shock tower clearance at final mounting has 6mm gap? i assume this is set only by how much the torsion tube bushing pushes outboard on the spring plate after the torsion housing is buttoned down all of the way.

hoping to only cut once. :D

[NO_H2O]

I found an extra cutting wheel arbor and some rotory files. I will call you so we can hook up. Then you can MAN-UP-N-GRIND. :D

[Maynard]

I'm doing the same thing and was wondering if you have to provide clearance for both bolts or just the e-bolt?

[zen]

I'm doing the same thing and was wondering if you have to provide clearance for both bolts or just the e-bolt?

see post #8 above. it will show you the path of the bolts. both have to be clearanced.

[Stuart]

I don't advice to cut in to the shocktower. This will weaken the tower to much. My solution is to just grind 1 mm from the tower and 1 mm from the face of the bolt. Thats all. It works great for me and have no problems with clearence!!! :)

[zen]

thanks for the advice Stuart. i agree with you. i am not overly comfortable with having to do it, but i clearance one side all the way through. my fitments don't show 2mm clearancing cutting it. not sure how tight VW's tolerances are in this area of the years and models. the bolts are 6mm thick and the shock tower webbing 7mm. can't see 1 or 2mm of webbing making that much of a difference. i can bend that by hand.

i have the one side cut and will fit the spring plate up a final time to double check clearance. if i can get away with less on the other side, i certainly will. hoping that the cup brace will help make up some of the difference in lost material. very worst case i will replace shock towers with less clearancing if needed.

i am only thinking of having a piece of flat steel welded on the inside to make up for the lost webbing.

question...how much load are you guys starting the spring plate with? using the bottom of the spring plate and the bottom stop as the reference point, i am debating between the slightly above the stop that my previous setup was at (no preload) and one spline down from that making about 7-10mm below the stop.

[boygenius]

What do you guys think of boxing in the entire backside of the shock tower like Zen said. I have access to pieces of steel big enough to box the entire rear side of the shock tower in but it is only 2.5mm thick. Is that thick enough????

I will have a kafer cup brace to help stiffen up the rear chassis.
I will also probably have a 10 point cage to help also. :D

[boygenius]

Hey I found some steel plates laying around the shop that just so happen to be the right size for my shock tower braces. The best part is that the metal is 6.25mm thick almost as thick as the metal removed from the other side. :D

[NO_H2O]

You might have to TIG it in. That is fairly thick and the shock mount is cast. You could try 100% argon and the right wire, then max out your MIG and see what you get. You might even need to use a tri-mix gas. Ask someone at you local welding supply shop.

[boygenius]

My mig will weld 3/16" in a single pass so think I can weld it. I will angle the metal back at a 45 degrees so I can use about three passes to get a good weld. We shall see, I should be able to weld them up tomorrow night so I will let you know how it goes. :D

[boygenius]

I could try fluxed wire for some deeper penetration at the cost of being neat. :(

[zen]

Hey I found some steel plates laying around th eshop that just so happen to be the right size for my shock tower braces. The best part is that the metal is 6.25mm thick almost as thick as the metal removed from the other side. :D

did you find 4 by chance? :D

[boygenius]

did you find 4 by chance? :D


There might be enough metal to make four braces. I will cut them out with a torch tomorrow at work. If I can get four pieces out of the metal I will ship you up a set. :D :D

[zen]

that would be too cool. let me know what i owe you and how well the mod goes.

what were you thinking for fitment. my thought was to go inside the ib initially, but because there is the horizontal rib, you would have to go with two pieces.

anyone know the stength/structure implications of mounting outside the ribs rather than inside? my assumption would be that going on the outside would be weaker and just relying on the weld and inside the load is spread more laterally across the whole piece. :confused:

[boygenius]

OK here is where I am at right now. I can make four shock tower braces but there is a problem. I am making the braces large enough to reach up to the shock bolt. What do you think of that? The only real problem with that would be possible water entrapment in the pockets of the shock tower causing rust and the fact that the shock towers are angular and the steel is flat. Were you thinking of only bracing in the bottom of the shock towers? If I were to cut the metal into several pieces it would be easier to fit into place. You will probably need a torch to heat the metal enough to bend it If you want the one piece brace. And if you are heating of hitting anything on your shock tower you might want to weld a temporary brace between them so you don't bend a shock tower. Let me know what you want. :D

[zen]

my thought was to just do the areas in which material had been removed. should be any water trapment issues that way anyway. and i will install the cup brace before installing these pieces.

[boygenius]

OK. I will cut your pieces to only cover the areas where metal was removed. If you want I can cut the two pieces and you can trim them down to fit inside of the webs if you want. I should get my cup brace in the next few weeks. :D

[zen]

that's very cool of you. i appreciate it!!!!!!

[boygenius]

My torch took a crap at work today. :(

I'll have to get the shop to buy a new one. :D


I'll practice on mine first then just knock yours out. :)

[zen]

cool. thanks.

i got all of my clearancing done today and one trailing arm going on. looks like i took off just enough from the shock tower. tolerances must be different across the cars. i will post pics tomorrow, but i took the webbing off in the same place as yours genious and it is just barely enough to clear.

the trailing arm is not bolted to the spring plate yet and that may pull the spring plate out some by the looks of it, but there is no way that 1mm off the plate and the bolts would have made it on mine. i hate having to cut that much nonetheless.

[boygenius]

What do you think of cutting the bump stop off the old trailing arms and welding it to the shock tower upside down to hit on the trailing arm. I figured that would be a little more secure than bolting them to the aluminum trailing arms. Whats your opinion. :)

[zen]

funny, i was looking at the same thing today. i am no engineer (well not mechanical...i am a computer sustems engineer/architect) so i am the wrong one to ask. i don't see why that wouldn't be as strong or stronger. i would think a bolt in one is ok too. all of the stress would be dead onto the rubber. no shearing stress. i have yet to find a bolt in one though. let me know if you have seen one.

[boygenius]

I'm not sure if the bolt for the bump stop would be on a flat surface of the arm to line up with the shock tower. Are you using the late or early aluminum arms. Don't the early arms have a place for a bump stop?

[boygenius]

Zen, got one of the braces cut out today. I had to use an angle grinder since my shop wouldn't buy a new torch right now. I'll run out to home depot tomorrow to get some more cut off discs. The way I have mine sofar is that it mounts flush with the top rib following the contour of the shock tower and contacts the lower rib at a 90 degree angle. I wish I had a digital camera. :(

Also thinking of going with some 2" tall bump stops from the Summit catalog. I think I can mount them to the inside of the shock towers and have them hit the trailing arms.