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relocating rear struts to allow wider wheels/tires


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like everyone else out there i'm in the search for more traction. i know that width isnt everything when it comes to traction but it sure is alot. first and formost zg or other fender flares are out of the question because i simply dont like they way they look and i dont want it to LOOK any more agressive than they already do :mrgreen:...

 

but back on track i have been thinking about moving the rear struts in about three inches which theoretically would allow about 76 more mm in tire width.

 

i dont know a ton about suspension but in MY thinking and from doing 4 link suspension on classics, trucks etc(mostly air ride applications) i figured that as long as i keep the struts at the same angle it should have little to no effect on the handling of the car correct. the ultimate goal is to fit a 315/35-17 or something similar in width with preferably a lower profile. my thinking is to simply take a couple extra sets of rear hubs, cut off the lower strut mounts and weld them next to were the originals are like shown in the picture below... thn smply add some supports. for the top mounts just cut them out, move em in to match original strut angle and add new sheetmetal to fill the gap and re-inforce.

 

here's a quick sketch on ms paint to kinda show what i'm talking about. i'm up for any helpful advice on why it is or isn't a good idea or why it will or wont work.

 

Untitled-1.jpg

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First thought: leverage. You didn't mention it but I'm sure you've consider it. You'll need a firmer spring to retain the same relative spring rate (bad wording, sorry).

 

Is the spring/shock assembly the only thing preventing a wheel/tire from reaching a couple more inches into the wheel well? I've assumed there were other clearance issues that were essentially a non-issue while the spring/shock assembly is in its stock location.

 

Still, it's an interesting idea and shows you're thinking outside the box.

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If you do what you're planning you'll run into other issues, like the tire hitting the inside of the fender. By the time you tub it and relocate the strut tops and modify the struts themselves, you could have swapped in short/long arm suspension or backhalved the car and put in a solid axle.

 

If you want the max clearance for stock wheel wells, you don't need to relocate the strut. You just need coilovers and smaller 2.5 inch springs.

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i figured that as long as i keep the struts at the same angle it should have little to no effect on the handling of the car correct.

 

Nope. You're changing the lever arm (as mentioned above) and reducing the wheel rate. That requires spring changes and adjustments in shock valving. You're also reducing the support on the hub and giving the stub axle more leverage on the control arm pivot.

 

As Jon mentioned above, its completely doable but a lot of work to get right. Are you building a street, drag, autocross, or road race car. If its the last two, your chances of this mod making things "better" then the stock setup are slim to none.

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I can appreciate your idea, but these guys are right... it's not an easy path, and done poorly it could be detrimental to your handling even with the bigger rubber.

 

In the end, it would probably be a cheaper, easier and probably better solution to run coilovers and flares, and get your 315's in that way.

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We have similar self-imposed goals - getting the widest tire possible without adding flares. You didn’t specifically mention it, but I assume you don’t want to tub it either. If this is the case, I don’t think that 315’s are a possible solution, even if you relocate the struts. In my case I went with coilovers and 8†springs so that the lower perch would sit above the tire. The limiting factor is the available with between the inside of the fender wells and the fender itself (I’ve rolled the lips on my fender so there’s no more room to be gained there). I played with various combinations of offsets using different spacers and got my 275’s almost perfectly centered in the space available and there’s almost no room left over. In fact I think that the differences in manufacturers would be enough so that there are probably some 275’s out there that wouldn’t fit without rubbing.

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Nope. You're changing the lever arm (as mentioned above) and reducing the wheel rate. That requires spring changes and adjustments in shock valving. You're also reducing the support on the hub and giving the stub axle more leverage on the control arm pivot.

 

As Jon mentioned above, its completely doable but a lot of work to get right. Are you building a street, drag, autocross, or road race car. If its the last two, your chances of this mod making things "better" then the stock setup are slim to none.

the car has tokico illuminas and i could get a stiffer rear spring, i will weld in supports to re-inforce the hub, the car will be 70% street 20% drag(just for fun against friends) and 10% roadrace(would be alot more but the closest track is 5 hrs away.

 

I can appreciate your idea, but these guys are right... it's not an easy path, and done poorly it could be detrimental to your handling even with the bigger rubber.

 

In the end, it would probably be a cheaper, easier and probably better solution to run coilovers and flares, and get your 315's in that way.

coil overs are a plan for sure but flares are out of the question.

 

Or you could move the whole strut assembly inboard. You'd need to redo the wheel well, shorten the halfshafts, and control arms.

i thought about that but i figured that would harm the handling alot more than my original idea.... especially since these cars are so narrow as it is

 

We have similar self-imposed goals - getting the widest tire possible without adding flares. You didn’t specifically mention it, but I assume you don’t want to tub it either. If this is the case, I don’t think that 315’s are a possible solution, even if you relocate the struts. In my case I went with coilovers and 8†springs so that the lower perch would sit above the tire. The limiting factor is the available with between the inside of the fender wells and the fender itself (I’ve rolled the lips on my fender so there’s no more room to be gained there). I played with various combinations of offsets using different spacers and got my 275’s almost perfectly centered in the space available and there’s almost no room left over. In fact I think that the differences in manufacturers would be enough so that there are probably some 275’s out there that wouldn’t fit without rubbing.

 

sorry i didnt mention tubbing but i was 99% sure i'll have to to get where i want which isnt a problem. my fenders are already rolled as much as they can be. the difference from a 275 and a 315 is only 2" at most so i didnt think it would be THAT hard to accomplish... but then again this is my first z and i'm still new to it all

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looking here at your picture you can see w/ a little tubbing and bracketing it should be able to move at least 2" over w/o having to cut into framerails which is what i would like to keep from doing. but i can see here how tight it is w/ your 275's

1536512254_a92c52771f.jpg?v=0

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