Ground Control Coilovers

[Diseazd]

Anyone know of a good website on installation of G/C coilovers on the 240Z? The instructions provided by G/C are a little lacking in detail.

[jmortensen]

What do you need to know?

[Diseazd]

First of all I need to know what pattern and dimensions to cut the shock towers for installation of the camber caster plates......next,they say to leave 5" front and 7" rear on the shock strut from lower bracket to the spring perch, but there is a section to be rewelded above.....how do you determine the length of that portion of the shock strut? Last of all, when you're installing the camber caster plates, do you use any portion of the stock mount, or just the top spring seat supplied by G/C?

Edited June 29, 2009 by Diseazd

[jmortensen]

How to use the top of the plate as a template to cut, and a discussion as to whether to install the plate on top of or underneath the strut tower: http://forums.hybridz.org/showthread.php?t=102847

If you're using the same plates in the thread above, you don't need any of your stock spring insulator parts.

I'm not following the question you asked about the "section rewelded above". If you're sectioning the struts, I'd suggest that you section them first. You should cut the original spring perch off, then grind off the weld smooth, then section (I like to section right up at the top about 2" down, just a bit below the step in the tube thickness). After you've cut out a section that is appropriate for the struts you're using, weld the housing back together and grind your weld smooth, then slide the adjuster over the strut tube with the adjuster spun all the way up and install the strut insert. Set your spring on the lower perch and put the top hat on, and the plate too.

From here what I do is push everything up so that the adjuster hits the spring and the spring hits the top hat and the top hat hits the camber plate. Mark where the adjuster is on the tube, and that's where you want to weld your spring perch on. Unless you're planning on preloading the spring, putting the perch there will allow you the maximum amount of height adjustment, going from everything touching but not preloaded and down from there.

[Diseazd]

Jon....Thanks for your reply....I've got the same camber plate as the red car in your thread. I must say I like it mounted on top better. How would you suggest that I reinforce the shock tower if I choose to mount this way. Also, you wouldn't happen to know of a thread that takes you through step by step on cutting,welding etc.(I like to measure twice and cut once). You mention welding a perch onto the strut, however G/C provided only the threaded sleeve and the adjustable perch,and top hat......am I missing something? Last of all, now that I've made the investment,do you think coilovers are worth the bucks? Thanks for your help....Guy

[jmortensen]

I wouldn't mount the camber plate on top unless you put a reinforcing plate underneath. How to make a plate? Well, I suppose I'd get some 1/8" plate, cut the shape of the strut tower out 4 times, cut the pattern for the camber plate 4 times, drill holes to mount, paint and just put it on the bottom and the camber plate on top. As you can see in the thread I linked to, when asked GC said put it on bottom.

GC used to send a big huge flat washer for the spring perch (by perch I mean the part that the sleeve sits on). When I did my last set I just found a tube with a close ID and cut it into 1/2" lengths and welded it to the tube. I think that looks nicer than the flat washer.

Here's a thread on sectioning struts: http://forums.hybridz.org/showthread.php?t=103860

Camber plates and coilovers are well worth the money if you are racing, and the GC plates are the best you can buy.

[Diseazd]

Thanks for the help....I'll try to post pics of the install. We're also installing Willwood disc brakes F and R. Guy

[coop]

Just a word of warning.

When I sectioned my struts, I followed GC's instructions exactly. The result when using their Advance Design shocks had the car lifting the inside rear off the ground in corners. Their directions had me shortening the struts one inch too much. What would happen is, as the car leaned over in a corner, the inside shock would reach the end of its travel thus lifting the wheel. Made the car very twitchy to drive at the limit. I had to then have a machinist make me a one inch thick camber plate to relocate the top of the shock a little lower in the frame.

I recommend you closely examine where you want the center of travel point on the shock - somewhere between bottoming and full extension. This is about where the car should sit at static ride height. You may want to leave a little extra room for bump travel. Then, without the spring installed, do a mock-up to see if the shock will have full travel as the suspension does its full travel. This is what i would have done if I had to do it over again. Might not be a problem depending on what shocks you use. Yours may be longer so they may have more travel than mine.

Has anyone else had this problem on the rear struts?

Also, mounting the camber plate on the underside of the strut tower is the way to go. As the strut compresses, it will transfer compression forces upward and force the plate into the lip you've created around the top of the tower. This lip if cut properly will resist the compression loads and transfer them over a large area. If you mount the plate on top, the loads become tension loads transferred completely through the plate mounting bolts, nuts and washers. Looks pretty but not nearly as strong.

FWIW,

Coop

[Diseazd]

I appreciate the info......G/C certainly isn't very specific on installation instructions for the coilovers or the camber plate.Obviously someone else has had the same problem as mentioned in Jon's sectioning site. http://forums.hybridz.org/showthread.php?t=103860

Edited July 1, 2009 by Diseazd

[jmortensen]

Has anyone else had this problem on the rear struts?

Wayne Burnstein is quoted in John Coffey's strut sectioning post that I linked to earlier saying basically the same thing. If you section too much the strut tops out on rebound and can create some loose conditions at very inappropriate times. Since the rear struts are 2" longer in the 240, it makes sense that you should not section the strut to fit the insert, especially if you're using an aftermarket insert where the same one is used front and rear. This really limits the droop and also leads to the front and rear struts riding in much different parts of the travel (the rear will have to sit much higher on the strut and will therefore be more likely to top out).

Oddly people have been using droop limiters with good success in the front and rear. I think part of it has to do with spring and shock valving rates, more spring and/or rebound valving means the strut is less likely to top out HARD and unload the rear tires. There is some info and some vid clips buried in this tech filled thread: http://forums.hybridz.org/showthread.php?t=130005

Also, mounting the camber plate on the underside of the strut tower is the way to go. As the strut compresses, it will transfer compression forces upward and force the plate into the lip you've created around the top of the tower. This lip if cut properly will resist the compression loads and transfer them over a large area. If you mount the plate on top, the loads become tension loads transferred completely through the plate mounting bolts, nuts and washers. Looks pretty but not nearly as strong.

Agreed 100%.

Edited July 1, 2009 by jmortensen

[John Coffey]

I think droop limiting is generally used on the non-driven end of the car. The front on a RWD car and the rear on a FWD car. There are exceptions to as evidenced by a lot of DTM and BTCC cars.

[jmortensen]

I think droop limiting is generally used on the non-driven end of the car. The front on a RWD car and the rear on a FWD car. There are exceptions to as evidenced by a lot of DTM and BTCC cars.

Cary has specifically addressed using it on the rear of a Z, and there are pictures related to that in the post I linked to below. I do recall him saying that you have to run more droop in the rear, but I think the idea is that if you have 4 inches of droop on a car with 500 in/lb springs where the sag is only an inch, you've got more than you need, and extra droop just allows extra roll.

http://forums.hybridz.org/showpost.php?p=883058&postcount=57

Edited July 2, 2009 by jmortensen