Fox/SN95 strut with coilover kit question.

On a mostly street/sometimes strip car-truck combo that you want to set Fox/SN95 strut ride height as low as possible, what's the minimum bump-stop clearance where you can drive around town and not be beating the crap out of the car bouncing off the stops all the time?

Well I emailed both Team Z & Maximum Motorsports to see if either had any suggestions.

MM's suggestion was to just keep lowering a car's spring seat until the strut started riding the bump-stop, then raise it back up a 1/4". That might be a good idea to use on a finished car. But that idea doesn't really help during the initial mock-up stage when your hanging the Fox/SN95 struts (on a car other than a Mustang) trying to see if they will be too tall at the desired finished ride height.

Team Z suggested no less that 1 1/2 inches air gap between the strut & the bump-stop. That does sound like a usable minimum number to shoot for on a mostly street use car since 1.5" bump travel at the strut is probably around the 1.75" range (maybe even 2") out at the wheel.

I am interested in this too since putting the fox/sn95 stuff under my truck.
My struts have approx 6" of stroke....rather than split it evenly I gave it 2" on bump and 4 on rebound.
I do however have about 1/2" more I can get by adjusting the spacers at the top strut mount.
hopefully by spring I should have it on the rd.

Its all but done now though so if its not enough my options are limited to: shorter fox strut, raise my ride height or do dropped spindles.

What are you working on dave?

I'd probably go with 2" to be safe. This will get you some mock up numbers. If the final product ends up sitting high, you could always raise the spring retaining nut to get another 1/2" or so.

dirt_worker wrote:What are you working on dave?

My '66 Ranchero.

I was cleaning up the shop this week, (or at least trying to ) dug the 'Chero out of the corner and figured since I had a set of SN95 spindles & struts laying around I would see how they compared to the modified Ranchero control arm/Mustang II spindle setup I fabbed up for it long ago. I have never really been happy with how the current setup turned out. It did allow me to get the 460 in the car by moving the shock towers farther away from the engine (by shortening the factory upper/lower control arms & moving the factory pivot points to mimic the M II geometry). But that upper control arm & lower part of the tower assembly is still kinda close to the heads, might make it harder to get a decent sized header in there.

Well after mocking everything up it's looking more & more like I might not be able to use the SN95 strut/spindle assembly on the Ranchero with how low I want it to sit at the desired ride height.

The first problem is they move the wheel/tire farther out (closer to the fender) than the Mustang II spindles do using the already shortened lower control arm length. This reduced fender clearance is a drawback, but on the plus side this spindle placement does place the center of the top strut body/caster-camber plate almost centered on the top of the already moved & trimmed tower. I guess I could shorten the factory LCA again (or make new tubular ones) to gain back some tire/fender clearance. But that will also move the top of the strut/CC plate assembly closer to the inside edge of the tower reducing available coil spring side clearance.

Second problem is the strut body height. At ride height (and using the SN95 strut) the top of the strut body only has about a 5/8 to 3/4" air gap away from top of the tower. Not nearly enough space to squeeze all the top coilover hardware + bump stop + at least 1.5-2.0" air gap in there. Using a shorter Fox strut would gain a little more room, but still not enough. One possible fix for this could be to cut the tops off of two SN95 (or Fox) strut bodies, gut them, shorten them, and weld a threaded sleeve into the top for a strut packing/gland nut so they can hold a shorter strut cartridge inside.

Third problem is while at ride height and using the SN95 spindle (along with a SN95 ball joint) the LCA is running up-hill to the spindle at a steeper angle vs the angle achieved with the stock M II spindle. The LCA center-to-center force/load angle at ride height with the strut spindle is about 5-6* up-hill to the spindle. With the factory M II spindle it's about 2-3* up-hill to the spindle. And with a drop M II spindle the LCA angle would be either level with the ground, or slightly down-hill to the spindle a very small amount. One possible fix is to use the slightly longer Fox ball joint (instead of the SN95 ball joint) on the strut spindle. It should help level out the LCA angle a little, and an even longer Steeda 2X ball joint might help even more. But I do wonder how much turning load/side loading a real long ball joint pin like the Steeda has can take. I have no idea if they are meant only as a "drag use only" part, or if they are OK for heavy street use too.

Last problem is the SN95's brake caliper & caliper mounts won't clear part of the aluminum slot's mounting surface & backside of it's 5 spokes without using a thick wheel spacer, (and a spacer will move the wheel/tire even closer to the fender). Only thing I can think of to fix this problem is either to use another type of wheel, (not going to happen, I really like the retro aluminum slots) or to use the lathe & try to clearance the mounting surface & back side of the spokes to clear the brakes. Kinda scary thought depending on how much structural material might have to be removed from the wheels to clear the SN95 brakes.

I was looking forward to the increased engine/header room with the struts by getting rid of the upper control arm & trimming back the bottom part of the tower a bunch. But sticking with the factory M II spindle, or even a drop M II spindle, (for even better control arm angles) is probably about the only choice at this point. I have been thinking about if there was any possible way to convert a M II drop spindle into a "strut" spindle.....sure would solve all of the above mentioned problems. But welding on an aftermarket "forged" drop spindle probably isn't the best idea, even worse idea if it ended up being a cast drop spindle.


Here's where the wheel/tire will sit in the opening with the M II spindle at the desired ride height I'm shooting for.