Need help with MCS setup

[fbirch]

So I spent four hours this morning with a friend trying to install some MCS front struts on my race car- 1-way adjustable, non-remote MCS. These were intended to replace the non-adjustable Bilstein struts that were on the car when I bought it.

Bimmerworld recommended 6 inch springs (700 lb) with short helpers. In order to get the front ride height I need (about 12.75 inch wheel center to fender lip) I need to set the front perch about midway on the threaded zone of the strut body. This puts the spring perch at the mid point of the tire side wall. Even with my 12.5 mm spacers, the spring perch severely digs into the side wall.

If I remove the helper spring and thread the perch up to maintain front ride height, the perch just barely clears the sidewall in its static position It would definitely cut the tire under compression. BTW, there is severe spring dislocation at full droop without the helper.

I played around with washers under the 12.5 mm wheel spacer to see how much farther out I'd need to space the wheel to keep the perch clear of the tire. It looks like somewhere between a 15 mm and 20 mm spacer would be needed. I'm not sure if that much spacer will cause the outer face of the tire to crash into the fender lip under compression. Does the front end of an E36 gain any camber under compression? My current ride height puts the fender lip about 1/2 inch higher than the top of the tire. I'm not willing to cut my fenders, which are already rolled flat and very slightly pulled. How do current MCS users manage to solve this clearance problem?

The problem with these MCS structs is that the top of the shock body doesn't extend up high enough. If it were a bit higher, you could run a shorter spring and just thread the perch far above the top of the tire. Below is a pic of my Bilsteing strut next to the MCS strut, with the bottom mounting holes aligned. You can see how much lower the top of the MCS strut is compared to the Bilstein. If it extended up a bit higher, you could run a shorter spring and move the perch higher, as is the case with my Bilsteins.

Any recommendations on how to make these damned MCS struts work?

MCS Front Strut by F birch, on Flickr

[olemiss540]

It sounds like you darn near have a solution. Why not remove the tender springs and thread the collars above the perch. How would it dig into the tire under compression? The tire to collar position should be completely fixed.

The front sway bar should keep the springs seated during cornering so I am not too concerned with the spring during full droop.

[ScotcH]

What kind of wheels/tires? We have JRZ and Moton, and they are similar in design ... the perch sits at the sidewall, not above it like OE struts. In our case, we have around 1/8" clearance between the sidewall and perch. Plenty as the top of the tire does not deflect. I believe we ran a 15mm spacer ... maybe 18mm from what I remember with 17x9 Apex and 245 hoosiers. These days we're widebody, so I'm going from memory, but it definitelyt worked with stock fenders.

The car does camber gain under compression.

[fbirch]

It sounds like you darn near have a solution. Why not remove the tender springs and thread the collars above the perch. How would it dig into the tire under compression? The tire to collar position should be completely fixed.

The front sway bar should keep the springs seated during cornering so I am not too concerned with the spring during full droop.

Thanks for your reply and for correcting my mistake. You are correct about the perch not moving. That was a big oversight in my thinking - too many hours fiddling with this thing.

I measured the helper spring and joiner under full compression at 3/4 inch. So what do you think about a 5 inch main spring and a helper, effectively giving me a 5.75 inch spring? That would allow me to raise the perch just a bit more. Not sure if I have 1/4 in of remaining threads to go up, but I believe I could get another 1/8 inch at least before running out of threads. That would give me the actual front lift I really want. With a 6 inch spring and no helper I had to raise it about 1/8 inch more than I wanted to clear the tire side wall with a 12.5 mm wheel spacer. And even then I had no more than 1 mm clearance to the tire.

I'll definitely have to measure remaining lift on the upper threads to confirm I have at least 1/8 in more lift and ensure that a 5.75 in spring will work. If so, I'd have no room to raise the front any farther without changing springs again. But the back of the car has room to be lowered, so I could still play with rake that way.

With either of these setups - 6 in main w/ no helper or 5 in main with helper - I think I can get the tire clearance I need with a 15 mm wheel spacer. If the front gains just a bit of camber as Scotch says below, it should tuck in just enough.

[fbirch]

What kind of wheels/tires? We have JRZ and Moton, and they are similar in design ... the perch sits at the sidewall, not above it like OE struts. In our case, we have around 1/8" clearance between the sidewall and perch. Plenty as the top of the tire does not deflect. I believe we ran a 15mm spacer ... maybe 18mm from what I remember with 17x9 Apex and 245 hoosiers. These days we're widebody, so I'm going from memory, but it definitely worked with stock fenders.

The car does camber gain under compression.

Thanks for this reply. I'm running BFG R1 tires (245/17) on a 9 inch DFORCE wheel, which gives a nearly square sidewall. I think 15 mm is the Goldilocks spacer, but in my case the perch will still need to sit toward the top of the sidewall to take advantage of the tiny amount of tapering at the top of the tire.

[olemiss540]

What size spring (diameter) are you working with? Can also move down to a 2.25" spring and perch setup to continue to gain clearance on the inboard side?

[ScotcH]

What size spring (diameter) are you working with? Can also move down to a 2.25" spring and perch setup to continue to gain clearance on the inboard side?

That's a good point ... our motons and JRA use a 2.25" spring (or maybe 60mm), but smaller than 2.5", so that helps a bit.

[fbirch]

What size spring (diameter) are you working with? Can also move down to a 2.25" spring and perch setup to continue to gain clearance on the inboard side?

Unfortunately the springs are already 2.25", so no way to decrease. In the perch position pictured above it's really just the bottom edge of the perch that comes close to the tire. The old Bilsteins use 60 mm springs but clear the tire by a mile

[fbirch]

So does anybody know of a reason why 5 inch springs are a bad idea? The springs are 700 lb, so even if all the front weight of the car (round up 1600 lb) was applied to one spring, it should only compress 2.29 inches, so I don't think it would ever coil bind.

[jakermac]

Here's what I did to alleviate tire/perch clearance issues so I could fit 285/30-18 on 18x10.5 as far inboard as possible. This perch was custom made by the boys at Hanchey Vehicle Technologies years ago when Brian was still in business. I should take it apart and get it anodized. And at the bottom is what a buddy is doing to acheive the same, except he's trying to fit 315/30-18 on 18x11. And I personally have no issues running my 5.5" springs with no tenders/helpers. And though my front springs are 800lb, I have never experienced any coil bind (zip ties around coils in a few strategic places).

[olemiss540]

So does anybody know of a reason why 5 inch springs are a bad idea? The springs are 700 lb, so even if all the front weight of the car (round up 1600 lb) was applied to one spring, it should only compress 2.29 inches, so I don't think it would ever coil bind.

I thought you were already maxed out on perch height which is why you couldn't run a 5" spring? Also, it sounded like you had solved your clearance issue with the 6" spring by removing the helper spring? I am sure a 5.5" spring would solve all of your issues if you have enough perch height adjustment left in your shock bodies.

[fbirch]

Jake, that's a very clever setup! Not only does the MCS have a low threaded section, but their perches are also thick and relatively large diameter, compounding the problem. What you've done there is to basically slim down the lower section of the perch, a nice idea.

[fbirch]

I thought you were already maxed out on perch height which is why you couldn't run a 5" spring? Also, it sounded like you had solved your clearance issue with the 6" spring by removing the helper spring? I am sure a 5.5" spring would solve all of your issues if you have enough perch height adjustment left in your shock bodies.

If you squint really hard, that top pic shows just a thread or two protruding above the top of the top perch. So there is a little bit of scope to go higher. I'm guessing there is maybe another 1/8 inch, maybe a bit more if I can thread the top portion of that top perch a bit beyond the shock threads. Unfortunately I don't have access to the shocks right now to confirm. I suspect it's only 1/8 inch. A 5.5 inch spring with another 1/8 inch perch raise would still be 1/4 inch below the height I'm shooting for. And I'd have no scope to raise it. On the other hand, a 5 inch spring with 3/4 inch (compressed) helper and 1/8 inch raised perch would be perfect. Just not sure if a 5 inch spring would be able to coil bind.

The 6 inch spring with no helper gets me to the height I want, but there is only about 1 mm tire-to-perch clearance at that point (on the one side where I tried it). To be safe, I'd need a little wider spacer - from 12.5 mm currently to 15 mm I think - to provide adequate clearance. I've never run spacers that wide on the front before, so not sure if I'll need to start pulling fenders. Up until now, the car has been set way too low on the front, with the front tire tucked under the front fender lip in the static position and way too much rake. In that setup, the outer tire wall just barely kisses the fender lip under compression with my current 12.5 mm spacers.

So I'm thinking a wider spacer will require fender pulling, even though the front lip now sits 1/2 inch above the tire in the static position.

[fbirch]

Here's what I did to alleviate tire/perch clearance issues so I could fit 285/30-18 on 18x10.5 as far inboard as possible. This perch was custom made by the boys at Hanchey Vehicle Technologies years ago when Brian was still in business. I should take it apart and get it anodized. And at the bottom is what a buddy is doing to acheive the same, except he's trying to fit 315/30-18 on 18x11. And I personally have no issues running my 5.5" springs with no tenders/helpers. And though my front springs are 800lb, I have never experienced any coil bind (zip ties around coils in a few strategic places).

Jake - Spoke to Bimmerworld and they said a 5 inch spring at 700 lb/in would be marginal. They like the longer springs to avoid damage from bottoming. You have firsthand experience that says a 5.5 inch spring is fine. Just out of curiosity, do you know of anybody making an extended perch like the one in your first pic?

[JamesL71]

Curious how much camber you are running in the front?

I have MCS on my E36 Sedan, but it is flared and running 18x10s. I know people are using 245 on 9" wheels with these dampers on the stock profile(rolled) fenders...

[fbirch]

I'm running around -3.5 deg, which is pretty much maxed on the camber plates. My fender lips are rolled flat and I was previously getting just a bit of tire contact under hard compression with a 12.5 mm wheel spacer. It didn't help that my previous ride height was way too low before - front fender lip at least 1/2 inch below tire tread. So I'm hoping that boosting the front ride height a full inch will allow me to get away with 15 mm spacers.

I just took some measurements of the front shock and spring seat, and I can definitely raise the seat 1/2 inch. That means I could drop down to 5.5 inch springs and get the spring seat clear of the tire with the wheel spacer I have now. Unfortunately the MCS come with 2.25 inch seats and perches, so I also bought 2.25 inch camber plates. I can't find anyone who makes 5.5 inch race springs with 2.25 inch ID (I need 700 lb). H&R has a huge selection of 5.5 inch springs, but they are all 60 mm ID.

[aeronaut]

Interesting thread, I didn't know MCS were quite so finicky on fitment for a wide-ish tire. Good info.

You can figure out if you'll get coil bind by making a few measurements. Mainly, the length of the spring relaxed, and the diameter of the coil, and the number of total coils. When you count the number of coils, do it along a straight line along the height of the spring. You may have to measure 1 partial coil. Add up the total thickness of coil along that line, and you know the height of the spring when it's fully compressed. Now, if you know length of shock under full compression, you can have everything needed to know if you'll get coil bind with a particular spring and preload adjustment. Hope that makes sense.

[JamesL71]

It may be worthwhile to see whether or not another manufacturer's thinner collars fit the MCS strut. Or you could potentially have the MCS collars turned down a bit?

[jakermac]

I would be shocked if you managed to coil bind a 700lb spring at 5". And most spring manufacturers will have the "bound" data for their springs. You might have to ask for it. And the difference between a 60mm and a 2.25" spring ID and 3mm or about .120". I wouldn't worry about that AT ALL.

[fbirch]

It may be worthwhile to see whether or not another manufacturer's thinner collars fit the MCS strut. Or you could potentially have the MCS collars turned down a bit?

Both good ideas, thanks! When you're down to scrounging for an extra mm or two, every little bit counts.

- - - Updated - - -

I would be shocked if you managed to coil bind a 700lb spring at 5". And most spring manufacturers will have the "bound" data for their springs. You might have to ask for it. And the difference between a 60mm and a 2.25" spring ID and 3mm or about .120". I wouldn't worry about that AT ALL.

Yes, I've recently been in contact with a knowledgeable expert who is looking at this for me. I'll let you know if he comes back with anything positive.

I've read that 60 mm springs are surprisingly clunky on 2.25 inch perches, even though the diameters are very similar.

[fbirch]

No luck on the 5 in spring idea. 2.9 inches of total travel and about 1.1 inches of that is taken up by static load. So only 1.8 inches of available travel. Although it probably wouldn't bind in normal circumstances, it could potential do so with a minor off that ends up damaging expensive components.

It occurred to me that my Ground Control camber plates came with a sleeve bushing and two spacer bushings on the underside. I didn't measure them, but they looked to be around 3/16 to 1/4 inch tall per bushing. If I remove one or both of the spacer bushings, that would effectively drop the ride height, allowing me to thread the spring seat up to its topped out position. Between that change and shaving down the lower perimeter of the seat or replacing with a slightly smaller one, I might be able to squeak out 2-3 mm of clearance with the same 12.5 mm wheel spacers I have now. If I later want to boost the front ride height I could always reinstall one of the bushings. Hopefully, the tip of the shock/adjuster knob won't stick too far out the top of the shock tower to hit the hood.

It has turned out to be quite a challenge to make these front shocks work on my E36 with resorting to big wheel spacers/pulled fenders/cut-and-flared fenders, and I'm only running 245/40/17 tires, albeit wide and square 245's.

[ScotcH]

I'm not sure why you would not just try a 15mm or 18mm spacer? Seems like a far easier test.

[fbirch]

I've purchased 15 mm spacers as a fallback option when I try again this weekend. My car currently (before installing these MCS coil overs) has 12.5 mm spacers. Under hard compression I get fender rub on my rolled flat fenders. If the MCS strut creates the same wheel offset relative to the fender as the struts I have now (Bilstein) the degree of rub will get worse if I add more spacer. Sure, I can pull the crap out of the fenders and make it fit, but I'd rather avoid going that route if possible.

The other thing I'll be changing is static ride height - about an inch higher than my current setup. That may buy me a bit of relief on the need to pull fenders if I have to go with a bigger wheel spacer.

I've communicated with several people while trying to make this work who have advised against big spacers and also read a bunch of old threads with the same advice by some knowledgeable folks who do this for a living. Big spacers negatively affect motion ratio and other handling aspects according to that advice.

[fbirch]

No luck on the 5 in spring idea. 2.9 inches of total travel and about 1.1 inches of that is taken up by static load. So only 1.8 inches of available travel. Although it probably wouldn't bind in normal circumstances, it could potential do so with a minor off that ends up damaging expensive components.

It occurred to me that my Ground Control camber plates came with a sleeve bushing and two spacer bushings on the underside. I didn't measure them, but they looked to be around 3/16 to 1/4 inch tall per bushing. If I remove one or both of the spacer bushings, that would effectively drop the ride height, allowing me to thread the spring seat up to its topped out position. Between that change and shaving down the lower perimeter of the seat or replacing with a slightly smaller one, I might be able to squeak out 2-3 mm of clearance with the same 12.5 mm wheel spacers I have now. If I later want to boost the front ride height I could always reinstall one of the bushings. Hopefully, the tip of the shock/adjuster knob won't stick too far out the top of the shock tower to hit the hood.

It has turned out to be quite a challenge to make these front shocks work on my E36 with resorting to big wheel spacers/pulled fenders/cut-and-flared fenders, and I'm only running 245/40/17 tires, albeit wide and square 245's.

So I removed one of the two bushings in each one of the Ground Control camber plates. Each bushing is 1/4 inch tall. I then threaded the perch up by 1/4 inch. This made a big difference in tire clearance. It may not look like it, but each side now has about 7 mm of clearance between the lower locking ring and the tire and a bit more between tire and shock body. Best of all, I was able to retain the 12.5 mm spacers I had on there to begin with, so I should have no issue with tire rub on the fender.

MCS 2 by F birch, on Flickr

MCS 1 by F birch, on Flickr

I ended up with a bit more front end lift than I wanted. Each side is about 12 + 7/8 inch wheel center to fender lip. That gives me just under 1 inch between the top of the tire and the fender lip. In retrospect, I probably should have removed the second bushing from each camber plate. That would let me drop the nose by another 1/4 inch with the same perch height. I was concerned that removing bushings would make the adjuster tips protrude too far above the shock tower and hit the hood underside. But when I tested with silly putty (after removing one bushing) there was plenty of clearance under hood.

I have a test and tune day on Mon, so I'll drive it as it sits now. If I think the nose needs to drop, I'll remove the second bushing from the camber plates and will also replace the lower lock ring under the perch with a standard ring (less bulky than the bulkier-than-needed MCS rings). That would allow me to drop the perch a bit more, probably 1/8 inch.

So the bottom line is that these MCS shocks can be made to work with modest wheel spacers, but you have to get the spring seat/perch up near the top of the thread range. You have to pay attention to the thickness of the camber plate and each little tweak here and there.

BTW, those two "extra" grooves in the tire wall in the first pic were the initial seat and lock ring positions. That's when I also had helper springs in there. I was anxious to drive the car and didn't check the clearance first! No way you can run the perch that low on these shocks without giant wheel spacers.

BTW, BimmerWorld, Hyperco and MCS have been great throughout the process of figuring out how to make this work. A big part of the difficulty was my lack of knowledge going into it, and not understanding how the geometry differences between these shocks and what I had before required me to make other changes. I also appreciate the great info I got from the people posting in this thread.

[aeronaut]

This is just all kinda disheartening and really stifles my desire to buy MCS.
But....I'd likely run into some other issue with another brand.