anyone run MCS shocks yet?
 

anyone run MCS on rx8 yet? i'm in the market for double adjustable shocks. was looking at ohlins ttx before but they are quite pricey. mcs 2 ways none remote are $3500. they are very popular in the BMW community. i have ohlins RT custom valved now.

They generally work well but their valving is very wide because they build the same valving into the shocks for multiple different applications. So each click of adjustment is a big change, which is not really what you want.

I'd recommend a set of Penskes instead.

I autocross and I've moved from non-adjustable Fatcat revalves to MSC single adjustables this season. Profound positive difference in control.

I have not run them on an RX-8, but as an instructor for BMW CCA, I drive and ride in a lot of MCS-equipped Bimmers and have been impressed with them. If my budget were that high, they would be on my short list.

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If they did an inverted rear with both adjustments at the bottom like the Koni 2812 I’d definitely consider a set, but I seem to recall that their design doesn’t permit doing it that way.

maybe you can invert mount them in the rear like for bmw e36/46?

https://cimg0.ibsrv.net/gimg/www.rx8...2caf8d8114.jpg

If you happen to have the hookup on valving/rebuilding my suggestion is find a used set of the Penske's from a NC chassis MX5 cup car like I did... I'd say I probably have the cheapest setup of Gucci shocks anyone has on an RX8, and that even includes the consulting/tooling/parts to do the work myself. I found mine with all the mounting already sorted out, spherical front top hats, etc.

I have the same set of shocks. There are a bunch of sets of those floating around. I am willing to bet the spherical front uppers are the same as what you have as well, and while they're designed for an MX-5 they fit my RX-8 perfectly. One thing about them (at least mine), the rear shafts are a different diameter than what is generally sold now. It means it's a little harder to source a shaft if you end up needing one.

I made spherical rear upper mounts similar to what Tamra and Drew did on their car.

Yeah, I didn’t understand why you didn’t just take the aluminum MX5 rear hats and weld a spherical bearing cup into the top of it rather than modify the steel RX8 rear mounts?

Because I wanted to retain the shock tower braces, and it's easy to weld stainless steel bearing cups into steel.

Different size meaning length? All my shocks were the same diameter on the shafts and the rears were shorter iirc but all parts were available through Penske and RESuspension. I need to do the rear hats at some point, actually have a set sitting on the shelf ready for surgery, I am running the MX5 aluminum ones currently and haven't noticed anything, good or bad, about it.

yeah, I’d just weld some aluminum brackets on to make all that happen, but that’s probably part of why yours is done and mine is still sitting on jack stands 5 years later :dunce:

shaft diameter and threads are different than the ots stuff.

Interesting... have any numbers by chance? Part numbers or measurements...

The set I picked up do not seem to have any variation from OTS Penskes. I rebuilt them myself, swapped pistons, set valving, etc and ordered all the 'normal' parts for an 8300 in the process, including shaft wipers, ring nuts, etc.

My ability to fabricate stuff is quite novice and rudimentary compared to yours, and if I want to do anything interesting in Aluminum I have to go somewhere else. Eventually I'll pick up a TIG welder but for now I'm hacking away with a MIG

I should have been more clear. The shafts themselves are standard but the stepped portion of the shaft to mount to the top hat is a different diameter with a metric thread. Maybe yours are not set up this way but I know from talking to the Penske guys in Reading that the MX-5 cup stuff was all custom, so ordering new shafts to replace them as they come in needing repair means a new batch has to be run. I don't have the part numbers with me. It sounds like you have all your stuff figured out.

are all penske double adjustable for NC or RX8 use external reservoir? i need it to be non external reservoir to avoid taking additional mod points.

No, you can buy DA Penskes that are all internally adjustable. That's the 7500 series. The tradeoff is that the shock body needs to be long enough (really not a problem on the RX-8/NC) to fit the adjusters and get enough shock travel. Penske also recently came out with a double bleed adjuster that contains compression/rebound adjustment on the shock shaft, but the target application for that is for struts.

Let me rephrase that, I’m fairly certain that they can’t offer a non-remote DA that can be mounted with both adjusters easily accessible at the bottom. All non-remote DA monotube shocks have a potential length issue because the gas chamber and separator piston along with the oil/shaft travel all have to fit within the same body housing.

The Koni 2812 has been the only real option, but maybe MCS can offer something if they’ll make an adjuster end with an 18mm spherical eye needed at the RX8 rear upright end. For some reason the last year or two I raced mine kept having issues blowing out, leaking, etc. and nobody seems to be able to figure out why including Koni. Nothing more frustratng than chasing your own butt in this situation. So I’m just about ready to try something different if the situation continues.


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Well one thing I would add, if you went with the short NC MX5 rear shock setup, which uses the shorter aluminum rear hats, you could probably have both adjusters at the top and still access them. You just have to weld an aluminum spherical bearing cup into the top of OE aluminum MX5 rear hats.

You also lose the chassis tie-in point, which is also the mounting point for a rear strut tower bar. In theory you can add brackets to retain those, but it’s debatable if they’re really necessary with the shorter hats not having the same leverage arm as the tall RX8 rear hats. The only real issue, or thing I don’t like about doing it that way, is you have to use the delrin spring adapter at the bottom of the hat. All do-able though...

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I'd say you should ask your friendly neighborhood Penske builder to see if they can do an inverted shock with an eyelet at one end (hopefully they can fit one that's big enough) and a pin/stud mount at the other with a double bleed shaft. Otherwise, you're correct in that the Penske setups I've seen thus far for the RX-8 can't be done up like the 2812.

https://www.penskeshocks.com/wp-cont...eed%20tech.pdf

You’d need that with an 18mm or 19mm spherical end for the upright mount though; can’t recall exactly since it’s been several years since I last messed around with them. It’s fairy easy to do on the 2812 because they offer a blank steel top and you can cut down the proper size heim joint and weld it on easily. When it’s aluminum it’s hard to do that and have it be strong enough. It would need to be machined from billet or forged. Maybe they offer something similar though.

Well I sent a message to MCS asking if they’d be interested in exploring it. Not expecting a positive answer.


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Just remembered that Guy Ankeny has an inverted Penske for the rear of his and Steve's car, so Penske probably makes something that can fit the upright mount in the RX-8. It doesn't seem like much of a step from there to do a stud at the other end, if Penske makes such a thing.
https://cimg7.ibsrv.net/gimg/www.rx8...bb99ec5c69.jpg
PC: Guy Ankeny

Yeah, except the red knob there is rebound and the compression is probably on the other end up inside the shock tower.

The DB eyelet with that size heim might be an issue, but I’m no Penske expert. A lot of this stuff is kind of newish since the last time I gave then a serious look. I might ask if they can whip up some blank steel tops like the Koni.

On Guy's inverted setup as shown, he uses the NC top hat with the top cut. The remote canister with the compression stack lives in the trunk. The shock mounts to a custom-machined aluminum boss which forms the "cap" for the end of the aluminum shock hat. That boss / cap is then bolted to the NC top hat.

It's a very neat arrangement and Guy can put a setup together for you. Doesn't solve the OP's problem as it's still a shock with a remote reservoir. It's also, um, not cheap.

Ok, now I remember seeing the cut top a year or two ago now that you mention it. Be put way too much time into it imo

https://cimg9.ibsrv.net/gimg/www.rx8...211658d9b.jpeg

There you go. I didn't go this way because after talking to Guy, his implementation limits droop travel.

Well Trever @ MCS just called me and after discussing it he thinks it can be done with standard parts. I just need to send some pics and measurements to confirm. Will try to do this week, but it might be next weekend. Been meaning to do this for a long time and appreciate this thread for motivating me into action.

also, I studied a number of their valving curves and didn’t really see the issue you had mentioned previously about the changes between settings being too big?

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Just to be 100% clear, I was suggesting the dual bleed shaft with the inverted setup as Guy has it. However, John V is absolutely correct in that the shock travel of that setup is already limited, so further reduction by moving the separator piston back into the shock body would be a non-starter.

While I do think Guy would be willing to put something together like that, you'd pay $$$ to do so.

With the short MX5 shock tower, yes. The taller RX8 mount is going to allow a longer body for that to fit. So whether they can provide the DB eyelet with the appropriate large heim is the only question. All the pics I saw of the DB eyelet were aluminum machined with the usual smaller shock heim bearing.

One thing to consider with using the taller RX8 mount on an inverted setup is the center of the hat is effectively more outboard than with the short MX5 one, so you may run into interference between the hat and shock body on compression. I'm not sure I've phrased that correctly, I'll draw a picture if needed... haha.

Has to be considered, but no issue on my setup. This was also the same/similar setup that was used later on for the Koni Challenge RX8s. I was the first to have them made by Koni NA in 2006.

that's awesome, would love to see what the final solution would be for MCS setup. i know a few guys that run them on BRZ and BMW but have been told they have the best customer service. only thing i dont like about them is not being able to independently adjust the ride height like ohlins TTX. are you looking to do inverted rear?

Assuming you mean the ride height can be adjusted independent of preload, why would you want that?

I don't like to preload the springs for corner balance

i think you’re confused, you only need that feature to both have pre-load and be able to adjust ride height. It’s mostly for the Fast & Furious crowd. Real race cars/coil-over shocks don’t have that because it’s only really needed with longish, large diameter OE type springs rather than the usual coilover type. That’s what tender springs are for.

otherwise, corner balancing isn’t “pre-loading” anything ... that’s something entirely different


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not sure why you would dismiss shocks with independent height adjustment as ricer shocks, as most of the ohlins shocks have that feature. i have used shocks that doesn't have that feature and require the use of helper springs, AST, KW V3. i just prefer to have that feature.

Maybe you should instead explain why it makes any difference when most race cars don’t have the springs preloaded?

Do you understand that pre-load is created by actually compressing the spring when the shock is off the car; “pre” loading a force on it? The shock shaft won’t move until that pre-load force is exceeded. That’s why an independent adjuster is needed for small changes. The corner balance is still changed unless you can adjust them accurately down to the thousandths of an inch; good luck. That pre-loaded spring force is holding up the car weight. So to overcome it the overall length has to be changed. Race cars typically use shorter springs with soft or zero force tender springs to accomplish the correct ride height.

Who else actually does it other than a bunch of ricer brands? You don’t think Koni, Penske, MCS, Moton, JRZ, AST, et al can’t do that? It’s just a basic mechanical engineering 101 feature, not rocket science. It’s also not like Ohlins is dominating every segment of auto racing. They jumped into mountain bike forks and shocks the last several years and quickly found out they didn’t have quite the grasp on the market as was probably anticipated. Not knocking them, but let’s not be less than honest either.

i feel that most motorsport shocks don't incorporate independent height adjustment for a couple reasons. mainly cost effectiveness and most of the shock bodies are designed for universal use with multiple applications. i rarely see purpose built race cars use shocks with helper springs. i'm not ohlins fan boy by any means. i'll use any shocks that's the best value for what I can afford. that's why i'm interested in the mcs at the moment. have heard a lot of good feed back from people who uses them at the track and i can get them at a very good price. ohlins are used on a few super cars, so they must be doing something right. i dont follow mountain bike tech, but there's a few established shock companies in that market already. i think they are doing well in the motorcycle market? anyways, we're getting a little out of topic.

I have MCS 2 way adjustable with remote reservoirs. Love how 1 click can make all of the difference going from great to amazing. Access to the rear adjuster is kind of a pain.. but I was able to fab around it. Use swift springs and no preload.. saw you talking about it a bit but not sure what the conversation was about. Also use helper springs.. they just help get the wheel down for driveways.. Lex knows his stuff. You can even have him look in his records for a setup he built for me. PM me and I can jump on a call with you and MCS.

Side note, I love these shocks so much that I will be ordering another setup for a lot tamer of a spring setup for my fun/street rx8.

i’m talking to MCS direct initially, but if we get the fitment figured out on their side by using my Koni 2812 measurements my intention is to swing the actual order over to a shop that has done some considerable autocross RX8 setup work for the tuning work. I was planning on starting somewhere around 16kg/13kg spring rates initially, but still may need to refine that some.

This is pretty much what we need with an 18mm heim at the adjuster end and a 14mm stud on the other end for a 5/8” spherical on the shock tower top with tapered adapter spacers.

https://cimg9.ibsrv.net/gimg/www.rx8...42db8fea42.jpg


And a picture of my inverted Koni 2812 DA, the ABS cable is blocking a good view of the adjusters below the red spring hat ... full droop in this view with 6" x 2.25" spring and a zero helper spring at the bottom


https://cimg3.ibsrv.net/gimg/www.rx8...a51265ded5.jpg


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Tender springs exist to ensure that in a suspension setup with adequate droop travel, an unloaded or lightly loaded wheel will still have a force exerted on it beyond just the unsprung weight (wheel / tire / uprights etc).

Those height-adjustable shocks basically limit you to nearly zero droop travel

100% correct. but you can still run tender springs if you want droop, by running shorter main springs. the height adjustable shocks basically just allow you to change the length of the mounting points (not the shock travel).

good to hear you have good feedback with MCS on rx8.

If you want droop travel? Is there any reason to not want droop travel?

droop travel also depends on how big of a sway bar you're running (side to side)? unless both side is lifted, like jumping a crest.

Maybe this is pedantry, but droop -travel- is not affected by how big of an arb is on the car. How much droop you actually see in operation does depend on what bars are on the car and whether that bar's rate can be counteracted by the sprung weight plus the contribution of the tender.

But you didn't answer the question. Why would you not want droop travel in your suspension, in particular the rear?

Unless you're pre-loading the spring to the actual corner weight or higher it'll still be droop, but definitely less than a non-loaded setup.

I run Ohlin TTX's but I still wanted to put in a good word for Trevor at MCS. I've raced with him for years (he's fast) and he 'figuratively' grew up under a race car. He did setup for Dempsy among other pro teams. He is a great guy and will do anything he can to make the setup work for you. My car is about 5 miles from him if he needs to come over to get measurements.

Yeah, it looked like you lucked out on a set of very unique shocks

What I'm getting at is those adjustable-length coilovers adjust the ride height by shortening the distance between the mounting points with the shock fully extended. You end up with a shock that is by design artificially limited in travel, particularly in droop. And unless you always run the assembly at its shortest length, you're sacrificing travel in both directions.