C-Max suspension/handling upgrades

[Ymbiz]

In case it helps anyone, I have found it's possible to dramatically improve the cornering/handling of the C-max while keeping the ride quality very similar to stock with some relatively low cost mods.

 

Rear swaybar - This is a *very* cost effective way of making the cmax more eager to turn in, and minimize understeer. A gen 1 Mazdaspeed3 rear sway bar is cheap and fits the C-max; you can use stock Ford end links.

 

Summer tires - A big rear sway bar + decent summer tires will make the Cmax very responsive to steering inputs, and way more fun to drive. Swapping the wheels from my Focus ST, the grip levels actually feel very similar between the Cmax and ST. Comparing sound levels, the worn Focus ST tires (235/40/18 Goodyear Eagle F1 asymmetric 2 @3/32" tread depth) are 1-2db louder at 70mph on smooth concrete freeway vs. the OE Michelin Energy Saver AS tires at @5/32" depth.

 

Rear shocks: Koni adjustable yellows for the Focus (8040 1351 Sport) fit; no drilling required. At the softest setting, the ride is close to stock, but still reduces the C-max's tendency to rebound and porpoise. I'm pretty satisfied with the soft setting, but will probably adjust them a bit stiffer at some point.

 

With just the sway bar and tires, the C-max is more engaging in corners than my 2013 Focus was with similar mods. I think it's almost as satisfying in turns as one of my favorites, my 2005 Mazda 3.

Edited October 6, 2021 by Ymbiz

[takingittothemax]

Nice! I love the look of the C-Max with ST wheels. I've been thinking of doing that upgrade, but (you know) money and fuel economy.

 

Actually, how is your mileage after going to the ST wheel and tire combo?

[cr08]

Curious how long you've had these mods and what kind of tire wear you see with these? Anything better or worse than the normal camber/cupping issues seen stock?

[Lacienega]

I like the wheels too.

[Ymbiz]

On 10/5/2021 at 9:50 AM, cr08 said:

Curious how long you've had these mods and what kind of tire wear you see with these? Anything better or worse than the normal camber/cupping issues seen stock?

 

Overall, I would expect the tire wear would be similar to non-turbo Focuses. For reference, I had about 25k miles on the Energy Saver Michelins with no wear issues at all.

 

In my case, because the 18s were already well worn from track events, I didn't care about tire wear and ran them at lower pressures to increase comfort. I probably went too low on the rears (32 psi iirc) and given the extra weight of the battery, saw some increased inside tire wear.  When I get new tires, I'll get the alignment done, try 35-36 psi cold, and monitor to see if that pressure is ok.  

 

I would expect the rear sway bar to have no impact on tire wear. With really aggressive cornering, the big rear bar might reduce front tire wear by reducing understeer.

 

I wouldn't expect the rear shocks to affect the tire wear except if the original shocks are completely worn.

Edited October 6, 2021 by Ymbiz

[Ymbiz]

On 10/5/2021 at 8:19 AM, takingittothemax said:

Nice! I love the look of the C-Max with ST wheels. I've been thinking of doing that upgrade, but (you know) money and fuel economy.

 

Actually, how is your mileage after going to the ST wheel and tire combo?

Good question. It probably would be best to compare ST vs. the oe tire, but I failed to note the numbers. On longer trips, we also often have a roof box, a bike rack, and drive at 75mph+, so fuel economy of the tires isn't out biggest problem:). 

 

Back when I had similar mods on our 2011 Prius, I think I saw maybe a 10% drop. But the OE Prius tires were ridiculously high efficiency and very uncomfortable; the comfort improvement alone was worth $8/month in gas costs to me.

Edited October 6, 2021 by Ymbiz

[cr08]

On 10/6/2021 at 6:18 AM, Ymbiz said:

 

Overall, I would expect the tire wear would be similar to non-turbo Focuses. For reference, I had about 25k miles on the Energy Saver Michelins with no wear issues at all.

 

In my case, because the 18s were already well worn from track events, I didn't care about tire wear and ran them at lower pressures to increase comfort. I probably went too low on the rears (32 psi iirc) and given the extra weight of the battery, saw some increased inside tire wear.  When I get new tires, I'll get the alignment done, try 35-36 psi cold, and monitor to see if that pressure is ok.  

 

I would expect the rear sway bar to have no impact on tire wear. With really aggressive cornering, the big rear bar might reduce front tire wear by reducing understeer.

 

I wouldn't expect the rear shocks to affect the tire wear except if the original shocks are completely worn.

 

Thanks for the information. I've went through  a set and a half of tires so far in my 4 1/2 years of ownership and the uneven tire wear stock even with proper balancing and alignment has been frustrating. The cupping and associated noise is unnerving especially after doing a rotation at just 10k miles so all in all I've been on the hunt trying to find potential solutions I can look into. But so far it seems like the adjustable control arms mentioned elsewhere may be the primary option that is on my agenda once I'm due for a new set of tires.

 

I do have to ask: Do you actually track your C-Max? Curious if you have any videos. I'm fascinated at how well it handles on the track. Just seems like it'd be a strange vehicle to see out there. lol.

[TankII]

I have a Steeda 1" rear bar on my '17 Energi (and my daughter's '15 Energi) and it really took a major portion of the understeer out.  Much safer to drive in the snow/rain now.  Also evens tire wear.  I do swap the rims/tires for snows.

Front suspension is stock on both.

So far, I've replaced the rear shocks with OEM and KYBs, and spoke with Bilstein about their offerings.

OEM - Better cornering support than KYB, but the cars are twitchy on the highway because they are not variable valve rate.  The KYB solves that issue - but are excessively soft (even my daughter is complaining)

Bilstein - the C4 is the only offering.  I spoke with them about the C6, and they stated it is uniquely valved but softer (sounded like the KYB) and not recommended.

I won't touch Monroe anymore after they went from Sensatrac to OE Spectum and went soft.  I had one of each on the front of my '91 SHO for a while and the difference was remarkable - and unsettling.

Sachs - I put them on our old '01 Stratus ES Sedan, and they were great at low speeds, but slightly soft at high speeds because of no variable valving.  I would say they would be better than stock, but not much more.

I now run Gabriel Ultras on my SHO and they are stiffer than the Sensatrac were (and much better than the single-adjustable Konis I was running for years).  I put Gabriel Ultras on the rear of our '09 Focus which was my daughter's daily until I gave her the '15 Energi and she really liked it.  She doesn't like the KYBs at all.  But, Gabriel doesn't list a part for the C-Max, so the '10 Mazda 3 rears are the closest equivalent.  I plan on picking up a set soon, with the hopes they are at least as stiff as the OEMs at low speed and nice and stable at the Highway due to the variable valve rate.

 

TankII

 

[TankII]

Update:

The Factory rear shocks are:

Collapsed Length 22.5 inches

Extended length 28.5 inches

Total length 30.3 inches.

Stroke calculates out to around 6 inches.

 

KYB 553389 (Shared part number with 2010 Mazda 3) are:

CL 18.89

EL 28.34

Stroke 9.45

 

Gabriel 51983 (2010 Mazda 3 specific)

CL 18.58

EL 26.5

Stroke 7.92

 

Monroe 39129 (C-Max, Some Focus)

CL 20.230

EL 28.270

TL 32.25

Stroke 8.04

 

Gabriel G511134 (2011 and up standard Focus)

CL 18.74

EL 27.95

Stroke 9.21

 

I could not find any data on Bilstein models.

I also couldn't find specs for Sachs models.

I think the G511134 is a really close match to stock, with the exception of the much longer stroke which all the aftermarket units appear to have.  The Mazda specific fit Gabriel is too short, especially compared to the KYB offering for both models.

I would say any of the aftermarket ones with variable valving would ride better/control better than stock, though from experience the KYB is significantly softer on my Energi.  I would put the Monroe at the same ranking as KYB based on experience with other car installs.

The one thing the Gabriels above don't have listed is the piston diameter.  On my '09 Focus, the piston was 0.25" larger than stock, really firming up the back.  From the Gabriel site picture, it is hard to tell if there is a difference over stock with this part number.

While I would love to run coil overs, I haul with my cars, and would rather keep things at stock connection points just stiffer.  

FYI, the equivalent Konis for the same year Focus are are re-bound adjustable dampening only - which I really grew to hate on my '91 SHO.

[NRGTi]

I am SO happy to see someone finally modding their suspension. I didn't want to be the first! 

 

As for a tire swap, when my 2017 Energi's tires were done at 40 K miles, I changed over to the same size Michelin MVM4. My mileage dropped from 70 mpg to 60 mpg, which is still an excellent result. The new tires are runflats, but they ride about the same, without the infamous harshness.  

[Mrinohk]

Doing the same sway bar myself tonight on my 13 SEL. Very excited to get it in there after comparing the sizes of the old and new one. Looking at coilover kits next after this I think to try and get her an inch, maybe 2 inches closer to the ground. I'm seeing that a lot of the cheaper sets on ebay advertise any C-Max set as compatible with the focus non-st, and vice versa, so I'd expect a stiffer focus kit to be pretty good on our heavier cars.

 

Did the front tires last year with some continental extreme contacts, and been meaning to get the same ones on the back because every other tire rotation the front tires are useless if I accelerate too hard, but alas, I am lazy.

[totlco]

I am a newbie, so any advice would be appreciated. I have an extended service contract with Ford that covers the mcpherson struts. The dealer is telling me that the warranty does not cover front shocks but it does cover the struts. It it is my understanding that front shocks are a component of the mcpherson's in the front. When the dealer replaces the front shocks is the dealer also replacing the struts? In other words, should the warranty cover the front shocks as they are a component part apparently of the struts which are covered by the warranty? Any information would be appreciated. Thanks

[jzchen]

Usually fronts are struts, spring is mounted on a perch on the “shock”.  Rears are shocks, springs are mounted separately from the shock.

 

The front shocks are not covered because they are not shocks, they are McPherson struts.  The rears are shocks.  Bottom line is you should be covered by the warranty.