MCA Street Performance (Purple)

[Wombit]

So after having the SE for over a year, and wanting to get some coilovers, I finally got some MCA's.

I had been looking at all the possibilities on options, and for a long time was planning on getting the Ohlins DFV. However after poor response from a local seller, I began looking elsewhere, and decided it was MCA or nothing.

MCA have recently updated their product offerings from four levels (Blue, X series, Red, & Gold) to seven! (Street Blues, Street Essentials, Street Performance, Street Ultimate, Race Prime, Race Reds, & Gold)

These units feel very well built in the hand, and finish is flawless. There have also been a few physical changes to the design in the new series. These include a helper spring to keep the main spring seated when in droop, and only one locking collar for the spring perch with a grub screw to lock it in place against the thread body.

I will update with more information on ride quality after install, which will hopefully occur this coming week.

Originally, I had thought the 10kg/mm springs would be way too firm for my usage. My thinking is it may not be compliant enough over rough roads and particularly, mid-corner bumps. Luckily, this is only a small cost with MCA to change springs if necessary, but I'll know for sure after giving them a good shake down.

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[Snowmotion]

Nice set up.

I don't think you will find 10kg front springs too much. I run 10kg fronts and 6kg rears in MCA Blues on a NB8a. Whilst the ride is firm it is not jarring. I just did a 400km trip down the coast with the Wife in tow and no complaints or discomfort.

[project.r.racing]

Not a fan of the grub screw. A few makers in the 90s did that and it ruined some threads on the shock.

[Wombit]

That's my biggest concern so far. I am yet to see how it won't damage them, particularly after repeated adjustments to get the ride height set. I've sent them an email asking about it and will see where things go when I get a reply

[CrazyRacer]

I think you'll be fine with the 10/6 spring combination. I realised after I talked to you that my X-R setup didn't have 10/6 but actually has 11/7 springs which were a little firm, but still OK for the street. You just can't go with the suggested track damper setting, you need to turn it way down for street use.

I hadn't noticed that they'd now gone for a grub screw to lock the spring platform. I wonder whether its a cost thing or there's a technical reason for it?

[RS2000]

Surely the grub screw doesn't bite into the thread!
I'd hope the screw pushes on a small block that has grooves in it to match the thread

[Wombit]

Surely the grub screw doesn't bite into the thread!
I'd hope the screw pushes on a small block that has grooves in it to match the thread

Ultimately, this is what I'm hoping to hear from MCA on Monday. The only other way I would know sooner is to dismantle the whole assembly and look myself.

[legume]

Dont the two purple rings lock together? Where the grub screw is it sticks out lower than the face. Would the grub screw be holding a removable overlapping block the locks the two rings from turning?

[bruce]

and only one locking collar for the spring perch with a grub screw to lock it in place against the thread body.

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[legume]

ah, thanks Bruce. I didnt take that in while reading.
So the lower is part of the main body, and upper one for adjustment. Now I see the concern

[Wombit]

So Monday night, I was curious and decided to see what was underneath the grub screw, and if there was any damage to the threads. I found that the screw was snug but not overly tight, which was a good thing to me. After removing it, a small brass coloured piece of metal came out, which looks like it would deform easier than the thread.

Earlier today I received a response from MCA, and so nothing is lost in translation, this is what I was told:

"No need to worry about damage to the thread as there is a aluminium piece between the grubscrew and thread, also just so you know this only needs to be done up lightly, just so you can't turn the spring seat by hand. Do not heavily tighten the grubscrew as it can deform the aluminium and make them difficult to adjust. One of the main reasons for this change was to try and gain back height adjustment space that was lost due to adding helper springs."

This falls into line with the theories and only time will tell as to whether this was a good idea. After 30 years experience in the industry, I doubt MCA would implement something like this without testing it.

[CrazyRacer]

So if you're happy to move forward with them, bring the car around one night and we'll get them fitted up!

[Wombit]

Well yesterday, the MCA suspension went into the car with considerable help from CrazyRacer. I'd like to say that I helped, but in all honesty, I probably slowed the whole process down. The whole suspension change happened in about 2 hours flat, and then we went for a road test to see how the factory settings turned out. The picture shows where it sat after being put back on the ground for the first time.

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There was rubbing on the front end over even a small imperfection, and corners were not that easy to take without contact. When we returned, the suspension had settled so low, we had to jack it up to get it back on the hoist. There was roughly 25mm clearance from the tyre to the wheel well up front, so we had to adjust the bump travel through the base height adjuster. We worked out this was due to the larger wheels on the SE, being 606mm diameter compared to the 15" wheels at 586mm. The rears had no indication of contact, so we left the base adjusters where they were.

After measuring the ride height at each corner, some quick math was done to get towards the target height. The spring to ride height ratio was 2/3 (0.666) at the front, and 3/4 (0.75) for the rears. This means to raise/lower each end by 10mm, you wind the spring perch up or down by 6.66mm on the fronts and 7.5mm in the rear. For all this effort calculating each corner's adjustment numbers, we got to within 3mm all round on the first try.

The road test after this had no rubbing, even after hitting bumps with more force. The grub screw method of locking the spring perch seems perfectly adequate and sturdy. I've taken note of where each one is located to see if they move in time.

Going for a longer drive today through Beechmont was a great indicator of how much better decent coilovers are for handling. In the past, mid corner bumps could induce snap oversteer, so I was constantly busy with the wheel just to keep a line. It used to feel very skittish and unstable.

Initially I thought 10/6 kg/mm springs would be too harsh in the front. However as I've read before, it seems to be smoother in pretty much all circumstances. It's definitely firm hitting an uneven piece of road, but it remains composed and civil where before, the whole car would have a vibration pass through it in the same circumstance.

This is the first time I've bought a set of coilovers for a car, and I wish I had done it much sooner. The car has got that compliant and willing ride I remember from the first NA I drove years ago, and gone is the skittish and shakey feeling it used to have.

[lucmor444]

Great to hear these coil overs are making a big difference.

Are you able to explain how you calculate the spring to ride height ratio?

[Magpie]

For this you need to know the motion ratio. That is how far the damper moves when compared to the wheel (think of a lever). It is not a spring to ride height ratio rather the location of the spring perch to ride height

In Wombit's case a 6.6mm movement of the spring perch on the front damper causes a 10mm wheel movement. However, this is provided the spring and corner weight does not change. There are a few ways to calculate the motion ratio as there are a few different ways to set ride height...