Mountune Springs + B6?

[foodtruck]

In my defense, there are plenty of Mountune springs + B8 threads, but I couldn't find many with B6, so I'd like to hear if anyone is running this combination and what is the current height to the top of the fender arch.

-

What bothers me is Mountune is selling these springs for use with stock dampers and yet they package them with B8s for their Clubsport kit rather than B6s which are supposedly a better match for the stock damper length.

Furthermore, Swift-Rs which advertise similar lowering (if not a touch more) also go with stock dampers and there have been folks who successfull ran them with B6.

There's enough evidence to suggest that stock damper length offers plenty of preload for Mountune springs so the only explanation I can think of is B8 in Clubsport kit offers a bit more safety margin for compression travel in exchange for reduced droop but that's about it. But then again, since they do sell these for stock damper length, getting B6s should allow me to put on the springs more easily and get the extra droop.

 

[Dialcaliper]

Mountune springs work fine with stock dampers, there’s no reason they shouldn’t work with the B6’s just fine. The only difference with the B8 is the shorter shaft and less travel so you get more spring preload in droop (which is not necessarily a good thing).

You actually don’t get much more margin on compression with the B8. Shaft stop is shaft stop and the compression is controlled by the bump stop - the stock/B6 has plenty of travel for stock or even slightly trimmed bumpstops without bottoming the piston. It would only come into play if you completely hacked off 2-3” of bumpstop (MCU bumpstops generally will compress to 1/3 original height), or swapped in hard rubber bumpers that don’t engage in order to get your car “slammed” to the ground with some of the more extreme lowering springs, which the Mountune are not.

Front bumpstops are only 3” long to begin with - rears are about 5” for reference.

Function and damping between B6/B8 seem to be identical.

 

[foodtruck]

But then whyy did Mountune pick B8s for the kit?? I'm almost willing to pay money to have someone involved in the decision tell me, haha.

more spring preload in droop (which is not necessarily a good thing).

Could you elaborate on that? The reason I'm asking is my B14 kit is currently set to max height and therefore to max preload at droop and it feels like the car is cratering hard into every mild indent in the road. Looking back at your Excel sheet in the other thread, those indents are definitely less than +/-3in in depth which would be the free length of the damper around the ride height, so it's either just how 280lb/in feel like or I was also wondering whether dampers need to have way more free length than the feature depth/height to handle them properly. But perhaps preload somehow contributes to it?

 

[Dialcaliper]

But then whyy did Mountune pick B8s for the kit?? I'm almost willing to pay money to have someone involved in the decision tell me, haha.


Could you elaborate on that? The reason I'm asking is my B14 kit is currently set to max height and therefore to max preload at droop and it feels like the car is cratering hard into every mild indent in the road. Looking back at your Excel sheet in the other thread, those indents are definitely less than +/-3in in depth which would be the free length of the damper around the ride height, so it's either just how 280lb/in feel like or I was also wondering whether dampers need to have way more free length than the feature depth/height to handle them properly. But perhaps preload somehow contributes to it?

The max-height/max-preload issue is due to the fact that on the occasions when you do hit full droop, the force on the wheel (into the shock tower) makes a step-change from the preload to zero, which you will perceive as a sharp jerk that can unsettle the car. But it shouldn’t be happening that often except on fairly bumpy roads, and hard corners on the inside wheels. On normal roads like you’re describing, preload shouldn’t matter so much.

The “cratering” sounds more like jacking down, or a symptom of too much rebound damping bias and not enough compression damping. Theres not a ton you can do without opening the shocks. Slightly stiffer springs can help a bit in that case but can result in different problems.

One thing I discovered while messing around hat might help a bit is adding some “spring rubbers” to your existing springs rather than stiffen, as the foam/rubber elastomer effectively adds a little bit of extra compression damping along with stiffening the spring. It might not cure the problem but might be worth a shot. I used the Speedthane MCU type which work well, but are only for coil over sizes (~2.5”/60mm springs).

Some fairly soft polyurethane or rubber ones might work for the kit springs. Rubber will tend to give more damping effect than polyurethane, so just get some cheapo rubber ones to try out.

 

[Zormecteon]

When I first installed the mountune springs I left the stock dampers. I ran that way for years. (I bought the car new in 2014). Somewhere around 50,000 miles I replaced those shocks with B8s. ..

I don't know that I can recall the difference in the feel other than slightly more control now? .. i.e. the stock length works fine with mountune springs. B8s should be ok.