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Gforce · 05-27-2017, 11:26 AM

It's important to remember the difference between ground clearance and suspension travel. Changing the ride height does not affect suspension travel nor does it affect ride quality. Only changing the spring rate and damper rates to match will change ride quality. Changing the spring length (with or without changing the spring rate) changes the suspension travel. Changing spring length will usually require fitting longer travel dampers. You never want to do that to a BRZ.

Gravel roads are not off road. There are two hazards presented to the chassis by gravel roads, both due to maintenance interval. Where the gravel road forms part of the highway system as it does out here, maintenance is quite good.

Potholes are the biggies for ground clearance issues and they have to be avoided by cars regardless of suspension travel. Deep ones require significant suspension travel and very strong tires. Only pickups or real off-road suspension systems can ride potholes safely.

The most common issue is washboard compliance. Since the BRZ has a relatively high spring rate for its weight and good shocks, particularly 2017, it will actually ride washboard better than a more softly sprung car provided you drive fast enough to hit the correct harmonic.

Just as the more expert ski runs have deeper and steeper moguls so gravel roads develop washboard that coincides with the spring and damper rates of the most common vehicle using that road: the standard and unladen American style half ton truck. The washboard frequency matches the rear spring rates of those vehicles and so most users prefer that vehicle not realizing the ride they think is so good is actually the natural result of the rear drive wheels bouncing along at the communities' effective speed limit (not the posted limit, out here nobody drives that slowly).

Most people in softly sprung SUV or passenger cars drive too fast to match the washboard pattern. Since the spring rate of these vehicles is lower they need to go slower to get in sync with the washboard. Go as fast as the average unladen pickup in a car and you get the wallows. You can even get airborne if the washboard is bad enough.

The good news is you need to drive even faster on washboard in a BRZ....

05-27-2017, 11:26 AM	#11
Gforce Banned Join Date: Mar 2017 Drives: 2013 Subaru BRZ Location: Alberta Posts: 519 Thanks: 39 Thanked 162 Times in 109 Posts Mentioned: 5 Post(s) Tagged: 0 Thread(s)	It's important to remember the difference between ground clearance and suspension travel. Changing the ride height does not affect suspension travel nor does it affect ride quality. Only changing the spring rate and damper rates to match will change ride quality. Changing the spring length (with or without changing the spring rate) changes the suspension travel. Changing spring length will usually require fitting longer travel dampers. You never want to do that to a BRZ. Gravel roads are not off road. There are two hazards presented to the chassis by gravel roads, both due to maintenance interval. Where the gravel road forms part of the highway system as it does out here, maintenance is quite good. Potholes are the biggies for ground clearance issues and they have to be avoided by cars regardless of suspension travel. Deep ones require significant suspension travel and very strong tires. Only pickups or real off-road suspension systems can ride potholes safely. The most common issue is washboard compliance. Since the BRZ has a relatively high spring rate for its weight and good shocks, particularly 2017, it will actually ride washboard better than a more softly sprung car provided you drive fast enough to hit the correct harmonic. Just as the more expert ski runs have deeper and steeper moguls so gravel roads develop washboard that coincides with the spring and damper rates of the most common vehicle using that road: the standard and unladen American style half ton truck. The washboard frequency matches the rear spring rates of those vehicles and so most users prefer that vehicle not realizing the ride they think is so good is actually the natural result of the rear drive wheels bouncing along at the communities' effective speed limit (not the posted limit, out here nobody drives that slowly). Most people in softly sprung SUV or passenger cars drive too fast to match the washboard pattern. Since the spring rate of these vehicles is lower they need to go slower to get in sync with the washboard. Go as fast as the average unladen pickup in a car and you get the wallows. You can even get airborne if the washboard is bad enough. The good news is you need to drive even faster on washboard in a BRZ.... Last edited by Gforce; 05-27-2017 at 11:57 AM.