Rough and gravel road suspension setup

[BRZdart17]

I've been doing some research but I'm having a hard time finding an answer. I love my 17 brz all around(stock everything), but where I live the roads are concrete and pretty rough, not so many potholes, but more cross-road lines and frost heaves from winter, also I live near alot of gravel twisty roads(potholes) I'd like to drive "spiritedly" on. So The ride is Rough for me. I know decreasing the tire pressure will help, but would a taller sidewall help as well? And Would raising the car an inch help? I dont mind sacrificing a bit of cornering ability, I just want to smooth it out a bit. Any advice appreciated. Thanks

[strat61caster]

I wouldn't go straight to a taller tire, but rather same overall tire diameter on a 16" wheel to get more sidewall. 225-50-16 should fit the bill, and there's some nifty wheels that are rally style in that size that don't break the bank:

http://www.ft86club.com/forums/showthread.php?t=57975
(If you have the Performance Pack with the big brakes fitting smaller wheels might be problematic)

There's a couple springs/coilovers that target rally style, but nobody to my knowledge is running them in America and the guys running their 86's in rally competitions are mostly custom setups or near stock. Quick googling comes up with MCA and Ohlins providing setups for some people, but that's in the $3k+ range.
http://www.ft86club.com/forums/showthread.php?t=57564
http://www.ft86club.com/forums/showthread.php?t=79713

I wouldn't bother raising it up with spacers as it seems the primary concern is ride quality not ground clearance, you might get a minor improvement, but I'd focus on the suspension side of thing if you're going to be disassembling the suspension.

Maybe a softer coilover setup like off the shelf Ohlins or Bilstein B14's with the height maxed out might get you what you're looking for. I know the Ohlins can match stock height, there was a post here by works about it, and the more I think about it the soft springs and reputation for cushy valving might be a great match and without the top hats they don't really break the bank.
http://www.ft86club.com/forums/showthread.php?p=2749417

[BRZdart17]

Thank you for the informative reply strat61caster, I cant afford the ohlins coilovers right now, after putting 5k down on the car, so I'll probably go with the 16's. But just wondering, could'nt I go to a slightly taller tire on my factory 17's without rubbing on the fenderwells? Thanks. (yes I'm clueless on tires and suspension).

Also one other off topic question. The other day I went to do a burnout in 1st and my shifter shook left to right violently, and the rear end was jumping, not spinning like a normal burnout, like I could'nt even keep a grip on the shift knob. Is upgrading the transmission mount the cure for this? Thanks.

And those rally wheels are pretty cool. Cheap too!

[8RZ]

Buy a truck.

[BRZdart17]

Originally Posted by 8RZ

Buy a truck.

Already got one!

[gramicci101]

Originally Posted by BRZdart17

Thank you for the informative reply strat61caster, I cant afford the ohlins coilovers right now, after putting 5k down on the car, so I'll probably go with the 16's. But just wondering, could'nt I go to a slightly taller tire on my factory 17's without rubbing on the fenderwells? Thanks. (yes I'm clueless on tires and suspension).

Also one other off topic question. The other day I went to do a burnout in 1st and my shifter shook left to right violently, and the rear end was jumping, not spinning like a normal burnout, like I could'nt even keep a grip on the shift knob. Is upgrading the transmission mount the cure for this? Thanks.

And those rally wheels are pretty cool. Cheap too!

You could do a 225/50-17, and people have. It looks really meaty. The downside is that you've increased the rolling circumference and that will throw off your speedo and mileage counter. There are a few rally-oriented cars around here; dig around a bit and see what they've done. The inexpensive way is 3/4" or 1" spacers on top of the struts. The expensive and more functional way is longer travel coilovers. One problem with raising is dealing with the positive camber you've caused.

For the transmission shake, look at a transmission bushing insert and a rear shifter bushing. Both are inexpensive and easy to install. For the rear end hop, look at whiteline diff carrier bushings. The diff flops around pretty severely on the OEM bushings. The downside is a little more gear whine at low speeds. But that's ok, because racecar.

Rally thread:
http://www.ft86club.com/forums/showthread.php?t=105692

[strat61caster]

Originally Posted by BRZdart17

But just wondering, could'nt I go to a slightly taller tire on my factory 17's without rubbing on the fenderwells? Thanks. (yes I'm clueless on tires and suspension).

Also one other off topic question. The other day I went to do a burnout in 1st and my shifter shook left to right violently, and the rear end was jumping a bit, not spinning, like I could'nt even keep a grip on the shift knob. Is upgrading the transmission mount the cure for this? Thanks.

Yes you could go taller, there is lots of clearance to the fenders in this car, but in the interest of keeping things budget friendly you have a decent set of tires that should last tens of thousands of miles currently, it'd be kind of a shame to throw them away as they're about $180/each to replace (there are much cheaper options available of course).

You'll likely decrease fuel economy, increase weight (making the suspension work a little harder) and have to adjust for a speedometer that's no longer accurate due to the taller tire which will also slow your acceleration. But yes, you'll get taller sidewall and theoretically more 'cushion' to your ride.

The burnout description sounds totally normal, the shift lever is directly attached to the drivetrain, many modern cars have cable shifters (or automatics not attached to anything at all) which hide the drivetrain movement from the driver.

I have no experience with the transmission mount but that would be a logical conclusion to make. For me installing the whiteline subframe bushings helped the rear end (and as such the gear lever) feel more planted, the differential bushings not so much, but maybe I'm crazy, but that does lead to a bit stiffer ride and NVH, not much, but counterproductive to what you came in here with.

[BRZdart17]

So, I'm going to get the transmission mount 4 sure, And I guess I'll go with the 16" wheel setup, with a rally car looking theme, after these factory tires are toast. I'll be drifting the backroads in no time!
Because Rally/Racecar? Thanks again guys!

[Gforce]

Originally Posted by BRZdart17

I've been doing some research but I'm having a hard time finding an answer. I love my 17 brz all around(stock everything), but where I live the roads are concrete and pretty rough, not so many potholes, but more cross-road lines and frost heaves from winter, also I live near alot of gravel twisty roads(potholes) I'd like to drive "spiritedly" on. So The ride is Rough for me. I know decreasing the tire pressure will help, but would a taller sidewall help as well? And Would raising the car an inch help? I dont mind sacrificing a bit of cornering ability, I just want to smooth it out a bit. Any advice appreciated. Thanks

You have 4.9 in of ground clearance already. Buy a set of mud flaps for a FRS GT86 from your Toyota dealer and you'll be good to go. 2017 suspension will be fine for rough roads. Don't lower tire pressures though, not the solution.

A set of 205/55 x 16 tires on 16 in Impreza rims would work very well. Standard fitment for the BRZ in some markets like Australia.

Every BRZ should fit the transmission mount insert. Slight increase in gear noise idle is a very small price to pay for stability of the shifter.

I'd consider fitting a set of MCA traction brackets to reduce anti squat forces from the rear. That improves traction and ride.

[churchx]

I'd probably limit options of lifting by changes to suspension via coilovers and/or spacers within 10-20mm. I guess that in similar way if one lowers one >1", then if one rises by >1", one might also need extra parts, like roll center correction/diff lowerer and alikes ..
If you still absolutely need even more, then net that extra with bigger tires (not wheels).
I'm not sure you need extra ground clearance so much as shock travel.
BTW, worth thinking in investment in extra engine protection pan.

I'd try those mentioned TRD rally coilovers (probably will net you not just +10mm ground clearance, but also if there really is any real rallyiness in them, then maybe extra strength & extra travel too. About the only facts that kept me from getting those, i've yet to see any review of them from some owner and their suspiciously cheap price).

Or - KW/RCE ones + extra lift spacer of .. eg. 20mm. KW V1/V3 coilovers have minimum lowering below stock (thus spacers), but they have longer travel then stock.

No comments on GC, as i have no experience with those.

Better not to get generic aftermarket shocks that in most cases target lowering crowd, tarmac track racing and so on. Limited travel, even lower height, stiff springs.

"Real rally coilovers"? Forget about those. 1) they will cost $7-15K, 2) depending on abuse may need overhaul in 1-2K miles.

[Gforce]

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....

[Gforce]

One more aspect of this rough road topic. It should be remembered that these cars are not effete little Euro coupes. They are immensely strong, tough little street fighters. I drive mine on the street fairly aggressively and year round in all weathers. It's been on a poorly maintained gravel road. It only has the originally supplied squeaks clicks and rattles it came with from the factory (and the 2017 has most of these welded up or beefed up and fixed). Warranty service has been literally zero apart from the officially authorized attempt to lubricate the parcel shelf spot welds which I don't count as a "repair".

From an engineers perspective these cars are just Subaru Impreza's with two inches cut out of the floorpan and short overhangs. A two door Impreza Coupe with all of that car's endearing robust character. Perfect for driving on a gravel road in the real world.

These cars are so strong that they provide top notch occupant protection on a collision or rollover. You can take one off the showroom floor and thrash it around a track or time attack course all day and then drive it home and to work the next day. Nothing will have broken or fallen off.

These cars are built to take it.

[BRZdart17]

This is great advice. All of it. Seeing as I live in the "country" and I'm never plan on living in a "city" again. I am surely building my BRZ the Rally theme. Lowering the car "2inches" and having crazy camber and rims is not my thing. I want performance first, looks second. I have nobody to impress but myself, so performance is my goal.
And Thank you for all the great advice... (alot to think about)

[Cole]

Originally Posted by Gforce

These cars are so strong that they provide top notch occupant protection on a collision or rollover. You can take one off the showroom floor and thrash it around a track or time attack course all day and then drive it home and to work the next day. Nothing will have broken or fallen off.

These cars are built to take it.

Thought these cars were no good on the track? Didn't you say that a few days ago?