Poor ride quality on stockish suspension

Hi all,

Hoping to get some ideas/things to check before I take the car to a suspension shop.

It's possible I'm just getting old here, but I've been experiencing what I feel is poor ride quality on a stockish suspension setup. Car is fine on a smooth road, but if I hit a bump or a section of roadwork where the pavement is uneven, I'll get a loud thunking from the suspension, like it's not able to absorb the bumps properly, and even a little instability like the car is skittering around. It's uncomfortable and annoyingly noisy. However, I've replaced just about all the suspension components that would reasonably contribute to poor ride quality. Here's the specs:

Car: 230+k <- this may be the source of the problem right here, although it has clean title/carfax.
Alignment: iffy-the alignment itself seems fine but I think the camber is too positive as I had it done at a local service station after removing some lowering springs that I didn't like and I don't think they reset the camber.
Suspension and mounts:
speed source poly engine mounts
speed source aluminum front crossmember bushings
stock springs
newish koni yellow inserts front on softest setting
blown OEM struts rear (have new OEM in box but so far too lazy to install them)
NO bump stops front or rear (old ones disintegrated. have new ones all around but haven't installed yet) <- also possible culprit, but don't think I should be hitting bump stops that often on random city roads?
newish Moog swaybar endlinks all around
newish Moog ball joints
new OEM strut top mounts front
new OEM hub spherical bearings all around
new OEM inner control arm bushings front
new OEM swaybar bushings all around
full SuperPro bushing set (control arms) front and rear (minus spherical bearings on hubs)
http://www.gt4-racing.eu/ rear poly subframe bushings
Mario aluminum diff mount bushing

Things I DON'T think are the problem:
Bushings- The mounts and bushings probably seem pretty aggressive. I had the SuperPro set, rear subframe bushings and diff mount, and crossmember bushings all done at the same time recently to replace unknown mileage OEM bushings (the only non-original bushings that had been on the car for a long time were the poly engine mounts). I didn't feel a significant difference in ride quality before/after. It was poor either way. The bushings tightened up the response a bit, but didn't really affect the comfort level on bumpy roads.
Lack of bump stops- of course I shouldn't be running without them, but I'm skeptical that this is the source of the issue as I get poor ride quality even over low speed bumps. High speed bumps I could see them coming into play more. But I get consistently poor ride quality over any kind of bump or uneven pavement at any speed.

Things that may be the issue:
- the obvious discrepancies like the rear struts and bump stops that I need to address.
- the chassis itself: it's seen a lot of miles on northern roads. It's possible what I'm feeling is the chassis itself flopping around in response to suspension action. The windows are definitely loose and possibly the doors as well which may be contributing to the noise over bumps. I've had some rust repaired- notably the front swaybar mounting points. There could be more although I've asked multiple professional techs to inspect it for that very thing and they haven't noted anything structural.
- the konis: maybe these are just more aggressive than I had anticipated? Seems unlikely but possible for someone that is expecting a stockish ride quality.

I've never driven a low mileage stock alltrac for comparison but I previously owned a 140k mile '93 with a stock strut/intrax spring setup and a Tein SS setup with engine mount inserts and aluminum rear diff mount and neither of those setups felt uncomfortable to drive in any way (unless LA roads are significantly nicer than DC roads).

I'm at a bit of a loss as to what might be causing the issue so any suggestions welcome!

Thanks!

J

is this a new phenomenon or have it always felt this way?

alignment: if the camber is way off, you can visually see it. it is entirely possible that rough roads and bumps can throw your alignment off (might explain the skittish behavior-- usually a result of toe not being set correctly).

when you say "not absorbing bumps well" that points to the shock absorbers. you said the rears are blown, so that's definitely it. the fronts might be too? koni yellows on the softest setting is very soft and i'd say close to stock. check that they are set to the softest setting (sometimes the dial can get stiff and it may feel like you've rotated it all the way to soft but haven't). there's a big difference between the softest and hardest setting-- on hardest, it's stiff and uncomfortable/tiring for regular driving.

...and just in general, you suspension is not "stock-ish" lol... poly bushings really stiffen up the ride, especially if replacing 20+ year old rubber worn out bushings. so it'll ride stiffer and rougher than what you'd expect...

other than that, hard to really say without actually riding/driving your car. part of it is personal preference and tolerance for stiffness in ride. someone driving my car might think it's too soft and hate it, others might think it's too stiff and hate it. while i'm the only one that like the way it's set up...

Thanks for the reply Mike!

Yes, it's always felt this way, which is why I started replacing all the parts to try to resolve the poor ride.

The koni's I bought BNIB so I doubt they're blown already but I'll do a bounce check to confirm. When I've tried playing with the adjustment I honestly didn't notice a huge difference between full soft and full hard but that was before I replaced all the other components. I'll try it again to see if I can feel a big difference and confirm they're full soft.

Plan to go ahead and replace the rears with proper bump stops this weekend so I can finally rule that out.

I'm willing to believe that part of it might just be perception, although I don't think so based on my experience with my old car that had coilovers/diff mount/motor mount inserts. I think I expected that even with all the new bushings, you could still achieve a pretty soft ride if you maintained the stock springs and had mild or OEM struts. At the same time, the poor ride has been there even before the bushings when I just had the konis and poly motor mounts and nothing else. It's possible the motor mounts themselves are the main culprit in the stiffness but I would be surprised. Or maybe the konis are stiffer than I expected.

I really wish I could ride in a genuine bone stock suspension car to compare and see what a real stock ride should feel like. Or maybe I'll just sell it and get an Aston Martin.

Anyway, thanks for the feedback. I'll update once I get the rears changed out.

Try asking for a ride in someone elses AllTrac in here?
viewforum.php?f=28

Engine mounts have no relationship to suspension/ride-- it'll just make your car vibrate more, especially noticeable when sitting still at idle. It starts rattling things inside your car (dash, steering column trim, door trim), lol...

I was just reading your post again, and you noted chassis flex. It *could* have something to do with that. I know my car's chassis also has a bit of flex in it, noticeable when I go over harsh bumps, the windows rattle. And when I jack up one side of the car, it's noticeably harder to closer the door tight/perfectly due to the flex. I think it's just the way the car is, it's not a very stiff car (torsionally) compared to modern cars. It can contribute to the feeling of "harshness" in the ride...

A few weeks ago when I was riding on Konis on full stiff to the track (it was a 3-day back to back event, so I didn't bother dialing them back down for the street), it is *definitely* much harsher and stiffer than when I normally drive on full soft. If yours doesn't feel different from full soft to full stiff, I'd be concerned...? (Maybe because you only have it in the fronts whereas I have them on all 4 corners?)

^Yeah, I definitely experienced the same symptoms as you regarding chassis flex under the same conditions. The windows are very rattly and need adjustment as the passenger side one doesn't even seal well enough to keep water out at the car wash. Is there a way to tighten the way the doors themselves seat against the body to maintain stiffness? Despite copious warnings not to do it, I wonder if these door stabilizers for the FRS would work on our cars? http://www.titanmotorsports.com/trd-doo ... 18001.html

@MWP: good suggestion, although I'd be really surprised if anyone nearby was still running maintained bone stock suspension. But I'll def ask if nothing else pans out.

Anyway, I'll know more once I get the rears changed out this weekend and test the front struts again.

I replaced the rear struts today with new OEM struts and new OEM bump stops.

As I expected, it didn't have much effect on the overall ride quality. I'd say a 5%-10% improvement. I still feel like I can feel every crack in the road and over larger bumps where the suspension has to react quickly I still get a loud and uncomfortable thunking.

I'm starting to wonder if I just don't like the damping profile of the Koni Yellows up front. I've read somewhere that while the overall handling is comparable, Bilstein's have a more comfortable setup for the kind of bumps you'd experience daily driving while the Koni's are a little harsher over those same types of bumps (unfortunately no Bilstein inserts available for the Alltrac). There's a particular road I travel often that has some thin but tall bumps (some kind of regular paving imperfection) that I usually hit at 40-50mph which is where I get the super-nasty thunking. Although even at very low speeds (~20mph) when I go over patched/uneven pavement I feel like the fronts relay every bump into the cabin.

Any thoughts?

I have Bilstein PSS9's on my WRX - the are VERY comfortable for the level of performance.

As for your situation - The poly bushings are most likely the source of the harshness. The few times I have added poly suspension bushings to a car (with nothing else changing) there has been a large increase in transmission of 'hard corner' bumps, just like you are describing. In the WRX world, the front A-arm bushings are most responsible for this (especially when paired with an anti-lift kit - so geometry is important too).

-Charlie

The bushings could be contributing but I'm skeptical that they are the main cause because I still had the poor ride before I had all the bushings done. Also I didn't notice a really significant increase in harshness after the bushing install. The one thing that was the same pre- and post- bushings is the Koni's in the front.

I guess if I really want to rule out the struts I can remove the koni's and install some KYB GR-2 inserts I have. At one point I had lowering springs with the GR-2 inserts and found the GR-2s WAY too soft to use on a lowered car, but they might work with stock springs, although they'll probably make the handling worse compared to the Konis :doh: But I need to take the strut tops off to install the bump stops anyway...hmm, I'll have to think about that.

At this point I'll probably just leave the setup as-is and concentrate on NVH issues that I think may be contributing to the perception of roughness. Also I definitely need to get a proper alignment as I'm sure the current alignment isn't helping the overall feeling. I'll try to make it to the next NE meet and have some other alltrac owners drive it around and see what they think. They'll probably say it rides great

Just wanted to bump this if anyone else ends up having this problem.

I've narrowed down the issue to the Speed Source poly motor mounts.

I replaced the front motor mount with a new OEM mount and the 4 small front crossmember-to-chassis bushings with OEM (trans mount is still SS poly) and noticed an immediate improvement. The greatest improvement I've seen out of any of the changes I've made. I think this is why I didn't notice much difference between the old OEM suspension bushings and the new poly suspension bushings in the front: the common factor was that both setups used the SS poly mounts. This also explains why my old car with Kirkosaurus motor mount inserts and Tein coilovers was more comfortable and compliant that my current stockish strut and spring combo. The kirkosaurus are not nearly as solid a mount as the full poly Speed Source ones.

Hope this helps someone considering solid motor mounts in the future. The stiffest I'd go is kirkosaurus inserts on the street unless you do a lot of track driving or have nothing but smooth pavement where you live.

J

Wait, how could motor mounts have an effect on how the car feels over bumps?

BUMP!

Might just be that the motor mounts were transferring more shock and vibration into the chassis when the car gets unsettled over sharp bumps :shrug: Not really sure to be honest. Although I probably should have been more clear that the problem wasn't 100% cured by the mount change. I'd say maybe a 10-15% improvement. I still don't think the ride quality is great though. About the only thing left to try is switching to different inserts in the front (koni to Bilstein) and see how that goes.

The ride got pretty bad again recently but that turned out to be tie rod ends. I also had the front driveshaft U-joints replaced with OEM and that definitely improved some front-to-rear rocking and clutch engagement/shifting feel. The U-joints sort of improved the overall feeling of tightness which has made the subjective ride feel a bit better.