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CAinCA
CAinCA Reader
11/17/20 11:28 a.m.

Hey guys,

 

I need some input on the suspension on my GTI. I have OZ wheels that are 10 lbs lighter per corner, Ground Control camber plates, SuperPro poly control arm bushings (front and rear positions), H&R 26mm FSB and 24mm RSB (roughly twice as stiff as original). The rest of the suspension is stock.

The car feels great on smooth roads. Unfortunately a LOT of the roads around here are pretty rough and the car feels twitchy and bouncy on those roads. I'm thinking about moving up to something like Koni Yellow adjustable struts/shocks. Does this make sense? Will they absorb more of the roughness or are they going to make the car ride even rougher?

 

Thanks,

 

Chris

Stefan (Forum Supporter)
Stefan (Forum Supporter) MegaDork
11/17/20 11:43 a.m.

I suspect some of that is due to the polyurethane bushings and sway bars.

The Poly can bind the control arms, temporarily increasing spring rate to near infinity.  They also transfer more NVH into the chassis and cabin.

Disconnecting the sway bars and dampers and trying to move the arms by hand can tell you if you might have a binding issue.

Sway bars can also exacerbate things by causing the car to rock side to side on uneven bumps.

 

bentwrench
bentwrench SuperDork
11/17/20 12:28 p.m.

My Mini is on rails at an autoX but, 

On a back road at speed it is a twitchy rollerskate. If you just nudge the wheel the car moves instantly, requires a light hand on the wheel yet a firm grip as the car will need different input over uneven pavement.

I think it is the nature of the beast. Stiff suspension and a light car. You need quick steering to have good response, but that quick steering will also put you in the ditch. 

Messing with Toe-In adjustment will change the way this feels but I think there is a pretty narrow area where it's good. Tire wear is also comes into play here as well.

My lowered 2wd S10 Blazer has massive sway bars, yet I can bomb through stuff I would have slowed down for in the Dakota or in the Mini. I have not tried autoXing it yet though....

Keith Tanner
Keith Tanner MegaDork
11/17/20 12:36 p.m.

Shocks. You need good shocks.

matthewmcl (Forum Supporter)
matthewmcl (Forum Supporter) Reader
11/17/20 12:55 p.m.
Keith Tanner said:

Shocks. You need good shocks.

QFT.  Twitchy could be a sway bar problem, but bouncy is a shock problem. Fix bouncy first.

Tom1200
Tom1200 Dork
11/17/20 1:24 p.m.

Part of what your feeling is the poly bushings but Keith is spot on about good shocks / dampers.

CAinCA
CAinCA Reader
11/17/20 3:53 p.m.

The poly bushings and camber plates were the first thing I installed. I could feel more of the road but it didn't ruin the ride over bumps.

 

I'm pretty sure that the ride went from firm to harsh when I added the sway bars. It has a bouncy head shaky feel on rough roads. I can move the sway bars to the softest setting (~1.75X stock) for the street but it didn't make a huge difference when I tried it before. 

 

I went to the lighter wheels around the same time I swapped the sway bars. That shouldn't have made the ride rougher though, right?

 

I'm tempted to disconnect one end link on each end and then take it for a ride and see if it cures the ride issue. If it does then better shocks should help reduce the roughness or at least the shaky feeling, right?

Stefan (Forum Supporter)
Stefan (Forum Supporter) MegaDork
11/17/20 4:06 p.m.
CAinCA said:

The poly bushings and camber plates were the first thing I installed. I could feel more of the road but it didn't ruin the ride over bumps.

 

I'm pretty sure that the ride went from firm to harsh when I added the sway bars. It has a bouncy head shaky feel on rough roads. I can move the sway bars to the softest setting (~1.75X stock) for the street but it didn't make a huge difference when I tried it before. 

 

I went to the lighter wheels around the same time I swapped the sway bars. That shouldn't have made the ride rougher though, right?

 

I'm tempted to disconnect one end link on each end and then take it for a ride and see if it cures the ride issue. If it does then better shocks should help reduce the roughness or at least the shaky feeling, right?

The shaking feeling is exactly what happens when the body is trying to sway and the bars are counteracting that in combination with too little damping.

Disconnnecting the sway bars will eliminate that at the expense of transient response (but the actual grip level should go up, it just takes longer to get there).

dps214
dps214 HalfDork
11/17/20 4:31 p.m.

Twitchy and bouncy could both be because you removed 90% of the compliance from the system. (ride in something like a 911 GT3 with super fancy active dampers...it rides really well but you can still pretty clearly tell that it has metal or super stiff rubber bushings everywhere, you just can't totally tune those characteristics out with damping) But yeah, better dampers would probably help bring some of that back. Not exactly sure konis are the right thing for that though.

Olemiss540
Olemiss540 Reader
11/17/20 4:36 p.m.

Not sure you will get what you want out of Konis. Having had them and also buying high end shocks (motons/jrz) the difference is INCREDIBLE. How smooth the car feels over imperfections even with double the spring rate is absolutley shocking (pun intended)....

Love motons, JRZ, MCS.

CAinCA
CAinCA Reader
11/17/20 5:35 p.m.
Olemiss540 said:

Not sure you will get what you want out of Konis. Having had them and also buying high end shocks (motons/jrz) the difference is INCREDIBLE. How smooth the car feels over imperfections even with double the spring rate is absolutley shocking (pun intended)....

Love motons, JRZ, MCS.

I'd love to have a premium suspension like those you listed but those are way out of my price range. I'd start looking for a Cayman S rather than spend that kind of money on this E36 M3 box.  ;^)

thatsnowinnebago (Forum Supporter)
thatsnowinnebago (Forum Supporter) UltraDork
11/17/20 5:47 p.m.

In reply to Olemiss540 :

I'd sure hope the coilovers that cost like 5x more ride way better laugh 

I'd bet on Konis helping OP's ride issues. He's just got some extra camber and a set of swaybars. Maybe add some nicer bumpstops too, to slow down that last bit of travel. 

Olemiss540
Olemiss540 Reader
11/17/20 7:35 p.m.
CAinCA said:
Olemiss540 said:

Not sure you will get what you want out of Konis. Having had them and also buying high end shocks (motons/jrz) the difference is INCREDIBLE. How smooth the car feels over imperfections even with double the spring rate is absolutley shocking (pun intended)....

Love motons, JRZ, MCS.

I'd love to have a premium suspension like those you listed but those are way out of my price range. I'd start looking for a Cayman S rather than spend that kind of money on this E36 M3 box.  ;^)

My freshly rebuilt Motons cost me a cool 2 grand, which is around double what a set of Konis would have cost. Worth it.

L5wolvesf
L5wolvesf HalfDork
11/17/20 8:01 p.m.
Stefan (Forum Supporter) said:

I suspect some of that is due to the polyurethane bushings and sway bars.

The Poly can bind the control arms, temporarily increasing spring rate to near infinity.  They also transfer more NVH into the chassis and cabin.

Disconnecting the sway bars and dampers and trying to move the arms by hand can tell you if you might have a binding issue.

Sway bars can also exacerbate things by causing the car to rock side to side on uneven bumps.

This plus perhaps greasing the poly so it won't bind may help a bit.

Twice as heavy of a bar sounds like a lot for a street car.

Keith Tanner
Keith Tanner MegaDork
11/17/20 8:29 p.m.
L5wolvesf said:
Stefan (Forum Supporter) said:

I suspect some of that is due to the polyurethane bushings and sway bars.

The Poly can bind the control arms, temporarily increasing spring rate to near infinity.  They also transfer more NVH into the chassis and cabin.

Disconnecting the sway bars and dampers and trying to move the arms by hand can tell you if you might have a binding issue.

Sway bars can also exacerbate things by causing the car to rock side to side on uneven bumps.

This plus perhaps greasing the poly so it won't bind may help a bit.

Twice as heavy of a bar sounds like a lot for a street car.

Not really, actually. The sway bars are only a contributor to overall roll stiffness, and in the Miata application (at least) doubling the stiffness is about where you start to notice. I think we've got a bar that's about 400% of stock (off memory, I don't have my notes), and ours are relatively flexible compared to others on the market.

Poly bushings can definitely bind. It's a feature.

CAinCA
CAinCA Reader
11/17/20 10:26 p.m.

I took all four end links off the car and took it for a drive tonight. Even with both sway bars disconnected the car has kind of a bouncy ride. I read on a couple VW forums that a lot of people think that they are under damped from the factory. That gives it a "lively" ride. 

 

One of the right front bushings is squeaking when I go over bigger bumps like a speed bump. I tried loosening up the front bolt to see if the bushing would reseat at ride height. I thought I might have tightened it while the car was on jack stands. I also sprayed some teflon spray on the bushings on that side. It helped a little, but if I put new shocks on the car I'll probably sway the poly bushings out for harder than stock rubber bushings (from the RS3). 

 

I wish I could have someone who has driven a few sports cars take it for a drive and tell me what they think. I think next summer I'm going to Turo a couple cars just to see how they drive (I'm looking at you ND, M3, and Cayman).

thatsnowinnebago (Forum Supporter)
thatsnowinnebago (Forum Supporter) UltraDork
11/18/20 2:29 a.m.

Poly bushings are gonna squeak. You can kinda fight it with that super sticky grease, but it'll always come back.

Sounds like you confirmed you need new shocks. Now you get to play the "which shocks do I buy" game. There should be scads of choices for your GTI.

kevinatfms
kevinatfms Reader
11/18/20 6:07 a.m.
thatsnowinnebago (Forum Supporter) said:

Poly bushings are gonna squeak. You can kinda fight it with that super sticky grease, but it'll always come back.

Sounds like you confirmed you need new shocks. Now you get to play the "which shocks do I buy" game. There should be scads of choices for your GTI.

A friend recommended to wrap the bar 2-3 times with teflon tape around where the bushing rides then put the bushing on with the supplied grease. Seemed to have worked on several of his cars to stop squeaking for long periods of time.

Keith Tanner
Keith Tanner MegaDork
11/18/20 9:31 a.m.

A word about "underdamped" - a lot of people equate an overdamped shock with a "sporty" feel. You want to run as little damping as you can to control the spring in my opinion. If you have an adjustable shock that can be easily adjusted, start at the soft end and start increasing the damping until you feel the car start to come in to focus and stop wallowing. Bouncy would more typically be used to describe overdamping.

If you do find yourself behind the wheel of a 2016-17 Miata convertible with the Bilstein "Club" suspension, that's what overdamped feels like. If you're driving a 2006 Miata with the Bilstein "Sport" suspension, that's what underdamped feels like. If you're driving a 2018+ convertible or 2017+ RF Miata with the Bilstein "Club" suspension, that's properly damped.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
11/18/20 10:37 a.m.
Keith Tanner said:
L5wolvesf said:
Stefan (Forum Supporter) said:

I suspect some of that is due to the polyurethane bushings and sway bars.

The Poly can bind the control arms, temporarily increasing spring rate to near infinity.  They also transfer more NVH into the chassis and cabin.

Disconnecting the sway bars and dampers and trying to move the arms by hand can tell you if you might have a binding issue.

Sway bars can also exacerbate things by causing the car to rock side to side on uneven bumps.

This plus perhaps greasing the poly so it won't bind may help a bit.

Twice as heavy of a bar sounds like a lot for a street car.

Not really, actually. The sway bars are only a contributor to overall roll stiffness, and in the Miata application (at least) doubling the stiffness is about where you start to notice. I think we've got a bar that's about 400% of stock (off memory, I don't have my notes), and ours are relatively flexible compared to others on the market.

Poly bushings can definitely bind. It's a feature.

I think that is highly dependent on the car though.  If you go too stiff on sway bars and the left drops in a pothole, it's going to transfer some of that load to the right.  While one wheel drops, it's going to want to drop the other one which will further exaggerate the problem.

Poly bushings are a choice.  I did it for a while and finally took them out in favor of Delrin.  Much quieter, allowed for easy motion of the arms eliminating the phantom spring rate, and even less deflection.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
11/18/20 10:38 a.m.

CA... do you notice understeer/oversteer when you push it hard?

Keith Tanner
Keith Tanner MegaDork
11/18/20 12:43 p.m.

I don't run poly bushings anymore. Too much of a PITA. They bind way too easily. 

The side-to-side movement you get with stiff sway bars causes head toss and sometimes some harshness, but it's rarely characterized as "bouncy". Taking the sways out of the equation was the right troubleshooting step here.

CAinCA
CAinCA Reader
11/18/20 12:46 p.m.
Curtis73 (Forum Supporter) said:

CA... do you notice understeer/oversteer when you push it hard?

With the sway bars I have the car is really well balanced. It's probably a little on the understeer side, but if I trail brake hard enough I can get the rear end loose enough for the DSC to go into full panic mode. ;^)

One of the reasons I bought the H&R sway bars was because of the bushings that they use. The bushings are teflon lined and they say that they never need grease. A lot of the GTI guys bought other brands and then replaced them with H&Rs for the same reason. Last night while I had the end links off the car I checked both bars and they move smoothly.

If I tear into the front end again I'll put a set of stock bushings on the front position of the arms. If that doesn't cure it I'll put the RS3 bushings on the rear position. They are a lost stiffer than stock but shouldn't squeak.

BTW: I guess I should have stated that the roads around here are rough but they aren't filled with potholes either. 

CAinCA
CAinCA Reader
11/18/20 6:57 p.m.

Well, I bit the bullet and ordered the Koni Yellows, new bump stops, and RS3 rubber bushings (stiffer than stock GTI rubber) for the front end. I have next week off so hopefully all this stuff will arrive while I'm on vacation.

CAinCA
CAinCA Reader
11/23/20 10:20 p.m.

I installed the front struts today. I pulled the stock struts out then opened up the top of the strut towers with a 2-1/2" carbide hole saw. I turned a pilot to match the saw arbor to the existing hole. I used a 2" sanding drum to clean up the hole. I pulled the camber plates and springs off the stock struts and then compared the compression and rebound to the Koni Yellows. The Konis feel softer on compression but stiffer on rebound. It will be interesting to see how they feel on the road but it sounds like what the doctor ordered. While I was in there I took a look at the lower control arms. The bushings are definitely bound up and squeaky. The TT-RS rubber bushings are supposed to be here tomorrow. Once I get those installed I'll install the new rear shocks.

 

 

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