You asked about the ride....

[mdg8gxp]

Well I posted a few weeks back about picking up the GXP, and someone asked about the ride now that I have the BMR bushings and Xa's. I said it was on par with my previous car, a 540 M-Sport. Over the past several weeks I have been traveling, not much chance to drive the car. Now that I'm back and have a few miles on it, other than interstates, I can say unequivocally, I hate it. WAY too stiff and harsh on anything other than a pool table flat and smooth road. I need to adjust the shocks big time, and hope that fixes it. Argghh.

[Crazy8]

Good to know. I've been considering some suspension options, but I am worried about making it ride to harsh since I drive it a lot.

[mdg8gxp]

Going to Behe Performance next Friday - they are certain they can fix my ride. I'll keep you posted on the results. I hope they can, now I have some noises from the rear. From what i've read here, probably rear sway bar links.

[Lucifer]

That was me that asked. My father has had multiple BMWs, everything from a Z3 to a M5, so I was interested to see what you thought. Hopefully you get it tweaked.

[hflores3]

What was the final recomendation here? My car is entirely too harsh!!!!

[WhiteDeathLSX]

Ultimately, as you improve suspension components with stiffer, performance oriented pieces AND you incorporate that with similar bushings upgrades... the ride will inherently become stiffer. I've replaced nearly every suspension piece with Spohn and Pedders parts. The GXP is definitely stiffer than I would desire, but I forget all about it when I request canyon-carving twists and turns. :)

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[mdg8gxp]

I had put the update in a seperate post, should have just added it to this. I went to Behe, adjusted the Xa's up about .25", 1 corner was actually .25" lower than the other side. Tightened the sway bar links and the noise is gone. As to the ride - I now have about 4000 miles on the car since the suspension was adjusted, and have the same answer as WhiteDeathLSX, it's definitely stiffer than I need, or should have, for a daily driver, but man once I'm on a good stretch of road all is forgiven. Sometime in the next couple of months I think I'm going to soften it up, but not really sure where to begin. Go back to rubber everywhere but the rear cradle and diff mount?

[laserred]

This has kinda been discussed in some BMR threads.... seems if you are looking to retain "stock" ride characteristics but pick up some tautness, BMR swaybars and the Pedders cradle and diff mounts are about all you can really do without making it nearly intolerable as "transportation" vs. "excitement". Another thing most people fail to add into the equation is when going up in tire diameters and widths, the sidewall takes a huge hit as far as the height, and this obviously negatively impacts ride as well. I am sure some of the harshness for daily use could be quelled by going back to a 245/45/18 tire and running the recommended 35/39 psi like on a stock car.

The most I will likely do to my suspension is the BMR sways, Spohn forged LCA's, Spohn rear LCAs (adjustables) and toe rods, and some sticky BFG tires. While the handling can always be tighter, when trying to steer a 4000lb barge through the cones you have to realize there comes a diminishing point of returns somewhere. Handling that much mass requires a very stiff chassis, springs, struts, and sways, so thanks for your testing letting everyone know where the tradeoff is.

[mdg8gxp]

I've kept the stock 19" tire diameter with the GXP, toyed with the idea of going to the 18"s, but decided if it was good enough for Pontiac/Holden, it was good enough for me. I run the General G-Max's (245/40 and 275/35) around 39 psi, and have been very happy with them to date.
I'll certainly keep everyone posted on my mis-adventures through the suspension changes in an effort to get to the ideal compromise for a daily driver. I do want to go to the Spohn forged LCA's as soon as my stock parts are shot, and still want to do the brakes but all that will wait until I sort out the ride. Just a note on the weight, when I was at Behe we checked the corner weights on the car - I expected 4000 lbs, but was pleasantly surprised at 3779 lbs with half a tank of gas.

[laserred]

Edit: should have been "wheel" diameter, not tire. 275/35/19 is definitely a shorter sidewall than 245/45/18. Maybe see if you can borrow someone's set of 18s for the weekend to see how they ride?

3779 sounds great, but unless you have been cutting major weight in other areas, it sounds like their scales might be off. I weighed my car on a certified commercial scale, with no extras in the car, no spare or pump kit, and stock mufflers removed, with less than 1/4 tank, and my car was 3960. I weighed the mufflers individually and they were 20lbs each, bringing the car to 4000 on the nose with the mufflers on. I just don't see Pontiac being over 200lbs off on the curb weight as that is one of the ways they determine recommended tire inflation. I suppose it's possible, but unlikely.

[mdg8gxp]

Trying some 18's is a good idea, need to look into that further.

I agree with you on the weight, I asked them when was the last time they had their scales calibrated. I plan on getting an independent measurement soon. On the other hand, they do an enormous amount of SCCA prep, you would think that if the scales are off that far that somebody would have figured it out by now.

[laserred]

Well, the scales being exactly accurate is not as important as them being consistent. Corner to corner and front to back is more essential than overall weight.

[greggy]

Why not try lowering your tire pressures first. Owners manual say 35 or 36 psi (depends on tire) front and rear when not fully loaded. 39 is not required by any means and it will suite you better.

[mdg8gxp]

I should give that a try. Also need to talk to Rob at Wretched, see what the Pedder's expert says. As to the scales, consistency is important, but if they are off that far somebody could end up bumped out of a class in road racing. The good news was I was consistent corner to corner, well within the tolerance they recommended. I will be out of town next week, but plan on finding an independent calibrated scale to check the numbers when I get back.

[WhatNext]

What were your Xas originally set at and where are they now (the dampening adjustment)? Just curious.
In a thread about Koni adjustables for G8s, a user said he loves them on a road course but "despises" them anytime else. Meaning they are way too harsh for a daily driver (even when set soft). I was ready to jump on the Koni-s until hearing that (great input). Sounds like maybe the Xas are doing the same to you and I'll take them off my list of mods to do.

[WhatNext]

What were your Xas originally set at and where are they now (the dampening adjustment)? Just curious.
In a thread about Koni adjustables for G8s, a user said he loves them on a road course but "despises" them anytime else. Meaning they are way too harsh for a daily driver (even when set soft). I was ready to jump on the Koni-s until hearing that (great input). Sounds like maybe the Xas are doing the same to you and I'll take them off my list of mods to do.

[Eidolon]

I'm with WhiteDeathLSX here. I just replaced everything on my car with BMR and mostly Spohn. The only thing that's still stock is the rear upper control arm. I'm still running the stock shocks, albeit with Eibach Pro-Kit springs. I've adjusted to the new ride pretty quickly, so my impressions are unfortunately a little skewed.

But in retrospect, the effect of the poly bushings is kind of disappointing. They aren't transformative. Rather, their greatest effect is to quell any unsettling motion in the suspension. So bumps settle out REALLY quickly, and I do appreciate the absence of the wander and wiggle the rear was formerly characterized by. Together with GForce axles, my wheel hop is also gone!

Road vibration, meanwhile, more readily enters the cabin and causes plastic panels to vibrate. The vibration itself doesn't bother me, though the buzzing panels do. Bumps also hit more sharply, since there's no pliable bushing to cushion the initial impact before the spring gives. The car's not my DD anymore, though, so it's a good deal more livable. :)

Really, I think I need to crank my sway bars back up. I miss that stiffness. Setting those higher with the poly bushings should be a nice effect. Right now the front's on 1/2 and the rear's on 2/3.

[mdg8gxp]

My Xa's are set at 8 front and 9 rear, been there since I installed them - I need to back off a couple of clicks and see what happens. Ride height is at 27" on each corner, was 26.5" (!) when I first did the mods. Sway bars are at full soft on both front and back.
Hard to say if the poly bushings were transformative, I did all the mods to the car in 1 shot, so overall the change transformed the car - it was a night and day kind of thing. I recognized when I did this that the poly bushings would stiffen the car considerably, but didn't think it would be this stiff. I don't think the Xa's themselves are the issue, I honestly think I may have gone a little overboard in the name of handling with a full poly suspension. (mea culpa there)

One of the problems I've encountered in trying to tune the suspension to a liveable set-up is that when I go to Behe in Carroll county and make changes, the roads up there are great so I have a hard time finding any that will really shake the car. Back home in Baltimore county the opposite is true. So driving in Carroll county is a pure joy, I've never driven a car this large that handles this well. Problem is I don't live there.

I don't have any problems now with platic buzzing inside, but given enough time I'm sure it will develop. If it wasn't a daily driver I could be far more tolerant.

[Eidolon]

I've had the BMR bars all the way up, front and rear, and their impact on ride stiffness is honestly minimal. As for the suspension parts, I wouldn't say that the bushings so much stiffened the car as they removed the damping that existed between the cabin and the road. You can feel road imperfections and bumps, where before they were damped out. The benefit is the lack of motion that you don't expect as the old bushings would give and allow the suspension geometry to be compromised.

So, honestly, I'd point the finger at the Xa's. Definitely try dialing them down a few clicks. If that doesn't do it, and cost isn't prohibitive, try swapping back to your GXP struts and springs and see how it feels, then.

Then again, unfortunately, car ride is incredibly subjective. What you and I call "stiff" may be worlds apart, so it's not an absolute measure. I've adapted already to the new ride of my car such that all that bothers me is the buzzing interior plastic.

... Oh, and the whining coming from the rear that I can only assume is the diff gears or tires on the road. I didn't expect THAT. It both amuses and bothers me, just because I'm a stickler for eliminating random noises. Tradeoffs!

[mdg8gxp]

So I did another round of adjustments on the Xa's; now at 27-27.5" front and 26.6-27" rear ride height after settling in. Shocks were set at 3 clicks from full soft front and rear. Preload on the springs was double checked. Still too harsh after a few weeks use. Dialed them back to full soft and got some tire rub going up a ramp, not even pushing it...so now at 4 clicks rear and 3 on the front. I'm thinking the Xa's are just tooo harsh for the roads around here, maybe go back to the stock set-up - not sure, I really need to explore all my spring/shock options.