Are bushings really the BIGGEST problem?

[00 Trans Ram]

From reading posts on other boards, and looking at products offered by the aftermarket, a person would think that the bushings in this car are the biggest problem with them (handling-wise).

I'm just not sure that I can buy that, though. I mean, I guess it's possible. But, I've never heard of a single person who is trying to upgrade their car to handle better say that they're doing bushings first. It's almost always springs and shocks.

Again, I'm not basing this on any experience, since I haven't had a chance to test out every combination on this car. I'm just going on what I hear from the dozens of guys that I race with. They'll have Civics, S2000s, Vettes, Vipers, Impalas, BMWs, STis, etc. They'll want to be more competitive in autox/road racing, and they always go buy shocks, springs, strut bars and other things. I've never heard any of them say, "I'm gonna replace my bushings and kill you guys!"

I know that bushings may be "a" problem - but are they "the" problem?

[G8V8]

I'm sure Pedders will chime in at some point but the busings are the weakest link in the G8 suspension. Before mine I could feel the rear step out but not after the bushings. The rear sub-frame mounts the rear suspension and differential. If the sub-frame moves, it doesn't matter how god your shocks are. the chassis and rear suspension move relative to each other.

From a bang for the buck, the Street 1 kit replaces the rear sub-frame bushes, differential bushes and front inner radius rod bushes and cost about $500-$600 for parts( I think).

[00 Trans Ram]

OK, then let me ask another question. Why does the subframe need to move at all? The wheels need to move - but they have control arms?

If the bushings are such a problem, why not replace them with solid mounts?

http://community.webshots.com/photo/fullsize/2404593860054308893DCXrlV

Per the above picture, I see no reason why the subframe needs to move independently of the rest of the chassis.

[Chewy]

<div>
(00 Trans Ram @ Aug. 14 2008,1:50)</div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">OK, then let me ask another question. Why does the subframe need to move at all? The wheels need to move - but they have control arms?

If the bushings are such a problem, why not replace them with solid mounts?

http://community.webshots.com/photo/fullsize/2404593860054308893DCXrlV

Per the above picture, I see no reason why the subframe needs to move independently of the rest of the chassis.</div>
Noise?

I imagine they are trying to isolate as much as possible... http://forum.grrrr8.net/non-cgi/emoticons/rock.gif

[00 Trans Ram]

On other question. When you say, &quot;Stepping out&quot; what do you mean? Is that &quot;stepping out&quot; a bigger problem than dynamic body roll? Is it worse than having a relatively high roll center?

I&#39;m just naturally skeptical when a solution is offered that is completely different than convential thought. Oft times they are right - but I always like to ask the questions first.

[G8V8]

For a race car they probably don&#39;t but Pete or mike can better answer that.

[00 Trans Ram]

That&#39;s my problem - I tend to look at things from a slightly &quot;racier&quot; perspective than most&#33; Please forgive&#33;&#33;

[GRRRR8]

Forgiven. On my personal car on hard launches and shifts you feel it wiggle (stepping out). This is caused by the flex in the factory rear diff. bushings and the X frame needing the inserts installed. From what I have read and heard this will solve all that movement in the rear area.

[G8V8]

The bushing are used to isolate noise, insulate vibration and cushion the chassis. The G8 bushings are biased on the comfort side of sporty as opposed to the sport side of comfort so as cars go, it is not a bad suspension for daily driving given the low over-temp setting on most people&#39;s personal g-meters. If you kick it up a few notches, some of the compromises engineered into the g8 start to show. It is undersprung and underdamped. The chassis moves too much on the sub-frame that holds the rear suspension. there is too much body lean.

The bushings that hold the subframe act like small springs and dampers between the chassis and the subframe, which holds the suspensions springs and dampers. These bushes have viods in them to isolte noise and vibrations. They are soft springs and dampers that work in series with the rear shocks and springs.

At speed, in corners where you are accelerating out, or in transitions, you can feel the chassis move outward until the the bushings have been compressed and shifted by the side and vertical loading of chassis and the rear subframe until they have given all they can. Then, and only then, can your rear springs and dampers work to full effect. It takes a finite time for these bushes to deform and the subframe to actually move. In a single turn or transition you will feel it like you would if your rear tires crossed a very small slippery area, lost grip and slid (stepped) slightly to the outward side of the transition. This feeling get worse the faster you go. At 130 just crossing the crown in the center of the road makes the stock car feel light, like it is on its tiptoes. It a series of tight turns, the rear feels like it is lagging, not quite in step with your inputs.

The bushes also compress vertically and that allows the body to lean in transitions. It is sort of like little springs on the ends of your sway bars.

All that went away with the new bushes. This is the way it seems to me. Pete and Mike take their G8 on the track and really know the suspension. if my head is where the sun don&#39;t shine, i hope they join us and set the record straight.

Ed

[GRRRR8]

Nice write up Ed.

[G8V8]

Thanks. Hopefully Mike will check in.

[dms]

I seem to be having challenges getting logged in. This is the second time I will be writing this post. The first time I hit submit, and it ejected. So hear we go again.

To start with your questions, the most important 1st step foe the G8 is struts and springs. The OEM units are seriously undersprung, and the struts are not even gas struts, therefore, will allow a very serious amount of body role and softness.

Now to start, let me tell you the pre and post tests I have done to define improvement. I have done this on 3 GTs: On a very safe road with no ongoing traffic, with divided white lines, drive as fast as you can by keeping the left front tire within the white lines, and making as fast as you can sharp 90 degree left then right (from center) turns. The pre test will get you to a 40-maybe 45mph with the oem suspension. the issue is that it gets extremely unstable due to you are turning faster than the body can role. The tires begin to squeel quiite badly and am starting to get to an unsafe driving. Now with a Pedders TrackII without bars, you can get to 60mph with no tire squeel, but at that speed, the tires start to loose traction, and traction control starts in the back.

Now the next issue on the list are the rear subframe or xmember bushes. Like the Chrysler LX /Mercedes E class rear suspension, these bushes allow a total disconnect of the rear suspension to the body. You can feel the movement. On the LX product, you literally can see the scuffing on the body and it moves over 15mm. We call this "step out" GM does this to meet legacy thoughts and engineering. By making bushings soft and gooey, the body is insolated form a lot of sins of the suspension, wheels, and tires. Now I can tell you there are quite a few GM engineers who own G8s that have bought our suspension. There are even a lot more that have driven Pete's G8 that has our XTREME coil overs, which are very performance oriented, and they cannot beleive how good things handle with a high level of comfort!.
One of the gret things about the Pedders Xmember bushes is that they are pretty easy to install. You have to lower the rear cradle, and you will install poly inserts in the top and bottom of each bush, and fill in all the voids. This is about an hour's job. It makes a huge difference.

The next 2 bushes are important and fall after the xmember bushes. The rear diff bushes (3 of them) are very soft, and I think could contribute to wheel hop. The other is the front radius rod bushings. They are fluid filled just like the GTO. They allow a lot of movement. Our bushing is a VERY seriously stout bush, and also includes our caster shim pack to add approx 1 degree needed caster. These bushings, however, can take up to 10 tons to get pressed out and new ones back in.

Now lets not forget the Pedders multi adjustable sway bar kits. They will eliminate aprox 25% of the body role. Now Mike Haddad of Hadd MotorSports is destined to be the G8 KING of the west coast. I likes his set up at full strength in the front, and weakest setting in the back. But everyone has their own feel, and thus the reason for adjustabilitiy.


And there is no doubt, tires and tire size are a serious limitation of the G8. We need some BEEF! More on that later.

So did I answer your questions?

thanks
mike
dms

[Chewy]

I seem to be having challenges getting logged in. This is the second time I will be writing this post. The first time I hit submit, and it ejected.

VB times you out so my recommendation is if anyone is posting a novel ;) they should type it in Word or even open outlook and type it like it's an email and then copy and paste it here. That way you no get timed out! :rolleyes:

Thanks for the great info!

Chris

[00 Trans Ram]

Thanks for the great replies!

Most of my previous cars were something other than IRS/RWD, and were older models, so I'm not overly familiar with this new method of building.

I guess I understand that they'd do this for noise concerns. But, soft bushings in the control arms, isolators on the springs, and bushings on the shocks (though I've heard that even rod-ended shocks contribute no noise) should accomplish all the isolation one would need.

I wonder what would happen if you solidly mounted (welding, solid bushings, etc.) the rear subframe to the chassis?

[EcoBrick Bob]

In a recent (I think Road & Track) article, the new 09'Maxima posted a faster slalom and "G" time than the G8 GT. That car is both a front driver and has a CVT tranny. The G8 FE 2 suspension falls short when you really push it because it is a compromise. In the Caddy CTS, you can get the FE 3. but it rides considerably rougher. In fact, my daughter's 07' Honda Accord rides much firmer than my G8, even with my tires pumped up about 8 lbs. above stock. Guess that's why my wife likes the G8 so much...

Unfortunately no Pedders dealers anywhere near me in IA, and a long way away from Naples in FL.

RRM

[G8V8]

The rear subframe bushings are not hard to do. A lift, transmission stand and airtools would be a piece of cake. Jack stands, hydrolic jack and breaker bar would get it done in a driveway. In both cases, 2 people would be a BIG help.

[G8V8]

Thanks for the great replies!

Most of my previous cars were something other than IRS/RWD, and were older models, so I'm not overly familiar with this new method of building.

I guess I understand that they'd do this for noise concerns. But, soft bushings in the control arms, isolators on the springs, and bushings on the shocks (though I've heard that even rod-ended shocks contribute no noise) should accomplish all the isolation one would need.

I wonder what would happen if you solidly mounted (welding, solid bushings, etc.) the rear subframe to the chassis?

New! Improved! Now Fully adjustable! No messy hydrolics to mess with! Quaranteed never to leak!

DuraJolt Shocks at an AC-Delco Dealer near you. Ask for them by name-DuraJolt!

http://img.villagephotos.com/p/2002-11/65524/durajolt.JPG

[EcoBrick Bob]

For us older geezers, this would be hard on our false teeth....

And... heaven forbid if the wife went braless....:eek:

[00 Trans Ram]

New! Improved! Now Fully adjustable! No messy hydrolics to mess with! Quaranteed never to leak!

DuraJolt Shocks at an AC-Delco Dealer near you. Ask for them by name-DuraJolt!

http://img.villagephotos.com/p/2002-11/65524/durajolt.JPG

Damn that's funny!!!

[G8V8]

Thanks. Wish I could take credit for it.

[GRRRR8]

Hey! No wooden wheels on the G8s. Wood dont "BLING" old timers......well not that "wood" anyways.

[dms]

Guys,

We have done some testing. One of the premiere rides in the USA is the M5 BMW. This ride is fantastic but alittle complicated.
the M5 is an $83K to $93K VEHICLE.
Add a procharger or maggie, and a trafor the $45k, y ou can also get some oversized wheels and tires. Will have to spend a few more bucks to get the brakes there. But you will be in the $48K max range and will blow the doors off of a $93K M5!!

mike
dms