Need Suspension Mod Suggestions

[CrazyAl]

ORIGINAL: ponyman Why do you suggest the spherical bearing w/ the poly bushing for the diff as opposed to the poly bushing UCA with the diff bushing? Wont the spherical bearing transfer A LOT more noise to the car? Wouldn't the poly be a little more bearable for the guys who have their pony as a daily driver? I was just wondering if you could further explain this recommendation? Thanks.... No problem: Thespherical bearing +poly bushing setup has two important advantages over the poly-poly setup. First,it is much stiffer in the longitudinal direction (compression and tension). So, when you get on the gas hard the rear-end geometry does a better job of staying where you want it--there is less deflection. Second, it allows the axle to pivot very smoothly.This means that when the axle has to moveabout thedriveshaft axis(for example, a going over a bump orrough road surface or when cornering) it can do so freely (like it should be able to), whereas with apoly-poly setup it will bind. The "combo" type does have slightly more NVH than the poly-poly setup, but with the one poly bushing still kept in place, it is still fine for most people. The difference in noise between this and the poly-poly is minor.

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[ponyman]

So what kind of NVH increase would I be looking at between the spherical/poly combo for both the UCA and LCA? Are we talking metal clanking sounds when I go over bumbs and rough roads, or just some stiffness? Also is it going to be a big increase during say cruising on the freeway? I'm just trying to get a feel for what I should expect when I go through with the control arm upgrades (as soon as I finish my taxes).

Thanks....

[CrazyAl]

You would see some more stiffness and a smallincrease in road noise. By "road noise" I mean that constant background "hiss" type of sound that's always there when you drive....something like the sound you get when you drive slowly on a gravel road, although nowhere near that loud.

Aside from really bad roads or potholes, a suspension setup--even something like this--should NEVER clank or bang. Clanking or banging is a sure sign that something is installed wrong or a part has failed or worn out.

[Red06]

ORIGINAL: CrazyAl

No problem:

The spherical bearing + poly bushing setup has two important advantages over the poly-poly setup.

First, it is much stiffer in the longitudinal direction (compression and tension). So, when you get on the gas hard the rear-end geometry does a better job of staying where you want it--there is less deflection.

Second, it allows the axle to pivot very smoothly. This means that when the axle has to move about the driveshaft axis (for example, a going over a bump or rough road surface or when cornering) it can do so freely (like it should be able to), whereas with a poly-poly setup it will bind.

The "combo" type does have slightly more NVH than the poly-poly setup, but with the one poly bushing still kept in place, it is still fine for most people. The difference in noise between this and the poly-poly is minor.

Crazy Al,

The UCA setup is the last part I need to buy for my suspension upgrade. Do you have the BMR spherical UCA? I’ve gone with the poly / spherical combo in the adjustable LCAs and Panhard bar. On those pieces, the poly bushing connects to the body hopefully reducing the NVH/road noise. On the UCA, the spherical end is connected to the body thus increasing the potential for noise. I haven’t been able to ride in a car using spherical bushings do I don’t know if I’m making too big an issue out of the whole NVH thing.

What do you think about the BMR and Sphon poly pinion bushings? I don’t recall anyone talking about replacing the rubber bushing with a poly bushing in the pinion housing. Do you have any other suggestions for replacement bushings?

Many thanks go out to you and F1Fan as well as others on this site, for sharing your knowledge and experience.

[CrazyAl]

Yes, I have the BMR poly-spherical UCA.

It doesn't matter if the spherical end is on the body or the axle side. The road noise is generated where your tires touch the road. So long as there is a broken path between that and your body, the noise will be diminished. By "broken path" I mean a rubber or poly part somewhere in the chain.

In the case of the UCA we are talking about, the noise can travel freely up to the diff housing (Becasue it's nothing but metal between the tires and the diff housing) but the noise stops at the rubber or poly bushing in the diff housing, so it never really enters the UCA at all.


I do like the poly pinion bushings. I am using the Spohn one in my car. I think the Spohn one is a better choice if you are using the Spherical-bearing UCA. If you are using a poly-bushing UCA, then BMRs may be a better choice. The spherical bearing can tilt freely without binding so there is no need for BMR's "multigrade" bushing.

I recommend the bushings, but be forewarned that removing the OEM one is a pain.

[F1Fan]

ORIGINAL: sdwndr


I have had my GT for a few months now and I love it, but one thing has been bothering me.

Sometimes when making a turn or taking the curves on an on-ramp, if there is a slight bump in the road, I will feel the car lurch as it goes over it, almost as if the rear wheel are about to leave the ground and the car is about to spin out of control. The bump doesn't have to be that big and I don't even have to be going that fast for this to occur.

Why does this happen? I am guessing there could be some suspension mods that could help with this? If so, which ones?

Hi sdwndr,

I LOVE my S197GT too! What suspension setup did you choose to go with?

As to why you get that momentary loss of rear grip on irregular surfaces, thisisjust one of thelittle negative "features" of having a soild rear axle. Short of ripping out the solid axle and installing a well designedIRS (indepenant rear suspension, Griggs and MM are working on this), there is no cure for this behavior. This behavior is a limitation of using a soild rear axle in a performance application onreal world roads. The solid rear axle design works great on a smoothroad surface but when it gets bumpy all you can do is reduce unsprung weight andcontrol (firmer damping), and better locate (stiffer bushings and control arms),axle movementas best you can to slightly improve this issue but it will never go away. But don't worry you aren't going to spin out or fly off the roadanytime soonbut use caution with the throttle when it's wet or icy, the Mustang is no 100bhp front wheel driver. [sm=nono.gif]


HTH

[savagewater]

Hi CrazyAl!
Very impressive write-up you just did. Which gives me second thoughts about my next mods. Tomorrow on top of having a Magnaflow X installed, I will also have Tokico D-Specs put in and....Eibach antiroll kit.But now you got me wondering about changing the front sway bar... For now, suspension wise, the car has been lowered with Eibach Pro-kit, and a Steeda panhard bar. LCA'S are next. But tell me...You seem to know alot more than me about this stuff so should I install the rear and leave the orig. one up front or go ahead with the whole kit?

Since we're at it, tell me: Last year I bought new wheels also. Boze Stixx forged 18X9 all around. I know I should've gone with 9.5 in the back for now I run 255/45/18 on all 4. Could I still put 285's in the back on 9" wheels? Everywhere I looked the say 285's need 9.5.

BTW, here are all the mods so far on my 05 Sonic Blue GT:
Eibach Pro-kit
Boze Stixx 18X9
BFG G-Force 255/45/18
Hurst shifter
Steeda adj.panhard bar
SCT II with custom tunes (running 93 octane tune now)
FRPP (stingers) axlebacks
Steeda CAI
+ the above going on tomorrow.

Thanks for reading me and all input will be appreciated.
Jean.

[CrazyAl]

Hey Savage,

If I were you I'd install just the rear bar from the Eibach kit. Then I'd put the Front up on Ebay, sell it, and use that $$$ for something else.

I'm not a big expert on tires, but what I would do is check the literature all the tire makers put out. For each size of tire they will publish approved rim widths. Make sure your wheel width fits in that range.

Another option to consider is to have your rear wheels widened. There are various companies that can do this such as Weldcraft in Michigan. I have no idea if this is possible with your exact wheels, but you can talk to them about it and find out. I had my FR500 style wheels widened in the back to 10.5" so I could fit 295s on there with optimal width. (http://www.weldcraftwheels.com/)

[savagewater]

ORIGINAL: CrazyAl

Hey Savage,

If I were you I'd install just the rear bar from the Eibach kit. Then I'd put the Front up on Ebay, sell it, and use that $$$ for something else.

I'm not a big expert on tires, but what I would do is check the literature all the tire makers put out. For each size of tire they will publish approved rim widths. Make sure your wheel width fits in that range.

Another option to consider is to have your rear wheels widened. There are various companies that can do this such as Weldcraft in Michigan. I have no idea if this is possible with your exact wheels, but you can talk to them about it and find out. I had my FR500 style wheels widened in the back to 10.5" so I could fit 295s on there with optimal width. (http://www.weldcraftwheels.com/)

Thanks Al. I guess I needed that. So I'll just go with the rear for now and see what the suspension changes really do on the car once it comes out of hibernation. But for now I'll sure let you know about the sound of the X tomorrow. Can't wait to hear it.

[Brian_Zinchuk]

Hi crazyal... great post. I just learned a lot from all the part explanations. I have no aftermarket mods to my suspension. What would you do first... LCA?