Subframe Bushings - Who Needs Them?

[AZhitman]

Nope, not at all. I just have thick skin, and I "***"ume everyone else does. Sorry.

I'm saying I think making your own subframe bushings is a GREAT idea, that's why I posted it (mere seconds before it dawned on you).

Good thread - Let's leave out the namecalling.

[AZhitman]

AA - Based on your comments, I'm going to remove my subframe spacers completely and replace my bushings with something more appropriate as well.

I have THE MOTHER OF ALL WHEEL HOP going on in the 'vert, so maybe it's time for me to take my own advice.

[AmoebAssassin]

It's not that what we're saying doesn't pertain to his question, but rather that it seems as though he's ignoring our perfectly logical and spelled out arguments because he's got some hell-bent desire to not spend what, 75 bucks for a proven modification.

There's no need to re-invent the damned wheel if the wheel has been working this long, savvy?

[yokota180sx]

two threads in a row from him might i add

It's not that what we're saying doesn't pertain to his question, but rather that it seems as though he's ignoring our perfectly logical and spelled out arguments because he's got some hell-bent desire to not spend what, 75 bucks for a proven modification.

There's no need to re-invent the damned wheel if the wheel has been working this long, savvy?

[AZhitman]

Lesson learned.

I think Edub and I are pretty similar - sometimes you gotta hit us in the head a few times before we get the point.

[AmoebAssassin]

AA - Based on your comments, I'm going to remove my subframe spacers completely and replace my bushings with something more appropriate as well.

I have THE MOTHER OF ALL WHEEL HOP going on in the 'vert, so maybe it's time for me to take my own advice.

Greg, this is a good plan for cars making good amounts of power.

You will notice that your car will feel much more planted coming on and off the throttle, as you will no longer experience subframe deflection due to cornering loads and differential torque reactions, and therefore your rear end geometry will be closer to optimal at all times. Closer to optimal = more traction and a car that doesn't shimmy around on launches or during transient cornering (turn in and turn out).

There are a few writeups on the site, but if you have questions I can answer them -- I plan on doing this to my car when it warms up enough to work on it without losing a limb to frostbite

[Edub1]

Are you guys suggesting using the shims or using aluminum bushings?

I appologize for being so inept, but how exactely does an aluminum bushing provide cushion or otherwise isolate the subframe?

I'm envisioning an aluminum bushing making everything rock solid. Where does the cushioning effect come from?

[94_240sx]

I'm envisioning an aluminum bushing making everything rock solid. Where does the cushioning effect come from?

Don't forget that you still have springs, struts and tires. I suggest you go with aluminum collar/inserts before your oem bushings go completely bad.

[Edub1]

Looked under my car today. Things are smaller and more cramped than I remember.

I think I'm going to try those Peak Performance Urethane inserts and call it a day.

[corey240]

if your bushings are bad. you replace them either with another rubber bushing. or. replace them with a solid alluminum one. if they are good then collars are good for you to get, but if your bushings are bad then collars wont help anything. i actualy was thinking of making some urethane ones myself but i already have solid ones so its ok. they were 80$ on ebay, way beter then 150 for a car im just trying to sell.

[BHayes_S13Coupe]

If your oem bushings wear out, body and subframe will be disconnected eventually. If that's the case, aluminum bushings won't do any good. I know some people took them out cuz oem bushing were shot and aluminum bushings were making bad clunking noise. If your oem bushing are still in decent shape, you can get more soild feel and prevent old bushings going bad. Phase2 has them $75 per set. It's based off of Kazama. That's what I'm going to get. I know many other places sell aluminum bushings, but look like phase2 has a nice set at decent price. Besides, I'm not a big fan of red, blue and gold color bushings. I just want plain silver ones.

http://phase2motorsports.store....html



If your bushings are shot, this is what you have to go through. zerothread/97924

I've learned all these by reading other people's posts. Please feel free to correct me if I'm wrong. I don't want to give out wrong info to other people.

I have spl's aluminum bushings and i knew there was going to be increased noise and vibration, but is clunking included in that noise?The rear of the car is alot more stiffer and feels more planted but there's a clunk when i shift in lower gears and sometimes when engaging the clutch is this normal?

[AmoebAssassin]

What condition are you differential bushings in?

[BHayes_S13Coupe]

I forgot to the car i drive. Its an S13, so no diff bushings.

[K]

The rear of the car is alot more stiffer and feels more planted but there's a clunk when i shift in lower gears and sometimes when engaging the clutch is this normal?

I have the Phase2 aluminum spacers (same as all the others), and there is some serious clunkage when i shift or sometimes when i turn corners. It's just the nature of the product.

They did stiffen things up in the back substantially. Oddly enough, my shifts are now cleaner than before i had them, this was an un-expected advantage.

KRM

[BHayes_S13Coupe]

Cool, I havn't heard any clunking from turning though. Even with blown rear shocks i feel every nook and cranny. I noticed my shifter feel was more crisp. I need to stop being lazy and install coilovers, links and such tomorrow

[240sx_megasquirt]

No, you're as wrong as you can be. It is NOT a known fact that aluminum is stiffer than steel; thats just plain idiocy.

Here, if you don't believe me, here are the elastic moduli for aluminum and steel:

http://www.mse.cornell.edu/cou...s.htm

Steel Elastic Modulus: 200-207 GPaAluminum Elastic Modulus: 69 GPa

See? Steel is about three times more rigid than Aluminum.

Yokota, the collars still rely greatly on the stock bushings. The holes in the collars are not clearanced tightly around the subframe mounting studs, and by virtue of this cannot transfer any significant load from the subframe to the unibody. They work by compressing the stock bushing and stiffening it in this manner. Although they do work, they do not eliminate bushing slop completely, as your stock rubber bushing remains the main mode of force transfer between the subframe and chassis.

A "strength-equivalent" aluminum structure, having used deflection (stiffness) as the design criteria, will have been built using roughly 50% greater plate thickness. We might then say that this strength-equivalent "one and a half inch" thick aluminum plate will yield at around 51k per square inch of surface area (around 29% greater yield strength than the "equivalent" region of steel plate), and will fail at around 67.5k psi (around 12.5% greater ultimate strength than the "equivalent" region of steel plate).

Of course these broad generalizations are intended only as a way of illustrating the approximate relative strengths of the materials. However, from these considerations we can see that the aluminum vessel will have a greater overall strength than the steel vessel per square area of plate. The reason for this is that the aluminum plate will, for the sake of stiffness, be 150% the size of the steel plate.

[AmoebAssassin]

A "strength-equivalent" aluminum structure, having used deflection (stiffness) as the design criteria, will have been built using roughly 50% greater plate thickness. We might then say that this strength-equivalent "one and a half inch" thick aluminum plate will yield at around 51k per square inch of surface area (around 29% greater yield strength than the "equivalent" region of steel plate), and will fail at around 67.5k psi (around 12.5% greater ultimate strength than the "equivalent" region of steel plate).

Of course these broad generalizations are intended only as a way of illustrating the approximate relative strengths of the materials. However, from these considerations we can see that the aluminum vessel will have a greater overall strength than the steel vessel per square area of plate. The reason for this is that the aluminum plate will, for the sake of stiffness, be 150% the size of the steel plate.

Sources please?

And as far as I'm concerned so far, you've said nothing other than that a thick aluminum plate will be stiffer than a thin aluminum plate. Not only is this obvious (the aluminum plate will have more material), but it is completely insignificant in this argument, as plates in bending are mechanically different than cylinders under bearing loads.

[Edub1]

I was mistaken in thinking that a given chunk of aluminum is stiffer than steel.

I made this mistake because I confused a given piece with a complex structure.

Take for example two car frames of equal weight. Obviously equal weight is the key here. What MegaSquirt is saying and what I mistakenly was thinking of was that the aluminum frame, pound for pound, will clearly be the stiffer of the two.

I agree that this would not apply to a bushing.