Subframe Bushings - Who Needs Them?

[Edub1]

As far as I can gather, all subframe bushings do is eliminate a bit of road vibration. Please correct me if I'm mistaken.

I've seen the writeup on installing aluminum bushings and it occured to me that this should be about the same as eliminating the bushing all together as aluminum has no dampening ability what so ever.

So, I'm wondering if it isn't feasible to simply weld or bolt the subframe to the frame using some metal stock. Another way would be a couple of chunks of polyurethane sandwitched and through bolted - taking the pressure off of the stock bushing.

Either way, it seems like aluminum bushings would have the same effect as simply fastening the subframe in place.

Is there any reason why this wouldn't be good?

[burntricer]

also very interested in knowing this, seems very fesable,

[AmoebAssassin]

The only reasons solid subframe bushings are a bad idea are two-fold:

1) Solid subframe bushings will transfer more road and suspension vibration into the vehicle's unibody, increasing the car's NVH rating (Noise, Vibration, Harshness). If you have a pair though, this will not be a concern for you.

2) Solid subframe bushings transfer more impact load to the subframe mounting studs/unibody than soft bushings do. If you doink a curb with your rear wheels then, you're more likely to bend up your unibody or bend the four subframe mounting studs, so dont hit anything hard.

Other than those two, solid subframe attachment is a great idea, and does wonders to stabilize your suspension geometry under heavy load cornering!

Making your own spacers is a good idea if you have access to a lathe and are a decent machinist.

The methods you describe (welding, using metal stock scraps, polyurethane sandwich) are ghetto as hell, and are a bad idea.

[Edub1]

I'm confused. You are saying that a solid connection between frame and subframe is good - draw backs not withstanding.

But, welding the two together is bad? I'm sure the weld will be 10X as strong as the bushing so how is it bad?

[FratGuyBelushi]

I'm confused. You are saying that a solid connection between frame and subframe is good - draw backs not withstanding.

But, welding the two together is bad? I'm sure the weld will be 10X as strong as the bushing so how is it bad?

I believe what he's trying to say is that a direct connection between the two is great for cornering and handling in general, however because it transfers so much direct energy it would be prone to damage on the street; with all the speed bumps, pot holes and curbs... In summary, if you're only taking it to the track, its probably a great idea, but on the street you'll still need bushings in between to prevent any damage, and its just a more pleasant ride.

Also if I didnt make it clear, damage with a weld wouldnt be caused to the weld itself, but the frame from all the energy being transfered.

[Edub1]

I believe what he's trying to say is that a direct connection between the two is great for cornering and handling in general, however because it transfers so much direct energy it would be prone to damage on the street; with all the speed bumps, pot holes and curbs... In summary, if you're only taking it to the track, its probably a great idea, but on the street you'll still need bushings in between to prevent any damage, and its just a more pleasant ride.

Also if I didnt make it clear, damage with a weld wouldnt be caused to the weld itself, but the frame from all the energy being transfered.

Then would it also be the case that aluminum ones are not good for street use? Aluminum is more rigid than steel. Anyway, wouldn't the shocks & springs absorb bumps? I would think the bushing with it's limited travel would absorb vibration and road noise more than anything else.

[95_240]

I think it's pretty obvious when stating that welding as opposed to bolting is more feasible when you are driving a street car in this case. Mainly because if something breaks you can't just unbolt it. Just send your 150 dollars to spl and call it a day.

As for damage he isn't reffering to everyday driving. Unless you hit a curb everyday. It's just that when you do hit something the damage is just going to be worse than if you had stock bushings.

[AmoebAssassin]

I'm saying a welded subframe is a bad idea because the second you bend a subframe, you're better off buying a new chassis.

Trying to grind off a subframe and weld a new one on with the correct angle and alignment is near impossible without a frame table or something like that.

Every other method you described is ghetto, and I would not allow any blood relatives of mine to use any of those methods you described.

Stick with the aluminum bushings.

You're wrong by the way. Steel is MUCH more rigid than aluminum, but is a good bit heavier.

[Edub1]

Are you talking about those insert pieces. I've read that those are short lived. But after seeing their stuff, I'm thinking of some making adjustable links that would take over the job of the bushings.

Can't hurt to experiment.

[AmoebAssassin]

How are they short lived? And how are you going to make a link replace a bushing?

You don't need adjustable links to attach your subframe to your car, and attaching it as such would add play and failure-prone parts to a high-stress area of the chassis.

Yes, it can hurt to experiment. It can hurt when your poorly engineered "links" break and send you into a wall, barrier, other car, or oncoming traffic.

[95_240]

I have never heard of the solid subframe bushings breaking maybe you could post a link. I don't see how adjustable links can take over the job of the subframe bushings.

I think you're just going to end up turning something that is easy to do into something that would just be to hard and a waste of time.

[Edub1]

First, I don't poorly engineer anything and if I make it it won't break.

The aluminum shims get reamed out. I saw a post where a guy installed them and they were reamed in no time. I'm sure the complete bushings are much stronger but they require removal of the entire subframe.

What I'm wondering is if anybody knows of any particular function of these bushings other than dampening vibration and road noise. If that is all they do I am fully confident that I can fix the subframe to the chassis in a way that makes it the strongest point on the car. I could make it withstand a bomb if I wanted to.

Now if someone said they have done it or have installed aluminum bushings and it made the car intollerable that would be one thing. Or if someone said the flex is a crucial part of maintaining a proper tire contact patch that would be something else. But it seems that the aluminum bushing is just an over hyped way of making a solid connection between the subframe and the chassis. In what way is this better than a thick piece of square stock welded to each piece and 2, 5/8" grade 8 bolts on each side of each bushing?

I'm concerned with the mechanical dynamics of it. The last thing I'm worried about is my harware failing.

[FratGuyBelushi]

First, I don't poorly engineer anything and if I make it it won't break.

The aluminum shims get reamed out. I saw a post where a guy installed them and they were reamed in no time. I'm sure the complete bushings are much stronger but they require removal of the entire subframe.

What I'm wondering is if anybody knows of any particular function of these bushings other than dampening vibration and road noise. If that is all they do I am fully confident that I can fix the subframe to the chassis in a way that makes it the strongest point on the car. I could make it withstand a bomb if I wanted to.

Now if someone said they have done it or have installed aluminum bushings and it made the car intollerable that would be one thing. Or if someone said the flex is a crucial part of maintaining a proper tire contact patch that would be something else. But it seems that the aluminum bushing is just an over hyped way of making a solid connection between the subframe and the chassis. In what way is this better than a thick piece of square stock welded to each piece and 2, 5/8" grade 8 bolts on each side of each bushing? I'm concerned with the mechanical dynamics of it. The last thing I'm worried about is my harware failing.

As far as I'm aware of, the main use of the bushings is to reduce road noise and vibrations and with that you gain another way of preserving factory workmanship. I can't answer the rest of your questions as competently as others, so I won't try to. Although I don't see why the hell you'd ever want to do this on a street car, or get rid of an effective system when it's already there. If you were in MN, you'd never dream of doing this. Our highways and streets buckle on really hot days because of the year-round weather. However, if you do choose to do this, let us know how it goes.

[95_240]

I'm sure the complete bushings are much stronger but they require removal of the entire subframe.

So welding and "engineering" is going to take less time than installing these. Yeah, okay.

The whole point of replacing these bushings is to help reduce wheel hop on most cars and and replace the sogginess of worn bushings.

I could make it withstand a bomb if I wanted to.

Wanna bet?

So to most people it would appear to be pretty conclusive to just buy these instead of welding crap on your car that could damage it upon removal.

[yokota180sx]

Dont ask, just getTHey cost 65-120 a set, put them on, feel your rear end handle way better.les wheel hop (in my case) more stable drifts, just do it

nvrmind, i just realized the OP.

enjoy explaining to this guy, he couldnt find the suspension faq

[AmoebAssassin]

First, I don't poorly engineer anything and if I make it it won't break.

Hahaha, an engineer with a huge ego. I see you killing people with by virtue of prideful neglect in the future, should any proper engineering firm hire you. But for now you list yourself as an "entrepreneur," so I can be fairly sure of two things:

1) You won't be hired by any proper engineering firms and I can stop worrying that some design flaw you overlooked because "you're the ****" will eventually harm someone I care about

and 2) You are not a certifiable source of information on any engineering topic in this discussion

You thought aluminum was a more rigid material than steel, a mistake that any first year engineering student could find, easily. You could barely perform a search in you anti-squat thread, and even then could barely wrap your mind around the concept of it, and instead resorted to childish bickering with another forum member (only to get your panties in a bunch and cry for a moderator, may I point out). You don't exactly make a particularly stunning case for your own competence, I'm sorry to say.

Quote »The aluminum shims get reamed out. I saw a post where a guy installed them and they were reamed in no time. I'm sure the complete bushings are much stronger but they require removal of the entire subframe.[/quote]Please review the design and functionality of the subframe spacers. The fit and finish of the holes is irrelevant, as the holes do not bear any load in that particular application. The function of subframe spacers is to sandwich the existing rubber bushing between the collars, thereby eliminating any slack that has developed over the years and to reintroduce some rigidity to the bushing material. The collars themselves are not actually designed to support load, and are quite thin.

Removal of a subframe and installation of four solid bushings is no more than a lazy sunday's work, working from noon til 9pm.

Quote »What I'm wondering is if anybody knows of any particular function of these bushings other than dampening vibration and road noise. If that is all they do I am fully confident that I can fix the subframe to the chassis in a way that makes it the strongest point on the car. I could make it withstand a bomb if I wanted to.[/quote]Please read above, I already explained the two main functions of subframe bushings. But silly me to think you would read anything anyone else wrote.

Again, you've proven yourself incapable of understanding mildly complex issues. You do NOT want your subframe attachment point to be perfectly rigid on a street car unless you are certain either that you will not crash the car, that you can buy a new chassis when you damage your subframe mounting studs or even your unibody in a serious impact, or that you can afford to repair the aforementioned chassis damage.

Solid subframe mounting transfers more energy from the subframe to the chassis, and in a wheel on curb impact, because rubber has a lower elastic modulus (material spring rate) than aluminum, and is therefore capable of transferring a much lower inertial impulse than aluminum is. Where a bushing would absorb and dissipate some of that impact energy, now a much larger percentage of it is going directly into the four 12 or 14mm diameter studs that hold your subframe to your car, and the unibody area directly around them.

Quote »Now if someone said they have done it or have installed aluminum bushings and it made the car intollerable that would be one thing. Or if someone said the flex is a crucial part of maintaining a proper tire contact patch that would be something else. But it seems that the aluminum bushing is just an over hyped way of making a solid connection between the subframe and the chassis. In what way is this better than a thick piece of square stock welded to each piece and 2, 5/8" grade 8 bolts on each side of each bushing?[/quote]How is subframe flex ever a crucial method of maintaining tire contact patches? The entire goal of a proper suspension, in practice, is to make damn certain that whatever alignment values at different positions of suspension bump, steering angle, and vehicle roll are as close to the engineered values as possible. Bushings, although necessary to control NVH, only introduce slop into the system and allow actual alignment values to differ from engineered alignment values. That is why people who are serious about motorsports use solid bushings, rod ends, and spherical bearings instead of bushing connections. I guarantee you will never see a rubber bushing in the suspension of any respectable race car.

Aluminum bushings are certainly not over-hyped. They are popular because they are cheap, and they work well. This solution is better than your weld'n'bolt kindergarten solution because:

-It is lighter-It is a simple, albeit slightly time consuming installation process-It retains factory geometry and build tolerances, as opposed to your drill, weld, and bolt solution.-It does not place questionable, amateur welds under cornering stresses, and does not expose said amateur welds to repeated strain and intense vibrations over a large frequency range-It does not introduce as much slop into the subframe mating scheme as would drilled bolt holes and square stock.

Quote »I'm concerned with the mechanical dynamics of it. The last thing I'm worried about is my harware failing.[/quote]Alright there ace, I'm sure we'll all be waiting for your "Boo Hoo Hoo I wrecked my 240sx" thread.

Cheers,Neel

[Thrwnsprkz]

OMFG AYFK!welding the subframe is the greatest idea ever!SO STIF PERFECT FOR STIFFYNESS

...dont ruein your carif your that cheap were you cant afford solid subframe spacers, make your own...ive seen some cars in Drift Tengoku that welded washers onto their oem bushings after cutting them shorter, its ghettofied method of stiffening the subframe but doesnt involve compleatly feuxoring the entire chassis.

I have seen hardware fail, I have seen subframes snap in half. the more gheto the build the shorter lived the car. ~rules to live by

peace~Fro

[yokota180sx]

this kid doesnt even know what drift tengoku is

basically, do it right, or pay it twice

[Edub1]

I don't see the need for insults here. I did not insult you and I can't figure out why you feel the need to insult me. I never claimed to be an engineer - I was in fact a molecular bilology major.

It is a fact that aluminum is more rigid/stiffer than steel - installing aluminum bushings should be just as stiff if not stiffer than other options.

Even if I do decide to fabricate some type of stiffening setup the stock bushings will still be in place, so causing a catastrophic failure is not a concern.

Really though, given your guys need to insult me with no provocation what so ever and the fact that you are unwilling to consider my suggestion fairly, I'm simply going to ask that you stop posting into my thread.

[yokota180sx]

dude, its a 100 dollar parts, dont overthink it

just putt hem on and enjoy

[94_240sx]

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.

[yokota180sx]

well....subframe colars like the ones you pictured

dont really rely on teh stock bushings at allehy sandwich the subframe between the collar, making it almost solid.the stud then goes through, and the washer and nut hold it all together of course

[AmoebAssassin]

It is a fact that aluminum is more rigid/stiffer than steel - installing aluminum bushings should be just as stiff if not stiffer than other options.

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.

[AZhitman]

Amoeba and yokota: WELL SAID.

Edub, gotta go with the majority on this one... Keep in mind there's a difference between subframe SPACERS (an admittedly stop-gap measure, I have them) and actual solid subframe BUSHINGS.

I have a GREAT solution for you: Go pull my article on making your own motor mounts and MAKE a set of subframe spacers. You can dial in hardness, shape and thickness to your liking, and it'll be cheaper than ANY method already proposed.

Carry on!

[Edub1]

Are we talking about shims or bushings?

I don't want to pull my entire rear end out of my car to replace my perfectly good rubber bushings with aluminum ones. I fail to see how aluminum ones are even "bushings" at all. Since all they do is make the connection a solid one, perhaps they should be called "bushing replacement inserts."

The more I think about it the more I'm leaning toward fabricating a urethane motor mount type block to use in conjunction with the rubber bushings.

If it works like I think it will I just might make some for sale.

[AZhitman]

I have a GREAT solution for you: Go pull my article on making your own motor mounts and MAKE a set of subframe spacers. You can dial in hardness, shape and thickness to your liking, and it'll be cheaper than ANY method already proposed.

The more I think about it the more I'm leaning toward fabricating a urethane motor mount type block to use in conjunction with the rubber bushings.

Who's the Daddy?

[WDRacing]

What if we remove the use of said vehicle for street purposes and then assume that a frame jig can be used to straighten out anything twisted or damaged during any unforseen incident. In the off road community, this is done alot more often then you'd figure. I've personally cut out a section of frame and welded in a new portion. No lazer precision used at all, just good old hand tools. That car drove straight at 130 MPH.

I'm not saying I agree or disagree with welding the the crossmember to the frame. I am however saying that a discussion on the matter isn't a bad idea or make an individual ignorant for bringing up the topic to begin with.

So far I've seen some good arguments on both sides. No need to let this thread deteriorate into mindless blathering about who is a poor engineer and who isn't. I'm no engineer and I could weld the subframe to the main frame and not have it break. But that has nothing to do with the actual conversation.

When people started welding the spider gears together for full time posi traction, they were called idiots. But look what people have been doing for the last 30-40 years now. People said remote mount turbo kits were stupid and would not work, I was one of them. But they do work and work very well.

Basically, for any conversation to yeild any good points, both sides have to maintain an open mind towards the topic. I don't see that happening on anyones part in this thread, to include the OP.

Suspension isn't my fortay at all so I can't volunteer an opinion on either side. I'll bring this up to a friend of mine and have him pop in here and see what he has to say.

But for now, if you don't have anything to say that actually pertains to the thread, then STFU

WD

[Edub1]

Amoeba and yokota: WELL SAID.

Edub, gotta go with the majority on this one... Keep in mind there's a difference between subframe SPACERS (an admittedly stop-gap measure, I have them) and actual solid subframe BUSHINGS.

I have a GREAT solution for you: Go pull my article on making your own motor mounts and MAKE a set of subframe spacers. You can dial in hardness, shape and thickness to your liking, and it'll be cheaper than ANY method already proposed.

Carry on!

AZ, I'm confused. Are you condoning these guy's unprovoked insults?

I have seen your DIY motor mount post - that's what I'm thiniking about. Are you saying this is good or bad?

[AmoebAssassin]

There's no need to dissassemble your rear end to gain some stiffness in that area.

The way I see it, you have two quick, cheap, pre-made solutions:

1) Subframe Collars/Spacers like the one 94_240sx posted. These install quickly and tighten up the rear end a good bit, but still rely on the stock bushings and therefore will never completely eliminate wheel hop or subframe deflection.

2) Solid subframe bushings, which require you to cut out your rubber bushings and install solid aluminum bushings. This requires you to drop the subframe from the chassis, but again, this is only a day's work if everything goes right.

Both solutions are effective, easy to install, and cost less than 100 bucks.

[Edub1]

What if we remove the use of said vehicle for street purposes and then assume that a frame jig can be used to straighten out anything twisted or damaged during any unforseen incident. In the off road community, this is done alot more often then you'd figure. I've personally cut out a section of frame and welded in a new portion. No lazer precision used at all, just good old hand tools. That car drove straight at 130 MPH.

I'm not saying I agree or disagree with welding the the crossmember to the frame. I am however saying that a discussion on the matter isn't a bad idea or make an individual ignorant for bringing up the topic to begin with.

So far I've seen some good arguments on both sides. No need to let this thread deteriorate into mindless blathering about who is a poor engineer and who isn't. I'm no engineer and I could weld the subframe to the main frame and not have it break. But that has nothing to do with the actual conversation.

When people started welding the spider gears together for full time posi traction, they were called idiots. But look what people have been doing for the last 30-40 years now. People said remote mount turbo kits were stupid and would not work, I was one of them. But they do work and work very well.

Basically, for any conversation to yeild any good points, both sides have to maintain an open mind towards the topic. I don't see that happening on anyones part in this thread, to include the OP.

Suspension isn't my fortay at all so I can't volunteer an opinion on either side. I'll bring this up to a friend of mine and have him pop in here and see what he has to say.

But for now, if you don't have anything to say that actually pertains to the thread, then STFU

WD

Much appreciated.