Smart Car Forums - Reply to Topic
Thread: Axle support beam bushing Reply to Thread
Send Trackbacks to (Separate multiple URLs with spaces) :

Register Now

In order to be able to post messages on the Smart Car Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


  Additional Options
Miscellaneous Options

  Topic Review (Newest First)
10-20-2018 06:36 PM
InjuredAgain That is one beautiful M, and BBS wheels too! I sold my '95 after five years and 50k miles because all of the maintenance was coming due again, and combined with the a leak from the rear main or transmission inlet seal, along with seeping from the oil pan gasket and oil control rings that weren't controlling any more on a nearly 200k motor, it was looking like motor out/rebuild or swapping in a new motor, and I just didn't want to go through all of that especially since the convertible top was also starting to show some wear spots. Now 15 months later, I'm kinda sorta looking to get into one again, but stock ones are super rare, and nice stock ones are even more so. If you ever think about selling, I'm all ears!

I saw your previous thread about the stiffer end links, and my thought was that it would increase the understeer more - the opposite of what I want. I also currently have a C6 Corvette that I've been transforming into a car for track days, and one maker of high rate sway bars believes in the philosophy of much stiffer front roll stiffness. I ended up buying that set of bars because it is close to the rate I wanted for the rear, and I thought I could use the softest setting in the front to get the balance I wanted. I have to say that I was surprised - the really stiff front end makes the car turn instantaneously without feeling understeery, and transitional handling is razor sharp. What I don't like, though, is that if the turn is long enough for the suspension to fully settle, it does transition to understeer, which then transitions to oversteer if I get on the throttle a little too abruptly and I'm not straight. And the more I'm still turning, the more sensitive it is to throttle. With a more balanced set of bars, it was a lot more benign. I'm sure in the hands of a good driver, it would be fine, but since I'm lucky to do more than a handful of track days a year, I'm just not polished enough of a driver and I feel like I want a bit more latitude. The handling is great, but it does feel like a razor's edge.

That gets me worried about doing the same to my fortwo. It's eye opening how easily a short wheelbase car like this can rotate, and last winter showed that I'm not always going to catch it, even in the slow speeds I'm driving like when I'm on snow. It makes me reluctant to do something which on my Corvette made it both more understeery and more oversteery, and why for now I'm just chasing more rear roll stiffness. But you may very well be right about the short wheelbase also making changes affect both ends. Hmm, the story always seem to get murkier before it gets clearer.
10-20-2018 03:47 PM
banzairx7 A man after my own heart. Here's my 95 M Edition-

I would play with the front roll a bit more too. I've added stiffer end links and Delrin bushings to my front bar and it helped with overall roll with out adding understeer. My thinking is this car is so short and stiff that reducing the roll at either end tightens the whole car up.
10-20-2018 01:46 PM
InjuredAgain The backstory: I went from a '95 Miata to the 451 ED, and I've debated modding as decreasing the limited range wasn't something I wanted to happen. With the Miata, I kept it mostly stock, primarily adding roll stiffness and shocks with more rebound damping but leaving the stock springs. With a good alignment, I had a nimble, tossable vehicle that was very eager to turn and had very benign and neutral handling behavior.

With the smart, I found that the stability control system as a whole just isn't compatible with driving near the limits of traction. One major problem that can't be solved even by disabling the stability control and ABS is that the regenerative braking gets shut off if the sensors believe a loss of traction is imminent. This occurs at certain times even when there is no loss of grip and not cornering near the limits of tractiion, such as when hitting an apex that is at the crest of a rise. The sudden unweighting causes the car to start freewheeling, which then **causes** a loss of traction as all of a sudden the rear braking just goes away and the car starts to understeer more heavily.

So I've given up on trying to make my smart into a Miata clone, instead concentrating on just making it good at 80% and realizing that above that and there are going to be deficiencies that can't be driven around. With that said, I've only addressed front track width, using 20 mm spacers in the front behind the OEM 155/60-15's, and having my alignment shop loosen and retighten all of the components up front, getting me between -0.4 and -0.5 degrees negative camber at each front wheel while also setting toe at 1/16" or 0.05 degree toe-in at each front wheel, versus the factory spec of 0.25 degrees toe in.

These changes have reduced understeer by about a third, have removed most of the rut/tramlining/wind sensitivity at freeway speeds, and have helped transitional behavior as the front tires just don't grind as much with the wider track and little bit of negative camber. Cornering speeds have gone up about 2-3 MPH in the wet in steady state, maintenance throttle turns that previously could be taken at 30 MPH, so the traction gain is pretty significant. It really is about where I'd want it to be, if I could just further reduce the understeer more, so it just feels more eager to turn.

I don't know that I want to put spacers in the back. The front and rear track are now close enough that cornering feels natural, and I'd hate to get back to the stock track stagger that it had because it felt like the turn vector was just weird, kind of like riding a tricycle almost - this is probably that crabbing that you were talking about. Rear wheels on the front sound like a good idea and that's where I was planning to go, but I'd much rather address rear roll stiffness first, seeing how much more I can get, before adding more grip to the front that may make the understeer feel, feel worse.

Be happy to hear any other suggestions. I've taken my smart to a track driving instructor I know who also has fabrication experience, and he says he can custom make something to get me around -1.5 degrees front negative camber, but it's going to cost a few hundred dollars. A custom rear sway bar would be about the same cost as ordering the one from Europe - roughly $600 to my door. Those, I thought, were the only choices I had until hearing of this bushing upgrade. I'm really interested in finding out more about it before making a tire/rim choice.
10-20-2018 01:13 PM
banzairx7 Not sure what you've got done to your car at this point suspension wise... I've only had my Smart for about 2 months so I haven't delved super deep into it yet. One thing that I was surprised how much it helped front grip and turn in was wheel spacers. I put 15mm spacers on the front, 20 rear, and it made a world of difference. The car felt like it was crabbing almost through hard turns. It would slip and grip, slip and grip very quickly. The spacers reduced that by 90%.

If you're going down the tire route putting maybe some rears up front would help. That's next on my list of mods.
10-20-2018 12:37 PM
Originally Posted by banzairx7 View Post
Injured- The poly bush will do what your looking for. I don't think you're going to see as much stiffness as adding a bar though.

As far as squeaking goes it's been very hit and miss for me. I've had some bushings that have made a racket and others that have been totally silent. Wish I knew what the difference was.
I don't think I want as much stiffness as a bar can give me either, especially since I haven't done anything to really address the lack of front negative camber. I'm pretty used to a car that has a bit of situational oversteer, though my preference would be for just a hint of steady state understeer. My experience in driving the smart last winter though, shows me that I'm not always a good enough driver to catch a fortwo before it starts to spin, so I'd be happy to keep a bit more understeer for a bit more safety margin if I'm really pushing it. My wife would never get that close to the limit in the wet or snow, but I know she also thinks the smart feels reluctant to turn.

I'm due for tires soon, and I've always thought that if I'm going with a rear bar, or now this stiffer bushing, that I need to get that done before I do the tires so I can use them to address the amount of grip front and rear that would give me the breakaway characteristics that I need/want. It seems that Powerflex only has two different bushings while Smartkits has three, and it's the middle of the Smartkits one that sounds like the one I would want to use. I need to find out who can do the swap for me and how much this will cost. If it's like four hours of labor and the service life of the bushing is 50k miles, then I think I'd be better off buying the sway bar and doing something to soften up the roll resistance. However, if it's only a couple of hours of labor and I can get 100k miles out of it, then the bushing seems to be the way for me to go.

As far as squeaking bushings, I got a small tub of some secret sauce polyurethane lube from Pfadt, and no matter how badly a poly bushing has squeaked, this stuff has **always** cured it and has lasted several years.

I'll try to find a mechanic who can do the work, and will report back what they say as far as labor hours.

10-20-2018 11:53 AM
banzairx7 Injured- The poly bush will do what your looking for. I don't think you're going to see as much stiffness as adding a bar though.

As far as squeaking goes it's been very hit and miss for me. I've had some bushings that have made a racket and others that have been totally silent. Wish I knew what the difference was.
10-20-2018 10:14 AM
Richnjohn One caution is that the polyurethane bushings squeek like heck. I put them in my VW and the car squeeks when I sit in it and going over bumps. I lubed all the bushings but they still squeek.
10-20-2018 08:57 AM
Originally Posted by banzairx7 View Post
That poly bushing is available stateside here-

You want the street version for sure. This is one spot where a softer bushing is better. If the bushing is too stiff the axle won't want to tilt side to side. Better for cornering but not so good for ride quality.
I've been in search of more rear roll stiffness, primarily in the form of a rear roll bar, and have only found one source with a cost of about $600 to get it to me here in the states. I assume the stiffer this bushing, the intent is to more stably laterally locate the deDion from cornering forces, rather than to provide more roll stiffness. But if it also makes a substantial change in roll stiffness, it's worth considering for me even at the expense of shorter service life. So how much if a difference will result from changing this bushing?
10-20-2018 05:39 AM
banzairx7 Installing a poly bushing is super easy. It's getting the old one out that is the problem.There are a few ways to get out the old bushing. The easiest is if you have the right tooling you can do it something like this-

The other way is use a drill bit and drill out what's left of the rubber bushing. Then you have to feed a hack saw through the bushing and cut through the outer metal sleeve that's still in the axle. Then you can bang that sleeve out with a hammer and punch. This is probably a 1-2 hour process and can be a bit of a nightmare but very doable.

That poly bushing is available stateside here-

You want the street version for sure. This is one spot where a softer bushing is better. If the bushing is too stiff the axle won't want to tilt side to side. Better for cornering but not so good for ride quality.
10-20-2018 12:44 AM
Axle support beam bushing

Ok guys,
So has anyone ever replaced their support beam bushing with a after market polyurethane bushing? Mine has went out and the mechanic says I have to buy a whole new support beam for 450 and with labor itll be 1000. All over a bushing..fml

But i found for 40 dollars a replacement performance bushing from a EU place. I mean if they are selling it, it's obviously possible to just replace that and not buy the whole shabana right?

I kinda just wanna buy it and be like you said they only sold it with the beam...but here I found one install it pretty plz. Lol

I wasnt sure if he meant it wasnt possible or if it's just not something he is willing to do. I do understand it is a bit hard to get the bushings in and out. But In my opinion worth it.

Has anyone ever did theirs? I cant find ANYTHING online for replacement video or even just talking about it

Links to support beam

And bushing

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

For the best viewing experience please update your browser to Google Chrome

Clubs, Garage Plus vBulletin Plugins by Drive Thru Online, Inc.