rmcdaniels

I've been having some severe issues with my rear stepping out under hard cornering at HPDE's. My rear would step out wide and abruptly before my tires even started to complain (very exciting at Roebling Road at 70 MPH). JDogg suggested that my ES poly trailing arm bushings may be binding, so Friday evening before I went to VIR I replaced them with Mugen hard rubber bushings.

Here's a thread with some pics:

https://honda-tech.com/zerothread?id=1589298

The new bushings made a huge difference at VIR, it was like I had a different car. The rear is much more stable and no longer steps out. I was able to push the car much harder than I previously could, it was really amazing. For a few laps I just drove the car around like an idiot, making the tires scream as much as I could just because it was possible. It also gave up traction very gradually and easily, plus it was very easy to recover.

I can't believe how bad the ES poly bushings were, ES should be kicked in the nuts for making that product.

ryan12321

did you make any alignment changes when using the two bushings. Remember the poly doesn't let the rear toe in under compression as the mugen will. That alone will make the difference in handling.

Its just like using different tires. They each need to be tuned to work right.

I was very pleased with the effects of the poly bushing in my car.

rmcdaniels

I had it aligned after I put the ES bushings in. It was great for daily driving and even some auto-x, but on a road course it was very unstable when cornering hard.

ryan12321

yes, but did you alter your alignment settings from what you used with the rubber bushings. I'm not sure how much the rear toes in under compression, but just for discussion I'll use 1/16".

If you start out with 0 toe on the back. With the ES bushings under compression its going to stay at 0. The rubber will let the rear toe go to 1/16" toe in under compression during a turn. Thats going to be more stable.

Now if you set the alignment to 1/16" toe in static with the ES bushings during a turn it will still be at 1/16" toe in. Now you should have the same handling during a turn than with the rubber bushings.

You can also use this to your advantage as you don't have to run as much toe out staticly which can increase your stability during braking. At least thats what I did and it worked great.

Use the resistance of flex(aka binding) of the poly to your advantage.

rmcdaniels

But how does that work for daily driving, tire wear, etc?

ryan12321

That would depend on what toe settings you are using right now. factory toe specs at toe in to begin with so using rubber bushings most people go with 0 or toe out in the back, which would mean you are out of factory specs.

rmcdaniels

So maybe the real problem is that ES recommends you use OEM alignment settings with their trailing arm bushings (2 degrees in on the rear) and then says that they "dramatically help the vehicle maintain proper rear toe and caster under high performance driving conditions". It's kind of a pisser if I did all that work when I just needed to zero my rear toe.

jisu009

Just so you know.....

Mugen bushings are the exact same as the ones the dealership currently offers.

rmcdaniels

If you check out the link to the picture thread, I pretty much assumed that, but I don't have a durometer.

jisu009

they are exactly the same.

Vitt1

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jisu009 &raquo;</TD></TR><TR><TD CLASS="quote">Just so you know.....

Mugen bushings are the exact same as the ones the dealership currently offers.</TD></TR></TABLE>

Just curious how do you know that, and can you share any info on it, so we can lay this "Mugen bushings are harder than OEM or not" to rest, or at least have some clarification.
How about it?

jisu009

Having the two in your hand at the same time you will quickly see that they are the same.

This has been covered before.

Tyson

i think what may be key here is that maybe that the new "OEM" bushings (which are probably the same as mugen ones) are not the same as the original factory installed bushings.

so i dont think its about mugen falsely representing theirs as "hard rubber" when its the same as whats available currently from the dealer, because remember, for a long time, the bushing itself was not available individually.

what i may theorize further, is that mugen had always made their "hard rubber" bushing, and honda just piggybacked their order of individual bushings off their process. which mugen just uses the same OE parts manufacturers anyway to make their parts.

Black R

I don't care about that so much as whether rmcdaniels changed his alignment settings at all between bushing changes.....

rmcdaniels

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Black R &raquo;</TD></TR><TR><TD CLASS="quote">I don't care about that so much as whether rmcdaniels changed his alignment settings at all between bushing changes..... </TD></TR></TABLE>

I had the rear toe set to the value that ES recommended, 2 in, and I think that was a part of the problem.

Vitt1

rmcdaniels, sorry, didn't mean to hijack your thread.

Thanks Tyson, that's more the answer I was looking for. Since the RR/AX forum is under the "Technical" category, it's only fitting to expect that a more technical or scientific explanation (like: "a durometer was used and...) is given to a statement like that. For no other reason than this is the internet...

I also agree that Mugen would not falsely state that their bushings are harder rubber than OEM for many reasons.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tyson &raquo;</TD></TR><TR><TD CLASS="quote">i think what may be key here is that maybe that the new "OEM" bushings (which are probably the same as mugen ones) are not the same as the original factory installed bushings.

so i dont think its about mugen falsely representing theirs as "hard rubber" when its the same as whats available currently from the dealer, because remember, for a long time, the bushing itself was not available individually.

what i may theorize further, is that mugen had always made their "hard rubber" bushing, and honda just piggybacked their order of individual bushings off their process. which mugen just uses the same OE parts manufacturers anyway to make their parts.</TD></TR></TABLE>

rmcdaniels

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Vitt1 &raquo;</TD></TR><TR><TD CLASS="quote">rmcdaniels, sorry, didn't mean to hijack your thread.

</TD></TR></TABLE>

NP, I made the post to get some feedback and it's been good so far. The only thing I've seen comparing Mugen to OEM is that one old guy who made the Web page where he did some writeups on the stuff he did to his white hatch. He actually had the two in his hands and couldn't tell the difference, but without some type of measurement his opinion is not conclusive IMO. I saw on another board where somebody got some information from Mugen in Japan that they perform some extra type of treatments to their bushings beyond what the OEM ones get, but that's not really conclusive either. Any body got a durometer?

The toe information is very interesting too, wish I'd known that before I replaced them. I actually did check with ES about rear toe recommendations with their trailing arm bushings and they told me their bushings are designed to be used with OEM alignment settings, but it makes sense that it might need to be changed because the ES bushings don't have the front-back play of the OEM units.

I'll probably be getting the JHPUSA spherical bearing cups eventually, just have to scrape up an extra $250.

Vitt1

I wish I had access to a durometer, because I have some Mugen upper shock bushings and they do feel a lot like the OEM (big price difference). I decided to keep urethane on the front of the car. But without the durometer I can't make a conclusive statement.

That info on the TA is also really good because there have been lots of posts about the potential binding and associated problems.

Please keep us posted about your experiences after you've been to the track. That will definitely be good info on this topic.

rmcdaniels

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Vitt1 &raquo;</TD></TR><TR><TD CLASS="quote">

Please keep us posted about your experiences after you've been to the track. That will definitely be good info on this topic. </TD></TR></TABLE>

Well VIR this past weekend was awesome, but mostly because of how badly it sucked at Roebling Road before I changed out the bushings. The car actually feels pretty good now, I may leave it alone and just drive it for a while. I think Roebling is coming up again soon, have to check the calendar.

ekim952522000

this comes up about once a week I think we have established that poly bushings in the RTA are a bad idea and do not let the suspension work the way it was designed to.

jisu009

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ekim952522000 &raquo;</TD></TR><TR><TD CLASS="quote">this comes up about once a week I think we have established that poly bushings in the RTA are a bad idea and do not let the suspension work the way it was designed to.</TD></TR></TABLE>

Yes, this subject has been beaten time and time again.....

However....

I am starting to wonder if using a Poly RTA bushing is possibly OK. On a racecar that is sprung heavily in the rear you are certainly not subjecting the suspension to the full range of motion vs. a softer or factory suspension.....so maybe the multi axis range of motion is less important on a CRX with 750lb springs in the rear?

ryan12321

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jisu009 &raquo;</TD></TR><TR><TD CLASS="quote">Yes, this subject has been beaten time and time again.....

However....

I am starting to wonder if using a Poly RTA bushing is possibly OK. On a racecar that is sprung heavily in the rear you are certainly not subjecting the suspension to the full range of motion vs. a softer or factory suspension.....so maybe the multi axis range of motion is less important on a CRX with 750lb springs in the rear?</TD></TR></TABLE>

yes they do not allow the suspension to move the way it was designed, but you can use it to make it do something else. Poly won't completely bind. Its still a fairly flexible material with the heavy loads put on it.

DavidR

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jisu009 &raquo;</TD></TR><TR><TD CLASS="quote">

Yes, this subject has been beaten time and time again.....

However....

I am starting to wonder if using a Poly RTA bushing is possibly OK. On a racecar that is sprung heavily in the rear you are certainly not subjecting the suspension to the full range of motion vs. a softer or factory suspension.....so maybe the multi axis range of motion is less important on a CRX with 750lb springs in the rear?

</TD></TR></TABLE>

I think what you have to consider is ride height, too. As the trailing arm moves upwards, it twists, which allows the adjustment for camber. If you lower the car to a height way below the factory settings and try to set toe/camber, you could possibly be putting everything in a bind while sitting still. This may be why poly trailing arm users see such twitchyness in the rear, because the trailing arm is trying to unbind itself, and when it does, it "springs". just my thought process outloud, feel free to discuss.

rmcdaniels

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DavidR &raquo;</TD></TR><TR><TD CLASS="quote">This may be why poly trailing arm users see such twitchyness in the rear, because the trailing arm is trying to unbind itself, and when it does, it "springs".</TD></TR></TABLE>


I wondered about that, because mine didn't feel like it was just an alignment problem, it felt fine to a certain point, then it suddenly jumped out sideways. My brother was behind me at Roebling Road when it happened once and he said the tail just flipped out sideways at one point during a turn, and we weren't even going very fast. In the car I got a "tipping" feeling that I learned to recognize as the sign that the rear was about to lose it, and after a while I just didn't push it any further when I got that feeling. Now if I push the car too hard, it gradually gives up, and it does it pretty evenly front-back, slides a bit sideways until it slows down and then I can carry on.

redzcstandardhatch

i was about to install poly bushings in my rear trailing arms..

maybe i wont now...