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Old 05-03-2013, 09:04 PM   #61
WDE46
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Originally Posted by Alex323Ci View Post
well reading that whole thread and not just that one post one can see their is not the consensus that PF poly RTABs are causing problems. it also seem on some other early brand and again back to the E36 pocket.

http://m3forum.net/m3forum/showthrea...=378468&page=4

also the "limiters" are "Delrin" which as we know is like a rock solid plastic. so while the stock rubber bushing is used, when at it's limits it's hitting the solid limiters. and that will not bind in the rotational axis, but will transmit and put likely more load on the mounting brackets thin metal around it as the trust pushes/twists it forward and/or aft. . i'm sure that bracket deflects more than what it's doing to the mounting pocket of the rear trailing arm mounting points..no? also to address the poly rtabs they have built-in "hats" or what the Delrin limiters try to duplicate being introduced as "limiters". so the way i see it (in this regards) the polyurethane will be more forgiving than the Delrin material anyday.


my thoughts on this. which are open for discussion and maybe a dispute. always like to see what others know or have proof of.
My thoughts exactly Alex. Good points on the limiters. At the limits, I think the PU and Rubber w/ limiters will experience the same sort of restrictive forces.

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Originally Posted by Mango View Post
I'm not using limiters. You'll still keep your grand designation despite disagreeing with me on RTAB flavors.

Still, I'm not convinced polyurethane has the same deflection properties as rubber. To add to that, not sure how you could trust a bushing that you can press in with your fingers versus the stock bushing needing to be pressed in with force.
They are both flexible materials. PU is merely more stiff than the OEM rubber. Also, you can't insert the PU bushings with your fingers. I had to press mine in. They are a tight fit. The PU rotates around the bolt/sleeve and doesn't move inside the RTAB trailing arm carrier.

Quote:
Originally Posted by LittleBear View Post
Yes, but this "pre-load', or more properly the trailing arm angle when the RTAB is tightened down, is only needed when using rubber bushings. Poly bushings don't need the angle set, but the rubber ones do because they twist themselves around the big bolt every time the suspension goes up & down.

Murf
I forgot about this preload, though I am not familiar with how to accomplish it. It was very convenient to not have to worry about any sort of preloads for FCABs or RTABs with the PF PU bushings.
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Old 05-04-2013, 02:48 AM   #62
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Yes, but this "pre-load', or more properly the trailing arm angle when the RTAB is tightened down, is only needed when using rubber bushings. Poly bushings don't need the angle set, but the rubber ones do because they twist themselves around the big bolt every time the suspension goes up & down.
Murf
Yes I was aware of all that. no need to convince me. im afraid i may have misunderstood your earlier post. i thought you said there was no mention of this in the Bentley and there is, REAR SUSPENSION 330-9. i

was just stating there in fact is a "Special tool and alignment procedures" for this. that's all. and you find the Bentley calls it "pre-load" too.
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Old 05-04-2013, 09:09 AM   #63
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I vote Powerflex Poly. I used the bigger (66mm I believe over the stock 60mm FCAB's) and RTAB's. After 2 years they are still doing great with NO noise.
My stock rubber RTAB's and FCAB's were so worn that they chewed up the inside of my tires. The RTAB's were also a pain to get out and the FCAB's had sand in them. I put the Poly in and it made the car feel tight and elastic instead of Sloppy and loose. Now the only thing going wrong in my steering is the stock rubber coupler which I will change for an AKG motorsport Poly coupler. The roads here are nice so I don't care about the added NHV (which I have noticed slightly when switching to Poly. But now I feel connected to the road better and it isn't by any means uncomfortable.) I know I could have felt the same results If I switched to rubber but, After seeing how rotten the rubber was on my car and hearing other people complain about the short lifespan that rubber bushings have compared to Poly. Well......I chose Poly. And I would choose it again. Although by the condition of the Bushings now.......I won't have to in a long time.

My 2 cents.
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Old 05-04-2013, 09:13 AM   #64
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Yes I was aware of all that. no need to convince me. im afraid i may have misunderstood your earlier post. i thought you said there was no mention of this in the Bentley and there is, REAR SUSPENSION 330-9. i

was just stating there in fact is a "Special tool and alignment procedures" for this. that's all. and you find the Bentley calls it "pre-load" too.
Hi Alex,
I thought the original reference to the needed "Special tool and alignment procedures" meant rear wheel alignment, since the post wasn't too specific.
This trailing arm alignment is very easy & needs no special tool, just a long straight edge that will reach from the RTAB to the wheel hub. A search here will find the specifics.

Murf

PS: I am a little sorry if I was too rough & offended Mango; it was not intended, and I know he tries hard to help us folks.
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Old 05-04-2013, 09:23 AM   #65
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Hello BMW Experts!
AKG has lots of Poly RTABs, some specified for track, some for both, & some for street only @ 85A. The softest poly RTAB still seems to be from UUC @ 75A. Being moderately sane, this is what I got.

Murf
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Old 05-04-2013, 09:32 AM   #66
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Hello BMW Experts!
AKG has lots of Poly RTABs, some specified for track, some for both, & some for street only @ 85A. The softest poly RTAB still seems to be from UUC @ 75A. Being moderately sane, this is what I got.

Murf
Nooooo. UUC has had issues with RTABs.

AKG > Powerflex > Rogue > UUC.
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Old 05-04-2013, 01:21 PM   #67
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Hi Alex,
I thought the original reference to the needed "Special tool and alignment procedures" meant rear wheel alignment, since the post wasn't too specific.
This trailing arm alignment is very easy & needs no special tool, just a long straight edge that will reach from the RTAB to the wheel hub. A search here will find the specifics. Murf
PS: I am a little sorry if I was too rough & offended Mango; it was not intended, and I know he tries hard to help us folks.
oh I see, that makes sense.
don't worry about Mango. believe me, we have all bumped heads at one time or another. just state your reasoning for your stance and if solid he hears it. if its not solid expect him to shoot it down tho. if its an "opinion" thing just agree to disagree. it's all good
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Nooooo. UUC has had issues with RTABs.

AKG > Powerflex > Rogue > UUC.
I think that was in their earlier design. I think they changed it up and pretty sure not an issue since. Atleast I hope
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Old 05-04-2013, 03:39 PM   #68
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Sorry if I seemed a little rough as well. I don't want anyone to think it's my way or the highway. There are a few "issues" which i am passionate about. This being one of them. I'm sure you all have great experiences with your poly rtabs. I just think it isn't necessary and goes against the whole BMW design philosophy. Believe it or not, the Vorshlag opinion is very well written and makes a lot of sense. There's obviously enough truth to it that this debate happens in the first place. This debate is on every forum. I am still convinced a big reason people install the poly rtabs is because it's "easier to deal with." Would you guys that installed poly rtabs install poly engine/trans mounts? I wouldn't give much grief in those locations because the mounts just sit there and aren't subjected to the same forces and directions the trailing arm bushing is.

Since Alex has the RTAB tool, he probably installed the poly rtabs for performance/feedback reasons. but for most other people, I don't think that was the case.

LittleBear and WDE, how did you remove your stock rtabs?
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Old 05-04-2013, 06:11 PM   #69
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Nooooo. UUC has had issues with RTABs.

AKG > Powerflex > Rogue > UUC.
Uh oh. What issues with UUC RTABs?

"LittleBear and WDE, how did you remove your stock rtabs?"

I bought a used MIS tool, and rapidly sold it. I put my poly RTABs in for performance driving on dirty back roads!

Murf
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Old 05-04-2013, 06:53 PM   #70
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LittleBear and WDE, how did you remove your stock rtabs?
BimmerWorld RTAB tool. Really easy.
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Old 05-04-2013, 06:54 PM   #71
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...don't worry about Mango....
I think the prob with Mango & me is more cultural than anything else. After all, he comes from LaLa Land & I'm from Brklyn.
If we were to meet, after I smacked him upside his head a little bit all would be fine!

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Old 05-04-2013, 10:27 PM   #72
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Uh oh. What issues with UUC RTABs?

"LittleBear and WDE, how did you remove your stock rtabs?"

I bought a used MIS tool, and rapidly sold it. I put my poly RTABs in for performance driving on dirty back roads!

Murf
how exactly does it help with your performance driving? what other supporting suspension mods do you have?
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Old 05-05-2013, 08:16 AM   #73
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how exactly does it help with your performance driving? what other supporting suspension mods do you have?
My car has less rear wiggle when doing switchbacks & such. It tracks very predictably. Grooved & rutted roads now have less influence on my direction. I can't really compare this with how my M3+Limiters setup felt since they were new a few years ago (they were great when they went in), but going by memory, the polys are at least as good for handling.
My suspension mods are mild: FSD shocks, Meyle FCABs, JTD909 Gen.IV rr upper shock mounts, SSR Integral 17x8.5 forged wheels, 225/45/17 DWS, "Strong Strut" front tower brace (as much to reenforce the towers as for stiffness). And a 'sport' steering wheel! The 330i comes with factory sport springs, and lots of my other suspension rubber has been replaced.

Murf
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Old 05-05-2013, 11:21 PM   #74
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My car has less rear wiggle when doing switchbacks & such. It tracks very predictably. Grooved & rutted roads now have less influence on my direction. I can't really compare this with how my M3+Limiters setup felt since they were new a few years ago (they were great when they went in), but going by memory, the polys are at least as good for handling.
My suspension mods are mild: FSD shocks, Meyle FCABs, JTD909 Gen.IV rr upper shock mounts, SSR Integral 17x8.5 forged wheels, 225/45/17 DWS, "Strong Strut" front tower brace (as much to reenforce the towers as for stiffness). And a 'sport' steering wheel! The 330i comes with factory sport springs, and lots of my other suspension rubber has been replaced.

Murf
Wouldn't stiffer bushings mean more influence on your direction when you hit "grooved and rutted roads"? that's like saying stiffer engine mounts means less/slower response when you hit the gas.

If you have stiffer bushings that means when force is applied on your wheels/tires from the road, that force instead of being absorbed by the bushing is now being transferred more so to the vehicle. Just trying to make sense of what you said.
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Old 05-06-2013, 12:42 AM   #75
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Akg Rtabs 85A vs 90A

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For people who like the feel of rubber, the RTABs are the one place where it is acceptable to go poly. The NVH difference (RTABs only) is so small that if you didn't drive your car for a week in between you would not notice a difference.

Powerflex or AKG. AKG makes a part that is slightly softer than Powerflex and apparently cannot be distinguished from stock rubber. Stock rubber with limiters is more of a PITA than it's worth. Yes, I've tried that solution also.

Fellas:

Thanks for great feedback and the debate on Poly vs OEM was entertaining to say the least but all in all I think lots of great info was provided.

I have decided on AKG Poly RTAB but now the question is:

Akg Rtabs 85A vs 90A, I see some info on 80A vs 90A and a quick blurb that 85A is too soft so I am wondering if anyone has any insight on which one I should order?
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Old 05-06-2013, 01:32 AM   #76
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For people who like the feel of rubber, the RTABs are the one place where it is acceptable to go poly. The NVH difference (RTABs only) is so small that if you didn't drive your car for a week in between you would not notice a difference.

Powerflex or AKG. AKG makes a part that is slightly softer than Powerflex and apparently cannot be distinguished from stock rubber. Stock rubber with limiters is more of a PITA than it's worth. Yes, I've tried that solution also.
Not sure how stock rubber is a PITA. Trailing arm is down anyway and pressing the bushing in takes 60 or so seconds with hand tools and the RTAB tool (which I'm assuming you're using anyway to remove the old bushing) and maybe 10 seconds with powered tools.

Also if the AKG part cannot be distinguished from rubber then why use it? Especially given that the rubber bushing needs to be pressed in for a tight fit versus a plastic toy you push inside using your fingers??
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Old 05-06-2013, 09:11 AM   #77
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Wouldn't stiffer bushings mean more influence on your direction when you hit "grooved and rutted roads"? that's like saying stiffer engine mounts means less/slower response when you hit the gas.

If you have stiffer bushings that means when force is applied on your wheels/tires from the road, that force instead of being absorbed by the bushing is now being transferred more so to the vehicle. Just trying to make sense of what you said.
Or it means that the wheel does not get deflected thus not steering the car in one direction or the other. There isn't a clear answer here. This was one of my concerns with the poly bushings, but it ended up not being an issue. With the proper alignment and good tires, my car drives very straight and true now.
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Old 05-06-2013, 09:18 AM   #78
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Wouldn't stiffer bushings mean more influence on your direction when you hit "grooved and rutted roads"? that's like saying stiffer engine mounts means less/slower response when you hit the gas.

If you have stiffer bushings that means when force is applied on your wheels/tires from the road, that force instead of being absorbed by the bushing is now being transferred more so to the vehicle. Just trying to make sense of what you said.
The way I see it is that when the road applies a force to each wheel, soft bushings will allow that wheel to have it's direction changed. A stiffer bushing will resist the force better & the wheel will stay going straight, as the big car mass is doing.
Folks, replacing the BMW rubber RTABs is very easy if you use the MIS tool. Put some good grease on the threads, put an extra washer on the tool (I forget where & so can't explain it better), take your time to line it up & crank it properly, and it just works, no probs.

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Old 05-06-2013, 09:46 AM   #79
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The way I see it is that when the road applies a force to each wheel, soft bushings will allow that wheel to have it's direction changed. A stiffer bushing will resist the force better & the wheel will stay going straight, as the big car mass is doing.
Folks, replacing the BMW rubber RTABs is very easy if you use the MIS tool. Put some good grease on the threads, put an extra washer on the tool (I forget where & so can't explain it better), take your time to line it up & crank it properly, and it just works, no probs.

Murf
Yeah but you're probably also comparing your new poly bushings to your old worn out rtabs if what you are saying is your experience. you already said you don't remember how your M3 rubber rtabs performed when new.just sayin!
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Old 05-06-2013, 10:08 AM   #80
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Yeah but you're probably also comparing your new poly bushings to your old worn out rtabs if what you are saying is your experience. you already said you don't remember how your M3 rubber rtabs performed when new.just sayin!
I don't remember well enough to make a foolproof comparison, but I do have a distant memory of how the M3+limiter setup felt as new (after all, it wasn't that long ago!), which was very good.
Can't make a real A-B comparo, but I think the poly bushings are at least as good in that regard, maybe better. And for me, I think they will last longer (I hope).

Murf
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