BMW NCCCCA Member #485873
Im using BimmerWorld sourced RTABs been in for about 2 weeks now. Replaced along with my rear wheel bearings.
Did not notice any noise or vibration increase [although my old RTAB's were shot, and my wheel bearings noisy]
I would say unless you're very very sensitive these red RTABs' will not increase the NVH very much at all. I actually feel they increase the lateral stiffness, as my car sets up very nice in turns and hold the line very well. Granted, when I purchased this car the entire suspension was 'shot' so I do not have the best gauge of how it 'should' feel. I have replaced the entire suspension including FCAB, Control Arms, end links, tie rods, rack bushings, RTAB's were the last thing on the list [I have 1 slightly bad Front wheel bearing getting swapped out]
So in short, yes the Poly RTABs seem to be legit and a pretty painless upgrade. They went in much easier than the OEM part would.
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Do the poly bushings. I love mine compared to the rubber I have up front (will switch them next time as well). They do creak over speed bumps, there is an increase in nvh.
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Ireland Engineering said their urethane RTAB kits have a hardness of 70 and the rubber OEM parts are 60.
The urethane also have more material to compress as there is no metal "sleeve" either.
I ordered up a set to install this weekend.
Mine had separated and the outer bushing no longer had any connection to the inner sleeve on either side.
This effectively made the car have 4 wheel steering (in the worst way) and any lane transition or Bots dots would cause the car to dart 1/2 a lane on the freeway if you were not ready to immediately compensate.
It was basically un-drivable.
A true irritation was that TWO alignment shops inspected it and were unable to diagnose the RTAB as the cause of the problem...
trusted1
1998 318ti MSport W/DASC
1988 E30 M3
1997 M3/4
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I just replaced my 20 year old RTABs yesterday with M3 rubber bushings and limiters (tight fit!). Anyways, I really fretted and struggled with this. I followed these steps. However, marking a line on the rotor didn't make sense to me after I marked mine. Here's the problem I see- everytime you lower the control arm to get access to the carrier bolt to tighten it, it changes the angle of the carrier to the rotor. This is what I noticed with trying to align it with the hub. You can move the trailing arm and it changes the angle significantly without changing the angle of the rotor. Does that make sense?Originally Posted by bluptgm3
My solution was to use a 90 degree straight edge and make a mark on the mid part of the control arm in relation to the carrier bracket while the wheel was pre-loaded as described above. This way it doesn't matter what angle the control arm is at when you align the carrier and torque it down. Another way to check it is to mark the location of the carrier on the control arm when you remove it. If you are confident that the bushing you're replacing was properly pre-loaded (or de-pre-loaded) when originally installed then this is the easiest and quickest way to get it aligned properly. MANY DIYs I read on this procedure don't mention this at all (I think mostly because people default to installing the "easy" solution of polyurethane).
Anyways, just wanted to throw my 2 cents in. BTW, buy the specialty removal / install tool. I wish I would've and then sold it after I was done. Uggh
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Rotate the arm and rotate the rotor to align the RTAB body bracket to the mark on the rotor....this corrects the misalignment you have found (I believe I addressed this) ...or go to ECS Tuning and buy the BMW RTAB Alignment tool p/n 83300493688.
Last edited by bluptgm3; 11-03-2020 at 06:43 PM.
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This is what I did with the arm off the car. The purpose of the straight edge is to mimic the preload angle of the rtab console with the control arm off the car. It also allows you to get a torque wrench on the bolt which wouldn't be easy with the arm still mounted. Once the console is locked down at the correct angle and torqued to spec, you can mount on the car and not worry about premature wear of the bushings once the car is lowered to ride height. The tool makes this easy, but the straight edge is cheap and just as effective.
Untitled by Twistytee, on Flickr
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This is very close but I believe the original alignment tool keeps the center wheel point 8mm below the console line.
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Is this necessary with a stock suspension and RTAB's
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Yes incorrectly oriented Body Bracket relative to the RTA will apply excessive torsional preload on the RTAB bushing material, resulting in failure.
While the ride height of standard E36 and E36 Sport (M3) suspension ride height is documented and different, there appears to only one offset value/BMW orientation tool (83300493688) for location the Body Bracket. I am willing to speculate that the rotational orientation is a little soft.
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Last edited by bluptgm3; 11-22-2020 at 07:23 PM.
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Special tools and parts.
betta fish life span in a bowl
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Those that do not want to worry about preloading the crappy stock rubber bushings should just get poly bushings. Just found these on Amazon at a good price:
https://www.amazon.com/Rear-Trailing.../dp/B00KH4WDOU
Attn. NEWBIES: Use the search feature, 98% has already been discussed.
Click the search button, select "search single content type", select the "e36 sub forum" specifically, try the "search titles" then try the "search entire posts".
Member
The Rear Trailing Arm pivot joint is multi-axis, the use of single axis poly/Delron is at your own risk.
The ‘crappy stock rubber bushings’ with Toe Limiters alleviate failures considerably.
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Last edited by bluptgm3; 11-22-2020 at 03:34 PM.
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The poly are not single axis because they have limiters built in.
Been using them for 10yrs with zero issues.
Attn. NEWBIES: Use the search feature, 98% has already been discussed.
Click the search button, select "search single content type", select the "e36 sub forum" specifically, try the "search titles" then try the "search entire posts".
Member
Poly are single axis because they do not deflect like rubber. The swing of the RTA is not about a single axis.
The change of rotational axis of the RTA is driven by the two arcs described by the upper lateral control arm and the lower lateral control arm. They have different lengths and swing about different offset centers, adding camber as the suspension is compressed.
Even with poly/Delron/aluminum Toe Limiters, the rubber based RTAB is able to accommodate this change in axis internally.
https://www.bimmerforums.com/forum/s...ngs-Yay-or-nay
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Last edited by bluptgm3; 11-22-2020 at 05:45 PM.
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