RTAB kit experience /recommendation

[Tom44]

Has anyone used this on their e36 M3?

https://www.bimmerworld.com/Suspension-Steering/Trailing-Arm-Bushings/E46-E36-3-Series-and-Z4-Rear-Trailing-Arm-Bearing-Kit.html

Sorting out the rear suspension and debating what route to go for a street driven car (in the NE w/ shitty roads). Could also go poly.

This is for a 95 M3, using new stock shocks & springs. No suspension mods on the car. Any other options/recommendations would be appreciated.

Thanks guys.

[Gene V]

You could go stock bushings with limiters...

https://www.bimmerworld.com/Suspension-Steering/Trailing-Arm-Bushings/E36-E46-Z4-Rear-Trailing-Arm-Bushing-Limiter-Package.html

[pbonsalb]

I think either the ball joint in the holder or the latest bushings with limiters would be great and a better choice than poly, especially for a fairly stock car. I have run poly and the updated bushings with limiters. I did not have issues with poly, though some complain of squeaks.

[blckstrm]

I've done everything.

Poly or delrin are by far the worst of both worlds. Both the ball joints and stock are better from an NVH perspective, and the ball joints are more controlled than the plastics.

If you run 0 toe, get the ball joints since they'll keep you right at 0 even under load. If you don't, get the limiters and use the factory bushings.

[tjm3]

How are the condition of the RTAB mounting points? If the condition of your daily driving roads is not so good then you may want the stock bushings (with the limiters) in there to absorb some of that road shock.

[blckstrm]

How are the condition of the RTAB mounting points? If the condition of your daily driving roads is not so good then you may want the stock bushings (with the limiters) in there to absorb some of that road shock.

This is a great point and reminds me:

If you DO decide on the ball joints, you'll 100% want to reinforce the RTAB pockets unless you enjoy expensive and difficult body repairs.

[Tom44]

This is a great point and reminds me:

If you DO decide on the ball joints, you'll 100% want to reinforce the RTAB pockets unless you enjoy expensive and difficult body repairs.

RTAB mounting points are good
Also thinking of just doing the ball joints while I’m in there.

I’d like to avoid the RTAB pocket reinforcement welding if possible, at least for now. Again, car won’t be tracked and rear subframe is in good shape.

[aeronaut]

For street driven without pocket reinforcements, I'd go OEM with limiters.
They are perfectly fine for a street car, and even a moderately modified track car.

[golgo13]

Seems like a bit much for a street car, but it's not my money. :)

Getting the limiters are more than enough for your needs IMO.

[blckstrm]

RTAB mounting points are good
Also thinking of just doing the ball joints while I’m in there.

I’d like to avoid the RTAB pocket reinforcement welding if possible, at least for now. Again, car won’t be tracked and rear subframe is in good shape.

If you don't want to do the reinforcements, you've got your answer. I'd stick with factory + limiters. I wouldn't do either ball joints or poly / delrin without the pockets reinforced. This isn't about the roads so much as the driving you do. The RTAB absorbs the fore / aft shock of both all acceleration and the rear half of the braking.

But yeah, in my experience the ball joints are neglected too often. They've almost certainly never been done, and they'll tighten the rear end up considerably.

[Tom44]

If you don't want to do the reinforcements, you've got your answer. I'd stick with factory + limiters. I wouldn't do either ball joints or poly / delrin without the pockets reinforced. This isn't about the roads so much as the driving you do. The RTAB absorbs the fore / aft shock of both all acceleration and the rear half of the braking.

But yeah, in my experience the ball joints are neglected too often. They've almost certainly never been done, and they'll tighten the rear end up considerably.

To clarify, I’m assuming I’d only need to do the RTAB pocket reinforcement if I’m going to upgrade the RTA ball joints and Bushings.
If I’m refreshing the old joints with OEM Bmw/Lemfoerder and doing the Factory+ limiters for the bushing am I good to go without welding in the RTAB pocket reinforcements?

Plan is to tackle the reinforcement next year. Trying not to drop another $400-$500 for welding to stay on budget for suspension refresh.

[Steve1998]

I often see people recommending polyurethane for various bushings on this forum. I do not understand why. Poly is garbage in every application. Poly should never be used, and most especially not in the trailing arm. The only benefit is ease of installation.

Stock is the way to go for a street car. Just make sure you preload the bushing correctly. Reinforcement is not needed for a street car. You should do the ball joints too, and can get a whole trailing arm service kit for something like $150. It is an easy job with the proper tools.

[aeronaut]

Poly is "ok" as the FCAB. And fine for drive-line mounts. Neither without compromise.
But I agree, for a mostly stock street car, quality OEM everywhere is perfectly fine and good and healthy.

[pbonsalb]

If I’m refreshing the old joints with OEM Bmw/Lemfoerder and doing the Factory+ limiters for the bushing am I good to go without welding in the RTAB pocket reinforcements?

Plan is to tackle the reinforcement next year. Trying not to drop another $400-$500 for welding to stay on budget for suspension refresh.

Maybe, maybe not. I think the various reinforcements available for these cars are a good idea even on a stock car. Especially now that all E36 are 23-30 years old.

[scoobiedoo2029]

i think the biggest issue with the traing arm mount points is bolt torque on the 3 bolts from body to carrier/arm. there speced at like 40 ft lbs and are and 18mm bolt, its 1mm larger then a lug bolt and like half the torque. the bungs theise bolts go into are just tack welded into the body. you could easly spin one of theise bungs out of the chassis with an air gun.

a seized bolt might even be enough that releasing it might crack one of the tiny little tack welds. or an alignment "tech" with a 4 foot cheater pipe on a rachet....

[blckstrm]

Seriously - to both of the above. Which is both a good reason to do the reinforcements and to do your own work.

[JARblue]

Know a good welder in the area that'll do the reinforcement in my garage with the M3 on jack stands? Both of my rear trailing arms are out and the car won't be going anywhere for a while.

[QtheGenius]

You could go stock bushings with limiters...

https://www.bimmerworld.com/Suspension-Steering/Trailing-Arm-Bushings/E36-E46-Z4-Rear-Trailing-Arm-Bushing-Limiter-Package.html

This. I've done this years ago, and it's a best if you plan on daily or even weekly driving.

[blckstrm]

I don't. I had mine done at a shop and wasn't very pleased with the work (lol - see my comment above!). But I doubt if they'd make house calls anyway.

[Steve1998]

For those bushings that see less movement maybe, but the RTAB is certainly the last place you want poly. There is a great thread on the VW forum that explains it.

The bolts are actually 57 ft-lbs. Granted, the advanced age of these is one factor that would make me think about reinforcement. But look at all of them out there. Nine out of ten or more probably do not have that reinforcement.

You do not hear about this failure often. It is not nearly as widespread as E46 RACP/subframe failure, for example. That leads me to believe it is not necessarily an inevitable design flaw, but a symptom of pushing the car beyond what it was designed to do on the track.

[RBNetEngr]

Has anyone used this on their e36 M3?

https://www.bimmerworld.com/Suspension-Steering/Trailing-Arm-Bushings/E46-E36-3-Series-and-Z4-Rear-Trailing-Arm-Bearing-Kit.html

Sorting out the rear suspension and debating what route to go for a street driven car (in the NE w/ shitty roads). Could also go poly.

This is for a 95 M3, using new stock shocks & springs. No suspension mods on the car. Any other options/recommendations would be appreciated.

Thanks guys.

I put these exact RTABs in my ‘95. There was no increase in noise, or any stiffer response to bumps. They are really an excellent replacement for the stock rubber RTAB bushings. They allow full articulation of the trailing arm. Rubber and poly RTAB bushings allow for articulation as well, but by flexing and distorting the rubber or poly bushing. Over time, this is what causes the RTAB to crack.

Once the black mounts are pressed into the RTAB (tight fit!), the end caps screw on, and the caps can be removed to easily replace the spherical bushing in the future.

Another nice thing about these spherical RTABs is that you don’t need to tighten the carrier bolt with the carrier aligned at a specific angle, to avoid RTAB bushing pre-loading. Just bolt the carrier onto the trailing arm, then rotate it into position to re-attach it to the chassis.


-rb

[Tom44]

I put these exact RTABs in my ‘95. There was no increase in noise, or any stiffer response to bumps. They are really an excellent replacement for the stock rubber RTAB bushings. They allow full articulation of the trailing arm. Rubber and poly RTAB bushings allow for articulation as well, but by flexing and distorting the rubber or poly bushing. Over time, this is what causes the RTAB to crack.

Once the black mounts are pressed into the RTAB (tight fit!), the end caps screw on, and the caps can be removed to easily replace the spherical bushing in the future.

Another nice thing about these spherical RTABs is that you don’t need to tighten the carrier bolt with the carrier aligned at a specific angle, to avoid RTAB bushing pre-loading. Just bolt the carrier onto the trailing arm, then rotate it into position to re-attach it to the chassis.


-rb

This is the reason the Bimmerworld kit was recommended by my repair shop.