Urethane Upgrades

[Aptyp]

When you get yours, take the race and measure these for us...

This way we can see how much AKG one moves.


^this is a bad pic of K-macs, but adjustment looks to be at the most outer edge, where in AKG, it looks like adjustment hole is still very close to the center.

And K-macs are urethane.


Personally, I am not a fan of either adjustable bushing (AKG or K-Mac), because of the time it takes to dial in camber and toe. When you adjust 1 bushing, you're adjusting both camber and toe, instead of adjusting one or the other first. What I'm trying to say is: you have to set toe and camber simultaneously, as when you're adjusting one, you adjusting the other.

[guibo09]

yes, the adjustment is more difficult. but with a good system and understanding, you can achieve good results.

there doesnt seem to be a single good solution for alignment adjustability on semi trailing arms. i dont like the weld-in adjusters because of the binding that they cause. at least the eccentric bushings always keep the inner races on the same axis.

[Aptyp]

I got weld-ins :D. $400 I'll forever miss, but adjustments are easy and I don't know what binding you speak of.

[guibo09]

I got weld-ins :D. $400 I'll forever miss, but adjustments are easy and I don't know what binding you speak of.

in theory, there is binding. in practise, i imagine it may be negligeable, depending on how soft your bushings are.

just visualise it in your head. in stock form, both inner races of the outer and inner pivots are on the same axis. when you use the weld-ins, you actually push the inner races away from the axis in different directions. this offsetting forces the bushings to twist and torque, and cause binding.

if for example, your RTABS were solid (ie aluminium), you wouldnt be able to articulate your suspension anymore. with weld-ins, your setup needs some give to it, that give comes at the expense of bushing wear, squeeking and binding.

[Aptyp]

same happens with AKG and K-macs...

the thing is, when you set toe and camber, your bushing SHOULD be taking all the torquing and twisting, and that's why TABs must have a little give. Korman urethane TABs do the trick. Korman runs that setup on race cars, and some of their cars spend lifetimes on the track. I tend to not argue with what works, and works well.


Now to clarify, I ran AKG with standard setup, no adjustments. Would be unfair to judge them otherwise.

[guibo09]

same happens with AKG and K-macs...

the thing is, when you set toe and camber, your bushing SHOULD be taking all the torquing and twisting, and that's why TABs must have a little give. Korman urethane TABs do the trick. Korman runs that setup on race cars, and some of their cars spend lifetimes on the track. I tend to not argue with what works, and works well.


Now to clarify, I ran AKG with standard setup, no adjustments. Would be unfair to judge them otherwise.

yes, there is still some binding with eccentrics, but it is different, and not as much. (you also have less adjustment).

i assume when you mean urethane, you mean softer poly? vs AKG which you dont consider as urethane for some reason? it's all urethane, just different durometer hardness.


edit: oh, and the eccentrics also dont play with the roll center like the weld-ins do.

[Aptyp]

well, technically, they are all polyurethane... and difference is not only in hardness, there are tons of different compounds that are polyurethanes.


The reason I draw a difference, is because "urethane" in suspension world tends to refer to a certain kind of polyurethane. Same as used by nearly every company in different hardness for different purposes. AKG uses a different polyurethane, and that's what makes them special.

[Aptyp]

Shock Mounts
ADDED 3.23.09

So this is the weakest point of e30 suspension. Stock mounts don't need 20 years to be destroyed, few of my friends were very successful destroying stock ones in matter of months. Beauty of stock ones, though, is that they are rubber and allow movement of shock with the trailing arm. Choices here are abundant, Turner Motorsports and Bimmer World sell 5 different kinds (6 if counting stock) each.

Pointless mentioning all contenders, as every vendor claims them to be their own, so we'll go by design, but I must add purpose to the rating.

__________________________________________________ ____________

1. JTD Design: the most inexpensive solution, and is actually a solution. Not the best performance optionr high performance driving and nothing much to look at, but it's the best replacement to original shock mounts. Apparently some places sell them with life time warranty.
Purpose: :):) Street, Daily Driving
Quality: :):):)
Price: :):):):):)

$40.00 :D:D:D+
__________________________________________________ ____________

2. HD OEM: definite attempt to repent, and not even by BMW. These ones are an alright substitution to stock shock mounts, but even these fail after a while. Allows great movement and wouldn't destroy
Purpose: :):)
Quality: :):)
Price: :):):)

$60.00 :D:D-
__________________________________________________ ____________

3. Ireland Engineering Urethane RSM: good choice for the money. I must tell you, that IE picture look much better than actual product, but actual product come with everything in the picture. It is definitely a bang for the buck, and when installed right, it allows shock to move the same way stock mount would. It comes with reinforcement for shock tower. This is the best bang for your buck in this category.
Purpose: :):):):)
Quality: :):):):)
Price: :):):):):)

$75.00 :D:D:D:D+
__________________________________________________ ____________

4. Ground Control RSM: great design, great performance. Design-wise, it's the same thing as a lot of other ones are, but it has a name "Ground Control" on it and in pretty GC color.
Purpose: :):):):)
Quality: :):):):):)
Price: :):):)

$97.00 :D:D:D:D
__________________________________________________ ____________

5. Turner Motorsport Urethane RSM: same thing as GC pretty much. Doesn't have the name, but oh so pretty.
Purpose: :):):):)
Quality: :):):):):)
Price: :):):)

$99.95 :D:D:D:D
__________________________________________________ ____________

6. AKG Polyurethane RSM: here's one product I endorse made by them. Material they use suddenly seems perfect for this purpose and they got design just right. It's very close in design of IE, but hemispherical bushings really do the trick.
Purpose: :):):):):)
Quality: :):):):)
Price: :):):):)

$100.00 :D:D:D:D+
__________________________________________________ ____________

Well this is it without getting into spherical/bearing designs, but then we're talking about whole different price market, and purpose better be racing. I currently run IE ones, and have run them on my last three cars, but if it wasn't for buying some other parts from IE, and getting it all shipped at once, I would be driving on TMS or AKG ones for sure.

[E30Eric]

I have the e30 m3 cabs and love them. After doing poly bushings on my integra, I will never use them again! Squeaked like a MOFO! Rubber or Delrin FTW!

[nando]

you forgot TCkline. :p

[Aptyp]

you forgot TCkline. :p

of course I didn't :)

They are same as something else on the list, prettier color though. Design-wise it's the same thing as GC and TMS, but with it's own styling package.

TC is a great guy to get parts from, not to mention he does amazing work

[StereoInstaller1]

Seems to me (back to the CAB rant) that the softer "street" version wasn't mentioned.

I lubed mine 2 years ago, still no squeaks.

Gonna do TABs soon, planning on the eccentric adjustable kit using BMW bolts (E39?) and still not sure which TABs to use.

I think I want urethane and I have no issues drilling and using zerk fittings.

Marine grease FTW!

Luke

[nando]

of course I didn't :)

They are same as something else on the list, prettier color though. Design-wise it's the same thing as GC and TMS, but with it's own styling package.

TC is a great guy to get parts from, not to mention he does amazing work

it looks similar, but don't GC and TMS use urethane inserts? the TCK insert is a special rubber.

[Mtriple]

Great thread Aptyp, I've had a few different setups and all I can pass on is that if you want a very nice, quiet, compliant setup for the street and track; Powerflex is the way to go. I'm running the FCAB's, RTAB's, and Sub frame bushings on my current car. No complaints here...

[Aptyp]

it looks similar, but don't GC and TMS use urethane inserts? the TCK insert is a special rubber.

I never got a chance to look at TCs, but from pics, material looks exact same as TMS.