Subframe mounts - OEM or Poly?
- BladeRunner919
- Joined: Fri 17 Feb, 2012 20:18
- Posts: 2225
Subframe mounts - OEM or Poly?
Any opinions on Powerflex vs OEM for the subframe mounts on a Z3?
Re: Subframe mounts - OEM or Poly?
Read a lot of good things about them, haven't tried them myself, be good to hear from those that have them installed.
Sent from my HTC Desire
Sent from my HTC Desire
Re: Subframe mounts - OEM or Poly?
Personally I would stay with OEM, reason being I have known failures that have occured using Poly bushes which (may have) caused a strut rod to fail (not on a BMW) due to the restricted movement using Poly over Rubber OEM bushes.
I have no proof just incase those Techie Engineers here wish to slam my personal thoughts on the subject
I have no proof just incase those Techie Engineers here wish to slam my personal thoughts on the subject
Gazza
"Understeer is when you hit the wall with the front of the car, oversteer is when you hit the wall with the rear of the car. Horsepower is how fast you hit the wall and torque is how far you take the wall with you"
Z3 S54 M roadster , BMW Z1, BMW M3 CSL, Z4M Coupe
"Understeer is when you hit the wall with the front of the car, oversteer is when you hit the wall with the rear of the car. Horsepower is how fast you hit the wall and torque is how far you take the wall with you"
Z3 S54 M roadster , BMW Z1, BMW M3 CSL, Z4M Coupe
Re: Subframe mounts - OEM or Poly?
I tend to agree with Gazza I would stick to OEM standard for a normal road car. The rear OE bushes are not a known fault area like the front wishbone (rear) bushes. They are therefore, a known quantity and have served their purpose well for 10+ years. I have picked up a lot of feedback that Poly ones can provide a harsh and squeaky ride when fitted at the back – the squeakiness is only addressed by applying certain lubricant.
- BladeRunner919
- Joined: Fri 17 Feb, 2012 20:18
- Posts: 2225
Re: Subframe mounts - OEM or Poly?
I thought the squeaking was the trailing arm bushes, which do undergo a rotational movement. The subframe mounts shouldn't squeak. The reasons for thinking Powerflex are that they will be easier to install, plus the oem ones have two voids in them (which some people plug with plastic inserts) so can give some movement.
The main reason is the ease, however, as I'm not planning on racing the car and it is only a 1.9 after all.
The main reason is the ease, however, as I'm not planning on racing the car and it is only a 1.9 after all.
Re: Subframe mounts - OEM or Poly?
I believe the plastic inserts are to take up the slack in an old bush, Mike Fishwick did a DIY insert install.BladeRunner919 wrote:I thought the squeaking was the trailing arm bushes, which do undergo a rotational movement. The subframe mounts shouldn't squeak. The reasons for thinking Powerflex are that they will be easier to install, plus the oem ones have two voids in them (which some people plug with plastic inserts) so can give some movement.
The main reason is the ease, however, as I'm not planning on racing the car and it is only a 1.9 after all.
Gazza
"Understeer is when you hit the wall with the front of the car, oversteer is when you hit the wall with the rear of the car. Horsepower is how fast you hit the wall and torque is how far you take the wall with you"
Z3 S54 M roadster , BMW Z1, BMW M3 CSL, Z4M Coupe
"Understeer is when you hit the wall with the front of the car, oversteer is when you hit the wall with the rear of the car. Horsepower is how fast you hit the wall and torque is how far you take the wall with you"
Z3 S54 M roadster , BMW Z1, BMW M3 CSL, Z4M Coupe
Re: Subframe mounts - OEM or Poly?
If you get chance to change the bushes I recommend you do it. You will notice a more stable and predictable rear suspension response. The fact that your car is a 1.9 doesnt come into it. The subframe bushes dont squeek - that is associated with poly trailing arm bushes, as you say.
Z3M with a few mods...and a little bit more power
Re: Subframe mounts - OEM or Poly?
+1. I have these from Ireland engineeringDeano1712 wrote:If you get chance to change the bushes I recommend you do it. You will notice a more stable and predictable rear suspension response. The fact that your car is a 1.9 doesnt come into it. The subframe bushes dont squeek - that is associated with poly trailing arm bushes, as you say.
Big improvement.
2001 M roadster S54 Laguna Seca Blue
Re: Subframe mounts - OEM or Poly?
Actually, the one area I think you need to keep OEM is the bush in the diff mount. it is the movement of that bush that does most of the boot floor damage and a stiffer bush there will only maker it worse.
The stiffer subframe bushes actually help reduce boot floor damage by preventing the subframe from moving around or twisting as much. The grooves you see on the Ireland bush above just allow it to slide into the subframe. There are 4 locating domes in the subframe recess. Other than that it down not move much at all, but due to the urethane does 'give' a bit.
IMO bush choices should be as follows
Front radius arm (lollipop) = new OEM, but from the ///M on all models
Front ARB mounts = Urethane
Rear ARB mounts = Urethane
Rear Subframe mounts = Urethane
Diff mount = OEM
Rear trailing arm bushes = new OEM
The stiffer subframe bushes actually help reduce boot floor damage by preventing the subframe from moving around or twisting as much. The grooves you see on the Ireland bush above just allow it to slide into the subframe. There are 4 locating domes in the subframe recess. Other than that it down not move much at all, but due to the urethane does 'give' a bit.
IMO bush choices should be as follows
Front radius arm (lollipop) = new OEM, but from the ///M on all models
Front ARB mounts = Urethane
Rear ARB mounts = Urethane
Rear Subframe mounts = Urethane
Diff mount = OEM
Rear trailing arm bushes = new OEM
2001 M roadster S54 Laguna Seca Blue