Urethane FILLED Subframe bushings

[Russell]

Well, I drove to work (30 miles of smooth city streets and undulating two lane roads) this morning after filling the subframe bushings with Windo-Weld urethane.

Note: I did not move the car for 3 days to facilitate curing. However, I am not sure the urethane has completely cured. Even so, subjectively I feel a “change” via the butt-meter. The car did not thump (in the rear) over bumps, seem tighter and had a bit better directional control (wandered less). It seem especially more stable when changing lanes or cornering. Seemed more planted. I did not notice any increase ride harshness, perhaps even less harshness. I think this is the desired goal.

Now, how long will it last???? If and when they fail, I will have my Indy install new bushings. I think I will replace the rear struts before replacing the subframe bushings. Hey- it never stops.


Below is the old bushing cleaned up with acetone before filling. Notice the cracks and possible separation especially just below the bolt..

[Russell]

Wandering is reduced. Cornering is different. Very little if any corrections needed as you corner. It used to be that a big correction was needed after starting a sweeping corner until the bushings (or something settled) settled. Turn in feels quicker...

Only one potential issue. Per my samples not all the urethane has cured even after over four days of setting in my cold garage. The center core is still uncured. Do this in warm weather! I suspect this will be a bit firmer after all material is cured. Even when cured, it is very firm and elastic. Very pleased.

However, I have found it interesting there seems to be limited interest in this process.

[Dash01]

Wandering is reduced. Cornering is different. Very little if any corrections needed as you corner. It used to be that a big correction was needed after starting a sweeping corner until the bushings (or something settled) settled. Turn in feels quicker...

Only one potential issue. Per my samples not all the urethane has cured even after over four days of setting in my cold garage. The center core is still uncured. Do this in warm weather! I suspect this will be a bit firmer after all material is cured. Even when cured, it is very firm and elastic. Very pleased.

However, I have found it interesting there seems to be limited interest in this process.

If you have a trouble lamp/work light, why not set it right next to the uncured stuff to add some heat: By tomorrow morn, it should be cured.

[Russell]

Good idea but my trouble lights are flourescent-not much heat. I did use a 1500 watt ceramic heater for about 30 minutes a side to get the bushings hot to the touch on Monday while I was around to check on it I am sure that helped the curing process a bit. Thanks.

[Russell]

Performace properties of Windo-weld for those interested.

Data is from 3M document Library data sheet. I believe this material is softer than some of the pourable poly urethanes some have used.

Tensile: 1200 PSI
Elongation: 700%
Hardness (Shore A) 55-60
Overlap shear strength (50% RH, 75 degree FH)
6 hours 65 PSI
48 hours 500 PSI

[525ikicker]

im very intrested in the bushing idea.... i have looked at prices for new subframebushings from racingking and for the price i think its worth the try for urethane bushings.... now the question is how long will the bushing last?
i hope for longer than 2k miles, if they do i will consider trying this.
real cool


justin

90
525i
m20
w/106k

[Dash01]

[QUOTE=Russell]Performace properties of Windo-weld for those interested...
/QUOTE]

What's your take on the stuff now, after it's had awhile to cure?

[Russell]

directional stability is much improved going through curves as it stays where pointed. Straight line wandering seems to have improved slightly. I think it rides just a bit stiffer.