Why not use bushing grease on a-arm bushings? Options

[Tdskip]

Hi guys - I know how it is commonly done including Ian’s great video. Is there a reason why not to use bushing grease instead of softsoap?

So you want the bushing NOT to move or rotate ones installed? I assume that is a reason but wanted to ask.

Thanks.

[Chi-town]

petroleum based greases will degrade rubber

[914werke]

An alternate to soap would be Glycerin

[Tdskip]

Hi guys - happy Saturday.

What about standard silicon based bushing grease?

[IronHillRestorations]

KY works great on factory rubber bushings

[bbrock]

The press fit of the original rubber bushings is so tight that I think those bushings are intended to act as rubber springs rather than a bearings.

The factory manual calls for "glycerine paste" on sway bar bushings. I substituted silicone grease since glycerine paste seems be a thing of the past.

[Tdskip]

The press fit of the original rubber bushings is so tight that I think those bushings are intended to act as rubber springs rather than a bearings.

The factory manual calls for "glycerine paste" on sway bar bushings. I substituted silicone grease since glycerine paste seems be a thing of the past.

Good morning and thanks all.

@bbrock - bingo, exactly what I was wondering. Doing mental gymnastics on if easier motion helps ride and handling or would make it sloppy and under damped.

[jmitro]

So you want the bushing NOT to move or rotate ones installed? I assume that is a reason but wanted to ask.

Thanks.

correct. with rubber bushings it's the twisting effect of the bushing that allows rotation. with bearings it's different. hence the reason for soap because it will dry out.

[Superhawk996]

So you want the bushing NOT to move or rotate ones installed? I assume that is a reason but wanted to ask.

Thanks.

correct. with rubber bushings it's the twisting effect of the bushing that allows rotation. with bearings it's different. hence the reason for soap because it will dry out.

@JMitro is correct. Bushing are intended to operate in shear (twisting inside of bushing vs. out side of bushing) and compression only. Rubber has very little tensile strength.

Allowing rotation between the bushing and the A-Arm will simply chafe away the rubber in no time.

Same is true of the rear control arm bushings unless go you to a solid bushing like Poly or Delrin in which case those materials will withstand rotation between the parts.

You want the water to evaporate and leave the surafaces with high friction between ID and OD.

water based lubricants only:
Soap & water
KY Jelly
Astroglide
Tire bead lubricant can be used in a pinch if the glycerin and water solutions don't work. I rarely have had to resort to this. Get a small dallop from your local tire shop or corner garage that mounts tires.

[Tdskip]

Great discussion, thanks

[Chi-town]

Or just use a quality poly bushing like Powerflex and let the torsion bar be the spring and not the bushings

[Superhawk996]

Or just use a quality poly bushing like Powerflex and let the torsion bar be the spring and not the bushings

The rubber bushing is there for isolation from road noise and road & impact harshness.

The bushing isn't there to be a spring. The "spring" effect of the bushing as measured in lbs force to rotate the A-arm per inch of wheel travel is trivial as compared to the spring rate of the torsion bar. What you esentially have is two springs in series. The lower rate "spring" (i.e. the bushing torsional rate) response is dominated by the higher rate torsion bar.

Poly bushings are a viable option for many reasons - particularly when racing to take compliance (deflection)and therefore steering resonse delays out of the vehicle. While this is great for track use, it will degrade noise and will lead to a bumpier, harsher ride quality. Likewise hard core racers go for a spherical heim joints to eliminate even the compliance that is present in a Poly bushing.

Some folks find that a switch to poly bushings makes the car less enjoyable on the street.

Evaluate what you want the vehicle to be used for, then choose accordingly.

[Tdskip]

Well - tried the URO bushings and they kept deforming even after following their directions in the YouTube video. Used lots of softsoap too....

[Superhawk996]

Well - tried the URO bushings and they kept deforming even after following their directions in the YouTube video. Used lots of softsoap too....

What setup are you using a hydraulic press or the threaded rod method?

Are you getting a straight press force? Any cocking / tipping will work against you. Have you powdercoated your A-Arms or bushing carriers with a "thick" coating. Just a few thousands of extra coating can create a really hard press fit (as if it wasn't hard anyway!)

Also check out the 914 Rubber video. Their way of boiling the busing with the carrier on it will help hold some heat in the rubber for an extended time and will allow a little more pliability.

http://www.914world.com/bbs2/index.php?showtopic=325834

[Tdskip]

@Superhawk996 - thanks for the detailed response.

I am using a press, did try to make sure the pressure was even. No coating on the assume, just cleaned and exterior surfaces painted (not where the bushing goes). I will double check there isn’t anything snagging the bushing but don’t think so. Details matter so will double check everything.

Thanks!

[bbrock]

Well - tried the URO bushings and they kept deforming even after following their directions in the YouTube video. Used lots of softsoap too....

URO bushings are purposely made a little undersized for easier installation, but don't make a good OE replacement from what I've read. Elephant Racing and 914Rubber make rubber bushings said to match OE. I went with the 914Rubber bushings but have not driven on them yet. If there isn't a copious amount of cussing involved in the installation, they aren't OE matched bushings. (IMG:style_emoticons/default/smile.gif)

[Chi-town]

When a rubber bushing binds it acts as just like the torsion bar. You can measure the force that it takes to move the arm away from the static point. It may not be a lot but it is measurable.

The stock rubber compressed as much as it is it's not doing a lot of isolation anyway. Most notice a difference of poly coming from wasted 40 year old stuck bushings.

There are a ton of different poly compounds. When you do the research you end up with a bushing that isolates nvh from the chassis and doesn't deflect. It also doesn't bind like the rubber stock units.

If I let you drive my 75 with Powerflex bushings in it and didn't tell you all that you would notice is how precise the steering / handling was. (IMG:style_emoticons/default/laugh.gif)

[Mikey914]

The OEM are intended to set a zero preload on the arm. At neutral they have a minimal load. As they are deflected they help to provide a load to return to neutral. The Elephant video was showing the URO spinning in the mount. Effectively providing no load to bring back to neutral.

If this was the intended design it would have been made with a bearings.

[jmitro]

It also doesn't bind like the rubber stock units.

If I let you drive my 75 with Powerflex bushings in it and didn't tell you all that you would notice is how precise the steering / handling was. (IMG:style_emoticons/default/laugh.gif)

you must really like your poly bushings. (IMG:style_emoticons/default/wink.gif)
when the poly bushings bind you have the worst of both worlds. Hence why poly isn't that popular.
My stock suspension enjoys the rubber bushings (IMG:style_emoticons/default/biggrin.gif)

[Chi-town]

If you get a Powerflex bushing to bind you have done something seriously wrong (IMG:style_emoticons/default/laugh.gif)

@mikey914 that's just it, they are never at 0 preload. If every car was exactly the same weight and at the same height for the life of the car this could be true. But variation in weight (empty vs full fuel tank) and height adjustment means they are always preloaded in some direction.

The torsion bar doesn't need a return force by nature they create it when twisted.

The rubber bushings are a classic "cost vs performance vs comfort" production car compromise.

Race cars use pillow ball, spherical or delrin (or similar materials) for bushings not poly unless some special need arises.

Bushing technology has come a long way since the rock hard Weltmeister poly bushings of the 80's and a whole lot further than the rubber compounds used in the 60's and 70's.

If you're doing a "correct" restoration sure use rubber
If you drive your car and want the best handling with little to no change in nvh there are better options available.