Spring rate from rubber bushings?

[safe]

Hi
I'm upgrading my car with right now with ER polybronze front and rear and 21/27mm t-bar setup. Shocks are 1 year old Bilstein HD in the rear and 10 year old, but good, Boge in the front.

I got everything installed, but not setup with correct ride hight etc yet.

The rear 27mm should be ~90% stiffer than my original bars, but when I push down on the cars bumper I dont think its much different than stock.

When I put my 230 lbs on the bumper in the rear it feels softer than when I do the same in the front.

Am I fooling myself?

How much spring rate were the old rubber bushings supplying?

[Wil Ferch]

Let me *try* to answer this.....

My completely unscientific guess answer.... rubber bushing twist adds next to nothing. Why?

In the spring plate angle calculator that I worked up ( math process)...and that Thom Fitzpatrick re-did into a slick plug-n-jug software package.....feedback from people say that it works fairly accurately in determining new ride height.

It wouldn't be accurate if the "installed" spring rate of the rubber bushings "twisting" would add a meaningful amount of resistance.

- Wil

[Chuck Moreland]

I think your hands might be a bit out of calibration

If the tbars you are replacing were stock, then you will definitely feel the difference when you drive it.

[safe]

Thanks Will, that makes perfect sense.

The spring plate calculator worked like a charm btw. I got 22-23 degrees out of it and I set my spring plates to 23 and it was almost spot on!

[safe]

Originally posted by Chuck Moreland
I think your hands might be a bit out of calibration

If the tbars you are replacing were stock, then you will definitely feel the difference when you drive it.

They must be

I'm dying to get the car out on the road and try out the new bushings!

I'll just have to find a reassembly flat floor to set my ride height, camber, toe etc. My garage floor is cracked due to frost damage.

I have some trouble getting my 205/50 on 7" fuchs clearing my fender lips (narrow body), even with a lot of camber. I might have to set it a little higher.
Its hard to tell how much clearence that is needed between lip and tire...

[Thrasher]

Safe, my garage floor was also cracked. I used a water level (just a tube filled with water and measured height at both ends) and a stack of cheap vinyl/VCT tiles from the home supply store.

Chalk outline each wheel where you'd like to do the work. Determine which corner is highest using the water level. Just keep adding tiles to the stack at each corner until the other 3 are level with the first (side-side level is most important).

I ended up leaving my front tiles in place because now whenever I pull into the garage, I can feel the front tires roll onto them, assuring I park in the same position everytime.

Craig

[safe]

I'll try out that water trick.