Another Spring Plate question

[bob hodges]

I have read the article by Wil Ferch on the math to figure the angle to adjust the spring plate on my 80SC. My question is does anyone know if the droop angle is with the trailing arm connected? I am thinking is has to be unconnected. Using the Gross weight from the door sticker gives my car's gross weight of 3219lbs. I know this is Gross weight but what should I figure for weight of the car for the sake of the formula? Last question..has anyone did this lowering task using this formula? http://vintagebus.com/cgi-bin/spring.cgi

[ckelly]

I used that formula for my 80 SC, worked perfect!! Leave the trailing arm disconnected and be patient with your torsion bar indexing, the inner splines give you about 1/2 degree or so, and the outers are more like 2-3 degrees. Try to get it right on if you can. Set the adjusters to midrange also. I used something like 2875 for my weight, right out of the owners manual. I've since weighed my car and it was pretty close to that.

Good luck.

[89911]

The spring plate drop is with the trailing arm disconnected. I think you should be using your cars curb weight and not GVW(fully loaded).

[marcesq]

Bob: Are you changing the size of the torsion bar??

[bob hodges]

Clay, 89911

Thanks for the tip...I am going for the formula...thats good info on the splines ...

[bob hodges]

Marc,

No the org torsion bars are still installed and I am measuring them at 24.1mm does that sound correct?

[marcesq]

I used a different method, so I can't help there.

My car was still at US 5 mph bumper specs when I bought it. I needed to come down 2 1/2 inchs. I disconnected the spring plate and let it fall to it's lowest point and measured the distance from the ground to lowest point of the spring plate. When I put everything back together (new bushings and set adj to middle of play) I re-indexed so that the lowest point was 2 1/2 inches HIGHER than the original measurement.

This required a few turns of the torsion bar in both directions, but when it was all buttoned up, I was a 1/4" off on one side which was easily adjusted with the plate.

[Neilk]

Wil and Thom's calculator work EXCELLENTLY. You need to disconnect the trailing arm and you might have to unscrew the botton bolt of the spring plate cover to get full droop.

My car was less than 1/4" off on one side.

[Wil Ferch]

Although Bob and I talked off-line, I would still offer that you should use actual car weight, and not gross ( laden ) weight. For my 1985 Carrera, the all up weight with gas and no driver was spot-on at 2760 lbs. I too believe the calcualtor works best with spring plate removed from the rest of the rear suspension...although I wasn't clear to Bob the last time we spoke about this.
Glad to see it works when we understand that the spring plate needs to be disconnected.
Further hint...when you look at the pocket spec books, it gives the proper droop angle for the stock TB sizes...interestingly, it says to go one degree shallower when using Bilstein shocks...an admission that they indeed raise the car a bit vs using pure hydraulic shocks.
---Wil Ferch

[BGCarrera32]

While we are on the subject, does anyone know the correct torque values for the 2 eccentrics and the securing bolts at the end of the arm (green arrows)?

I used the sticker on the door for my weight (for Wil's ride height calculator), should I be using something else? Stock 84 Carrera with 3.2....

Thanks-
BG

[Wil Ferch]

Stock 84 3.2 should be 2760 lbs...
-Wil Ferch

[marcesq]

BG: FWIW I took the plates to my local wrench and they used a 350 psi impact to get them off. I could not budge them with a 1/2" breaker bar and a 1 1/4" x 2' gas pipe.

When I re-installed I used the above tools to tighten as much as I could (probably about 170 or 180) as it was beyond my Craftsmen torque wrench.

[BGCarrera32]

marcesq-

I had the same problem with my smaller eccentrics, and required a propane torch to heat them free. Seems kind of ridiculous though considering how small the bolts actually are...

I hate just reefing things down tho without a spec to go by...

-BG

[bob hodges]

Well ..I have the right side set and working on the drivers side tonight. I am having trouble getting the torsion bar to set in the splines on the inside. I thought I was all set and tighten the torsion cap up and the end cap popped off showing the torsion bar. I had this condition twice and I finally gave up for the evening. I do believe the spines on the inside are dirty. I am going to give it a try tomorrow. I am setting the angle using the formula and I am convinced that this is the real method. I shall let everyone know how it turns out.

[89911]

I just did these so I am going to be close. The bolts holding the spring plates to the trailing arm are 90ft/lbs. The ecccentrics are 61ft/lbs. Aren't you going to get it religned anyway. Generally, if you are, you just need to get it "tight enough" until you get there.

[bob hodges]

Iam back on the ground and the formula worked perfect. I am 25.25 on both sides I am living with this setting. I can fine tune the rest of this with the adjustments on the springplates.

[marcesq]

So Bob . . . . when are you going to bigger torsion bars

[ChrisBennet]

As some of you have experienced, the spring plate bolts can be pretty hard to get off.
After experiencing this, a friend of mine reinstalled his spring plates using a liberal amount of antiseize and tightened everything down. He took the car for a ride to try it out and along the way heard a loud noise (like a shotgun he said). That antisieze had worked too well and his spring plates had dropped to their lowest setting...
-Chris

[Randy Webb]

anti-sieze alters the torque vs. tension relation of the bolt. Always do it the way the manf. (PAG) says. If they don't say anything for a fastener, then assume it is lightly oiled -- not same as anti-sieze.

[bob hodges]

Marc,

I have to say the springplates almost kicked my ass. I have the car in the shop doing the alignment. What does the larger torsion bars do for the ride? My next big project is getting the A/C swiched over to rotor compressor and change out the hoses. It is very hot here in Phoenix during the summer.