Sanity Check on Initial Spring Plate Angle

[zippy_gg]

With the engine out I refreshed all rear suspension bushings and wheel bearings.
Re-installing the spring plates I used Will Ferch's angle calculator 911 Spring Plate Angle Calculator, and my input was 25 mm for the TB, Euro ride height, and a weight of 3417lbs based on the VIN plate since I have no way to weight the car at this stage.


The calculated angle is 36°- 37°, and the car angle was measured at 0° so I set the spring plates at 36°- 37°.

I wanted to check with those with experience as it looks like the angle is pretty steep, but then again the trailing arm and shock are not attached



Does this seem correct? I'd like to make sure before I reinstall the spring plate covers and tighten everything up.
Any advice will be appreciated.

[pete3799]

I think you're going to be sitting pretty high using the GVWR
2600-2700# would be closer i think.

[HFR_Racer]

This is a photo showing the spring plate angle on my 87 930.

I have to just raise the spring plate slightly with a jack to get the cover plates on. Basically, the bottom bolt on the cover plate is slightly covered with edge of the spring plate when you apply upward (hand pressure) on it.

[juanbenae]

that does seem pretty steep. ive always set up with stiffer bars, so less sag after loaded.. #3400 does seem a bit heavy, but im not aware of any actual weight numbers... you say its an 86, so thats not a g50 car? your photo angle may be playing tricks too?

[juanbenae]

and oh yeah,, get some blocks under the trailing arm so it's not makin the brake lines get all hurt.

[zippy_gg]

Originally Posted by car 311

and oh yeah,, get some blocks under the trailing arm so it's not makin the brake lines get all hurt.

Trailing arms just attached to their brakets but not torqued, shocks not yet installed, and brake lines are being replaced and not yet installed. Playing safe; thanks!.

[zippy_gg]

Originally Posted by HFR_Racer

This is a photo showing the spring plate angle on my 87 930.

I have to just raise the spring plate slightly with a jack to get the cover plates on. Basically, the bottom bolt on the cover plate is slightly covered with edge of the spring plate when you apply upward (hand pressure) on it.

That is a very nice height!
Alas I cannot compare my situation (or pictures) with yours since the trailing arms and not connected to the spring plates yet.
I am at the initial stage with installing the plates and I wanted my starting point to be in the ballpark before everything gets re-installed.

Did I mention that is a very nice height on your car?

Edited: I see what you mean not being able to install the bottom bolt without raising the spring plate

[Porboynz]

Originally Posted by HFR_Racer

This is a photo showing the spring plate angle on my 87 930.

I have to just raise the spring plate slightly with a jack to get the cover plates on. Basically, the bottom bolt on the cover plate is slightly covered with edge of the spring plate when you apply upward (hand pressure) on it.

This is the same method I use. I install the spring plates each side such that the bottom bolt of the bush cover plate is only just able to screw in but you need to jack the spring plate a little to fit the removable bush. Seems to work OK and its an easy reference point.

[mreid]

That bottom bolt is actually the spring plate stop and is designed to keep the plate from dropping all the way and stressing the brake lines when the wheels are in the air. The lowest you should go is described above (just requires a slight lift with the jack to get the stop bolt installed).

Zippy, I think your car will have a 4x4 posture with that setting, particularly if you installed larger than stock TBs.

[ivangene]

helpful hint - there's an AP for that - I found several smart phone free inclinometer aps that you can set zero on the door sill and then rest on the arm for quite accurate angle measuring

your GVW is way high..as stated - most likely closer to 2800#

[E Sully]

Weight is probably 2700 lbs range. I get an angle of 31-32.

[jstobo]

The spec weight for your car is 2640lbs. The weight you are using is for fully loaded- passengers, gas ,luggage(what luggage?) etc. My 69 has a spec angle of 36 degrees. But it has a smaller TB than your car but it is also lighter by 400 lbs.

[zippy_gg]

Thank everyone for the replies. So much good info from people's experience here!
I guess I mistakenly used the GVWR instead of the actual car weight.
The calculator now shows 30-31 degrees for a 2640lb car.
I am keeping the 25mm TB for the time being as they are in good shape and the car will be used for street and canyon driving, no DE or track days.
I guess I better go to the garage and "fix" the spring plate angle!

[19-911-65]

This is for an earlier car....although may help

Banana Arms...does this look right?

[zippy_gg]

Originally Posted by 19-911-65

This is for an earlier car....although may help

Banana Arms...does this look right?

I did read your thread earlier, thanks! Clean car BTW...
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