Torsion bars and lowering theory/method help

[C-Pierce]

I have a stock 76 S still at the original ride hight PO never lowered it to E-Spec like most people have at this point. I need to replace the rear Spring plate bushings so I figr' its time to lower it to E_spec (25.5" Maybe?). anyhow, What is the theory to calculate how many teeth I need to move the T Bars when lowering it. I am sure there is a method that works very well, Any input from lowering pros?
As I understand it it should be level across the rockers front to rear but I am still not sure of measurement specs.

Front is a piece of pie I see..

Thanks
Chris

[boyt911sc]

Chris,

You need a good protractor (angle finder) to do this adjustment and minimize the trial and error procedure. As you are aware, the car's door sill should be near to horizontal. Measure this angle and the spring plate angle. It would also help if you know the sprung and unsprung angles of the swing plates as your reference.

The rear torsion bar has 40 inside/44 outside splines and each spline corresponds to 9 deg./8.18 deg. So if you move the inside spline setting one notch, the effect is a 9 deg. change (keeping the outside setting as is). However, if you move the outside spline setting one notch (opposite direction) the effect is less than one (1) degree. This how you get the smaller increments less than 8 deg.

Having an adjustable swing plate makes the work a lot easier. Hope this will help.

TD

[afterburn 549]

I have found do and die method....one up and on dwn. Reweigh and re measure. The protractor will tell you the angle but the corner weight will be what tells you to do next...no mater what the angle is.
I would go get adj. spring plates and make life a bunch ezr

[safe]

Do a search for springplate angle calculator. It will work like a charm.

[C-Pierce]

SHould have mentioned I have a friend with the protractor.

Adj Springplates? How much and from who. Used?

Chris

[afterburn 549]

all I know is the protractor will give you the angle..you will have to do a corner weight and then re adjust, mabe I am missing some thing here but I do not See how a protractor will help

[RoninLB]

I use this $10-20 hardware store unit.

[C-Pierce]

OK call me DUmb, What is corner weight-ing? Those in the "know" give me the definition... It sounds cool but what the hang does it REALLY mean?
Afterburn?
bueller?
anybody?

[patkeefe]

There is a specification for corner weighting the car. Here is some interesting reading: Corner Balance Discussion
Pat

[afterburn 549]

Wow..lets see in simple terms, AND this is more important then most give credit too.....corner weight : separate weight of all four wheels with car level , you actually can "jack" the car so one wheel carries a lot more weight intentionally or by mistake...for the street you want a 60/40 ratio rear hvy of course.
so as you set the ride ht you are also setting you corner weight. (diagonals too) sounds all complicated but after some research you will see its just a little math. For simple terms lets say you car weighs 2000 lbs. You want the front to Carry 40% and rear 60 % ea rear wheel would Carry 1/2 of the 60.....so that would be 1200 on the rear (600lbs per wheel) and 800 for the front (400 per wheel) this help ? ( hope I did my math right too many beers)

[afterburn 549]

The way I do it is with bath room scales, 4 lined up under each rear tire with a 2x6 across them to carry the whole load and add them all togather , and 3 under each front tire - same way 2x6 across them and add again.
( most bath room scales only go to 250 lbs so you need a bunch ..but they are a lot cheaper then paying someone to do it for you.
Now some may argue in favor on nuclear or digital....what ever...I ant going there,- + or - a couple of oz is never going to mater....even 10 lbs if you want to say they could be that far off....but they will not be

[C-Pierce]

OK I have use of a friends scales he uses for his short track stock car so that problem is taken care of. I guess I never put 2+2 together to fig'r out what they were doing. I asked and low and behold that is is what they are doing. so Coool.
But I still have one more question. Does anyone have optimum (street not Pimp!) ride hight for a narrow body car? I am running 15X6s with 205/60s front and 15X7s with 215/60s rear Factory Konis and T-Bars.

One more thing. How much Fuel should I have in the car? Does it matter, or is the idea that weight distribution will always be the same in all 4 corners no matter what is in the tank ?

TIA
Chris

[Matt-Man]

Try 24" rear & 24 1/2 " front for a nice (but low) street height. When checking your changes, be sure to roll the car back & forth a few times to be sure it settles into your height as it will sit a little high after being set back down on the ground. Also, if you are replacing bushings, allow a little fudge toward the high side as it will probably settle a bit the first time you drive it.

Matt

[gduke]

I raised mine which is still bellow the Euro ride hight. The previous owner lowered it too much and the car handled like a lumber truck(bad bumpsteer). It really helps to use the scales. And after you've lowered and corner balanced it it might be a good idea to take your car too a Porsche shop w/ the knowledge and eguip. to 4 wheel align your car.

Its definatelly worth the time and money to do the job right. You'll feel the difference.

Gary

[Gunter]

Here we go again.
You cannot just wack it down.
If you go too low, the rubber stops (Snubbers) in the shocks will bottom out.
You will also get bump-steer.
You will also need an new alignment.
First thing is to check the condition of all the bushings and shocks.
Then comes the lowering (I suggest 25" front/24.5" rear)
Make sure you understand the 40/44-spline principle before you start.
Go to the Tech section on PP and read, read.
If you don't have the bump-steer kit, get it and install under the rack.
Still have the old tie rods? Get the 930-tie rods.
Do more searches on this, lot's of info here at PP.

[C-Pierce]

SO Gunter, excuse my uneducated P knowlege, what is the advantage of the 930 tie rods? and how will I know if I am too low? I only expect I will goto E-spec or maybe to the height you suggested no lower,
what is the advantage/idea of Z Bump steer?

Chris

[Hoss3.0]

Search Wil Ferch on this site and you should get a great article on the whole procedure.

[Hoss3.0]

http://www.rennlight.com/cgi-bin/spring.cgi

This is the link to Wils method.

[C-Pierce]

Thanks Hoss!! That is super. Everyone should see this.

Assuming he has his calculations right, I'll follow that as a guide.

Cheers
Chris

[Hoss3.0]

It worked to a "T" on my "T"!!! Sorry that's lame.