Adjustable Spring Plate Question

Jtilden · 09-06-2009, 04:04 AM

Once I return to my home I will be changing to the adjustable spring plate setup. The question I have is this: When I re-install the "new" plate will i install it in the stock setting and lower it from there? Or will I install it as if it was non-adjustable by going up a spline or two and adjust from there? Thanks

Tilden

tonythetarga · 09-06-2009, 04:20 AM

You want to set the spring plate as close to your desired ride height as possible and then adjust from there. If you are using Carrera adjustable plates, the adjustment is fairly minimal and mostly used for corner balance adjustments. If they are sway-away then you have a wider margin of adjustment, but in my opinion, you want to be as close as possible to start with.

Shaun @ Tru6 · 09-06-2009, 04:43 AM

Do you have another car other than those in your signature? An 80 SC will have adjustable spring plates.

Tony is right, get the ride height to where you want it. The adjustability is more for corner balancing than making large adjustments.

Jtilden · 09-06-2009, 11:06 AM

ohhhhhhhhhhh....I was under the impression that a stock adjustable spring plate looked similar to this unit:

So for what I am looking to do I can either retain the stock spring plates and just move them up a spline or two until i get the right height, or I can purchase the set pictured and have more adjustability? So how are the stock spring plates adjustable?

Jtilden · 09-06-2009, 11:12 AM

Quote:

Originally Posted by Jtilden

ohhhhhhhhhhh....I was under the impression that a stock adjustable spring plate looked similar to this unit:

So for what I am looking to do I can either retain the stock spring plates and just move them up a spline or two until i get the right height, or I can purchase the set pictured and have more adjustability? So how are the stock spring plates adjustable?

Never mind: I think I got it....to "lower" the car using the stock plates it looks like all you have to do is loosen the two bolts closest to the bushings and this causes the rear height to drop up to 3/4 inch.

James Brown · James Brown's Garage

I think it's more involved than that. You might have to re-index the torsion bar. So, why not just re-index first then fine tune with the adjustment bolts? I don't really know but it sounds easer than those spring plates

tonythetarga · 09-06-2009, 12:09 PM

Lowering the car and taking things apart before you know what you're doing and what the consequences are is a bit foolish in my opinion. This procedure is a DIY job when you're prepared and have the tools and time to do it. Have you found the spring plate angle calculator yet? Do you know your cars actual weight?

I might suggest you get a copy of 101 Projects for your 911 and do a bit of research if you want to do this right. Then when it is all done, take it in to a proper race shop or good independent Porsche shop for a 4 wheel alignment and corner balance, which is critical for safe driving, street or track.

Jtilden · 09-06-2009, 09:01 PM

Quote:

Originally Posted by tonythetarga

Lowering the car and taking things apart before you know what you're doing and what the consequences are is a bit foolish in my opinion. This procedure is a DIY job when you're prepared and have the tools and time to do it. Have you found the spring plate angle calculator yet? Do you know your cars actual weight?

I might suggest you get a copy of 101 Projects for your 911 and do a bit of research if you want to do this right. Then when it is all done, take it in to a proper race shop or good independent Porsche shop for a 4 wheel alignment and corner balance, which is critical for safe driving, street or track.

Seeing as though I am still in Iraq, I have not yet begun the process, in the meantime I figured I would "mentally" work through the entire process and ask all the questions and take notes so that when the time finally comes, I will have hopefully acquired all of the necessary advice and equipment to do the job correctly. I thought by asking questions before hand I was in fact "preparing" to do the job correctly. I take offense to your comment, if you have not figured it out yet...and yes I have a service manual, and yes i have the 101 projects here with me in Iraq, but I like to ask questions, sorry for bothering you...

tonythetarga · 09-07-2009, 04:51 AM

My comment was not meant to be offensive and I'm sorry you took it that way. I also did not know you were somewhere other than Texas, which your location states. My only point was that people start making adjustments to the suspension without realizing that the four corners are a unit and doing something at one spot has an effect somewhere else.

jkh2cpu · jkh2cpu's Garage

I've got a set of the sway-a-ways as you have pictured here. They are not too difficult to get set up once you know what you are doing, which is a gentle way to say be prepared to be frustrated during the learning process. Guys on the forum have talked about adjustables in general, and it seems like it takes a number of re-indexings to get things where you want them. Having a way to measure the angle of the spring plates is really a good thing. I have two devices: a cheapy angle finder from Sears that is circular with the angle-finder-pointer free to point to the angle by swinging on a pivot in the center of the circle. Slightly more pricey from Sears was a torpedo level that had an electronic readout which measured in degrees how far from 0.0 the level was. Both work well.

If you are not making changes to the factory specs for torsion bar size, the degrees of droop for the spring plate will be in your owner's manual. I'd recommend setting up according to the factory specs, bolt it back together, and see what you get. Some here like to measure from the ground to the fender lip, but the 'official' measurement is a pain-in-the-patoot measurement from the axle center to the center of the torsion bar, plus 12 mm (word math problems; I'm sorry and so is Porsche, but it's the best way to get it right).

You will be frustrated, so plan to take some time and days and skinned knuckles before you get ti where you want it. Check in here and we'll try to help.

Jtilden · 09-07-2009, 08:09 AM

I cant remember where i found this article, but it is the one i have been using to plan my project. Please note that the author makes it seem pretty straight-forward. No mention of angle finders etc. I cut and paste the article to MS Word so the pics are not visible I have the complete file with pics if anyone would like a copy:

This project started because I wanted to get my ‘80SC to ‘Euro’ ride height, which is 25.0” rear and 25.5” front, when measuring from the ground to the top-most part of the wheel well arch. This really improves the looks and handling of the car.

Jack the car up and support it with jack stand on the INSIDE portion of the torsion bar tube. Scribe the position of the spring plate against the inner wheel well to use as a reference in case you need to start over, or, re-index the spring plate on the torsion bar. The reference mark is made BEFORE disconnecting from the trailing arm, you’ll make two more reference marks later.

Disconnect the shock to allow tension to be taken off the torsion bar. 24mm socket/wrench if I recall. NOTE: you should always support the trailing-arm with the jack. I removed mine to snap the picture. This also allows for easier removal of the shock bolt as there is no tension on it.

Keep the trailing-arm supported with a floor jack to keep full weight off the axle and CV joints. You can fine-tune the height in order to remove the camber, toe-in, and connector bolts since there is tension on them.

Remove the spring plate bracket, 4 bolts. There is also a spacer behind the bracket at the lowest hole.

Once the spring plate is fully disconnected from the trailing- arm and the bracket has been removed, scribe another mark against the rear wheel well. Again, this will be a reference to get things back to your starting point should you run into trouble along the way.

Take a measurement from the bottom most edge of the spring plate to the floor. In my case this was 8.75 inches. My current ride height was 26.25 and I needed to come down to 25.0, a difference of 1.25 inches. I removed the spring plate from the torsion bar and rotated the spring plate up, away from the ground until the measurement on the ruler was 10 inches. Luckily, there was a spline on the torsion bar at this location and I was able to slide the spring plate back on and keep the proper measurement. It appears that if you need to lower the car 1”, you can rotate the spring plate up 1”to get the desired results. I think I was extremely lucky since I got exactly 25.0 inches when I was done. In any case, this should get you close and you can do a fine adjustment using the eccentric bolt on the adjustable spring plate. If your spring plates are not adjustable, you will need to be a bit more exact. It may be wise to find adjustable spring plates from a later 911, or purchase a set of the Sway-A-Way adjustable spring plates from Pelican Parts

Then, you can fully remove the spring plate, exposing the torsion bar. NOTE: You should scribe yet another mark once you get the spring plate to the height you want in the previous step. I DID NOT do that here and had to futz with things a bit to get it where I needed it. The third scribe mark should lie between the two existing scribe marks. I did not make this mistake on the other side and it went much easier. You will need to remove the torsion bar access hole on the outside of your rocker panel in order to fully remove and adjust the spring plate. It is just a matter of loosening a nut and removing the cover itself and the seal.

Now for the fun part, removing the old, hard, extremely stuck bushings. I started with a utility knife and made multiple vertical cuts around the whole bushing.

Then, I used an old and DULL chisel to pry the pieces away from the spring plate, using the gentle coercion of a hammer.

Finally, I spent $2.50on a wire wheel for my bench grinder to take the rest of the old rubber off. What a nasty job! This really does the trick, though. Once everything was cleaned up I put a nice coat of black metallic paint on the spring plate to match my car, wire brushed the spring plate bracket and bolts/nuts.

Next, I installed the new Neatrix bushings. Make sure the surface where the bushing goes onto the spring plate is clean. Glue the new Neatrix bushings to the spring plate using the epoxy included w/bushings or use some other strong adhesive. Let glue setup completely, perhaps overnight. When dry, install spring plate with new bushings into in the torsion tube. Use baby powder or soap if needed to ease installation into tube. DO NOT USE GREASE OR ANY OTHER PETROLIUM-BASED PRODUCTS, AS THEY WILL BREAK DOWN THE RUBBER. I was careful to install the spring plate on the torsion bar using the reference mark I had made earlier. Once things were measured and checked, I re-connected the spring plate. NOTE: If your measurement is off a bit you can use the eccentric bolt on the spring plate to fine-adjust. This requires a really thin 36mm wrench because you need to fit it between the spring plate and the wheel well. Good news, you can head to your local bike shop and purchase one for $15.00 or so. Bikers use this for adjusting the headset on the bike. Plus, you’ll save big bucks over the specialized wrench sold through catalogs. When re-connecting the spring plate to the trailing-arm, you may need to fine adjust the height using the floor jack so the holes line up.

Well, it was a hard, dirty project, but well worth it. Here is the finished product, 25.0 inches the first try . NOTE: If your ride height is off you can make the same adjustment to the eccentric bolt on the spring plate mentioned earlier.

Once the project is complete you’ll need to get an alignment done. I had the shop set the camber to negative 1 degrees at all corners. You may want to have your car corner-balanced as well. My car handles like a dream!

jkh2cpu · jkh2cpu's Garage

Heh! This article is one way to do this puppy, but writers sometimes leave out the nasty stuff, preferring to write from the positive angle, which is more pleasing to editors. This is a dirty, messy job, and if well-done, you will be happy. If you are going to lower the front to 25.5 inches ground to fender, I think you will find that a bump-steer kit will be necessary, and for sure you will want the four wheel alignment.