Raising rear end on 75+ 911

axvel · 04-05-2006, 02:41 PM

How do you raise a rear end on 75+ 911? I was told something like 28mm Torsion bars, is that true?
My rear end sits too low and i need to bring it up a little, also i was quoted 800$ for parts and labor is that ok price or over the top?
Also is it hard to DIY it?>
thx

Paulporsche · 04-05-2006, 02:50 PM

You do it by changing the angle of the spring plates. Search Kurt V and setting ride height. You could also have other problems, such as worn spring plate bushings and / or shocks. Can't comment on costs.

axvel · 04-05-2006, 05:52 PM

checked the shocks, not leaking, where is the spring plate?

Dueller · 06:40 PM

If you look in the rear wheel well forward of the wheel you will see a flat piece of metal that connects from the hub area forward to the car body. This is the spring plate, It is attached with four bolts (you'll probably only see three) by the spring plate cover. The spring plate cover will have a round cylinder about 2.5 inches in diameter portruding from it. Your torison bars are behind the spring plate cover.

With some mechanical skill you could get it apart...whether you could figure out how to index the TB, I don't know.

TB's cost 250-350 aftermarket new for each end of the car. If they are worn out on your car I'd buy some used Carrerra TB's here for 50-100. I wouldn't pay 800 for just the rear, but then again you are in LALA land

. If I were to replace with new, I'd do both the front and rear.

Post a side shot pic of your car might help. What is the measurement from the ground to the top of wheel well?

Damn...I feel like I'm trying to explain how to tie a shoe

rnln · 04-05-2006, 06:40 PM

Dueller,
Sometimes "how to tie a shoe" is important to people don't know how. I want to raise my car a bit, maybe 1/2 an inch or 1/4, therefore verytime there is a post/reply related to this area, I read carefully. Still not sure yet.
Thanks.

rnln · 04-05-2006, 06:40 PM

Dueller,
Sometimes "how to tie a shoe" is important to people don't know how. I want to raise my car a bit, maybe 1/2 an inch or 1/4, therefore verytime there is a post/reply related to this area, I read carefully. Still not sure yet.
Thanks.

rnln · 04-05-2006, 06:47 PM

Dueller,
Sometimes "how to tie a shoe" is important to people don't know how. I want to raise my car a bit, maybe 1/2 an inch or 1/4, therefore verytime there is a post/reply related to this area, I read carefully. Still not sure yet.
Thanks.

Dueller · 04-05-2006, 06:52 PM

rnln...NO NO NO...my "tieing a shoe" comment was directed at my own frustration with MY lack of technical writing skills.

Heck, if I could figure out how to post a pic I'd have been a lot more helpful to the original poster.

Just trying to help the original poster.

jim

Dueller · 07:55 PM

I just notiiced you also want to raise your rear. On your car, the spring plate has an adjustment on it where raising it is relatively simple. If you have access to a lift you don't even have to take the wheels off with the proper slim ride height adjustment wrench (24/36mm I think) wrench. The older cars (pre SC) don't usually have it.

May I recommend Dempsey's book "101 Projects"? He covers adjusting ride height both front and rear in easy to unsedstand steps. It has been extremely helpful to me to learn my way around the car.

jim

Dueller · 04-05-2006, 07:09 PM

Hey guys...I just found a great tech article in here that does a much better job than I did:

http://www.pelicanparts.com/techarticles/911_suspension_bushings/911_suspension_bushings.htm

Axvel....your car likely does not have the ride height adjustment bolts that are closer to the spring plate cover (front of the car). rnln, your car should have these.

The two adjustment bolts towards the rear of the car are for camber and toe settings and are on both of your cars.

Good luck

Wil Ferch · 04-06-2006, 06:37 AM

You may want to look here for general suspension setting guidance and also how to use my ( and Thom's ) spring plate angle calculator -->

Help! Rear Ride Height

Also be advised that in 77, the spring plate was made as a two-piece unit to allow a "fine" tune on ride height without having to re-index the torsion bars. Unless your car was modified with the later units..you can't do this that easily.

Wil

axvel · 04-06-2006, 09:11 AM

axvel · 04-06-2006, 09:12 AM

axvel · 04-06-2006, 09:13 AM

axvel · 04-06-2006, 09:13 AM

Dueller · 04-06-2006, 12:49 PM

axvel--

Beautiful car...what year is it? Does it have the adjustable spring plates? (I.e., the ones with the two large bolts toward the front of the spring plate). I think you're right...it does appear to be a bit low in the rear.

axvel · 04-06-2006, 01:20 PM

axvel · 04-06-2006, 01:21 PM

axvel · 04-06-2006, 01:22 PM

Quote:

Originally posted by Dueller
axvel--

Beautiful car...what year is it? Does it have the adjustable spring plates? (I.e., the ones with the two large bolts toward the front of the spring plate). I think you're right...it does appear to be a bit low in the rear.

Its a 1977, by looking at the top pictures is that the spring plate you talking about? Thanks for the info

Dueller · 04-06-2006, 07:40 PM

BINGO...yup, Axvel, you have the adjustable 2 piece spring plates. Go to the two links posted above and you will see how to adjust. Essentially the front bolt holds the two pieces of the spring plate together; the rear bolt is the adjustment bolt.

When you look at the pics in the article, you will see how it works...essentially the rear bolt has an elliptical offset cam that goes thru a slotted hole in the spring plate. By loosening the nut on the "front" side you can then turn the bolt head from the back side of the spring plate which will change the position of the two parts of the plate thus raising or lowering your rear.

Not very difficult at all. You don't even have to take the biolts out...just loosen the front one then loosen and adjust the rear one. Keep in mind you're not gonna get a huge change in ride height thru this adjustment (less than an inch I suspect), but I would try this before considering changing bushings, TB's etc.

Keep in mind this adjustment may affect toe and camber (but not radically) on the rear (which are adjusted with the two bolts more rearward near the hub.

With a lift you don't even have to take the wheels off. While not absolutely necessary, this ride height tool listed with Pelican makes it easier because its such a tight fit between the body and the spring plate:

http://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_TOLtol_pg7.htm#item41

Definitely within the skills of the average DIY'er. Let us know how it turns out

jim