Ride Height - New Spring Plate or not?

[tiwebber]

I have just bought a 1972 911e. This weekend was the first time I had a passenger in it. My dad and I together weight about 400lbs. The tires rub on the fenders with this weight but it seems OK with just me. The previous owner spent a bit of time at the track and lowered the car for that reason. I might try it on the track for fun but 95% will be street driving.

THis car is stock minus the reccaro seats, steering wheel and 7" wheels (6jx15). There's lots of advice about switching to adjustable spring plates but is there a concern for changing these part with respect to maintaining originality?

I have read lots of threads about adjusting ride height and understand I am facing adjusting the torsion bars and then alignment and corner balancing. It sounds a little daunting but I might "want" to try it myself.

Here's couple of pictures. The fender to ground measurement on both back wheels is 24" - pretty low from what I have read. The tires are Michelin pilots 205/60/15's.

[wcc]

You might want to get under there and look at the height adjustment bolt. You may be able to raise the car without re-indexing the bars. But if it doesn't go high enough you'll have to re-index 'em. Mine were easy as pie to re-index, but I've heard horror stories where they weren't able to remove the bar without MAJOR force. But I think that is pretty rare. It really is quite an easy task to do for any shadetree mechanic to re-index the bars. When it's all done just get a 4-wheel alignment and forget the corner balance since it will be a street car.

Good Luck!

EDIT: I'd say "no" to new spring plates. But you may want to replace the bushings...

[Rot 911]

Bill no adjustment in the rear spring plates on an early 911. Even if you get the adjustable spring plates you have to pull the old ones and make some initial adjustments. I would just re-index the old torsion bars.

[wcc]

Oooops, I replied too quick. Sorry about that!!! Thanks for pointing that out Kurt....

[David E. Clark]

Originally posted by tiwebber
... There's lots of advice about switching to adjustable spring plates but is there a concern for changing these part with respect to maintaining originality?

I have read lots of threads about adjusting ride height and understand I am facing adjusting the torsion bars and then alignment and corner balancing. It sounds a little daunting but I might "want" to try it myself...

1. I don't see an issue with your first point. You can buy used adjustable spring plates from a later car and simply install them in place of the old style plates. If you ever sell the car and the new owner is concerned about originality, simply reinstall the old plates or give them to the new owner.

2. I still have the old style plates on my '73 E and adjusting the height without an adjustment bolt is a real pain. You have to remove the plates and pull out and reindex the torsion bars. For the alignment, get a copy of Ray Scruggs book about home alignment of the 911. Both of these tasks are time consuming but they are not anything you can't do alone in an average home shop. That's how I did mine. Plus you get the satisfaction of knowing that the job was done right.

I'm at work now and don't have my copy of Ray Scruggs' book but he is still selling them for only $10.00 and if you mention Pelican he'll toss in an interesting autocross book. Someone on this site has copied the book and posted it (do a search) but in my opinion the books are well worth the price and Ray deserves to be compensated. If no one has posted it by the time I get home, I'll post the address I have for Ray Scruggs.

[David E. Clark]

I forgot to mention one valuable lesson I learned doing mine. One notch on the torsion bar and one notch on the spring plate together equals about 1/3". So if you are trying to make a small adjustment, for example raising your rear height back from 24" to 25" which is "Euro height", I wouldn't go any more than three notches on both the spring plate and the torsion bar.

There is a good Spring Plate Angle Calculator on the Rennlist site which might help. Plus, Will Ferch wrote an article called Rear Spring Plate Angle Settings, also on the Rennlist site, that should help. Good luck.

[CHILI]

Yes, ajdustable springplates are a good idea. You can always keep the stock springplates if it's a concern for resale value (although, most will pay more for adjustable sprinplates already installed).

THe alternative is to put a little more negative camber in the rear wheels. Which I believe you can do with the stock sprinplates. But, it does tend to change the toe. Or is it, toe changes camber. Hmm,

Someone will chime in with that anwser. OF course tire wear may be an issue with more negative camber.

[Wil Ferch]

Conventional wisdom says 25.5" front fender lip/ 25" rear for "Euro" height...

...this is with a tire that has an overall diameter of 24.88" ( like a 205/55-16). Your 205/60-15 is only 0.1" diameter smaller in diameter.

You have a number of options:
- reindex the bars ( if the rub is from the back only...you didn't say)
- get 2 piece spring plates..but you still need to reindex the bars
- simply get rear Bilstein high-pressure gas shocks...this alone should raise the car about 1/2"...maybe more. It might be enough additional clearance, or maybe not. But then you've got new and better shocks installed as a by-product - - not a bad deal.

- Wil

[tiwebber]

If no one has posted it by the time I get home, I'll post the address I have for Ray Scruggs.

Thanks, would appreciate that. I agree that I can save the old spring plates and that takes car of my concern for having stock parts. Is geometery on newer spring the same? ie. do bolts line up?

if the rub is from the back only...you didn't say

The rub is the front. The fender actually rides down the side of the tire a distance that appears to be nearly 1" maybe a bit more. I'll try and post a better closeup of tire rub damage later.

Thanks for the advice.

[tiwebber]

if the rub is from the back only...you didn't say

Oops. What I meant to say is... Yes the rub is only the back tires but the contact point is the front of the tire and travel an inch (or more) down the sidewall. Pictures to come!

[Neilk]

Congrats on the new purchase. Dumb question, but if the PO tracked the car a lot and had it lowered, he might have updated the car to Porsche's adjustable spring plates. Check it out before you buy some. Also, you can get used spring plates for about $100 plus new Neatrix bushings. Good luck.

[tiwebber]

Congrats on the new purchase. Dumb question, but if the PO tracked the car a lot and had it lowered, he might have updated the car to Porsche's adjustable spring plates. Check it out before you buy some. Also, you can get used spring plates for about $100 plus new Neatrix bushings. Good luck.

Thanks - I am loving it. I thinks its an old spring plate based on pictures I have seen in other threads.

Here's something that I overlooked. I have never pushed on the rear end. I just did now. It seems really squishy. I can put my weight on the rear bumper and depress the back end 1-2". I cant quite get it to rub by my weight but close. The front is way tighter.

Here's a pic of the tire damage and below is the spring plate. Theres a band of tire just below the treadline that has been rubbed by the fender and you can see evidence of this still on the fender.

[David E. Clark]

Here is the first page from Ray Scruggs' book. His address is at the bottom.