Lower 911 Rear

[Bakester]

I have an '86 Carrera that needs the rear lowered about an inch. I figure I would try the eccentric adjuster bolts but have a couple questions.

1. Is it just a trial and error thing when turning the adjuster bolt or does a quarter turn equal X of an inch?

2. With the wheel on, loosen the locking bolt, turn adjuster bolt, tighten locking bolt, go around block, measure, repeat as required? Hopefully not much more complex than that. Thanks for the help.

[gamin]

I would like to know also. Replaced all shocks and car looks like it's ready to go off road.

[bkreigsr]

search is your friend
Pelican Technical Article: Lowering the 911 - 911 (1965-89) - 930 Turbo (1975-89)

[ClickClickBoom]

Originally Posted by Bakester

I have an '86 Carrera that needs the rear lowered about an inch. I figure I would try the eccentric adjuster bolts but have a couple questions.

1. Is it just a trial and error thing when turning the adjuster bolt or does a quarter turn equal X of an inch?

2. With the wheel on, loosen the locking bolt, turn adjuster bolt, tighten locking bolt, go around block, measure, repeat as required? Hopefully not much more complex than that. Thanks for the help.

Don't forget to corner balance when you are done!

[Bakester]

Originally Posted by bkreigsr

search is your friend
Pelican Technical Article: Lowering the 911 - 911 (1965-89) - 930 Turbo (1975-89)

Yeah, yeah, I've read that several times and have the book and the Bentley and have been searching here and Rennlist but no answer to my question. Maybe I'm making it harder than it is. Thanks for the effort though.

"If you have a later model 911, then you’re in luck, as you don’t have to remove the torsion bar covers and radius arms to get at least some degree of adjustment. On these cars, the radius arms were equipped with an adjustment screw. To raise or lower the rear of the car, simply loosen the large nut and bolt closest to the torsion bar. Then rotate the other bolt located next to it. This bolt is eccentric, and will cause the rear of the car to be raised or lowered as you turn it. Adjust the height as described previously, and then tighten the bolt located nearest to the torsion bar. Make sure that you don’t touch the two nuts located towards the rear of the car: these adjust the toe-in and the camber for the rear suspension, and should only be adjusted by a trained professional using an alignment rack."

[Bob Kontak]

[QUOTE=ClickClickBoom;7859490]Don't forget to corner balance when you are done![/QUOTE

If you are going to pay $400 for a corner balance, wouldn't you just want the pros to do the height adjusting? They will most likely adjust those settings anyways.

For a minor adjustment, like a one inch rear drop with the adjusters, what is the real down side if you only take peppy trips to the market and like to drive a little fast on windy roads to not corner balance?

I would think a knowledgeable alignment is due, but why the corner balance? $400-ish is not something to be taken lightly.

That said, I have never driven a 911 before and after that was corner balanced.

[Bakester]

[QUOTE=Bob Kontak;7860271]

Originally Posted by ClickClickBoom

Don't forget to corner balance when you are done![/QUOTE

If you are going to pay $400 for a corner balance, wouldn't you just want the pros to do the height adjusting? They will most likely adjust those settings anyways.

For a minor adjustment, like a one inch rear drop with the adjusters, what is the real down side if you only take peppy trips to the market and like to drive a little fast on windy roads to not corner balance?

I would think a knowledgeable alignment is due, but why the corner balance? $400-ish is not something to be taken lightly.

That said, I have never driven a 911 before and after that was corner balanced.

Yeah, I'll skip the corner balance and just get an alignment. I figured if the rear was easy as the front to lower, I didn't need to pay anyone to do it.

[tazzieman]

[QUOTE=Bakester;7860300]

Originally Posted by Bob Kontak

Yeah, I'll skip the corner balance and just get an alignment. I figured if the rear was easy as the front to lower, I didn't need to pay anyone to do it.

Not quite as easy , let us know how long it takes!

[uwanna]

You can try the eccentric adjusters on the spring plates, but you will probably be disappointed. Every 911 that I've owned, or have seen, came from the factory set so that
they can only be adjusted to raise the car! This all started with the US mandated bumper height regs. In the mid seventies, the local Porsche dealers made a good profit lowering
the rediculusy high rear ends, because the spring plates needed to be reindexed to make it happen! (which you will most likely need to do) Sure would have been nice if the factory had set the spring plate adjustment in the MIDDLE, so you could go either up or down.
I recently replaced my spring plates and set the adjustment eccentrics in the "middle" so I can tweak them for corner balance adjustment.
Good luck!

[Bakester]

Thanks for the info folks. I'll dive in and see how it goes.

[dipso]

I don't think you can get an inch out of the adjuster bolts. It's pretty easy to pullout the spring plate and move it a notch or two.
Just jack up your car, remove the tires, put it on stands, and then measure the distance from the tip of the arm to the ground. Write it down.
Lets say it is 8". Pull out and rotate the arm until it is 7". Reassemble.
The splines on the torsion bar are different degrees on the inside and the end that holds the arm.
By rotating both the bar and the arm individually, you can get pretty accurate.
Sometimes rotating the arm one notch doesn't get you where you want to be, so you have to rotate the bar and then rotate the arm again.
It's a pretty simple but neat system.

[kuba_kuba]

I was full of hope that my adjusters would allow me to lower, but as stated here, they were at lowest setting already. Ended up re-indexing. Not as hard as its made out to be. Takes a few stabs but if you go slow and steady and heed all the safety advice (don't break your hand!!) a very satisfying project that makes you feel like a pro at conclusion!

One thing I did was when I had the spring plates off, I set the eccentric in the middle position to allow fine tuning and corner balancing without having to reindex.

[uwanna]

when you reindex your torsion bars, this little calculator will be a big help! Used it when I did mine, and it was close to spot on.

911 Spring Plate Angle Calculator

[ClickClickBoom]

You cannot lower a stock set up Porsche with the eccentrics, per the Factory Shop Manual. As for a corner balance, it isn't windy roads, it's everything relating to the wheels. Wanna try something fun? Take a Porsche that hasn't been corner balanced after being messed with and try a moderate effort stop, mine would lock up the right front and actually feel like it was accelerating with the light front wheel hydro planing on reverted rubber.
Good luck....

[ClickClickBoom]

Fsm:





I have driven a ill wheel balanced Porsche, the braking was most severely affected, as in really only 3 of 4 doing the job.

[Bakester]

Just when you think everything that could have been posted about ride height.., haha. Thanks for the that, definitely gives more perspective on the whole relationship.

[Bob Kontak]

Originally Posted by ClickClickBoom

I have driven a ill wheel balanced Porsche

Thank you for that info. Damn, that is frankly awesome.

Puts to bed that issue, like right now.

[Uncle Enzo]

FWIW, I lowered my rear via the bolt and got roughly 3/4 of an inch drop but like you I could find almost no definitive answers. If you do it, make sure have the proper wrench sold from our host.

[SoCal911SC]

Originally Posted by Uncle Enzo

FWIW, I lowered my rear via the bolt and got roughly 3/4 of an inch drop but like you I could find almost no definitive answers. If you do it, make sure have the proper wrench sold from our host.

Using that method, which way do you turn the bolt to lower the car after loosening the locking nut? And how much turn translates into how much drop? Thanks

[sailchef]

You might want to disconnect the bottom shock bolt, remove the wheel, and take the weight of the trailing arm off of the spring plate useing a smaller jack. Just makes it easier to turn the nut. The locking nut and adjuster nut are both torqued to around 180; if they haven’t been cracked loose before they may be a bear to loosen without a long breaker bar or impact gun, and the wheel would just be in the way. I put the rear up on jack stands supported under the torsion tube. Use paint or a marker to scribe marks on your plates so you have a reference point from where you started. Nut on the right is adjuster with reference marks.



Watch the smaller plate move against the larger side. Large plate goes up, ride height goes down. Large plate goes down ride height goes up. You might get ¾ inch travel total on the plates which might equal a inch and a half in height. You don’t even turn the nut a full turn. You can sit there and turn the nut back and forth and you will see the plate moving. Don’t count on much more than an inch or so with the adjuster. If you need more adjustment you will need to re- index the torsion bars.
You will definitely need the proper wrench to fit between the spring plate and tub or you could make your own by grinding one down until its thin enough to fit.