rear end height issue

jdawg · 08-21-2010, 04:37 AM

This is my problem. I just had my 1983 911 aligned & corner balanced & it now handles like a Porsche should. The problem is that the rear driver is a full inch lower than the rear passenger. The guys that did the work are reputable & said that there was some body repair on that side that was off. How can I adjust this without losing the alignment & handling. It reminds me of a an extremely large guy driving a Ford Pinto even though I know it is probably not that noticeable.

tonythetarga · 08-21-2010, 05:31 AM

Post the weight results for the corners. The corner balance IS more important than the cosmetic look. How much fuel was in the car and did they seat someone in the drivers seat that was approximately your weight? You might have some room for adjustment but if the corner balance is good, there likely isn't much room.

wildcat077 · wildcat077's Garage

I'm affraid that there isn't much you can do about the left rear without reindexing the torsion bars ...
One full inch is a lot of change and if they did a proper corner balancing job then the problem is with the fenders not being exactly the same height.Don't forget that these cars were hand made over twenty years ago ...

I spent two days in my garage fighting over a 1/4 inch height difference while trying not to use the eccentric adjuster in the rear when i installed my 29mm rear torsion bars.I can't remember how many times i reindexed the right rear to get it to match the left side and that's not even corner balancing.That's a Winter project after i purchase my own scales ...
When it comes to the rear,it's a whole different ball game than the front.

Cheers !
Phil

dad911 · 05:39 AM

Is the front passenger side too high? Are you measuring from the wheel arches? Can you measure from spring plates or somewhere else on the chassis?

They may not have wanted to re-index the torsion bars.

You may want to get a second opinion. Were they a porsche specific shop, or an alignment shop?

911pcars · 08-21-2010, 08:14 AM

Do you have adjustable drop links on your sway bars? If not, the side-to-side height difference is preloading each bar making the corner balance inaccurate. In addition, ride height differences in the front will affect the corner ride heights on the rear. Did the shop provide a chart summarizing the final corner weights and height?

One way to isolate the front from the rear is to find a central lift point at each end and raise the vehicle. That eliminates one end (the lifted end) from affecting the ride height on the opposite end. This is called the "Tripod" method. Please look up in the archives. It's also in the factory manual.

Sherwood

Wil Ferch · 02:34 PM

Oh no ! ...groan!... another comment like...."Don't forget, these cars were hand made over 20 years ago..". Let's think about this...Porsche has some of the most demanding body assembly standards in the industry, even then. Shut lines and body panels were always near perfect as delivered from the factory. Notice all the problems when folks try to fit fiberglass body pieces with some amount of trouble ( because the "glass" is off-spec...not the body), but things like OEM steel decklids and engine lids fit fine on interchange....car-to-car...over a span of many model years. Porsche's body tolerances were pretty exacting. The only area that allowed some "fitting" was the front s-shape to the top/front of the doors where they met the front fenders. If you look at archival footage of the assembly process, you will see workers smoothing out this area with molten body lead. Most other body panels were modern stampings like most other cars. So let's bury this chestnut about "handbuilt" implied variation.

In the 1970's and 80's the 911's were built on an assembly line.....with a good portion "hand assembled"...but not "hand-made" by any stretch of the imagination. Certainly not to warrant a 1 inch difference in height.

Challenge.....how many Porsche's...as delivered to the dealers in the 1970's and 1980's...had 1 inch height differentials from the factory, if this were so?. I'd bet zero-to-none. The issue here is that you can get proper corner balance a number of ways. It's simply harder to do it right to get ride height AND corner balance within spec, because if the ride height ends up wrong after corner weights are right, it means one of the bars was off-set somewhat in initial setting. As someone here said, it would require essentially going back to square one and re-indexing bars and doing the rest of the good (balance viewpoint) work over. A shop that is paid by time won't do it...and would be hard pressed to waste this time if another paying customer is in the que.

jimbauman · 08-21-2010, 04:22 PM

dad911 is on the right track there.....

jdawg · 08-22-2010, 09:28 AM

The shop was Eurowerks in Charlotte, NC & they are a Porsche specialty shop. So should I not worry about cosmetic look or try to remedy the 1" difference. Would it make a difference if I dropped the other side .5" & raised the driver side .5" to even the rear up?

dad911 · 08-22-2010, 10:32 AM

If you make an adjustment like that, you will screw up both the alignment and corner balance.

Park on as level a surface as possible, and measure from the ground to the torsion bar covers in the rear.

Paul LeFevre · Paul LeFevre's Garage

Oh no ! ...groan!... another comment like...."Don't forget, these cars were hand made over 20 years ago..". Let's think about this...Porsche has some of the most demanding body assembly standards in the industry, even then. Shut lines and body panels were always near perfect as delivered from the factory. Notice all the problems when folks try to fit fiberglass body pieces with some amount of trouble ( because the "glass" is off-spec...not the body), but things like OEM steel decklids and engine lids fit fine on interchange....car-to-car...over a span of many model years. Porsche's body tolerances were pretty exacting. The only area that allowed some "fitting" was the front s-shape to the top/front of the doors where they met the front fenders. If you look at archival footage of the assembly process, you will see workers smoothing out this area with molten body lead. Most other body panels were modern stampings like most other cars. So let's bury this chestnut about "handbuilt" implied variation.

In the 1970's and 80's the 911's were built on an assembly line.....with a good portion "hand assembled"...but not "hand-made" by any stretch of the imagination. Certainly not to warrant a 1 inch difference in height.

Then why is it that the lower right hand gap at the point below the bumper where the rear valance and 1\4 panel never align properly? This always made me wonder whats up with this?
__________________

wildcat077 · wildcat077's Garage

It seems there is always "somebody here" with nothing better to do who will criticize other people's observations !
I sure wish my 89 Porsche was still perfect after 20 years on the road ...

Unfortunately most gaps seem to be off,who knows maybe some of the previous owners had a little fender bender throwing off the alignment even more,that is a reality we all have to live with !
If you want a perfect Porsche,leave it in the garage ...

Cheers !
Phil

tcar · 06:29 PM

What size wheels are those? 17's? 18's?

They look way too big for an SC. Proportion is off. Looks 'off'.

Put proper Fuchs on, it will look better; and leave it alone.

Do not re-index to make up for sloppy body work.

No one else will notice.

aston@ultrasw.c · aston@ultrasw.c's Garage

1" sounds like a huge difference: even for repair and driver weight combined!

what are the numbers: before and after?

If you don't have them, go back to the shop and ask them to put it back on the scales and show you. Something doesn't sound right to me.

Wil Ferch · 08-23-2010, 01:33 PM

Wildcat;

Not picking on you alone....but this sort of "mis-information"...when repeated over and over....will gain credibility when it shouldn't. That statement is simply false.

Sorry that offering corrections offends you ....but the case is such that it ends up being a false and perpetuated statement. Lets' use this board to get as many correct facts on the table as we can, as people tend to use the info given on these boards as being factual and correct, and others build upon these.

wildcat077 · wildcat077's Garage

Hey Will,

No problem,it's just that a lot of things could happen along the life of a 20 year old car,some good
and some not so good.I'm fortunate enough that my car only had two previous owners and the last one was a work collegue who owned it for ten years before he sold it to me ...

By the way i fought for a whole weekend to get the four corners somewhat balanced,even used your patented "Will Ferch Calculator" ... lol

I still have too many bodily mismatches on my car,oh well i guess when Hans and Franz hand assembled my car on a Friday morning in Stuttgart 21 years ago they must have been indulging in too many Schnapps at the Brauhaus the night before

Cheers !
Phil

Trackrash · Trackrash's Garage

Is there a 1" difference in the height of the FRONT as well? If the front is even then, yea its body work. Other wise take it back.
In my estimation the rear torsion arms should be even, (meaning the same angle on each side), so you may want to look at that as well.

Quote:

Do you have adjustable drop links on your sway bars? If not, the side-to-side height difference is preloading each bar making the corner balance inaccurate.

Good point on the sway bars.

jdawg · 08-24-2010, 03:22 AM

The front is dead even & it handles much better than before. Also the 1" difference is with the car sitting w/out a driver. So is the general opinion of you guys that it can be even on the back & still be able to be corner balanced & aligned? I would also like to thank all of you for your input on this site & to my posts. W/out Pelican Parts I would still be trying to figure out how to shift a 915 & how the #%@! freakin' heat works!!