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-   -   Okay, might have solved the DIY corner balance/alignment (http://forums.pelicanparts.com/porsche-911-technical-forum/838166-okay-might-have-solved-diy-corner-balance-alignment.html)

ZOA NOM 11-15-2014 09:26 AM

Quote:

Originally Posted by winders (Post 8354861)
Except that you are making assumptions that are just not true. A perfectly level 911 is not very likely to be balanced. If a 911 was a perfectly rectangular solid object made of one material with consistent density, your method would work. But, that is not the case.

Yes, corner balancing is performed by adjusting ride heights at the corners. But, weight is not distributed evenly side to side along the longitudinal centerline of the car. That is why some sort of real balancing needs to done.


Of course there are some considerations. This is a DIY method, for your garage, without scales. That was the premise from the beginning of the thread, Scott.

You level the car when you put it on scales, right? With all the variables you mention, you still end up adjusting the ride height to balance the car. If more weight needs to be on a corner, it will likely measure a different delta between the t-bar and the hub at that corner. Once balanced, even on scales, I'm guessing the measurements will be very close side-to-side.

It will get you as close as the tripod method, which relies on the same variables.

winders 11-15-2014 09:40 AM

No, the tripod method actually does some balancing. Your "method" does not.

Let's be clear. Your method has nothing to do with corner balancing because you are doing no balancing.

ZOA NOM 11-15-2014 10:28 AM

Ok, explain how they differ.

Quote:

No, the tripod method actually does some balancing. Your "method" does not.<br>
<br>
Let's be clear. Your method has nothing to do with corner balancing because you are doing no balancing.

DaveMcKenz 11-15-2014 10:40 AM

Hi Zoa,
I do like your ingenuity. Basically you are providing the car with a level stance and access to the alignment nuts. That setup ignores several factors that I believe are important for alignment and corner balancing. If you had an old fashioned service pit, and perfectly level ground you would accomplish the same thing. You have left out slip plates for camber adjustment, and you have made the assumption that equal ride height (difference from factory references) would give equal corner load. I think the last two omissions will give you only very approximate results. There are just too many assumptions that will not always be satisfied, and maybe never are.
Thanks for the great ideas, and I hope that you can perfect your method to take these short-comings into account.
Good luck,
Dave

boyt911sc 11-15-2014 10:56 AM

Corner balancing terminology..........
 
Quote:

Originally Posted by winders (Post 8354912)
No, the tripod method actually does some balancing. Your "method" does not.

Let's be clear. Your method has nothing to do with corner balancing because you are doing no balancing.



Hi Guys,

I've been following this thread right from the very beginning with one (1) post only by the OP and grew over the past days. The concept introduced by ZOA NOM was very interesting specially when he stated about corner balancing. I read and re-read each post by the OP waiting for the trick regarding "corner balancing".

It seems that ZOA NOM has inadvertently used the term "corner balance" for corner height alignment. I performed my own wheel and car alignment using laser beam and the result was very satisfactory. My garage floor is not leveled like most floor garages with a slight slope for water to flow out. So I built four (4) adjustable stands or tables for the tires to sit during alignment. Setting the wheel alignment and ride height for a "perfectly" leveled car won't mean it is correctly "corner balanced". But the car was "corner aligned".

In my humble opinion, the confusion began by using corner (weight) balancing and corner (height) balancing/adjustment by the OP. These are two different things. If ZOA NOM's technique could really do the "corner (weight) balancing" for 911 cars as he claimed, I bow my head to him and praise him for his novel technique.

Tony

ZOA NOM 11-15-2014 11:45 AM

I appreciate the kudos. Can someone explain how one might adjust the corner weights, and if you properly adjust them, what will the resulting ride height measurements be relative to each other?

Elombard 11-15-2014 11:51 AM

Yeah you have to tripod or use scales. You have to eliminate the effect of the spring on the right front on the left rear and vice versa. Just having it level does not = balance. After you finish everything else stick a jack stand with a point under the front x member (center) and see if the measure downs are the same in the rear. Adjust as needed. Dont forget to get the height at the front roughly correct or it shifts weight to the back un-evenly.

It will probably not be level ride heights when its Corner balanced.

ZOA NOM 11-15-2014 12:55 PM

Quote:

Originally Posted by Elombard (Post 8355041)
It will probably not be level ride heights when its Corner balanced.


Interesting. I wonder why the book calls for equal ride height settings with a full tank and driver in the seat? I guess I'll find out.

At the very least, I can simply convert this method to the tripod by jacking either end in the middle. It's the access under the car, and the ability to level it that is key to the method.

Elombard 11-15-2014 01:02 PM

I think what happens is that (especially when you run stiffer t bars) a corner can be off 100 lbs and you cant measure accurately enough to see it. But you can easily adjust 100 lbs out corner weighting and it will be noticeable to a decent driver. Particularly I think under threshold braking. Also when you tripod you can see much smaller amounts of weight differential.

I agree the access here and ability to set level that are a huge bonus.

ZOA NOM 11-15-2014 01:19 PM

Quote:

Originally Posted by Elombard (Post 8355138)
I think what happens is that (especially when you run stiffer t bars) a corner can be off 100 lbs and you cant measure accurately enough to see it. But you can easily adjust 100 lbs out corner weighting and it will be noticeable to a decent driver. Particularly I think under threshold braking. Also when you tripod you can see much smaller amounts of weight differential.

I agree the access here and ability to set level that are a huge bonus.

Well, I certainly appreciate your feedback. The stiffer bars explanation makes some sense. It will be interesting to see how much it's off.

I'll post the numbers when they come in. I'll also post the numbers when I get it on some scales.

winders 11-15-2014 01:20 PM

Quote:

Originally Posted by ZOA NOM (Post 8355125)
Interesting. I wonder why the book calls for equal ride height settings with a full tank and driver in the seat? I guess I'll find out.

Because that is what looks best.

The weight of the car is not evenly distributed side to side. How could the corner balance be right if the car is perfectly level?

ZOA NOM 11-15-2014 01:33 PM

Quote:

Originally Posted by winders (Post 8355158)
Because that is what looks best.

The weight of the car is not evenly distributed side to side. How could the corner balance be right is the car is perfectly level?

You didn't read the thread closely. The car was leveled at the hubs. Weight was added to the driver seat. My assumption was that once that was done, the factory ride height numbers would provide a balanced car, since there is no way to corner balance the car without adjusting the ride height adjusters. The assumption I made was that the measurements would be accurate enough to get the corner balance as close as the tripod method. I was envisioning a plumb-bob dangling from the roof inside the car, with it finding the CG when the corner balance was achieved by adjusting the four corners.

Having said all that, Erik's comment re the accuracy of the adjustment vs measuring it makes sense, so I will concede that converting this method to the tripod is probably the way to go. In the end, the ability to level and have access under the car, when you do not have scales, or a level garage, for the cost of four relatively cheap jackstands is something unique and worthy of mention.

winders 11-15-2014 01:49 PM

No, I read the whole thread. Like boyt911sc, I kept waiting for the balancing aspect of your method. It never came along.

And you keep making the same incorrect assumption. The weight of a 911 would have to be evenly distributed side to side with the driver in the car for your method to have any hope of getting close to properly corner balanced. That is not the reality of the situation.

From a performance perspective, adjusting the corner balance of a car is far more important than having the car perfectly level. Which really is unimportant.

boyt911sc 11-15-2014 01:56 PM

I admire your determination........
 
ZOA NOM,

I'll give a simple example where most people would have no problem following the logic. Let's say you have a rectangular and symmetrical dining table with about 30" long legs. Same length for all four legs and the dining floor is flat and leveled. With nothing on top of the table, the individual leg would exert an upward force equal to 1/4 of the total weight of the table. For demonstration: one bathroom scale at each leg of the table would show the weight (load).

Now, your wife is ready to serve dinner for seven (7) people including your guests (in-laws) for Thanksgiving Day dinner. If the food, tray, fruit bowl, plates, were spread out randomly on the dining table, the bathroom scales (4) would register most likely four (4) different weights. The total weight is the weight of the table plus the weight of the stuff placed on top of the table.

Now to corner weight balance the table (exaggerated) to the desired weight distribution you could either do:
a). Re-arrange the stuff on top of the table.
b). Adjust the length of table legs accordingly (impractical).

Now you have a corner weight balanced dinning table. Silly, but this a simple way to show you what a corner weight balance is about.

Tony

ZOA NOM 11-15-2014 02:00 PM

Quote:

Originally Posted by winders (Post 8355183)
No, I read the whole thread. Like boyt911sc, I kept waiting for the balancing aspect of your method. It never came along.

And you keep making the same incorrect assumption. The weight of a 911 would have to be evenly distributed side to side with the driver in the car for your method to have any hope of getting close to properly corner balanced. That is not the reality of the situation.

From a performance perspective, adjusting the corner balance of a car is far more important than having the car perfectly level. Which really is unimportant.


I guess I wasn't clear. The method is not to make the body of the car level. It is to level the car at the hubs, and provide access to the adjustments. I understand corner balancing. The mistake I made was assuming the factory numbers represented a corner balanced car. Thanks for your help.

winders 11-15-2014 03:00 PM

Rick,

That level setup you get to with what your doing is a great starting point. But then the car, if you are racing it, needs to be corner balanced. Of course, your competitors would be happy if you stopped at level!

ZOA NOM 11-15-2014 03:15 PM

Quote:

Originally Posted by winders (Post 8355277)
Rick,

That level setup you get to with what your doing is a great starting point. But then the car, if you are racing it, needs to be corner balanced. Of course, your competitors would be happy if you stopped at level!

Completely agree. I don't have the budget for a set of scales at the moment, so I intend to start here. As you know, I do race the car, and I'm not stopping here... :D


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