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Corner Balancing, Weight Jacking, Tripod Method

Just a real quick question regarding corner balancing in relation to the tripod method for the home user.

Where on the front of the car do I place the jack?

Do the front wheels come off and lower the front end back to the approx. height of 25.5 inches and thus begin working on setting the rear height?

Does the jack point have to be like a half of a steel ball to pronounce a teetering like position?

Where on the back to you place the jack?

Just need to complete this job ASAP before racing.

Thanks for any help!

86 911 Cab
Old 04-23-2005, 07:23 AM
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Hello,

I made a fulcrum for the front out of a 4x4 and some scrap metal. (Note the boards and metal used in the picture are all fastened/welded together so they won't tip over easily.) I suggest carefully marking what you believe to be the center of the car somehow because you may need to re-set it several times.





For the rear, just put the jack under the engine on the seam. Yes, the wheels need to come off of whatever end you are "tripoding". Be careful when all the weight in the back is up in the air.

Approximate the height you want on the fulcrum end of the car, but note that the height will not be exactly the same when you put the wheels back on. I just use the fulcrum as a relative tool for balancing left to right after the height is about where I want it.

I have had great luck using this method, and I do track my car.

Good luck.

Last edited by coloradoporsche; 04-23-2005 at 10:36 AM..
Old 04-23-2005, 10:33 AM
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Without scales?

If so, assuming the chassis is not tweaked and the torsion bars are not worn, you could use the tripod method to adjust each wheel on one end of the car to the same height. Approximate chassis balance should follow, but you cannot validate unless you can measure each wheel. However, this method effectively eliminates any height differences caused by a diagonally opposite wheel (it's easier to correct two wheels rather than four).

You could remove the sheet metal cover under the front crossmember and lift from there. Here's what I did to avoid removing the cover. I installed layers of flat aluminum bar stock, enough to span the space between the crossmember and the cover. Thus when lifting under the cover (with block of wood), the force transfers directly up to the crossmember.

You could roll the vehicle forward/backward on your floor jack from this lifted position to settle the opposite end, the end you want to measure. Yes, removing the lifted wheels allows the vehicle to rest at an approximate rolling height. In addition, the closer the floor is to level, the better. Detach a sway bar drop link from one side to eliminate any existing preload. Using adjustable drop links avoids reintroducing preload if the ride heights are not exactly the same (assuming the chassis is balanced). Of course with the tripod method, you will only approximate chassis balance.

Hope this helps,
Sherwood

Last edited by 911pcars; 04-23-2005 at 07:13 PM..
Old 04-23-2005, 07:09 PM
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I thought up about five different ways to perform this task. The sixth way was to have it done when I had my alignment done. I have to get it done again when I mount my new tires and wheels. Cost = $100 at the alignment shop.
Pat
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Old 04-24-2005, 06:09 AM
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Corner Balancing

Pat - I see you are from NJ. Could you recommend a shop for corner balancing and alignment?
Old 05-09-2005, 12:37 PM
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I went to Euro Tire in Fairfield. They did a really nice job. Where are you in the Garden State?
Pat
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Old 05-09-2005, 03:48 PM
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Unhappy Alignment

I live in Hillsborough just south of Somerville.

I'm looking to get the car setup for a semi track/street alignment.

Unfortunately, she is currently For Sale.


Old 05-10-2005, 04:08 AM
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When I did mine two winters ago, I didn't take my wheels off. I simple set the ride height around, then measured each corner when all four tires were on the ground. I jacked up one end and them remeasured the end that was still on the ground. If the side to side (Left/right) measurement differences did not change, then I knew that I was OK. For example, if the front of my car measured 25.5 (0" difference side to side) on each side and then I lifted it from the rear, and the new front side to side measurements remained a 0" difference (Obviously they wouldn't still be 25.5" with the rear in the air), then I knew that the rear heights were not influencing the front heights. If the measurements from side to side were 1/2" different from side to side with the rear end in the air, then I knew that the rear heights were effecting the front and I then slightly adjusted the fronts height and remeasured until they were even with the car in tri-pod mode.

I also track my car and since it brakes from 120mph in a straight line without pulling, then I know that the weights are not off by much. Much cheaper than the $400 I spent for the first corner balance years before.
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1980 Porsche 911SC w/ -22mm/28mm Torsion Bars | Custom Valved Bilsteins | 22mm/21mm Carrera Sway Bars | Elephant Poly/Bronze Bushings | Carrera Brakes | AJ-USA Brake Cooling | Carrera Oil Cooler w/ Fan | Elephant Strut Brace | Oh, and no ABS or PSM or A/C
Old 05-10-2005, 04:53 AM
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I wrote up a detailed (maybe too detailed) account of my home corner balance using the tripod. Search for "home + corner + balance" in posts by me if you're an insomniac ;-)

In short, I started with the rears, because they are harder to adjust and wanted to get them dialed in before doing the much easier fronts. Although I was aiming for 25"R and 25 1/2"F fender heights, I let the suspension heights from my (leveled) floor trump those if necessary. I removed the front protection pan and put a block of wood in my jack's pad, centering that block of wood under the crossmember's center point. I'd raise the front up until the front wheels cleared the ground and then remove them and lower the car back to near ride height. I wasn't so much concerned with the absolute height of the rear torsion bar covers, but that they were equal L-R when the fenders were close to 25".

Once the rear was done, I jacked the rear end up by the motor case and did the same routine on the front, using 25 1/2" as my target on the fenders. I got both front and rear to within 2mm L-R and took it to the scales. I was off by 19 lbs (LF and RR were high/heavy). I left it as-was and got the alignment done. It drives like a dream. I can't tell a difference from one side to the other when turning or braking.
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Old 05-10-2005, 08:45 AM
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In case anyone hasn't read this one (link attached), it is very enlightening and entertaining. My ride heights are uneven, and my weights are very close to 500/500/800/800. I don't have 10 pounds of difference anywhere F-F, R-R, or diagonal. I have to get mine done again due to tire, wheel and Elephant Racing bushings, and I'll spend the couple of hundred to do it.

* CORNER balanced - numbers from this...and the weight

Pat
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Old 05-10-2005, 01:55 PM
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Pat,
Not to be a wise guy, but did you remove the passenger seat and relocate the driver's seat in the middle? Otherwise, not sure how you could arrive at 50-50 L-R weight distribution.

I don't doubt your corner numbers. However, you quality your statement by saying your ride heights are uneven. That could be the explanation.

Sherwood
Old 05-10-2005, 02:20 PM
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Sherwood:
I recall you had a few responses in the linked thread. I also have the impression, after reading some of your past posts, that you know of which you speak, so I don't consider you to be a wise guy at all.

The essence of that discussion was equalization of the corner weights by weight jacking, as put forth by Randy Blayock. My fat little SC is weight jacked, and I also got a bit lucky. My stock sway bars were attached, thus introducing a measure of equalization to the side to side weighting. I also have a small battery (LF), A/C compressor (RR), no simulated drivers weight in the seat. It's a street car. My rear heights are around 24-1/2 both sides, rear, and around 24-3/4 and a bit under 25 in the front. I do not have the approximate 1/2 inch height difference F to R.

The jury is still out on the ride quality, as I am replacing the polygraphite bushings with Elephant Racing PolyBronze in the front. They really bind up badly, hence the replacement. I can say that I feel that there is a repeatability issue, which is why I'm going to have the balance done again. It was a PITA to balance with those front bushings. Enough such that there is a measure of doubt in my mind that the corner balance numbers will be the same.

I must also say that I am no expert at this stuff, but I am learning quickly.

Pat
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Old 05-10-2005, 04:19 PM
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Talking Corner Balancing

I completed the corner balancing using the tripod method last night with complete success.

I did not remove my wheels. Simply jacked up each end until the tires came off the ground. Worked like a charm.

Car sits perfectly and handles nicely. Just need to dial in the camber and toe setting for front and rear.

An alignment question: Does anyone use even camber settings all the way around the car and/or more camber in the front?

Tis a tedious task to set up the alignment but rewarding when you make a setting change for the better. Nothing better than learning by making mistakes. You can only blame one person.

Thanks for all your guidance.




Russ
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Old 05-11-2005, 02:58 AM
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Congrats - anyone else think pic's would be appropriate? -C'mon Russ! Get that camera out.
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Old 05-11-2005, 05:43 AM
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Russ,
When you adjusted ride height using this method, did you remove a drop link from the sway bars to disconnect L and R?

We need a guinea pig. Someone like Russ who tripod-balanced his car, then test it with some weight scales to see how close it is. This approach may suffice for the majority who aren't as anal as the minority of us/you guys.

Sherwood
Old 05-11-2005, 09:57 AM
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Quote:
Originally posted by 911pcars
Russ,
When you adjusted ride height using this method, did you remove a drop link from the sway bars to disconnect L and R?

We need a guinea pig. Someone like Russ who tripod-balanced his car, then test it with some weight scales to see how close it is. This approach may suffice for the majority who aren't as anal as the minority of us/you guys.

Sherwood

Sherwood - I just did this a month ago and went to the scales before aligning. I was *only* 19 lbs off - close enough for me, so I left it and did the alignment.

Here is the full write-up. Home ride height and corner balance success story
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Old 05-11-2005, 10:06 AM
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Russ, from your previous link:
".....It's really a 38 lb difference, but could be remedied by dropping the LF/RR a small amount, moving 19 lbs off of that plane and onto the RF/LR plane."

That was my thinking as well. Lowering LF/RR to shift some weight to RF/LR as you suggest also helps even out the front-to-rear weight proportion on each side of the car. If it's convenient to do (adjustable), I'd go ahead and do it, especially with good friends at Hunter. Good job and informative.

Thanks,
Sherwood
Old 05-11-2005, 10:22 AM
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86 911 Cab Pictures

I will try and rap some peek-chores off tonight for ya's.

I did drop the link off the rear and also greased the sway bar bushings in the front to help the binding issue.

Since I am going to be buying, fixing, and selling Porsches I am seriously thinking about purchasing the weight scales. I just saw it being done at someone' gargage to a Porsche Race car. You can get super exact on your weight distributions.
Old 05-11-2005, 10:33 AM
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Pictures

1986 911 Cab Prussian Blue
Old 05-11-2005, 01:35 PM
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HELP!

I'M Going out of my mind!

I completed the corner balance and alignment to the following:

1.5* of neg camber all the way around
full caster

1/16 toe in rear and front

Maybe someone can explain this to me. I built my Mustang to handle like it was on rails and it actually handles this way. Flat and predictable with instantaneous steering response.

I have factory everything, torsions and sways.

I used to have Pirellis all the way around to stock specs 205/225
I recently went Fuzion 225/245. Here's what happens: turn the steering wheel as if in a slalom and the rearend snaps to respond to the front steering request about a 1/2 second later. The car feels flat when turning and cornering but the overall feel is unresponsive and mushy.

I'm running 36 lbs and 38lbs of air.

Maybe I'm a perfectionist but I think and hope that a Porsche would handle better than a Mustang. And I realize that these are completely different cars.

My assumption is that the Fuzions can not handle the Porsche setup. Or the plus tire sizing contributes to a mushy feeling. Ther Pirellis felt tight with no sidewall give.

I just wanted to ask the question before replacing new tires.

Has anyone tried Fuzion tires?

Thanks

Russ
Old 05-11-2005, 02:57 PM
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