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:o SmileWavy

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.


http://forums.pelicanparts.com/uploa...1114280852.jpg


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.

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

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

Corner Balancing
 

Pat - I see you are from NJ. Could you recommend a shop for corner balancing and alignment?

I went to Euro Tire in Fairfield. They did a really nice job. Where are you in the Garden State?
Pat

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.


:o :( :(

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.

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.

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.

http://forums.pelicanparts.com/showthread.php?s=&threadid=212875&highlight=corner +balance

Pat

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

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

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.


SmileWavy

Russ
86 911 Cab

Congrats - anyone else think pic's would be appropriate? -C'mon Russ! Get that camera out.

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. http://forums.pelicanparts.com/showthread.php?s=&threadid=213694&highlight=home+c orner+balance

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

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.:p

Pictures
 

1986 911 Cab Prussian Bluehttp://forums.pelicanparts.com/uploa...1115847302.jpg

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?:confused: :)

Thanks

Russ

PP
I think you need to check the factory specs for alignment, and adjust from that baseline. How did you get your alignment precise to those numbers? Did you change the ride height when you changed the tires (larger diameter tires)? My novice opinion is that if you have a Mustang that handles better than that Cab, you have a problem.

Pat

Actually, I'm running the Fuzions in back (245/45/16) - and only on 7" Fuchs. They are fine - nice and stiff.

The only reason they're 245's is because they were on the Fuchs when I bought them recently, but I like them.

Air PRESSURE
 

Mushy unresponsive feeling SOLVED!

Are ya ready: tire pressure too high.

This morning I brought it down to 29/31 lbs

Just with this difference in air pressure the car responds immediately.

These tires are sensitive to air pressure.

YE-HAW:) :D SmileWav
__________________________________________________ _
Anyone have a recommendation on sizing sway bars for front and rear? I have new HD Bilsteins in front and new yellow Koni's in the rear. I would like to have a nice matched set.

Thoughts?

If I'm asking to many annoying questions, please let me know! I'll stop.SmileWavy

Matched set of shocks or sway bars?

Not sure this combination is in the archives. If you stay with one brand (of either), there's lots of info in the records according to your car and driving conditions.

Sherwood

Thanks for the easy to understand tips on this method, guys.

I did mine last weekend and found that I had a serious problem with the rear height even though it looked great and was set evenly. I was experiencing front wheel lockup on braking and a strange pull.

It took me several times to get the rear where I wanted it and the front was close. The car is incredible now. It really feels totally different. The pull is gone and it brakes almost perfectly straight. The whole car just feels like it's working as it should.

I believe the problem was the DS rear was not weighted properly with not much "downforce" to the wheel. Another benefit is that when exiting a left hand corner the DS wheel doesn't just turn to smoke. You can feel both tires diggin in and she just squast and goes. Sweet.

I'm just embarrased that I hadn't tried this method before now.

Thanks again!!!

Hey guys, just wanted to update everyone that a couple months ago I asked my mechanic to place my car on the scales as I have always been curious how close my weights were after using the tripod method several years ago. Well, the cross weights were within 25lbs!!! He told me that he struggles to get them that close using scales. Obviously, I was a bit lucky, but I think that proves that the tripod method works. The key is lifting your car in as close to the center as possible at each end. Good luck to others that will try this.

reviving this thread to life as i just did this tripod method last weekend.
don't know if it's placebo effect or not but i think the car drives much better. feels like all four tires sticking on the ground much better.
i measured the height rear and front both at the torsion bar covers. got L-R within 2mm. when i measure the fender height, L-R is much more different...like 5+mm. i hope it's because the car is 26 yrs old...i'd try not to worry unless someone tells me i should.

I have questions:

Q1: when i was tripod'ing, i did not take the wheels off. So i was measuring the height at slight more angle than when you'd take the wheels off and level the car to normal ride height. should i worry about it?

Q2: I also did not loosen the sway bars at the drop link. got lazy about that. should i worry?

Q3: I also got lazy and was lifting the car at the front condenser protection bar. I had 2x4 across the length of the bar so i did try to distribute the weight across the bar but would it be too risky? if someone damaged the car this way, please let me know. To lift the car at the center, i had a slit at the center of this 2x4 and had 3/8 extension bar - 10 inch long - between the 2x4 and the jack pad.

happy friday!

Q1: Method is not to set ride height but to eliminate the opposite end from affecting the other end while observing each corner. You want LF and RF to be the same/close. Same objective at the rear. You can always rotate the torsion bar adjuster(s) to set front ride height.

Q2: I would have disconnected one drop link first. It's better to have adjustable drop links, but if the front corners are the same, no problem.

Q3: The condenser protection bar mounts onto the front torsion bar cover, yes? Not sure how many times you can lift from there without fatiguing the bar brackets.

To lift the front end from the center of the vehicle, I permanently stacked aluminum spacers (~1x10" flat stock) on the sheet metal cover of the crossmember, enough to span the normal space between it and the crossmember. Lifting at the cover now lifts the front end at the crossmember. When lifting, use a wooden block on top of the floor jack.

If the car sits too low, use another jack at the side receptacle - take it high enough to slide the floor jack underneath. All you gotta do is lift high enough to some air space under each tire.

Or use a length of 2x4 spanning both front torsion bar covers, then lift at the center.

Sherwood

@Sherwood,
thanks. makes sense.
I'll try to see if i get any different measurements by disconnecting sway bar drop links tomorrow. that way should clear up my concern.
to lift the front, i agree, it's way safer to use the sub frame or the torsion bar cover. i'd get another, longer 2x4 and lift it off the covers. i just need to get un-lazy and have the car drive up on ramps or something to get the jack slide underneath the 2x4.

and i forgot another one to ask...

Q4: do i still put some weight on the driver seat when doing tripod method? I'd have to think about how... i really want to avoid something like "hey honey could you come down to the garage for a minute please?"

Q4: Yes. Place an equivalent amount of weight in the driver's area (cinder blocks, sandbags, exercise weights, etc.). The tripod method, as explained before, merely verifies front corners and rear corners are not affected by the opposite end which may have a corner out of whack.

Sherwood

I have used this method as well. I believe if you are careful it will do a good job. Of course I'm not at the top levels of racing where perfection is needed. I do regularly autocross and DE the car and It brakes and handles evenly.

I would like to share my modified method.

I start by adjusting the rear torsion arms to exactly the same angle with the rear jacked up. Then check to make sure they are still at the same angle with the rear on the ground and the front jacked up. I then go on to adjusting the front.

A couple of thoughts.

Some time ago Chuck at ER suggested in a thread here of doing the tripod method from the sides.

This just uses the normal jack holes. He suggested removing the wheels from the side jacked. Then measure from the point near the torsion bar ends to the ground. Then do the opposite side and look for the same measurements.

With the distance between the wheels being greater I would suspect it could be a little more accurate.

It should be noted that alignment can have an effect on ride height. Caster to some degree and camber can affect it a far amount. I got my car close using the tripod method, then had it aligned. Then I went for my finish corner balance but was careful to maintain my original heights as alignment will change with height changes.

Of course air pressure must be checked and the sway bar disconnected or it will fight the balanceing efforts.

Chuck M's method sounds interesting. With this, the height measurements, if I understood it correctly, have to be done by subtracting the hub center to floor length from torsion bar cover to floor length, correct?

I went back doing the tripod again.
This time, I disconnected the rear sway bar drop link. Also, took the wheels off up front and tried to lower the car. my findings were: sway bar was not affecting the measurements as there seems to be no or very small pre-load on the sway. but i feel good i found this out. another finding was that the taking wheels off to get the angle close to flat was not affecting the measurement results. this was also suggested by Sherwood and I just went doing experimenting this to convince myself.
front, as i have stock sway, i just left the sway alone as many suggested. This is good enough for me for now for a DD with occasional DE car.

I went on to measure alignment (toe, camber) using strings and had interesting observations. I'll post questions in another appropriate thread.

If your tire pressures are accurate you probably do not have to subtract the hub center. Just measure up to the chassis from the ground.

On a couple of 911's I did the front and back method. With the sway connected it seemed that any adjustment seemed to not have the sensitivity to adjustment I expected. Again, the sway bar can fight you.


There is a gauge called a Hydraulic Wheel Load Checker I read about here before. I suspect with this approach we can check our balance without disconnecting the sway bar.

See:

Hydraulic Wheel Load Checker

http://forums.pelicanparts.com/porsche-911-technical-forum/58329-corner-balance-without-scales.html#post379405

when you are lifting by the side jack points, how do you ensure you are lifting to the same height left and right? I'm trying to envision how this method works. So, you lift by the right jack point to a certain height. you go to the left side and measure the height of torsion bar covers front and rear respectively. you come back to the right, lower the car, go back to the left, jack up at the point to raise the left side - but by how much? then you go to the right side and measure the torsion bar covers front and rear respectively. you compare the readings from left and right and adjust heights accordingly. am i making sense or am i missing something? when you do this, you have to ensure you are lifting the side by the equal amount to compare apples to apple. how am i ensuring this?

i might be picturing something totally wrong... help... :-)

If the sway bar remains connected to a suspension corner and that corner is lifted independently, the sway bar will twist and exert its force on that corner thereby affecting (changing) the true weight supported by its spring (torsion bar).

Sherwood

@Sherwood,
this totally makes sense!

If you leave the sway bar connected and lift by the rear it is going to effect things to.

Myself, I would not attempt any balancing efforts using any method with out disconnecting the sway bar.

The exception might be with the wheel lift gauge I noted. Still, better to disconect.


As to lifting height from the side, you probably just want to make sure both sides are lifted the same amount off the ground. If you are off an inch on one side it probably is not going to effect your ground to chassis measurement on the side being worked on.

I think the wheel base is almost 90 inches and the wheel width at the center of the tires is about 55 inches. Thus, I would think lifting from the side would be more accurate as the balance is spread over a wider stance. On top of that each wheel is adjusted for a specific value, not a balance on a car that is not balanced to begin with.

I have to say I have not tried the side balancing method. I have tried the front/ rear method and it just did not feel that sensitive to adjustment. Especially when doing the front. However, I did not put anything under the tires so they could slip to keep them from introducing side load that might have an effect. I did push up and down on the fenders with my adjustment efforts to overcome sticktion but the final result seemed a guess at best.

With the side method and using a floor jack, I suspect there would be little worry about the tires and maybe even the bushings loading up and effecting one's efforts.

Still not a match for a set of corner balance scales and adjustable sway bar drop links.

I am just trying to figure this out like most of us so this is just a discussion.

One's wheel spring rate is a combination of mostly the torsion bar and the sway bar. On the 86 and later cars the front torsion bar is about 19mm and the sway bar is 22mm. I belive the front sway bar becomes half of the front's spring rate. This could be a big effect.

At rest it might be possible to have a car look balanced with the torsion bar adjusted say +50 lbs heavy and the sway bar -50 lbs light. On a set of scales or if lifted by the center of the opposite end the car might look balanced.

However, take that same car and lift one wheel say 3" and test it's load and then the other sides the same amount and test its load and the difference should then probably show up.

This is why I wonder if we can leave the sways attached using this method more so that any other approach.

Still better to disconect the sways when ever ballancing.