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914World.com _ 914World Garage _ Corner Balancing a Twisted Tub ...
Posted by: SirAndy Apr 22 2006, 02:00 AM
so, McMark and i spent all day today trying to corner balance my tweaked and twisted tub.
i started out with all 4 corners the same ride-height. but the car felt awful. twitchy like hell and the left front always wanted to slide on me.
so, we got a bunch of scales and went to investigate.
almost 3/4 tank of gas and my fat ass in the drivers seat ...
the end result is still not perfect, but *much* better than before.
interestingly enough, now that the corners are balanced, the tub looks all crooked. 
i guess it makes sense, it's either:
- twisted tub, same ride height on all 4 corners, corner weights waaaay off
or
- twisted tub, corners balanced, tub looks bend.
we'll see how it holds up at the AX this AM, but it felt *much* better on the ride home from napa ...
thank you Mr. McMark!
here's a printout from the high-tech software we used to track the data ...
Attached thumbnail(s)
Posted by: SirAndy Apr 22 2006, 02:12 AM
oh, and btw. looks like my car comes in at around 2000lbs without me but 3/4 tank of gas ...
not too shabby for the gallons of bondo the PO threw at it ...
Andy
Posted by: McMark Apr 22 2006, 02:53 AM
Yeah, a nice set of scales from SMART is on my short list.
I had a good time and learned a lot.
Tomorrow morning we'll see if it was worth it. 
Posted by: r_towle Apr 22 2006, 09:01 AM
Ill have to say..
The graphics on that software is amazing.
The details and the ability to see all the data on one portable screen is perfect...
And I love the fact that the battery never runs out...
Nice job.
Would you mind showing us how you used scales...without the special racing scales....
Rich
Posted by: rhodyguy Apr 22 2006, 09:31 AM
did you alter the corner balancing after the alignment? where did you make the biggest move? the adj perches, up front, or a combo?
k
Posted by: Flat VW Apr 22 2006, 09:50 AM
My bookie runs that same software.
John 
The graphics on that software is amazing.
The details and the ability to see all the data on one portable screen is perfect...
And I love the fact that the battery never runs out...
Rich
Posted by: McMark Apr 22 2006, 11:38 AM
Would you mind showing us how you used scales...without the special racing scales....
Ghetto corner balance. It actually worked pretty well. Scales went up to 360+ lbs even though they were only rated for 300 lbs. $6 per scale on sale.
did you alter the corner balancing after the alignment? where did you make the biggest move? the adj perches, up front, or a combo?
The car was aligned when we started, now it's a little out of alignment. That the price you pay for night-before adjustments. The image Andy posted shows how obviously tweaked the chassis was. The left rear was above 600 lbs constantly, the front right was below 500 lbs most of the time and the front left/right rear were pretty stable and balanced at around 550 lbs. The left rear suspension pickup is probably tweaked downwards and the front right suspension is visibly tweaked upwards. So we made a lot of progress, considering the chassis.
Next step for Andy's car is the Celette Bench!
Posted by: SirAndy Apr 22 2006, 07:26 PM
Tomorrow morning we'll see if it was worth it.
well, what do you know? for some reason, we got it "dead on"!
weird bump-steer and random lane change is gone. it felt really nice on the freeway on the way home ...
then the AX today, well, what can i say, the car handled great! crisp turn in and perfect balance. even the (more or less random) sway bar setting was dead on. just a tad of oversteer, which is gud on a guttless 1.7L. felt like i had power oversteer, helped a lot in getting the car around those tight turns ...
i was only 3 secs of trekkor, which was plenty good enough for me ...
Andy
Posted by: SirAndy Apr 22 2006, 07:29 PM
and here's the fun part, this is *AFTER* the corner balancing, holy mother of bent tubs ...
Andy
Attached image(s)
Posted by: Qarl Apr 22 2006, 07:36 PM
quick question...
what does one do when corner balancing to "adjust" the weight distribution?
Does it involve adjusting spring height, torsion bar tension, etc.??
Just curious?
Posted by: SirAndy Apr 22 2006, 07:39 PM
Does it involve adjusting spring height, torsion bar tension, etc.??
yupp, all of that ... basically, move each of the corners up/down until you get the weight numbers on each corner you want.
BUT, it sounds much easier than it is, a good setup can be tricky, not to mention when the tub is bend ...
Andy
Posted by: Qarl Apr 22 2006, 07:42 PM
So what was your final distribution percentage Front/Rear?
Posted by: Andyrew Apr 22 2006, 07:46 PM
Wow andy... thats bent!
How was the difference in handling?
Posted by: SirAndy Apr 22 2006, 07:48 PM
So what was your final distribution percentage Front/Rear?
total weight, with me (~215lbs) and a 3/4 tanks of gas: 2210 lbs
front/back ratio: 46/54
still slightly heavier in the back, but i don't want to go any lower in the front and i didn't want to put that twisted back up in the air any more ...
car looks funny, but it handled great at the AX today ...
Andy
Posted by: Van914 Apr 23 2006, 06:48 AM
Andy,
The drivers side should be higher without you in the seat. Let's see a picture with you in the seat and compare.
Having the same issues,
Van914
Posted by: kwales Apr 23 2006, 09:10 AM
I agree wth Van, getcher butt in the car and reshoot the pics.
Van, your car looked perfect from what I could see. Shiny black paint and door gaps usually show up those kinds of issues.
Bet I have the same problem as you guys. Dang PO bondoed the right front wheel well and front bulkhead so I coudn't seee the ripples. 
Trying to come up with a ghetto method of frame checking and fixturing using my rusty spare car as an alignment baseline. It has many fewer miles and only one rear fender crunch, but a lot more rust. If it measures good, it could be used to make alignment fixtures off of it, and supply good unbent parts to fix my suspected bent car. Move the fixture to the bent car, and use it to "align" the new parts for welding. Kinda like a ghetto Cellete.
Ken
Posted by: rhodyguy Apr 23 2006, 09:23 AM
note the ds rear is high and the pass front is low. i would think the car will settle a bit with the driver's weight in the seat but more of a complete f to r side change. i'll look for my final alignment figures on the silver car after while. you two went through all of this just for an a-x? if trekor took off 2 plug wires and leveled the playing field i think you would've beat him.
k
Posted by: McMark Apr 23 2006, 10:17 AM
The car isn't going to sit level until it's straightened. Even with Andy in the seat it still looks funny. We went through the trouble because it was fun. Isn't that what these cars are about?
Posted by: SirAndy Apr 23 2006, 12:37 PM
The car isn't going to sit level until it's straightened. Even with Andy in the seat it still looks funny.
with the 250lbs springs in the back, even with me in the car it looks pretty much the same. the car doesn't move all that much when i get in the car ...and kevin is right, the car was hit in the drivers rear AND pass front, presumably at the same time ...
Andy
Posted by: Aaron Cox Apr 23 2006, 12:41 PM
whats it run to straighten a tub on a cellete fixture?
Posted by: Dave-O Apr 23 2006, 01:33 PM
That looks like a good idea for a corner blance on the cheap. How do you take into account for the motion of the suspension while the car is being lowered onto the scales? Does that bar slide easily on the scales?
Posted by: SirAndy Apr 23 2006, 01:52 PM
whats it run to straighten a tub on a cellete fixture?
your price or mine?
let me just say this, if i had to pay full shop hours ...
Andy
Posted by: Dr. Roger Apr 23 2006, 01:54 PM
Ok, I'll be the dingleberry to ask a dumb question....
If you lowered the LF and LR suspensions exactly 1" wouldn't you have almost identical weight numbers and a more level car?
Let the critisizms begin.... LOL....
Roger
Posted by: SirAndy Apr 23 2006, 01:54 PM
How do you take into account for the motion of the suspension while the car is being lowered onto the scales? Does that bar slide easily on the scales?
easy is not the word i would use but yes, we made sure everything was perfectly centered once the car sat on the scales.
we centered the bar on the scales, then centered the scales & bar under the tire, then moved the scales out/in along the bar until they both read the same.
Andy
Posted by: SirAndy Apr 23 2006, 02:00 PM
If you lowered the LF and LR suspensions exactly 1" wouldn't you have almost identical weight numbers and a more level car?
no.
it's not that easy at all. the car doesn't behave like that. two wheels in the diagonal will always form a plane on which the car "pivots".
so, it's either LF/RR or RF/LR and the car will pivot along that diagonal.
the trick is to get the other two wheels in a position where all 4 are in a plane and there's no pivoting going on at all.
and the *really* tricky part is to find that plane on a ride-height and front/rear balance that is close to where you want it to be.
this is a *very* tedious process because once you get close to all 4 wheels in one plane, even minute changes can have a big impact.
AndyPS: if i did what you're suggesting i *would* have a more leveled car, BUT the corner weights would be completely off!
read my first posts in this thread. that's exactly what i had when i started. car level. handled like shit. corner weights were waaaaaaay off.
remeber, the tub is bent.
Posted by: Dr. Roger Apr 23 2006, 02:07 PM
i understand planes and pivots.
so, hypothetically speaking, if your 4 wheels are now in a plane, won't you still have a plane if both the wheels on the left side are lowered thesame amount?
Posted by: SirAndy Apr 23 2006, 02:19 PM
i understand planes and pivots.
so, hypothetically speaking, if your 4 wheels are now in a plane, won't you still have a plane if both the wheels on the left side are lowered thesame amount?
yes, the *body* would be in a plane, but *not* the corner weights ...
i told you it isn't that easy ...
Andy
Posted by: SirAndy Apr 23 2006, 02:26 PM
yes, the *body* would be in a plane, but *not* the corner weights ...
to quote myself ...
here is what happens if i did that, lowering both the drivers front and rear. yes, the car would look more leved, BUT what would happen weight wise is that i would now have 3 (three) wheels form a plane, DF/DR/PR and the pass. front wheel would "hang" in the air with almost NO weight on it whatsoever.
this is *exactly* what we measured when we first set the car down on the scales!
i had the car leveled (same ride height on all 4 corners) but i always felt that in left hand corners, the pass. front wanted to move out on me (no grip).
when we measured the weight for the first time, the pass. front had almost no weight on it at all and the drivers rear was way heavier than any of the other corners.
basically, the car was sitting on the drivers rear corner with the drivers front and the pass rear forming a 3 corner plane and the pass front floating in the air.
but the car looked perfectly level. just handled like shit (doh!)
remember, the tub is bent ...
Andy
Posted by: (*)(*) Apr 23 2006, 02:34 PM
Have you asked Yeaman what it would cost to untwist it?
BTW...you ever sell those long studs you had in yer signature?
Posted by: SirAndy Apr 23 2006, 02:37 PM
Have you asked Yeaman what it would cost to untwist it?
BTW...you ever sell those long studs you had in yer signature?
yes and yes. sold the studs and scott yeaman is the only one i know with a celette bench AND experience in pulling 914s ...
Andy
Posted by: (*)(*) Apr 23 2006, 02:48 PM
So what did he say it would cost to pull it out right?
Posted by: Aaron Cox Apr 23 2006, 02:54 PM
So what did he say it would cost to pull it out right?
guessing 2 large
Posted by: SirAndy Apr 23 2006, 03:02 PM
So what did he say it would cost to pull it out right?
aaron is in the ballpark. doing it on normal shop hours is *expensive*. besides the need for an experienced operator, it's a time consuming process and time is money ...
Andy
Posted by: (*)(*) Apr 23 2006, 03:57 PM
Well as good tubs are getting more expensive. It may be worth it sometime soon.
BTW....if we ever have a WCC 07, I have a set of scales I'll bring and we can do a corner balance clinic. They are used for balancing heavy computers and I can "borrow" them pretty much any weekend.....
Posted by: Wild 6 Apr 23 2006, 04:40 PM
Andy,
Reset your ride heights and this time if you adjust the right front lower, adjust the left front higher. Same with the rear. All adjustments have to be made in tandem - this keeps the ride height level.
Posted by: SirAndy Apr 23 2006, 08:38 PM
this keeps the ride height level.
except .... if you have a twisted tub ...
guys, there is *NO* way to get this car Level AND Balanced at the same time ...
Andy
Posted by: J P Stein Apr 23 2006, 08:51 PM
We (Britian & I) just did mine. It was damn close to start out.
We lowered the drivers rear about 3 turns on the sleeve and bingo.
It took longer to set it on level scales that it did to balance it.
Raising or lowering any corner effects the other 3 weight-wise.
Posted by: Borderline Apr 23 2006, 08:58 PM
What did you do with the rear sway bar? IIRC it doesn't have adjustable links. If you just re-connected it, then you would preload the bar one way or another and that would change your corner weights. 
Posted by: trekkor Apr 23 2006, 09:05 PM
Well if everybody is doing corner balances now, sign me up. 
KT
Posted by: SirAndy Apr 23 2006, 09:13 PM
What did you do with the rear sway bar? IIRC it doesn't have adjustable links. If you just re-connected it, then you would preload the bar one way or another and that would change your corner weights.
good point. both swaybars were disconnected during the balance act.
i did reconnect the rear bar afterwards, i'm sure it shifts some weight around as it has to be under preload, the way the tub is bent.
Andy
Posted by: sean_v8_914 Apr 23 2006, 11:55 PM
Good persistent german, good job. I think you need adjustable drop links...or srtaighten your tub did you read john Roger's psot about his corner balancing results?
did you shave off any time?
Posted by: SirAndy Apr 25 2006, 02:02 PM
did you shave off any time?
can't tell. this was my first AX after i "downgraded" to a 1.7L ...
felt good. got within 3 secs of trekkor. biggest problem i had was that *tiny* gate right after the long right-hand sweeper.
my car is 10"+ wider than treks or nathans car and that gate only left me with 1" on each side and i was in 3rd at that point ...
3 out of 7 were clean, the other 4 times, i sent the cones flying ...
Andy
Posted by: Brett W Apr 25 2006, 04:06 PM
What are your cross weight percentages? That is what really matters. Pulling your tub back into shape should not be that expensive. I had a chassis done for less than 400$ and another car done for $300.
Posted by: byndbad914 Apr 26 2006, 06:04 PM
What are your cross weight percentages? That is what really matters. Pulling your tub back into shape should not be that expensive. I had a chassis done for less than 400$ and another car done for $300.
I totally agree - $2K for a straightening!? That seems way outta whack, though I have never had a "tub" car straightened, I had a friend's subframe car tweaked back after I put a monster 383 in it and he bent the car first day out with it. I think it was $500 including welding in subframe connectors. That is a few years ago, so maybe $700 now with some inflation, but not $2K.
Seems like Pcar guys get screwed left and right. Just like when I was quoting out my tube chassis build for my 914 - everyone in the "Porsche" world was quoting $15K plus with no custom suspension and I am having a baja shop do the work with custom suspension stuff for MUCH less. No custom suspension quote was less than half the $15K!!! And frankly, tubes is tubes - and AJs welding is hands-down some of the best I have seen and witnessed first hand. Apparently a little
makes for some steady welds 
Posted by: SirAndy Apr 26 2006, 06:22 PM
putting a car on a celette bench is not your normal body shop "pulling" ...
figure 8-10 hours times two worker-bees working the bench, normal shop-rate.
that is, if everything goes smooth. if not, more ...
plus renting the fixtures.
fixtures for the celette are about ~100 day.
that does NOT include stripping the tub ...
you do the math ...
Andy
PS: as i said, that would be your normal shop rate during normal biz-hours.
Posted by: r_towle Apr 13 2007, 11:58 AM
<!-- quoteo(post=664983:date=Apr 22 2006, 08:01 AM:name=r_towle) --><div class='quotetop'>QUOTE(r_towle @ Apr 22 2006, 08:01 AM)
</div><div class='quotemain'><!-- quotec -->Would you mind showing us how you used scales...without the special racing scales....<!-- QuoteEnd --></div><!-- QuoteEEnd -->
Ghetto corner balance. It actually worked pretty well. Scales went up to 360+ lbs even though they were only rated for 300 lbs. $6 per scale on sale.
<!-- quoteo(post=664996:date=Apr 22 2006, 08:31 AM:name=rhodyguy) --><div class='quotetop'>QUOTE(rhodyguy @ Apr 22 2006, 08:31 AM)
</div><div class='quotemain'><!-- quotec -->did you alter the corner balancing after the alignment? where did you make the biggest move? the adj perches, up front, or a combo?
<!-- QuoteEnd --></div><!-- QuoteEEnd -->
The car was aligned when we started, now it's a little out of alignment. That the price you pay for night-before adjustments. The image Andy posted shows how obviously tweaked the chassis was. The left rear was above 600 lbs constantly, the front right was below 500 lbs most of the time and the front left/right rear were pretty stable and balanced at around 550 lbs. The left rear suspension pickup is probably tweaked downwards and the front right suspension is visibly tweaked upwards. So we made a lot of progress, considering the chassis.
Next step for Andy's car is the Celette Bench!
I have a few questions, cause I am about to do this.
did you do all four corners at once? Do I need 8 scales?
Or did you jack up and move each corner one at a time...
Or front then back...
Please let me know...I gotta go buy some scales.
Rich
Posted by: McMark Apr 13 2007, 12:39 PM
You need 8 scales. Keep us posted on how it works for you.
Oh and you really should balance with your weight in the car. We balanced Andy's car with him in the drivers seat and me reading the scales.
Posted by: John Apr 13 2007, 01:17 PM
The only way to get an untwisted car to corner balance and have the chassis level is when the car is unloaded and on level ground.
When you add the driver's weight to one side, it will effect the way the car sits (when done, it will sit high on the drivers' side). If you want the car to look statically straight while parked, you do the corner balance while NO driver is in it.
If you want the best handling car, you corner balance with driver weight in the seat and the car set-up exactly like it will be run. The car may sit strangely (without massive springs), but it will be balanced and offer balanced handling.
just my $0.02
P.S. I only use 4 scales. My version of "Ruggles" scales offer a 4:1 ratio so a single 300# scale is enough per wheel.
Posted by: McMark Apr 13 2007, 01:42 PM
What do you mean sit weird? 
Posted by: r_towle Apr 13 2007, 01:47 PM
the nice part is I have three boys, all my size...
So that will be a non issue...sit here, be quiet..
I also have loads of free weights if they are busy.
Rich
Posted by: John Apr 13 2007, 08:10 PM
What do you mean sit weird?
Yes, Andy's car WAS twisted, and in that picture it does sit weird.
I would like to see a comparison with an AFTER pic of Andy's car after all the work has been done to straighten it an to make it go faster.
BTW, what did that car look like with ANDY sitting in it? Was it more level? (Just how much weight was in the Drivers' seat when it was corner balanced?)
Posted by: SirAndy Apr 13 2007, 10:24 PM
BTW, what did that car look like with ANDY sitting in it? Was it more level? (Just how much weight was in the Drivers' seat when it was corner balanced?)
all of my ~220 lbs in the drivers seat.
BUT, i run 250lbs springs, so the car actually doesn't move much when i get in.
even with me in the seat, it was still very much tweaked ...
Andy
Posted by: John Apr 13 2007, 10:46 PM
BTW, what did that car look like with ANDY sitting in it? Was it more level? (Just how much weight was in the Drivers' seat when it was corner balanced?)
all of my ~220 lbs in the drivers seat.
BUT, i run 250lbs springs, so the car actually doesn't move much when i get in.
even with me in the seat, it was still very much tweaked ...
AndyLet's see an after pic. Isn't it done YET???
Posted by: doper Apr 13 2007, 10:49 PM
Gents,
If you ever get to the mid west I have real nice alignment bench I'd be happy to let you use for a beer or two ..... if it would help ....
later
Posted by: doper Apr 13 2007, 10:51 PM
Umm .. I should specify ... northern mid-west ... although I send a crap load of time in KC I'm 800 miles north ...
Posted by: SirAndy Apr 14 2007, 12:12 AM
Let's see an after pic. Isn't it done YET???
nope, it's not done yet ...
and the corner balance is the second to last thing on the list, right before the alignment.
Andy
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