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  #16 (permalink)  
Old 11-15-2006, 10:38 AM
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This past weekend I supported the car on jack stands under the rear axle and the front lower A-arms close to the lower ball joints. Then laid out a 6 ft by 15 ft rectangle around the car and centerline based on plumb points off the original chasis. The original chasis is square to the point the front clip was welded on.

By further plumb measurements the front clip appears to be skewed: the lower left (drivers side) ball joint grease fitting is 13/16 further foward on the drivers side and the clip is 1/4 inch offset toward the passenger side. At the end of the clip side rails where the front sheet metal is attached, the clip is 1 inch offset to the passenger side. The sheet metal is centered on the center line howewer.

One thing that doesn't add up is that the lower A-arms are angled down 3 degrees toward the front but the caster as measured by the alignment shop is 12 degrees positive. Aren't these contradictory?

From what I understand, the caster problem could probably be corrected with adjustable or offset upper control arms, but is there any what to address the skewness without taking the frontend apart and repositioning the clip?

The good news is I am retired and have time to work on this, the bad news is I don't have the equipment so will have to farm it out. Maybe the local street rod club can steer me to the right people.

John

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  #17 (permalink)  
Old 11-15-2006, 02:27 PM
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As far as caster- it's the angle from vertical (in the front to rear side view plane) between ball joints- if that makes sense. Think of turning a motorcycle or bicycle front wheel/ fork back an forth. This has allot of positive caster. A shopping cart front wheel when pushed forward has allot of negative caster.

The lower control arm being tilted can effect anti-dive/ pro-dive but the caster is adjusted independent of this.

13/16" is allot. I know it's obvious- but have you checked if either control arm or subframe is/was bent and double checked all measurements? Also where did you take measurements off of the original frame? I'm thinking a '39 Olds frame could be quite a bit "off" from the factory.

As for the 1" shift to passenger side, maybe frame was offset so the driveshaft runs straight back (when viewed from the top)...

My experience in stinging a car is on my DIRT modified (tube frame), we square the axles and take all measurements off of the rear motor plate/ firewall, so you can still line things up if the frame's a little tweaked. Hopefully somebody with more experience with stock frames could help you out with the measurements.
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  #18 (permalink)  
Old 11-15-2006, 03:15 PM
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If it was me in your situation, I would find a shop with a frame machine and a tech who can actually run the machine on the fly. see just how far out you are with the wheelbase discrepancy and the side shift. Measuring the car on the floor is OK, but there are more accurate ways.

From your measurements it sounds like you could cut loose the passenger side frame to clip joint, lengthen it 13/16" and reweld and that would bring the front frame horn over about that much and it would put the 1/4" side shift of the frame back into alignment.

That would make your front wheels fit better in the fenders also.

You could cut and shorten the drivers side with the same effect,but you will put the wheels back into the wheel openings further than they are already.

If you do either of those micky mouse fixes, you will halfway to cutting the whole clip off and doing it right.

It will do nothing for your caster angle problem though. If, after you cut it loose on one side , and you do put it up on a frame machine and you can get the guy to push on the frame at the welded joint, IF it doesn't break the weld, you might get the lower control arm angle back where it is supposed to be.

then you can put some new springs back in to raise up the car again. And try to rectify the excessive caster..

Have you double checked the caster at another FEA shop to see if the first guy was right?

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  #19 (permalink)  
Old 11-17-2006, 08:22 AM
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Just nitpickin here. What you describe is not oversteer. Oversteer is when the car turns more than the wheel turn says it should. It is what happens just before you spin out. Understeer on the otherhand is what happens just before you hit the wall headon.
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  #20 (permalink)  
Old 11-17-2006, 12:19 PM
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Is it possible they put the upper control arms on the wrong sides of your car? On metric circle track cars sometimes people do this to gain a ton of caster while using "stock" components. The "straight" side of the upper should be to the front of the car and the "angle" side should be towards the rear. Just a thought.
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Old 11-17-2006, 01:21 PM
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Koolaid,

Swapped A-arms -- didn't realize that was possible.

I have added a picture of the drivers side A-arm to my photo gallery. I can't tell which is the straight side and which is slanted.

But, note that the front edge in the picture has had some metal trimmed from it to allow tire clearance. Just another example of what was done to this car without thinking. I belive they had some extra wheels from the shop mounted on the car to move it around and they rubbed. There is no reason stock wheels should rub on this stock front suspension. My Vintec wheels have 3.75 inch backspace I believe. Stock might have been 4.00 inches.

Also, what is a metric front suspension? The clip is from a 1988 RWD Cutlass -- would this be metric?

John

John
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  #22 (permalink)  
Old 11-17-2006, 01:45 PM
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John - sure looks to me like they put the left upper on the right and the right upper on the left. Look dead on at your picture - see how the back of the arm is almost perpendicular to your frame? This should be the front edge.

A "metric" is kind of a common/slang term for the G-body cars from 78~87 (guess there were a few 88's in there too). This would be the Monte Carlo, Cutlass, Regal, and Grand Prix. These are very popular for stock car racing.

Hopefully this is good news for you - a little cheaper then re-clipping the car!

I can post a picture tonight if you'd like of how the arms should look for verification - my stock car is sitting in the barn with all front sheetmetal off of it.
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  #23 (permalink)  
Old 11-18-2006, 07:16 AM
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Koolaid,

Sure, I would like to see a comparision picture. But, unfortunately, I might still have to reposition the clip due to it being skewed.

John
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  #24 (permalink)  
Old 11-18-2006, 01:04 PM
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I believe Powerrodmike and Techinspector have hit it right on the nail.\
When they welded the clip on they didn't put the clip parallel with the stock frame.
When viewed from the side it will give the appearance of the frame being bent up at the front. \
Outside of tire rake the bottom of the front crossmember should be parallel to the floor. yours most likely shows a noticable drop to the rear.

I've run two vehicles over 100k each with Camaro/nova stubs. a 48 chev pickup and a 51 Mercury. Personally I prefer the rear steer stub as it allows for a cleaner installation. Yes the steering column to box is a challenge that has to be delt with but you don't have that scab hanging out in front of the crossmember.
I wouldn't waste my time or money on band aid fixes. As PRM noted the correct way is to cut it off and redo it. Also the least expensive in the long run.

To put the clip on correctly
1. Level the stock frame at the ride height that you intend the car to sit at.
This is fore and aft along with side to side. Don't worry about rake at this time.
2. level the clip at it's stock ride height. You want it to sit exactly as it would
on a the stock vehicle that it came from.
You can compensate for a difference in tire diameter if needed.
Again this is side to side and fore and aft
On most of these frames the bottom of the front crosmember will be between 6 and 7 inches off the shop floor. (when we did the Merc we measured a stundent's Nova that had stock wheels and tires to get the desired measurement.

3. do all of your normal measuring and fitting as mentined in above posts.
Square. centerline and fitup.
4. Tack it in place with enough welds to hold everything but don't over do it
at this time.
5. Check everything for fit and correct angles. At this time I think I would
set the engine and trans in and fit the front sheet metal.
6. If everything meets your satisfaction, pull the sheetmetal back off, lift the engine back out and do the finish welding and plating.

I know this was a bit long winded. I taught high school automechanics for 13 years and before that I specialized in front end work and wheel alignment in tire stores and Pontiac dealersips.
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Old 11-18-2006, 06:23 PM
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I am convinced the front A-arms were installed on the wrong sides after being rebuilt. In my photo gallery, the first picture shows the driver's side A-arm in its original position with the rolled up edge to the rear.

The first picture on the lower row was taken last weekend and the flat edge is mounted to the rear and the trimmed front edge is rolled.

So that's part of the problem.

Is it a pretty easy wrench job to remove the A-arms and swap the sides? The ball joints and springs stay intact, right?

John
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  #26 (permalink)  
Old 11-19-2006, 02:32 AM
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It is easy enough,

I take it that the car has the engine in it. you need the weight to keep the springs somewhat compressed.

Jack up the car with the jack under the lower A frame as far out towards the spindle as possible.
you are going to want to have both sides jacked up at the same time.

Make sure that the car is solidly supported and I would reccomend putting blocks under but not touching the frame about even with the front edge of the doors ( if the jack or block or stand under one of the lower A arms slips the car will still be supported.

Take out the cotter key in the upper ball joint stud and loosen the castle nut several turns. take a large hammer (I use a 2 lb machinests hammer) and hit the side of the spindle where the stud goes through it with a solid hit.
This should pop the stud loose from the spindle, you then can remove the nut.
remove the two nuts on the studs/bolts that hold the arm shaft to the frame.
you can then jocky the A arm out. Repeat on the other side and put the A arms back on the proper side, replace the nuts and tighten them. If there are camber shims present just devide them evenly between the front and back bolts and the alignment folks will move them around to get proper caster and camber.
slip the ball joint stud through the hole in the top of the spindle (this can be tricky at times and you may need a buddy or two to put some weight on the front of the car to push it down enough to get the stud through the spindle) and replace the nut and tighten it. replace the cotterkey. you may have to tighten the nut a bit more to move the slots to get the key through slots and hole.
Bolt the wheels back on and set it back on the ground.
Get the wheels properly aligned before doing any driving.

If you don't feel up to doing the switch, have the alignment mechanic do it.
They are set up to do it and it will take them less than an hour to do it. Unless there is a lot of stuff in the way.
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Old 11-19-2006, 08:13 PM
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My apologies not getting you a picture sooner - I actually forgot when I was in the barn, but looked through my old pics and found a front suspension shot from this spring:



Changing the uppers isn't a big deal, but treat the springs with A LOT of respect. Their is a lot of energy their waiting to seriously hurt someone if you aren't paying attention. I agree with Chopt48 on how to do it - if the engine is in the car you shouldn't have a problem jacking up the lower control arm to compress the spring. In those pics it looked like the upper balljoints were still riveted in (meaning they are OEM) - why not install new ball joints while you have the arms off? New Moog's are only about $18 per side.

If you have any problems with the front suspension just ask - I've played with my stock car A LOT in the last two years and I'm sure a lot of people on here know a lot more then me about the stuff too!
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Old 11-19-2006, 11:36 PM
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Yep, sure looks like mine are reversed from yours. Your ball joint appears to be closer to the front while mine is closer to the rear.

The springs shouldn't be a hazard should they since they stay contained between the lower CA and the frame?

But what happens when the upper ball joint is pushed out of the steering knuckle --won't the wheel assembly tend to fall over because it is just held by the lower ball joint?

Thanks,

John
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  #29 (permalink)  
Old 11-20-2006, 06:15 AM
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Quote:
Originally Posted by JohnTN
But what happens when the upper ball joint is pushed out of the steering knuckle --won't the wheel assembly tend to fall over because it is just held by the lower ball joint?

Thanks,

John
Yes it will, not a big deal though. It is not too difficult to get the spindle and ball joint lined up again.

Position your jack on the lower arm as far outboard as possible. This way, if you are having some trouble getting the joint into the spindle, you can jack the lower arm up to meet the upper. There is more leverage at the end of the arm than at, let's say, just under the coil pocket.

Bryan
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Old 11-20-2006, 07:32 AM
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Quote:
Originally Posted by JohnTN
The springs shouldn't be a hazard should they since they stay contained between the lower CA and the frame?
They shouldn't be a hazard, but I was thinking more along the lines of if your jack slips from under the control arm allowing the lower to rapidly unload the spring could come flying out. You will still have the shock mounted in through the center of the spring so that should catch it in case you have a jack failure.
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