Squaring your rear axle

[Midnight Special]

Still trying to track down my gremlin--

ANYONE KNOW HOW TO SQUARE A REAR AXLE TO THE FRAME USING A LADDER BAR SYSTEM

I know it involves stringing and plumb-bobs---anyone have a simple method or a tech method which can provide printable instructions for simple guy like me.......

SOmeone?

[doug 371]

just cross measure side to side. find a point on the rails with some type of hole or stamp and cross measure move it around till ur cross measurements are equal

[Midnight Special]

just cross measure side to side. find a point on the rails with some type of hole or stamp and cross measure move it around till ur cross measurements are equal

That works great for side to side....but there are front to rear squareing also

[doug 371]

ur measuring from the front for ur cross measurements. the measurements wont be equal unless its square to the front

[Midnight Special]

ur measuring from the front for ur cross measurements. the measurements wont be equal unless its square to the front

Got any simpler instructions??

[kawazuki8097]

I think this is where Doug is headed.

[attachment deleted by admin]

[70 Dustpan]

OK this is how I watched my friend that does chassis work do it.

Put the car up on stands and level it front to back and side to side. Find the center-line of the car front to back and plumb line them to the floor and tape a string line to the shop floor from point to point. Measure from the center line to the outside of the rocker panel, then use that to measure out on the front and back on both sides keeping it all square. Tape line from these points to one another. What you are doing is making a box under the car.

Then pick a few spots on the car that a in the same spot on each side of the car and plumb them down to the floor. Front of the frame, K frame mounting bolts, cross member, center of rear wheel openings, rear of frame. Places like these. Do at least 4 spots checking to see if they are square to the front to rear lines.

Tape string across these spots to the outside of the box making a grid. Then you have a square lay-out to set-up you chassis from.

Also use something to permanently mark your points on the ground just in case you mess up your strings with a jack or creeper or something.

[doug 371]

thank you ray...you are truly an artist.....and u understood my babble

[70 Dustpan]

Midnight Special your PM box is full.


Brent

[Midnight Special]

OK DUSTPAN FIXED IT

[Midnight Special]

Where are the factory/OEM jigging points on the frame rails.  The ones I've found are about the size of a half dollar and an oblong 1/2 x 1.5 inch hole just forward of the transcrossmember and frame ajoining brace.  Where else are they on the front half as reference points for plumb-ing to earth?  

[74swinger]

Put the car up on stands and level it front to back and side to side.

I've asked this before, and I'll ask it again, since I have yet to get a reasonable answer.

Where do you put the level?  What do you place the level on?  What size of level?  How exactly do you level a car?

I have eyeballed my car level when I do chassis mods. I do not have a tube frame chassis, so nothing is straight or flat.  I can put a 24 inch or a four foot level and make any car look out to lunch, or bang on the money by changing where you place the level.

Does someone have a photo or two to show how to level chassis?

Be warned, that I have been through this many times in my feeble mind.  I might argue most of what I see.

 

[loiq]

Put your level on the rockers and across the rockers.

[70 Dustpan]

Well I have levels from 6" to 8' just cause of the work I do. But with a good 2 or 4 foot level and a straight piece of metal square bar you can make it a 8 footer.
First the reasons you want it level is:

1. So that the car is not twisted or sagging so when you start welding things in the the car will stay that way.

2. Is when you drop your plumb bob down to the ground if the car is not level the mark will not be on target.


Now how to level the car:

1. Check the ground that you are going to be on is pretty close to level. 1/4" off in a 8' run is not bad, 2" is.

2. Places to check from side to side is across the front fender, bottom of the rocker panels, across the top of the tail panel, places that should be the same on both sides.
If you check 5 or 6 places and they are read pretty close to one another then your good. For front to back going off the under side of the rocker panels is good.

3. To adjust your stands. Start with some 1/4 squares of plywood that are around twice the size of the base of the stands, then some squares of 1/8 and 1/16" pieces of sheet metal.

4. Placement of the stands. It's best to have 4 under the body of the car and 2 under the front and 2 under the rear of the car to keep them from sagging. A good thing to look at is if the body gaps stay good and if the doors open and shut the same as on the ground.

5. How level is level? Your not going for dead nuts level, if you get the bubble with in the lines then your level enough as long as it is leaning to the same side as the other places. You don't want chassis twisted. What I'm saying here is if the front is just a touch of to the left and the back is just off to the right.

One other thing: To check if your level is reading right sit it on somethnig that should be close to level ( kit. cabinet ) read it then flip it around and see if it reads the same. If yes it's good. If not then it's off. A good level will have adjustment screws.

[440WIP]

If you'd like to improve a little on Dustpan's instructions, go to a RV Dealer and buy some RV leveling jacks. They are fine thread and work like a hot dam. I'm sure you can see the advantages using them over raising and lowering a standard jack to slide in pieces of wood.
Daryl

[70 Dustpan]

If you'd like to improve a little on Dustpan's instructions, go to a RV Dealer and buy some RV leveling jacks. They are fine thread and work like a hot dam. I'm sure you can see the advantages using them over raising and lowering a standard jack to slide in pieces of wood.
Daryl

Very true they do work great, I was just trying to stick with what more guys already have in their garage.

[74swinger]

I understand a little better now the "how" you guys have done it.    I appreciate the coaching.

By the way, I modified my own jack stand to have a threading system like the RV jacks.  It is the only way to go and you can get a car dead nuts level that way.

I haven't needed to do the level front to back yet, but I will give it a try later.  I hope it works on rusty rockers...

[Midnight Special]

We located Centerling of the chassis(measured at furthest point forward and measured furthest point aft)
Drew a chalk line. All off Plumb

Found Crankshaft C/L, in addition to Drive shaft C/L and C/L of yoke on the Dana 60.
Drew a Chalk line.  All off Plumb

This created two parellel lines one for chassis one for drivetrain c/l.  The difference was 1 7/16 of an inch.

At two points in both lines, we drew two intersecting 18" circles to make a chalk line and to draw a perfect perpenduclar line (left to right) as the car sits.

Measured from Hole on the Mosiers on both sides and recorded thos measurements.  One side was off.  Made adjustments to the laddar bars.

NOW--how does one adjust for the offset C/L of the drive train which on my car was 1 7/16 inches from chassis lenterline.  Do ya split the difference to attempt a total in line driveline?

[Midnight Special]

I wanted to quarry front suspension experts.

I've been experiencing a twisting problem on my 71 Dart since the beginning of the season, when launching the Dart and a "dog tracking" down track.

From the ET finals last yr, I did nothing except align the front end and replace the tires.  The front suspension is OEM with the exception of front drag shocks, with PST parts.(All parts less than 2 yrs old )

We've looked at the entire chassis  from the rear to the front for a broken anyhting, sent the shocks off for rebuild, had the laddar bars checked by Chassis engineering for broken or being bent, have squared the axle into the chassis using plumbbobs and measurements as if you were setting up a new rear end, checked every weld, joint or place underneath where a broken part could be found....with zero results.
The T-n-T this weekend changed nothing and we even made major adjustments at the track(moved everthing) to make it launch softer, harder with all the results being the same.  It picks the left front tire high in a twisting motion, leaving the right tire near of barely off the ground, then pulling to the right, having to correct with left direction steer.  Preload is on the right side from major preload to neutral preload...all with the same result.

My questions would be:
If the front end was not properly aligned, (Caster/Camber/Toe) and the torsion bars not properly adjusted or a broken front end part, could this cause the uneaven lifting (twisting as in lifting the left front tire 18-24 inches upon launch with the right front tire barely off the ground)?  Does any front end adjustment effect the "lifting" upon a launch?  Besides Caster/Camber/Toe what effects cause "dog tracking"?
What "ties" the front end to "lift" even upon a launch?

Anything suggestion wise that someone may have as to what we hadnt looked at yet?

Thanks in advance
MSR

[AA-slingshot]

double check your front frame to floor wwelds and your firewall very closely for cracks. Usually the front end alignment has nothing to do with the twisting factor. Maybe it's had alittle to much   

[Midnight Special]

double check your front frame to floor wwelds and your firewall very closely for cracks. Usually the front end alignment has nothing to do with the twisting factor. Maybe it's had alittle to much   

DOUBLE A--well check that too.....this twisting isnt from NOS Usage

[loiq]

The rear end is squared in the car, but is the housing itself straight?

[Midnight Special]

The rear end is squared in the car, but is the housing itself straight?

Dana 60--yeap its streight as a laser will measure it

[Dartsport]

You said that you put new slicks on it for this year?? What kind? Did you try switching them from side to side? May have a bad sidewall in one of the slicks? If you switch them from side to side, and it still does the same thing, then it isn't the slicks. If it twists to the opposite side, and pulls to the opposite side, then it is a bad slick.   Just something to try!!!

[Midnight Special]

You said that you put new slicks on it for this year?? What kind? Did you try switching them from side to side? May have a bad sidewall in one of the slicks? If you switch them from side to side, and it still does the same thing, then it isn't the slicks. If it twists to the opposite side, and pulls to the opposite side, then it is a bad slick.   Just something to try!!!

We may have discovered the culprit

We dropped the Dana last evening and found the welds on the Dana 60 (both the OEM hole welds and the tube welds) broken on the right side tube and the axle tube had rotated upwards from the torque.  It also moved outward 1/4 to 3/16 ".
 
Thus, when launching the housing just rotated and not planting the HP/TQ.  The axle is out and in a jig being rewelded as we speak.  Hopefully this solves the problem.  This is a wake up call for HP producing guys and gals that check the welds on the axle tubes on your year end off season irrespective of what your running....check the welds and such

[bOb shingler]

you may want to try dialing more compression into the right rear shock and less extension into the front left shock, also more extension in the right front may help out. less extension in the left rear too. the hotrod pulling to one side can also be corrected by checking the length of the rear coil springs and compressing the one on the side it pulls to by about a 1/4"

[Dono]

I have run into this my self with the rear being totaly straight with the car in the air then when back on the ground she is crooked.  Not much just enuff to dog leg a bit.  With the weight on the rear measure off the back of the T bars.  Straight back and cross ajust from there.  Even then like bOb said under power she will acted totaly different again so you may need to put her in straight but ajust the shocks under power to shoot straight.

Don.