Laser aligning a drive train??

1329 Views 8 Replies 7 Participants Last post by XQZME, May 28, 2007

Strider

Discussion Starter · May 27, 2007

Twin turbo mentioned laser aligning a drivetrain and this would have saved me many hours of doing it the old fashion way.
The only way I knew at the time was dropping plumb lines from the front of the crank right behind the harmonic balancer, another on on the output shaft of the tranny, another on on the pinion yoke and finally one dropped from the center of the hole on the spring mount. The cover has a little hole drilled for the head of the through bolt on the spring to hold it in alignment.
I dropped these 4 plumb lines then took a string and with a large loop on the end put it around the front sway bar. I then used a set of folding steps out behind the car and tied the other end of the string to these steps.
I then had to juggle the string front and back so it just about but not quite touched the front harmonic balancer plumb line and the rear cover plumb line.
You move the front loop along the sway bar and at the same time the steps behind the car.
I wanted these 2 plumb lines about 1/16 off the centerline sting.
When that was done it showed the tailstock and the pinion nose plumb lines were not on the same plane and both needed rotating the motor towards the drivers side and the pinion also towards the drivers side.
We all see this with prying the tailstock over to start the bolts.

It would be so much easier if I knew how to do it with a laser, more accurate too. I have a laser but not the knowledge of how to go about using it for aligning the drive train???

Could you give me a rough run through Marck of how to go about this???
Thanks

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mrvette

· #2 · May 27, 2007

I"m still trying to figger how in hell I going to even do a string alignment, and how much work that will be.....I"m sort of thinking along the simple route and just popping the bolts on the tailshaft, and then the pass side mount, and thereby releiving pressure on the driver's mount....realign the tailshaft where it's in line pretty much pointing to the rear, and then redo the pass mount...

not sure how exactly I am going to accomplish redoing the pass mount, as I dont want my exhaust system YET AGAIN hitting those damn pass through loops.....

I have never had the body off the frame on this car....and certainly don't wanna start all THAT over this relatively minor issue...second off is I wish I had of cut/modded that cross member long time ago....with the exhaust through it like it is, it's a PIA.....whole thing is a subject of PRO Crastination...

:spanked:

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010752

· #3 · May 27, 2007

Adapting a pinion yoke to accept a small cylindrical laser gun sight would be real simple. These are pretty cheap these days too.

You could chuck it in a lathe and shoot the the tailstock centre to set it up.

Just food for thought. :thumbsup:

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Strider

Discussion Starter · #4 · May 27, 2007

010752 said:
Adapting a pinion yoke to accept a small cylindrical laser gun sight would be real simple. These are pretty cheap these days too.

You could chuck it in a lathe and shoot the the tailstock centre to set it up.

Just food for thought. :thumbsup:

I made a tool that consists of a 1 diameter round stock and a plate welded on the end of this solid piece. I then put it in a lathe, turned the plate that is welded to the solid piece so it is square to the round stock. Drilled the whole thing, reamed it and then honed it for a precision fit of a 3/8th ground rod 28 inches long. This rod is pointed on both end, fits the hole really well.
I put this flat plate on the pinion , slide the rod back, it is pointed and it slides into the center drilling on the pinion itself. I then clamp the flat plate to the face of the pinion flange.
I then slide this 28 inch rod forward and it touched the tranny output, it is also center drilled. It quickly shows if the pinion is rotated enough, pointed straight ahead or cantered towards the passengers front wheeel like mine was.
It quickly told me my alignment was really off.

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TwinTurbo

· #5 · May 27, 2007

It is very easy but only doable on a bare frame w/ the drivetrain installed. The laser levels usually have a magnetic base. You put one on the transmission (my tranny has a nice flat surface on the rear), I actually use 2 clamped together. 1 aims to the front and the other to the rear. I use the rear aiming one for the aligment, the one aiming to the front is used to make sure the lasers are parallel to the drivetrain axis. This means measuring the distance from the laser to the center in several positions and adjusting it so it's straight (remember, the one used for this is off center next to the one aiming back which is set on center). Then I use the one aiming back to take similar measurements, just hold your ruler or a large straightedge to pick up the laser marking spot (these lasers don't scribe a single line, they actually create a fan shaped "plane" when looking from the side, this leaves you with a very visible clear red line all the way to the back. it also isntanly shows you where the drivetrain axis intersects the pinion crossmember, this position is 1" off center (or a difference of 2" between measuements on each side). Mine was actually exactly 51,5mm and the same measurement done on the front (motor mounts) resulted in this same reading. Since these laser levels have a set of spirit levels and adjsutable legs to position them you can accurately measure this stuff. I also have a tape measire w/ a laser and spirit levels that I use for some of this.

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010752

· #6 · May 27, 2007

Here is the type I meant. Cheapies are around 50 bucks.
You just need old tranny and diff yokes and a lathe.
Once set up, they would be super fast, just slide on and off.

On second a laser pointer like instructors use might be okay and they are dirt cheap.

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BBShark

· #7 · May 27, 2007

010752 said:
Here is the type I meant. Cheapies are around 50 bucks.
You just need old tranny and diff yokes and a lathe.
Once set up, they would be super fast, just slide on and off.

On second a laser pointer like instructors use might be okay and they are dirt cheap.

I made a couple of laser alignment tools with the "instructors" cheapies. The only thing you have to look out for is that the cylindrical case and the laser axis are not necessarily co-axial. So if you machine a bore and slide the laser pointer in, the beam may be off axis. I used the longer ones from Radio Shack and found them to be accurately aligned.

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big2bird

· #8 · May 27, 2007

BBShark said:
I made a couple of laser alignment tools with the "instructors" cheapies. The only thing you have to look out for is that the cylindrical case and the laser axis are not necessarily co-axial. So if you machine a bore and slide the laser pointer in, the beam may be off axis. I used the longer ones from Radio Shack and found them to be accurately aligned.

:agree: Yep. I chucked a cheapo in a lathe once. Thought I was at a rock concert.:laughing:

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XQZME

· #9 · May 28, 2007

At work we used a laser level to mark a floor for setting bays of telecom equipment that could span over 100ft long several decades ago. The laser head rotated like a lighthouse only much faster and created a nice red stripe for reference. It could be setup to shoot horizontally or vertically and was unbelievably accurate. We insured accuracy with plumb-bobs and water levels (the old clear tubes on either end of a garden hose). It sure beat the old chalk line method and sped up the task of making straight parallel lines.

I'm sure the equipment was outrageously expensive back then, probably still fairly expensive now but it sure was a luxury to use.

I can see a car up on a 4 post lift with the chassis leveled and a vertically aligned laser shooting the frame from underneath would be a big help.

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