Hi all,

I am an auto mechanic by trade but being that many of you work with lasers I thought I would see if I could get a bit of advise. With out going into lots of complex details, here's the scenario, I have a metal 3 fingered flange on the back of a transmission that I need to basically draw a straight line out of dead center of this pointing towards the back of the car 4 feet or so. The point needs to maintain any angle that this flange may be on so obviously I cannot use any kind of auto leveling device.

There really is not any other references so no way to measure or calculate the position I need so a laser is the only idea I have, I am thinking to make some kind of fixture that will attach to the flange and mount a laser. Ideally I was thinking a crosshair type beam but I will consider anything.

I don't have much experience with lasers at all and I have searched a bunch but but might not be using the correct terminology so if any of you can point me in the direction of the right kind of device I would really appreciate it.

If you would like anymore info to help you better understand, please just ask and thanks in advance for any help!

What are you trying to achieve. Pinion angle? The basic geometry of the rear end/ transmission?

I went to school to design cars many moons ago. No I own a technology company. Lol

Well ceied, kinda, I have a Chrysler 300 limousine I am working on, in place of u joints they now have rubber flex couplers. These must be kept as straight as possible unlike a u joint, all of the factory provisions have been removed and I need to align the first driveshaft to the transmission output shaft as straight as possible.

Sorry, I have no idea what a 3 fingered flange is, but if you want a straight line from the centre, wouldn't that depend on the "fixture" you build and not the laser. You can get a laser pointer at a dollar store and it will do the job if it points in the right direction but if it is not set-up correctly even the best laser will be far off.

So there is no carrier bearing mid drive shaft? And it's a single sleeved drive shaft? Can you make a crude drawing?

This is a 4 piece drive line with carrier bearings on the ends of the first 3 shafts. I am actually trying to properly position the the first carrier (end of the first shaft)

Easiest way I can think is to get a tripod and put laser on it. Adjust height of laser to be center of the splines of the output shaft and then postition and shim the height of the carrier so its center is center with the laser. This will give you the proper height for the center on the carrier bearing and don't forget to take in the downward angle of the transmission(if any) this will be basic geometry

(Think drop ceiling in a business and laying out the outer wall grids... That's basically what I am suggesting)

For left to right adjustment you can use a simple string and a pencil and do arc lines and that will give you center left and right.


Easy peasy done!

If this is going to be something you need to do more than once( you work for a coach builder) simply get a drive shaft yoke. A simple torpedo laser level and create a jig for the level by welding a peice of stock to it do that the center of laser is at the center of the yoke Now it's as easy as putting the yoke on the tranny turn on the laser and a few quick tack welds to position the carrier mount

Thanks so much for the help, due to running into this problem more then a few times, and it being a difficult area to access and see due to obstacles, I am thinking I'd like to make a fixture of sorts that would bolt on the trans output flange and shoot a beam rewards to make it easier and quicker. Do you think this is a feasible idea?

Hope this thread helps:

[Link: yellowbullet.com]

In a few posts back I gave you how I would make the process repeatable... I think making the plate to bolt up to the flange creates issues for you. Center of laser will not be center of carrier

I could make the tool in less than 30 minutes with an extra yoke and a simple laser level and an arc welder

I must have been writing my reply when this posted, thanks, I will play around this tomorrow...

Nice find William, good reading!

Let us know how it works

Good luck with your project.

How incredibly interesting, and what a bunch of knowledgeable guys we have here!