Questions on a dlm alignments.

[abco]

As far as squaring a rear end to the centerline, if u make 2 bars one front one rear equal distance off the centerline of the frt and rear of the car, then pull strings frt to rear at hub height!! This works really well \\ at the end of the day when u figure out what works u gotta be able to repeat that car to car, week to week!!

[LM14]

Had 5 different brands of LM thru the years. Rayburn, Shaw, Warrior, GRT, Shiltz. All did it a little differently.

Put it in by bar lengths like the builder says to do. That is his design and may, or may not, be square. I know cars with the rearend trailed on the RR from the start. I've had cars with the midplate not square to the rearend. MOst don't match left to right on the wheelbases. Some line up left side tires, some kick the LR out several inches. It all varies by builder.

You need to be able to replicate what the builder intended more than the rearend being "square".

If you want an easy, sure fire way to square a rearend drop me a PM.

SPark

[zeroracing]

So what you are saying is the rear end and the engine plate sould be the parrallel to each other. If I set the rear end bars (including the J-bar) and ride heights are established, would the last thing to do would be to check/adjust the rear end against the motor plate. Am I correct???

The midplate should be true to the world... Rear end may or may not be. Some may run RR trail, you would find this by measuring this way. I would set as much up as I can from chassis builder, then check everything like I outlined to see and note if the rear is square or car should dog walk, also will give you measurements incase you crash.

If you cannot reach a builder and have no sheets I would square the rear, line up lefts and tune from there.

[EAMShater]

I run an 09 bwrc and the book Barry gave me at the seminar I went to days the cross member in front of the radiator is square to the rest of the car and to drop plumb bobs off the front of that bar on each side then run a string across the two strings hanging down out past the front tires and be sure it is tight. Then get about a foot and a half of 1/2 inch threaded rod and take the axle caps off and screw the threaded rod into the axles. The measure from that string to the rod on each side and that should give you your lead or trail on the reared. Also you can take the grease zerts out of the lower ball joints and screw small bolts in that hang down and measure from the string to that bolt and it will give you your lead on the front end. I run my lower ball joint on the rf about a quarter inch ahead of the lf. It seems to help it steer in a touch better.

[jason29a]

I run an 09 bwrc and the book Barry gave me at the seminar I went to days the cross member in front of the radiator is square to the rest of the car and to drop plumb bobs off the front of that bar on each side then run a string across the two strings hanging down out past the front tires and be sure it is tight. Then get about a foot and a half of 1/2 inch threaded rod and take the axle caps off and screw the threaded rod into the axles. The measure from that string to the rod on each side and that should give you your lead or trail on the reared. Also you can take the grease zerts out of the lower ball joints and screw small bolts in that hang down and measure from the string to that bolt and it will give you your lead on the front end. I run my lower ball joint on the rf about a quarter inch ahead of the lf. It seems to help it steer in a touch better.

That's the best advice i've seen yet.

[abe_05]

How do you find the centerline of a dlm?? How do you square the rear end to this centerline?? Is that something you want to do?? New to this stuff and when I ask car builders, all I ever get is just measure the rods, square the rods to the Rearend tubes (just eyeball that!) and set the J-bar. Everything is fine after that. I would like to know more. We had a Rayburn and CJ did tell me the the right frame rail was set at 2 degrees. I got on ACAD and did some measurments and found a way to square the rear end to the right side rail. It made a huge difference in the car! We have had several 4 bar cars and I have never been comfortable not knowing this info. Am I worring about nothing??

Your must had a pull bar in Rayburn, very critical to square rear end with pull bar. If rear end moves left to right very slightly it changes pinion angle. It seems like your are talking about left to right on 4-bar. Start with recommended length of j-bar you can change it by just lengthing or shorting j-bar 1/4-1/2". I would shortin j-bar 1/2" on real slick track, this is moving rear roll center and helps with side bite in our case. To answer your main question it is not near as criticial as Rayburn but it is always smart to make notes, simply putting angle finder on j-bar is easy way to watch changes like by increasing lr bite will move angle more than one might think. In setup always make note were j-bar is mounted on pinion (measure or what hole), frame, and then measure the angle. A lot setups sheets tell you were to start on j-bar but they are just giving a good starting spot. Example if you start j-bar on pinion just say on bottom hole and on frame 4" up, j-bar angle may be 10 degrees with 50 lbs of bite in car, change bite to 150 lbs angle may go up 20 degrees. May not sound like a lot but by just simply adding bite to car and not checking j-bar angle, now you making more adjustments than what most racers think about.

[late96]

This is how we were showed years ago,tell me if I'm wrong. We would set front caster to zero, drop plumb bob from grease zert, plumb bob rear end draw a line, set birdcages zero, than adjust bars to get square. Be sure to re-check bird cages as you adjust.Don't know if this is at all correct, but no one has shown me any differant.

[Egoracing]

This is how we were showed years ago,tell me if I'm wrong. We would set front caster to zero, drop plumb bob from grease zert, plumb bob rear end draw a line, set birdcages zero, than adjust bars to get square. Be sure to re-check bird cages as you adjust.Don't know if this is at all correct, but no one has shown me any differant.

Most dirt late models are built with the RF further forward than the LF some as much as 2 inches. This helps the car turn into the corner.

[abco]

Just do yourself a favor, when u figure out where ur axle is square and everything is happy put some center punch marks on the frame and center of the axle tube for a quick refrence! (16" or a 20"#) Saves alot of time at the track !

[late96]

So how important is it to have your birdcages alligned or indexed?

[twisterf5]

So how important is it to have your birdcages alligned or indexed?

very!! it can put the rear in a bind if they are going the wrong way

[hpmaster]

I run an 09 bwrc and the book Barry gave me at the seminar I went to days the cross member in front of the radiator is square to the rest of the car and to drop plumb bobs off the front of that bar on each side then run a string across the two strings hanging down out past the front tires and be sure it is tight. Then get about a foot and a half of 1/2 inch threaded rod and take the axle caps off and screw the threaded rod into the axles. The measure from that string to the rod on each side and that should give you your lead or trail on the reared. Also you can take the grease zerts out of the lower ball joints and screw small bolts in that hang down and measure from the string to that bolt and it will give you your lead on the front end. I run my lower ball joint on the rf about a quarter inch ahead of the lf. It seems to help it steer in a touch better.

I agree with this statement. I heard this many years ago and have measured all cars from this point since and found it gives the most consistant measurements of all suspension pick up points and chassis attachment points.
Measuring a car chassis from a part mounted in a chassis by 4 welded tabs and in most all cases AFTER the entire chassis has been completed makes no sense at all if you just take a minute to think about it.
As for lead on the RF I have played with for it for over 5 years and using too much lead on the RF, .5 inches or more can make a car turn well but hurts drive off traction, why I am not really sure of.

[late96]

very!! it can put the rear in a bind if they are going the wrong way

Well I hav'nt seen a new car with bars set to specs. that they are straight up and down. So what's the best method without changing a lot? Thanks

[twisterf5]

Well I hav'nt seen a new car with bars set to specs. that they are straight up and down. So what's the best method without changing a lot? Thanks

the way we do it could be wrong but it works for us. we made a level that we touch both hiems i set the right just towards the rear and the left just forward of level.

[chasingthatedge]

I agree with this statement. I heard this many years ago and have measured all cars from this point since and found it gives the most consistant measurements of all suspension pick up points and chassis attachment points. Measuring a car chassis from a part mounted in a chassis by 4 welded tabs and in most all cases AFTER the entire chassis has been completed makes no sense at all if you just take a minute to think about it. As for lead on the RF I have played with for it for over 5 years and using too much lead on the RF, .5 inches or more can make a car turn well but hurts drive off traction, why I am not really sure of.

this is how we set up the car mostly....over the years I have squared rear to midplate ...then lined up left side tires and adjusted at track from there....many diff ways to set up car.....mainly go with chassis builder recommendations and then adjust car to what the car is doing as per the driver...no 2 cars are exactly the same and every driver is diff.....as far a birdcages , the idea with the level is a good one....timing can affect the way car gets up on bars and car acts...just remember to give the car what the car wants....conditions change and so does how a car acts...hope all this helps some....you have to think about the whole picture