OK, this is driving me crazy. I am trying to get my TCI MII crossmember centered in my frame. I've got the front boxed and the original wheel center marked and I moved the wheel center line forward 1 1/4 of an inch forward. The problem im having is when the crossmember is centered in the frame and also centered in relation to my wheel marking on the frame which is 19 inches back from the front shackle. When I cross messure to be sure it is centered I'm getting it off by as much as a half an inch on the drivers side. I went ahead and evened it up in the frame by pushing it back in the frame until I got exact cross messurements and even measured straight back and front messurements which were also good. I'm using the bottom control arm mount in the back of the cross member for my reference point. It doesn't make any sense to me why all the messurements are exactly the same on both sides of the frame but the cross member won't line up with my wheel center lines.

Any ideas as to what I may be doing wrong? I've done a million measuments from just about every whole and rivit on the front half of my frame to be sure that something isn't out of wack and everything seems straight. I'm not sure what else to check or do.

It's 1am and waaaaay past my bedtime...it's going to be fun at work tomorrow trying to stay awake.'ve had enough for one night so I hope to get some good ideas from my fellow

Thanks again!

 

Does your frame have a diamond in it , meaning is it possible that one frame rail is back, making it diamond shaped, that is where i would start. Do this by measuring from one front frame rail to the opposite rail in the rear then do the other side, they should be the same.

 

I have measured the frame from the front half and the back half but not all the way across because the cab is still on the frame. I have moved the cab back a couple of feet on the frame. I have measured from several different points in the front half of the frame and I'm off by 1/8 at the furtherest points. I measured from the front frame area where there are two holes on the top on each side of the frame (last set of wholes behind the bumper) then measured back to the wholes on the inside side of the frame just past the front cab mounts (big whole about 1 inch across). I got 75" from LF to R passenger side rear and RF to drivers rear it's 74 1/8 so it's not off by much. On the passinger side where the boxing plate is welded it dipps in (like a bow) about 1/16 to 1/8 right where the cross member would weld in but I can't see how that would affect it (could it?). Also, I put a straight edge on the outside where it bows on the frame and it is perfectly straight where as when I do the same on the inside where the boxing plate is welded on it bows a little. The other side is perfect.

I've taken measurements from as many different areas as I can on the front half of the truck and they all check out or are barely off by no more than 1/8. Some of those may be due to me having to measure by myself using the head of the rivits but none are off as much as 1/4 inch which is the difference that the cross member has to be pushed back to have the measurements exact on each side.

It's just very weird and really frustrating trying to figure out what could be the problem.

 

Rodney,might want to put that puppy on jackstands and use the plumb-bob method to verify chassis is square, put 2" tape on the floor to drop your mark to, then once you have all 4 corners marked..have a friend help you doublecheck your marks for square.

It's really easy after that to find chassis centerline..just by measuring/splitting the width of your marks..may as well do a chassis perpendicular line while your at it...
You can essentialy layout your desired crossmember on the floor, then plumbbob back up to your frame for position....
Even if your frame is diamond'd or racked, using this method will get you where you want to be....hope that make's sense to you and things progress smoothly...Good Luck!

 

Thanks CMORTIZ for the help. I will try that when I get home this evening and post my results either tonight if I get in early or tomorrow when I get to work.

 

Ok, I marked all 4 corners of the frame on my garage floor like you suggested and the results that I got were 185 7/8 from corner to corner. I put the crossmember back in last night and measured from the front crossmember mounting rivits to the mounting control arm mount facing the back of the truck and got consistant measurements using different rivits. When I measured from the control arms back I my results were off.

The PO somewhere down the line had repaired the frame on the passinger side by welding a piece of another frame inside the trucks frame and I'm wondering if that may have something to do with the problem. I drew a diagram of my measurments so I could keep up with all the results I got and I'm going to see if I can post it on this thread or in my gallery section.

Well, I can't add a new gallery section so I tried to edit and add the diagram to my existing "suspension" gallery but it wont post the picture. I'll try again later...maybe a temp issue.

 

So you've got a "+" sign on the floor at each corner, and a diagonal measurement..front to rear measures 187 7/8..even right?Both sides?..You can assume the frame is square...looks good so far.

If you still have a nagging question in your mind ( I get that too..just before tacking things in...)..measure the width..front and rear..sometimes helps visually to snap a couple of chalk-lines..front to rear...then carefully measure the distance between the front 2 marks,and the rear 2 marks..split the difference....thats your center-line...strike another chalk-line on the floor on your new marks...
You should now have 3 lines the length of the frame...
next is to find a perpendicular line...it's easy too

Depending where you want to put your front axle center-line...
I used the previous axle as a guide, using the previous front axle bumpstop mount hole,then recocile the difference,and moved new axle forward 1.25 ".... I'm assuming the old axle's gone in your case ,so let's use the bumpstop hole at bottom of frame...with me so far??
Plumb-bob down from the bunpstop hole...same place..both sides...mark with tape...make your mark...this is just a rough reference guide mark..chalk a line between these ...left to right
Go to your chassis center-line and your bumpstop line..careful here..mark a new spot on your center-line 1.25 " fwd of the bumpstopline....Now measure 3 foot fwd and 3 foot back from that point...using a string and marker,adjust string as nec,so that you have a 3 foot marking device ,on the end of your string..swing an arcfrom the very front mark to the out side of the frame...same fror the rear mark ...where they intersect is your new perpendicular-line
Make several up and down the frame ..checking each existing crossmember position until you find something outa whack...
Maybe find nothing,if fortune is in your favor!Good Luck!

 

I'm with you until I got to the part I quoted. So do I have a string starting at the center of my crossmember marking streched out to the 3ft. mark and then from that point use the string to draw a arch type line to the outside of the frame? I do the same from the back mark and where those two meet is my axle center on the frame?? You also lost me when you said to check each crossmember position. If it's out of wack then then it wont intersect?

Sorry, I'm a little confused with this part...not trying to be a pain

 

Here's a long shot.....check the crossmember to insure that it is assembled square from factory.....highly unlikely as it is jig welded,,,but stranger things have happened.

 

....LoL...
Yeah ,so much typing in a hurry , I may have confused myself..LoL
Once you have determined the perpendicular-line...you can go to each crossmember ..plumb down to the floor ..make a mark....and see if it's parallel to your perpendiclar line...just double checking each member for square ,with the frame...
I found it was alot easier to figuire the perpendicular line,by playing with a small compass..you know the one that holds a pencil in one end ,and apointed area that always draws blood?
I'm at work now,gotta get back to it but I'll keep checking thru out the day...after 6 est I'llbe back to clarify anything..Good Luck!

 

Fergusonicford, I thought about that also and as far as I can tell it appears to be square.

cmoritz...I have that problem with typing fast and confusing myself sometimes. You did a good job explaining it and I read it a few times which helped me to catch all the details. I think I got about 95% of it now. I seem to be having a problem on where to setup the string to make my arch. Could you explain that part again and where it should endup? I would really appreciate it. I'm really close to getting it...I promise. - Thanks.

 

Rodney, sorry ,got caught up in some surprise's when I got home..all is good...!!

I re-read my last post and think I know where things went adrift....

Let's create a perpendicular line
Since you have a good chassis center-line ,...pick a spot,point,..anywhere along that line...let's name that point"A"...measure 3 ft fwd...make a mark ( with tape and marker) on the floor ...let's call that point "B"
now measure 3 ft aft or rearward ,and make a mark ( with tape and marker)...let's callthat point "C"....now here's the tricky part.....you have ( if your carefull) ..
6 feet betweenPoints " B" and " C"....take a nice straight piece of steel, aluminum,wood..and drill 2 holes in it..EXACTLY 6 foot apart. The holes need to grasp a nail or other pointed object firmly...
Swing an Arc from Point "B" to the left and right side of the chassis..out towards the framerail..both sides...
Swing an arc from point "C" ,left and right ...out towards the framerail..
Both of these arc's will " intersect" to the right and left of Point "A"...
Chalk a line across these intersecting arc's , and they're ya go

As a side note ,...yeah 3 ft / 6 ft is a long way,and may be cumbersome and awkward,
But it leads to better results and a more acurate # ...IMHO

from this line you can measure parallel to the chassis perpedicular-line up and down the chassis , to locate/verify mounting's ...Good Luck!

 

Thanks cmoritz. Great job on explaining this method. I'm gone for the weekend taking the wife and little one camping. I'll tackle this first thing next week and post my results. One thing of interest as I mentioned before the PO welded part of a frame to fix a crack in the truck frame. I was looking over my frame again and where the crack was welded there is a whole on top of the rail that is half of it's original size where the frame was welded back together. The frame is off by 2/8th. on the pass. side. when measuring from the front to just under the front of the cab (about 12" past the crack). That's also how much smaller the orginal hole was. Before the crack everything is square as can be.

Anyway, I'll check back in with some results after the weekend. You guys have a great weekend and thanks again for everyones suggestions and help.

Rodney

 

Ok, here is the latest. After a really busy few weeks at work and home I finally got a weekend to spend figuring out what the heck is going on with the crossmember. I did the perpendicular line method and I've got lines all accross my garage floor. I took a tape measure and a carpenters square and checked where the lines intersected and everything looked good and the frame is square. I decided before I go any further I was going to call TCI and see what they had to say. The person I spoke to gave me some ideas on measuring the CM for square and it is definately not square. To me it doesn't seem that off but what do I know...this is my first build. I figure it is off enough to cause some problems though. I'm going to call them back in the morning and see what they say. I'll let you know how it goes.

 

Rodney, Hopefully TCI will remedy your problem. I would have thought that the crossmembers were jig built. Hoping that you haven't lost your sense of humor over all of this but is the Jag IFS still in your garage?

Geez what a smart axx!