Shimmed the K-Member - A few more questions

[XH29N0G]

I have been slowly building up a plan to shim the K-member on my car by 1/2 inch.  I want to run my plan by the board to see if I am missing anything.

Steps:
1) loosen torsion bars
2) loosen K-frame bolts (do I need to support the K-frame with some sort of support?)
3) Remove bolt on support that ties K-frame to radiator.
4) remove K-frame bolts on one side, then jack up side using frame rail to slide in spacer assembly (picture below). and then replace the K frame bolts on that side loosely
5) remove K-frame bolts on other side, then jack up side using frame rail to slide in spacer assembly (picture below). and then replace the K frame bolts on that side loosely
6) torque K-frame bolts to 150 ft/lb (should I put something on the bolts - lubricant to help with torqueing to spec?)
7) put 1/2 inch shim on support that ties K-frame to radiator.
(that is supposed to be a numeral 8 with a closing paren).....not a sunglass emoticon..... Reset torsion bars to original specification " measure distance from lowest point of one adjusting blade to floor (meas. A) and from lowest point of steering knuckle arm to floor (meas B), The difference should be 1 7/8" +/-1/8" (http://www.dodgecharger.com/forum/index.php/topic,99879.msg1233519.html#msg1233519)
9) take the car to check the alignment.

Questions:  Is there anything this geometry will change that I also need to pay attention to (e.g., the steering)?


Picture Caption : 1/2 inch shims on K-frame bolts.  The spacers  are stainless steel 1/2 inch thick with 1.5 inch diameter (see picture).  
To make the shims fit the K-Frame bolts (which have a shoulder) I made an insert out of 3/4 inch thick wall stainless tubing.  This can be seen in the picture too. My first set of inserts protrude slightly, which I assume is OK (I do not know if it is just the K-frame opening or also the opening above the K-frame in the frame itself that has a slightly larger spacing.

The picture below shows the spacer.  (I worried about the spacers being only 1.5 inches in diameter rather than a 1 x 2 inch rectangular spacing, but then thought it would be OK).  If this seems like a problem, let me know and please explain why.


I appreciate everyone's help in advance.

[green69rt]

If you shim the K frame that will lower the engine in the front (relative to the body) and since the back of the engine hangs off of the trany and the trany mount isn't moving, this will cause the tail piece of the trany to kick up and change your drive shaft u-joint/pinion angles.  Maybe others can say how much and if it serious.  Also since the trany linkage goes between the body and the engine/trans you might want to dicsonnect it to prevent bending things up.  Auto or stick shift?

[XH29N0G]

If you shim the K frame that will lower the engine in the front (relative to the body) and since the back of the engine hangs off of the trany and the trany mount isn't moving, this will cause the tail piece of the trany to kick up and change your drive shaft u-joint/pinion angles.  Maybe others can say how much and if it serious.  Also since the trany linkage goes between the body and the engine/trans you might want to dicsonnect it to prevent bending things up.  Auto or stick shift?

Sorry I didn't explain, this is actually what I am trying to do.  I have a Tremec transmission and the tunnel was not modified enough, so I am trying this before looking into pulling it apart and modifying the tunnel.

[cdr]

sounds about right, mine is shimmed 1/2, & yes it will need alignment. loosen the steering column bolts to firewall so it can drop down

[XH29N0G]

sounds about right, mine is shimmed 1/2, & yes it will need alignment. loosen the steering column bolts to firewall so it can drop down

CDR, Thanks Just to make sure I loosen the right bolts, you mean the one that is in red and any others (I don't know if the yellow one counts or if there are others) that holds the steering column to the firewall, but not the ones traced in green that I use to drop the column when taking out the cluster.

[cdr]

Yes   

[cdr]

i put jack stands  on the frame behind the front tires, then put the floor jack under the kframe, then loosed all bolts & put one spacer at a time in.  your spacers look sexxy , but I made mine larger, the same size as the mounting pads of the kframe,to spread the load out so the bolt wont rip the nut in the frame  out  

[XH29N0G]

Thanks for the pointers.  I was concerned about whether the spacers I bought would have enough area to distribute the force on the K-Frame as you describe.  I am not an engineer so I don't know how to judge the issues.  When I think about it more, I suppose the pads are actually where the force is distributed because the weight of the body is pushing down on  the pads, but the bolts are really just holding them together.  I'll think about it some more.  I should be able to calculate the difference in contact area, I calculate 1.3 square inches with what I have and if the shims were 2x2 then I would get 3.6 square inches for those (I subtracted out the bolt hole) so that might actually be significant.  I'll keep thinking about it.

[cdr]

think about it from a shearing load.or, hitting large bumps & shoving the small spacers through the frame

[XH29N0G]

Yes, that is what I was not thinking about before.  Neither of those.  I think I will measure up and get some 1/2 inch thick aluminum bar to make it.  Do you recall the dimensions you used?   

[cdr]

sorry, I don't

[XH29N0G]

No problem.  I'll figure it out.  Thanks so much for responding with specifics.  I am glad I asked about the plan.

Just did a quick measurement.  The frame rail is 2.25 on the flat part and 2.5 " total wide.  3" looks like it would cover most of the contact between the K-frame and the frame rail.

[cdr]

No problem.  I'll figure it out.  Thanks so much for responding with specifics.  I am glad I asked about the plan.

Just did a quick measurement.  The frame rail is 2.25 on the flat part and 2.5 " total wide.  3" looks like it would cover most of the contact between the K-frame and the frame rail.

AT 3" on some of them you will have to grind the edge a little so the will sit flat on the frame rail, you will see what I am talking about when installing them

[XH29N0G]

Thanks.  

One quick additional connection.  The bolts have a shoulder that fits through the K-frame.  Do you remember if there is recessed receiver in the frame rail?  So, would it be important to have some sort of 3/4 " sleeve that sticks out (above) the shim (as describe  on the page at: http://www.bigblockdart.com/forum/showthread.php?5062-K-member-shims. The poster calls them positioners.

[cdr]

I did not make a shoulder on mine.

[HPP]

Questions:  Is there anything this geometry will change that I also need to pay attention to (e.g., the steering)?

It will also change the front suspension geometry slightly as you are lifting the upper control arms mounts 1/2" above their relationship with the lower control arm. Will this be a huge impact, probably not and I doubt you will feel it in the seat of your pants.

[Mike DC]

  
Even a small change in the LCA's inner pivot height will affect the front suspension "roll center" noticeably.  

If you were to get that entire 1/2-inch difference by lowering the K-frame 1/2-inch (and the rest of the body stays at the same height) then it would lower the front roll center by about 2 inches.  That's arguably a good thing overall since Mopars have some pretty high RC's from the factory.  But it slightly increases the need for front swaybar stiffness as a side effect.
 
In the big picture it's not a dramatic difference.  If you aren't into corners/handling then you probably won't notice it. 

[Dino]

You sure you don't want to just redo the trans tunnel? All you need is a cutter, some metal, and a mig.

[XH29N0G]

You sure you don't want to just redo the trans tunnel? All you need is a cutter, some metal, and a mig.

That scares me a bit.... so I'll try this for now. 

[cdr]

You sure you don't want to just redo the trans tunnel? All you need is a cutter, some metal, and a mig.

That scares me a bit.... so I'll try this for now. 

shimming kframe works GREAT & it is easy to do, it also corrects some of the bump steer problems these old cars have, my car drives very good, I do have an 1 3/8 front sway bar on the front.

[Dino]

You sure you don't want to just redo the trans tunnel? All you need is a cutter, some metal, and a mig.

That scares me a bit.... so I'll try this for now. 

shimming kframe works GREAT & it is easy to do, it also corrects some of the bump steer problems these old cars have, my car drives very good, I do have an 1 3/8 front sway bar on the front.

Good to know! Maybe we all should shim it then. I'm all for better handling.

You sure you don't want to just redo the trans tunnel? All you need is a cutter, some metal, and a mig.

That scares me a bit.... so I'll try this for now. 

I understand. At least it's easily reversed if it doesn't work out, but it looks like it will!   

[XH29N0G]

I put in the spacers (1/2 inch) 2" x 3" with a small 3/4 in tube for alignment (like above but with rectangular prismatic rather than cylindrical). 

Question:  Should the ride height be set the same?  1/7/8" difference from lowest point of one adjusting blade to floor (meas. A) and from lowest point of steering knuckle arm to floor (meas B),  (http://www.dodgecharger.com/forum/index.php/topic,99879.msg1233519.html#msg1233519).  I ask because right now the car looks level with a little over 1" between A and B.  I know the eye is not necessarily a good judge of this, and will tighten the torsion bar adjusters to raise the height if necessary.

Second Question:  In tightening the Crossmember bolts to 150 foot lbs, I stripped one of the rear bolts. I had a spare bolt and replaced it and it threaded fine. I am concerned that my torque wrench is not good enough to do this.  (It is a click kind.)  Do others have a recommendation for a torque wrench.    Is there anything else I should look for with this.

The shop that I normally go to for work told me today that they use specs from cars and were hesitant about promising they could get -.5 camber and the other specs people here have recommended for alignments.  I said that the 2005 mustang specs were what had been recommended and he said they could do that.  I just want to verify this before taking the car in.

Thanks for the help so far, and thanks for future guidance.

[cdr]

I set my ride height by the fender well , so it is a little lower in the front than rear, 25" from top wheel well. to ground, my tire is 26.2 " tall.

I torqued mine to 110. 
stang specs should work

[XH29N0G]

Thanks for the additional information.  

I just checked front/back and both fender wells appear to be 25.5" off the ground with the present set up. The car looks flat as is, and when I had the ride height closer to spec (never reached that) the front end was higher.   Tires are 26.6 front, 27" rear.

[XH29N0G]

In setting the ride height before taking the car to be realigned, I drove it around the block to let things settle in.  I noticed there was no return to center on steering.  I would like to check whether my intuition is valid or if I am missing something. 

I suspect this is because the shims and lowering to a ride height after shimming altered the geometry such that the castor and camber are off.  I am writing to make sure I did not miss anything while making this modification.  I followed the recipe above (namely):

1)  loosened

• K-frame bolts,
• (two) bolts on the firewall associated with the steering column.

2) raised the K-frame with a jack, and loosened the ride height bolts on the torsion bars (not all the way though).

3) raised one side of the car to make space between the K-frame and the frame rail,

• removed the k-frame bolt,
• slid in and centered the spacer,
• replaced the K-frame bolt.

4) repeated for other side,

• snugged all K-frame bolts,
• reset torsion bar bolts to original position (counted turns),
• lowered car,
• tightened K-frame bolts to 150 ft lb with one mishap described above (that one is now at 110 ft lb)

5) reset ride height with torsion bar bolts to nearly level car, rocking and rolling and driving in between (is 25.75 on all fenderwells except passenger rear which has always sat higher).

I think I am all set.  The person I would normally take to do the alignment has some reservations about it with his set up (something about the rear tires likely not fitting his set up and trying with just the fronts) but said he would try on Monday.  I also have another shop I plan to call that has experience with older cars, but I do not know if they do alignments.

[cdr]

on the steering column there is a large plate that it goes through & the plate bolts to the fire wall, it has 4 or 5 bolts, the bolt holes in the plate are larger than bolts, loosen these to let the column move down. yes the alignment is off & could cause the non centering steering.

[XH29N0G]

Thanks,  I will revisit the steering column bolts.  I only loosened two bolts when I made the swap.  I must have missed some or loosened the wrong ones. 

[Troy]

If you adjusted the torsion bars at all you threw off the camber/caster in the steering. It either won't center or it will be super twitchy. Always realign after touching the ride height.

Troy

[XH29N0G]

Thanks Troy.  That revelation hit me a day ago when I started to better understand the suspension geometry and how it works.  I have an appointment to get the car aligned and am now just waiting for that and looking forward to driving it. 

[469 runner]

Won't lowering K-member put your torsion bars into a bind?  You will essentially be having them bend to work the change in angle.  Also, the steering box is fatter towards its middle. This barely clears the frame rail. Now you will have it against the rail. Seems easier really, and definitely cleaner to modify the trans tunnel I think.

[green69rt]

Won't lowering K-member put your torsion bars into a bind?  You will essentially be having them bend to work the change in angle.  Also, the steering box is fatter towards its middle. This barely clears the frame rail. Now you will have it against the rail. Seems easier really, and definitely cleaner to modify the trans tunnel I think.

As for the torsion bars, there is some slack in the fit of the torsion bars in the rear socket.  If you just stick them in and the k member is not installed the end that goes in the k member will hang down at some angle.  So, lowering the K-member (only 1/2 inch) probably won't change the TB action.  If you tried to lower it 2 inches then you'd probably have a problem but that much change would also introduce so many other problems nobody would do it.

[Mike DC]

Won't lowering K-member put your torsion bars into a bind?  You will essentially be having them bend to work the change in angle.  Also, the steering box is fatter towards its middle. This barely clears the frame rail. Now you will have it against the rail. Seems easier really, and definitely cleaner to modify the trans tunnel I think.

As for the torsion bars, there is some slack in the fit of the torsion bars in the rear socket.  If you just stick them in and the k member is not installed the end that goes in the k member will hang down at some angle.  So, lowering the K-member (only 1/2 inch) probably won't change the TB action.  If you tried to lower it 2 inches then you'd probably have a problem but that much change would also introduce so many other problems nobody would do it. Twocents

Yeah, 1/2" of shim isn't a whole lot.

Also, bear in mind that the torsion bars are springs.  

[XH29N0G]

Putting the 1/2 inch shims required me to back out the torsion bar adjusters to bring the height of the body back to the way it was.  I suppose it could put more stress on the torsion bars. 

I also had the car aligned.  The camber was set at -0.5, the toe at less than 0.05 and the caster could only get to about 1.5.  I dropped the wheel as described.  I found in order to have it dropped that I needed to loosen the 4 bolts on the firewall, the 2 to the plate that goes to the firewall, the three that hold the steering column up to the dash and the four under the column.  It then slid down slightly closer to the power steering box and I tightened them up.  I think it might have been binding a little after putting in the shims.  After the alignment and steering column adjustment it recenters better (not perfect at speeds less than 20 mph, but well at higher speeds) and the car drives well.  It reduced, but did not eliminate my driveline vibration.  I can now drive up to a little higher than 70 mph before it sets in, and that is only on deceleration.  It is now very smooth at 65 mph.

Thanks for the help.  This will work until I get back to it and try to fix it some more, but that will probably be 12 or so months from now.   

[cdr]

I found after the kframe drop, I had room to raise the tailshaft some, & then had to remove the leaf spring pinion angle shims to get the angles correct. SMOOOOOOTH & quiet. so now my pinion angle is at the stock setting.