Align your car at home?

[Kern Dog]

You are welcome.
I was impressed at how it started to make sense as I got deeper into it all. The direct relationship of caster and camber was something that I'd heard of but hadn't seen in front of me before.
Two separate cars with similar construction, similar parts and they got similar numbers.
I've read for years from guys that had trouble getting adequate caster and thought my red car was somehow rare or unusual since I've always been able to get good numbers with it. Now with the second Charger getting similar numbers, I wonder how other guys have had trouble.
A buddy texted me today...His '68 Dart has offset bushings but was aligned to 1 3/4 degrees positive caster and 1/4 degree negative camber. That car should have been able to do much better. The guy is going to bring his car over here on Monday and we will see what numbers we can get with some adjustments.

[timmycharger]

Thanks for the write up, had I seen this a few years ago I would have attempted it. Next time I have the front end apart this is what I am doing!   

[Mike DC]

 
I once measured the front suspension to figure out how far off A-arms were compared to modern alignment specs (3 degrees of caster* and 1-2 degrees of negative camber).  Like, how much different would the A-arm dimensions be if the factory engineers had designed them for modern steering/tires in the first place. 

(3 degrees of caster is still not much for a modern car.  Some have 6+ degrees.  But the old Mopar front end starts getting out of whack when you take it that far.  Bump steer, etc.)


Getting modern camber doesn't take much. The upper ball joint needs to move around 1/4" inwards (towards the engine).  It partially depends on where you have the front end ride height set.  Lowering the ride height has a side-effect of improving the camber a bit. 

But the caster is a bigger change.  The ball joint has to move back (towards the rear of the car) about half an inch.  The bushing adjustments weren't intended for changes that big.

Adding it up, IMO there's a good argument for using custom/aftermarket A-arms.   



But the offset bushings aren't bad.  They do enough to offer a practical improvement. 

IMO it makes sense to prioritize the caster gains more than the camber gains (within reason).  Modern tires are more forgiving of camber issues than old bias-plys were.  The self-centering steering (from added caster) is a more rewarding change that you feel all the time you drive the car.  The camber improvement is most noticeable in rare moments when you are cornering hard.  And modern camber is actually a drawback for hard braking. 

[Kern Dog]

The Caster angles in newer Challengers is surprising.

[Kern Dog]

Yeah, you read that right...The SRT8 cars had over a degree of negative camber and right at 9 degrees of caster.

[Mike DC]

Yeah it's a big difference. 

I don't think it would work to take the old Mopar front end that far away from zero (the original spec).  Not with only a moved upper ball joint.  The whole front end has other quirks that modern stuff doesn't.  The upper ball joints move around a lot (by design) depending on where they are in the wheel travel.  Behind the LCAs, the torsion bars pass through the ideal place for the steering linkage so that's another compromise.  Etc.     

The old Mopar engineers gave the front end zero caster because everything was still designed around manual-steering cars back then.  They needed to keep the low-speed parking effort under control.  Putting big caster into front ends is a luxury you have when there is power steering to assist in parking lots. 

[Kern Dog]

Well given that I have power steering along with the majority of others, the zero or negative caster readings the factory service manual calls for is stupid.
Mine drives great with the 8 degrees of caster. The wheel returns to center with greater authority than before, The car has always been stable at speed.

[Mike DC]

Well given that I have power steering along with the majority of others, the zero or negative caster readings the factory service manual calls for is stupid.
Mine drives great with the 8 degrees of caster. The wheel returns to center with greater authority than before, The car has always been stable at speed.

Wait, you've got 8 degrees of caster on a '70 Charger?

[Kern Dog]

Yes. I was able to get over 5 degrees with 2 separate '70 Chargers using offset bushings in stock control arms.
The QA 1 upper control arms allowed me to get 8 full degrees and the 1.0 negative camber. I was amazed too.
My picture files are too big, I'd have to find a way to resize or take new pictures with the gauge attached to the spindle.

[Mike DC]

   
How is the feel of it? Bump steer? any other unpredictability? 

How raked is the stance of the car?   

[Kern Dog]

Since the wheel arches at the front are up slightly higher than the rear, the way that I usually measure my cars is not accurate to describe rake. I measure to the top of each wheel arch. The front of the red car sits lower than the rear by one inch. If I pulled a string line across the rocker panels, I could properly assess the amount of rake. I just haven't taken it that far yet.
As it is, the front reads an inch lower at the wheel openings on the red car. There is a 2 inch difference with Jigsaw, the beater Charger.
I noticed no difference in bump steer from the driver's seat. I didn't measure it during the alignment. I'm aware that tilting the knuckle back also tilts the ball joint steering arm down (increasing bump steer) but I didn't notice a change there. It feels stable, the steering effort didn't increase.

[Mike DC]

 
Yeah, I'm surprised you got that much caster without bumpsteer issues cropping up. 

[Kern Dog]

Well, I didn't drive on any cobble stone roads yet so who knows.
I've heard of guys cold bending their ball joint steering arms to get the bump steer numbers back down. I'd need a press to do that sort of thing.

[Mike DC]

 
It's not exactly recommended in shop manuals but it's do-able.  Those arms are just forged steel.   Off-road guys bend & fabricate that kind of stuff all the time. 

The 1973-up lower control arm design is more workable for this kind of tinkering.  The steering arm is an individual piece that's not integrated with either the spindle or the ball joint. 

[Kern Dog]

Yeah, but then you'd have to drive a 73-74 model instead of a '70.

[Mike DC]

Yuk, yuk.

The later front end has grown on me over the years though.  I'm a 2nd-gen guy but there are things to like about that isolated 73-up K-frame design.  I don't see THAT MUCH extra weight, but I see a lot more room to modify things without cutting the unibody.   

[Kern Dog]

Just messing around.
I actually like the 71-74 Charger and the 73-74 Satellites. There was a company that was selling lightly modified 73-74 B body LCAs for use in earlier models. The design allowed for more suspension travel.

[Mike DC]

 
Yeah the 73-up LCAs dip down farther in the middle which gives more bumpstop clearance.  I can't remember who was selling that conversion for the earlier B/E cars.     


I'd be curious to see how the 73-up K-frame would ride if it had a different bushing setup.  I'm picturing something that still uses rubber bushings, but the bushings would be shaped to hold the K-frame tighter on lateral movement. 

Many modern cars & SUVs have isolated subframes and they don't always feel too mushy in the big picture. 

[Kern Dog]

Firm Feel defaulted to solid spacers, I recall Mopar Action's Rick Ehrenberg suggesting cast iron.
I had a 76 Camaro that had a subframe that used rubber cushions between it and the structure of the car. I replaced those with plastic pucks to improve handling. I used what was actually the white plastic polyethylene we use for cutting boards in kitchens. It was 1/2" thick and had a small amount of cushion compared to steel spacers.

[Mike DC]

                           
Yeah most people who care about handling choose to lock out the subframe's movement with solid spacers of some kind.  Metal, or at least a plastic/polyurethane (which is close to solid).

But the factory used rubber isolators for valid reasons. I like the idea of keeping that extra ride smoothness without having sloppy cornering.  Modern cars seem to pull it off.  It's just something I might experiment with if I ever built a 73/74 B-body. 



I think the rubber LCA bushing on our old Mopars is too thin (the rubber layer).  They wear out too quickly, they transfer too much NVH to the chassis, and they transfer too much stress to the K-frame mounting tubes. 

I've wondered if Mopar's engineers ever experimented with making that bushing thicker. It seems like an easy partial fix for some of the issues that made them isolate the whole K-frame in 1973.  And they could have improved an issue on all the A/B/C/E-body cars with one re-tooling.  IIRC all Mopar cars used that same LCA bushing in the 60s/70s even though the actual LCAs & torsion bars varied. 
 
 

[Kern Dog]

The thin lower control arm bushing probably does transmit more harshness to the cabin than the big bushings found in other cars with an actual A design for the lower control arms. MY 76 Camaro had big bushings in them but it was still a great handling car.
I don't see a way around it for our cars though. I don't know how you'd be able to modify the car or control arms enough to use a bushing of larger mass to cut down on the harshness.
It is an interesting idea, maybe someone with the skills to fabricate custom LCAs could come up with something. I don't know that the gains would be worth the monumental effort though.

[Mike DC]

                 
That's my read on it too.  The idea might be valid but there's no way to implement it without doing way too much custom building. 

There isn't room to bore out the control arm's T-bar anchor piece to fit a bigger bushing.  And I don't know if a bigger suitable bushing even exists or if that would have to be custom too.


The whole LCA inner pivot area is just a bad design compromise IMO.  I like the torsion bar design in theory but they tried to make that LCA do too many jobs in too small of a space. 

It probably needed a layout that involved two separate rubber bushings - one between the LCA & K-frame, and another between the LCA & torsion bar. 

[Kern Dog]

The LCA bushings are thin on rubber but the urethane ones do give a noticeably rougher ride.
In the early 2000s when there were at least THREE major vendors making suspension rebuild kits, they all seemed to push the urethane angle. PST, Energy Suspension and Just Suspension all had kits with rubber or with urethane. I bought into the hype and installed a full urethane kit. After awhile, I swapped in rubber LCA bushings, then rubber offset UCA bushings. I still have the urethane bushings in the strut rods.
My car rides pretty decent. It is about as firm as the wife's 2015 Challenger R/T with the Super Track Pack option group that came with stiffer suspension and better brake pads.
I still get road noise that would be great to reduce, though I don't see it being possible to tone it down that much.
These cars were not built to be quiet like new cars are. The rain gutters, drip rails, exposed windshield wipers, vent windows and recesses tires/body overhang all conspire to grab the wind, not slip through it. Add to that a solid lifter cam, headers and 3" exhaust!

[Mike DC]

 
IMO the polyurethane boom has a lot to do with GM cars that are covered in thick rubber donuts and floppy perimeter frames.

A/B/E Mopars had much tighter bushings & frames from the factory.  I'm a fan of keeping them all rubber. The material is fine & preferable as long as it isn't worn out from age/mileage.

Yeah, the rubber parts need to be replaced periodically.  So do spark plugs and clutches and seatcovers and everything else.  If you never want to replace parts then you're in the wrong hobby.

 

[Kern Dog]

 
Yeah, old cars are not maintenance free!