lowering question?

[noff57]

What/how is the best way to lower the front and rear on a 73 charger?

[lisiecki1]

how low?

[Cooter]

Unwind the T-bars in the front and lowering/lift blocks in the rear...

[68X426]

Remember that when dropping the front, you may encounter tire clearance problems you didn't expect.

Also, you may want to get a re-alignment as the the geometry of steering/height/tires has changed.

[noff57]

how low would it lower the front when unwinding the t-bars? I would like to lower it 2-3inches

[ChargerST]

2" drop spindles

[Cooter]

Damn, That low, yeah, you better go with dropped spindles...With the T-Bars unwound THAT far, you won't have any suspension and it'll ride like a Road Wagon...

[375instroke]

I don't understand dropped spindles.  Suspension travel stays the same, spring rate stays the same, but the car is 2" lower.  My K-frame would hit when lowered with stock spindles.  Get lowering blocks, stiffer torsions, cut the rebound bumpers to 3/8" thick, and drop the front.

[HPP]

Drop spindles alter the location of the spindle shaft two inches higher, which when mounted results in a two in drop in ride height. This is how it allows full wheel travel because you aren't reduce travel to get ride height.

[ACUDANUT]

 I have lowered many 3rd gen Chargers by adjusting those bolts. 2 inches had no effect of driving.

[Mike DC]

I don't understand dropped spindles.  Suspension travel stays the same, spring rate stays the same, but the car is 2" lower.  My K-frame would hit when lowered with stock spindles.  Get lowering blocks, stiffer torsions, cut the rebound bumpers to 3/8" thick, and drop the front.

Agreed.  At least in most cases.  

The factory originally designed the car's "bottom-out" bumpstopping point to protect the K-frame & chassis.  If you hit a big enough bump to momentarily mash the tire sidewall flat on the bottom, the chassis wouldn't hit the ground before the suspension bottoms-out against the rubber.  

And let's not forget one more thing - header collector clearance.  


   
Drop spindles are good to help retain the stock geometry.  But you would need to raise the bumpstop position to protect the chassis if you're still running 14" or 15" wheels.  So there's no (safe) lowering improvement over the stock torsion adjuster unelss you're running larger wheels, just the slight geometry difference.   
   

[noff57]

I want to put 18in wheels on the front a 20's in the rear will there be enuff clearance if i lower it 2inches?

[lisiecki1]

I want to put 18in wheels on the front a 20's in the rear will there be enuff clearance if i lower it 2inches?

It's gonna look like a hot wheels....you might have enough clearance if you run rubber bands for tires....the ride will suck.

I'm not making fun by the way, I was originally going to do the over-the-top staggered fitment, but it just started to look goofy to me and after driving many different kinds of wheel and tire combinations on the supra I decided the ride would be harsh as hell and I just wouldn't enjoy driving it as much, and driving is the purpose of the car I'm building.

[noff57]

I love the look of this 71 RR on this site http://www.pro-touring.com/forum/showthread.php?t=47410

Its the brown 71 RR 3rd picture down.

I want my 73 to look alot like this except just lowered not on air.

[Nacho-RT74]

loose the T bar will make also a bouncy car like a worn spring. Would requiere A LOT STIFFER shocks. to get a lower ride with similar suspension Torsioned bar specs will require also a thick and new T bar

[Mike DC]

 
If you're gonna run 18" wheels then the 2" drop spindles should theoretically work.  That 2" of lost frame clearance will be eaten up by the increased wheel diameter.   

But make sure that those wheels/tires actually fit that far up into the wheelwell when you put it all together.  Take ALL the pressure off the torsion bar adjustment and see what happens when you jack the wheel all the way up as far as it'll go.  (That includes when you're turning the wheels side-to-side.) 

[noff57]

thanks guys for the help 

I think I have a grasp of what I need to do 

[Mike DC]

 
BTW:  You don't have to go very wide on the front wheels before that brace on the inside of the fender (at the top of the wheel arch) starts to be a problem.

The other big place for rubbing (maybe the earliest one) is the car's chassis.  Turn the front wheels way over to one side, and the inside tire rubs against the framerail.  I mean like back behind the steering linkage. 

[noff57]

Has anyone else put 18" in the front or am I the only one? If so I would like to know of any problems.

Mike DC has really gave me some good advice on where to check for problems.

[lisiecki1]

I've been contemplating going 17 or 18 and the only thing I can say for sure is that you should get some cardboard and cut it to the size of the wheel/tire combo that youre planning to run and check the fitment.  You can also do it with a straight edge and a tape measure.  With the vast difference in the way each car seems to be built back then what works for someone else won't neccessarily work for you.  Even body panels from another car of the same year and model require "adjustment" in many instances.

[375instroke]

I'm wondering why one needs all this suspension travel when you are going to hit the ground first.  How is the geometry compromised when lowering?  Look at this video of a Charger 500 with stock spec. suspension.  Looks like crap to me.  When lowered, the outside tire's camber moves negative faster, and the inside moves positive, helping the contact patch as the vehicle rolls in the turn.  At stock height, the outside camber gain isn't as much, and the inside tire moves negative, reducing the contact patch even more.  I wonder if anyone's done some track time comparisons with dropped spindles compared to stock spindles with lowered torsions.

http://www.youtube.com/watch?v=NqtbaQL8K9Y

[Mike DC]

That's a perfectly valid concern to raise.  But there's more to geometry than camber gains alone. 

I'm not saying which way is better or worse.  It's debatable depending on the specifics of the car and conditions. 

 

[375instroke]

I don't know either.  I just don't think suspension travel is much of a concern.

[HPP]

That video should show you exactly why wheel travel is a concern. With stock t-bars, which would have been .92 in the case of the 500, I would be willing to bet that car was getting 6" of wheel travel. If you drop the car 2" by turning the torsion bars down, which is common with many people, and not all of them step up the rate of their bars when they do it, you will bottom out the suspension travel and your wheel rate will go infinate and your tires will loose grip. By using a drop spindle, you maintain the stock wheel travel with the lower ride height and you get the best of both worlds.

Now, if you step up the t-bar rate substantially, then you also will limit the travel significantly with normal road cornering speeds. I have about 1.5" of wheel travel in my car, but with a 1.22 t-bar, I have never bottomed it out. Then again, combined with a 1.125 s-bar, I have practically no body roll either.

Even with lowering spindles, you should be riding on the rim before damaging suspension components if you have a flat, but it really does depend on the wheel diameter and tire aspect ratio to determine how much room you have to to play with. Now headers and oil pans are another scenario altogether. If you have a 8 quart drag race pan or headers, yeah, you're probably going to drag them on the ground.

Geometry wise, lowering the cars does not significantly alter a mopar suspension geometry. Mopars have negative camber gain under compression that is linear. It does not gain more camber if the car is lower than stock, but it will gain more camber if you use the taller FJM spindles. The one draw back to significantly lowering a mopar is that the front roll center can go under ground, which may lengthen the moment lever arm and in turn, increase body roll.

[Mike DC]

That video should show you exactly why wheel travel is a concern. With stock t-bars, which would have been .92 in the case of the 500, I would be willing to bet that car was getting 6" of wheel travel.

Yep, there's a ton of wheel travel in these cars compared to a modern sports car.  I measured it once years ago.  From full compression to full droop, it's about 8-9 inches in the front and about 10-12" in the rear.

If you drop the car 2" by turning the torsion bars down, which is common with many people, and not all of them step up the rate of their bars when they do it, you will bottom out the suspension travel and your wheel rate will go infinate and your tires will loose grip. By using a drop spindle, you maintain the stock wheel travel with the lower ride height and you get the best of both worlds.

The "bottom-it-out-to-make-it handle-better" thing seems to go in & out of style periodically.  Seems like every 15-25 years a new batch of racers will experiment with it again as if it's a new idea.  The compressed air in the tires is still suspending the car a little. 

Even with lowering spindles, you should be riding on the rim before damaging suspension components if you have a flat, but it really does depend on the wheel diameter and tire aspect ratio to determine how much room you have to to play with.

The factory built these cars so that you could run 14" rims at all four corners, get all four tires flat, compress the suspension to the bumpstops, and still not hit the pavement with the chassis.  Sticking the wheels 2" farther up on the spindles will mean you're taking a risk with anything less than 16" wheels.  I wouldn't run 15" rims on drop spindles without spacing up the bumpstops.  

Even without the tire blowouts, if you just caught enough air with the front end then you can bottom-out the suspension while compressing the tires momentarily down to the rims at the same time.  It's not a common event (outside of Hazzard County), but the consequences of it are too high not to wanna hedge against it.  Crushing an oil pan or some headers will ruin your week, but in the case of drop spindles we're talking about potentially hooking the CHASSIS into a pavement rut at full speed.  Not pretty.  


 

[375instroke]

Lowering does change the geometry in the sense that it moves the caster adjustment range in the positive direction, allowing more positive caster to be set.

I'm sure that bottoming out the suspension isn't helpful for handling.  Something bad must happen when the outer control arm stops moving, and the inside of the car starts pivoting on the outside tire instead of the roll center.

In a turn, when the outside tire moves up, the inside tire is pulled up also, thus lowering the entire front of the car.  Is this lowering also helpful for geometry and handling?  When the outside stops moving due to it hitting the bump stop, does that render the sway bar ineffective?

[Mike DC]

When you put the outside front wheel onto the bumpstop in a corner, it's equivalent to suddenly raising the spring rate on that corner by a drastic amount.  That works sort of like suddenly raising the swaybar rate on the front end.  It's like jacking the car up by that wheel all of a sudden.  It stops the body roll from increasing and throws more weight back onto the diagonally opposite rear wheel.
 
Some people like the handling effect of this.  But I think it has a lot more to do with "feel" than measurable stopwatch gains.  Any and all forms of suspension subtract road feel from the driver.  Putting the outside front wheel onto the bumpstop really lowers the amount of suspension action.  And it won't be pretty if you hit a bump in mid-corner because there is only the tire's air pressure & the rubber bumpstop remaining to absorb it.  Neither of which have any shock/rebound damping action.  They're purely un-dampened springs.




In regards to the whole front end height (average of both sides) being lowered for cornering, I think the main theoretical benefit is reducing the body roll w/o any additional suspension stiffening being used to achieve it.  For street cars like ours, IMHO the increase of negative camber is probably just as much of a real-world benefit as the reduced body roll.





Pro NASCARS have been playing with "big-bar, soft-spring" setups lately.  It means a stiff front swaybar and a soft set of front coil springs.  The result is that the outside leans into the corner and then the swaybar pulls the inside front corner down with it, so the entire front end spends the whole corner riding lower than it rides when there is no body lean.  

I think this setup has more to do with NASCAR's racing situation than what would be ideal in theory.  Their maximum front coil spring rate is rules-
limted, so the teams might decide that laying the outside wheel onto the bumpstop is a way to sidestep that rule. (Use the bumpstop to do the coil spring's job in the corners.)  The difference is that the BBSS setup means they can ride the bumpstops while also NOT leaning the body very far to get the outside corner that low.

Meanwhile they also benefit any time they can squeeze the whole car's ride height downwards just for aerodyamnic reasons.  Those cars spend half the miles of the race with the body leaning.  If all those miles are spent with the body riding an inch lower in front, that adds up to a lot of aero gain.    

[375instroke]

The lowered spindles do get the LCA to stay at a more downward angle, helping camber gain.  This is an advantage, but I still think the retained suspension travel isn't.  I'd raise the bumpstop to compensate.

[THE STIG]

Remember that when dropping the front, you may encounter tire clearance problems you didn't expect.

Also, you may want to get a re-alignment as the the geometry of steering/height/tires has changed.

Can't stress that enough, that's a great way to destroy tires.