Rear Caster Angle measuring and adjusting

[J TNT]

"Use these adapters, along with a magnetic Digital Angle Gauge, while performing alignment procedures on the 2013 SRT Viper (ZD)."

https://www.moparessentialtools.com/...003&type=tools

If anyone has a used set for sale let me know , I'll buy them !
Thanks !

[Zubik]

I read the service manual, but it goes into connecting drbIII to it and lowering and raising car to read the dynamic caster. Hoping a quick explanation what exactly one should do with that adapter and what reading to look for. Or are you still following the fsm with lifting car off suspension and taking measurements.

[SRT_BluByU]

These set rear Caster; you can read the FSM for instructions. In a nut shell these hook to the ball joint and spindle with the hooks and mate to the machined surface of the spindle. from there you set the mag inclinometer on the pad and use that to get the correct setting by adjusting the rear lower control arm camber bolts. Gen V recommended setting is .7; but best to look at service manual for your year.

Setting the dynamic toe, which moves the suspension through the compression and rebound range (+2", zero, and -2") , involves plotting on the graph and making sure the plotted arc is within the range and is similar to the ideal arc referenced.My understanding is this shouldn't be touched and is set from the factory - unless the car has been in an accident of some type or someone has accidentally adjusted the inboard toe camber bolts (frame side) which they shouldn't.... but sometimes happens.. This procedure is an iterative process that folks seemed to keep close to the chest.. after having to have it done a handful of times I was eventually forced to learn it myself chasing down another problem.. The Gen V service manual has the procedure and I image all the gen's are pretty similar.. some say there are quicker ways but I finally like the results we've gotten and the snake is slithering smoothly again.

random thought - Maybe a nice club perk would be if they got a set to loan out (with deposit of course) to members in need that could mail them back when done. I've found most of the local dealers don't have the tools and the ones that do don't always know they have them, or how to use them, or maybe want to use them... it takes a special tech who has the OCD for for the job - including patience and experience. I've been fortunate to have some wonderful alignment help lately!

[Back In Black]

incorrect.. they are tool steel. I own a set. You are probably thinking of the spindles on the car which are aluminum. In my opinion every Viper owner should own a set of these.. I wont let anyone attempt an alignment without them having these and understanding how to use them AND dynamic toe (what to do and what not to do). This was an expensive lesson for me.. Now finally sorted.


These are for the Gen V.. but ive been told they are the same back to Gen III

I stand corrected. Mopar labeled are steel. My Millers are aluminum.

[GTS Dean]

A small strip of steel gauge metal glued or screwed to the aluminum bracket will allow the use of a magnetic inclinometer.

[Zubik]

So I got a pair of the adapter, in aluminum. That's not a big deal, as I'll bond a piece of machined flat stock. My question is about the magnetic inclometer/degree measurer. The one I got is digital and needs to be zeroed to something. How does one go about zeroing it out to a good reference or should I get an old school analog one?

[TKO MOTORSPORTS TEAM]

So I got a pair of the adapter, in aluminum. That's not a big deal, as I'll bond a piece of machined flat stock. My question is about the magnetic inclometer/degree measurer. The one I got is digital and needs to be zeroed to something. How does one go about zeroing it out to a good reference or should I get an old school analog one?

use a bubble level if meter does not have built in zero to world. Level bubble level and put meter on it and zero. This will get you really really close to zero plenty good for what your doing. You also always want the least amount of caster possible. If spec is 1-2 always shoot for the lower number.

[GTS Dean]

Many electronic levels have a built-in calibration routine. It will usually require a couple of button presses and turning the gauge around to point the opposite direction while it takes an average. If that's not included, use the above recommendation.

[TKO MOTORSPORTS TEAM]

use a bubble level if meter does not have built in zero to world. Level bubble level and put meter on it and zero. This will get you really really close to zero plenty good for what your doing. You also always want the least amount of caster possible. If spec is 1-2 always shoot for the lower number.

You will probably figure this out but just in case. If your meter is oriented horizontal when you zero it on the bubble level it will be zero " horizontal" . When you check caster it will go "90" ( should be some "positive" number no matter what) so you will have to do the simple math to figure out your positive caster number. It probably sounds a little confusing so best way to figure out how this all works is to just do it, I think you will see how the meter and caster works pretty quick.

[GTS Dean]

I was checking on some alignment recommendations I had made to an owner a little while back. I had a lightbulb moment I thought I would share for making reasonable rear adjustments without rear inclinometer adapters and gauges. Most shops can calculate the rear axle thrust angle and wheelbase difference L/R. These are indirect indicators of caster imbalance, or toe that isn't set exactly off the vehicle centerline.

Begin up front with the caster/camber/toe in-spec and equal on both sides at the front. I still think it's a good idea to baseline your car by centering both cams on a corner, then rolling the bolts out in time to set camber. With camber held constant, adjust caster by rolling one bolt outward and the other wishbone bolt inward by equal amounts.

Next set rear camber as above, then adjust toe to zero and measure wheelbase difference and thrust angle. If one side has a longer wheelbase than the other - it means that side has less positive caster (lower ball joint further behind). To shorten wheelbase while holding camber fixed, you push the long side wishbone rear adjuster bolt inward and the front outward by equal amounts. Then, reset to zero toe and check readings again.

The Gen 1 and Gen 2 cars have 96.2" design wheelbases. I'm pretty sure the G3-G5 went several inches longer - maybe 4"? With the ideal wheelbase measured relative to correct and balanced front front spindles, the rears should come in without much trouble. Since you never want negative rear caster on G2-5 cars, I would want the wheelbase just a tad on the short side to be sure. This does not give you an actual angle, but could keep you from having squirrely behavior at the back of the car. Of course, this all assumes that there is no frame damage or twist - or else you'll be endlessly chasing your tail.