When checking caster (with an angle finder) should I find different readings measuring from the bottom of the Cs and the flat spots on the front of the pumpkin? My question is so because these are supposed to have an offset pumpkin to add about 6 degrees of caster. Am I correct? I'm seeing the same reading measuring from the two different spots.
Dynatrac PR44 Unlimited
- Thread starter T&ERun
- Start date
HDGasser
New member
Stock is 6*
Unlimited PR44 is 10*
I think your supposed to measure on the machined surface on top of the C's or the BJ's.
If your seeing 5 & 5 then you've got 5* of caster & 5* of pinion angle
I've got mine set around 6 & 4 and it drives real nice and no vibrations from the driveline
Unlimited PR44 is 10*
I think your supposed to measure on the machined surface on top of the C's or the BJ's.
If your seeing 5 & 5 then you've got 5* of caster & 5* of pinion angle
I've got mine set around 6 & 4 and it drives real nice and no vibrations from the driveline
This is incorrect. Stock caster is +4.2°. A stock axle will have a 6° of separation so when your caster is set at approximately +4°, a measurement on the front face of your differential case spreader holes will give you a reading (from the top) of 92° or 88° depending on how you are looking at it.
Again, this is not correct, the ProRock Unlimited has +6° of caster installed with a 10° of separation. This means a reading at the top of the ball joint should be at +6° with a measurement on the front face of your differential case spreader holes showing (from the top) of 94° or 86°
This is correct.
Thanks guys, very helpful info. One more question:
I'm having some issues with the way the springs are setting. The driver's side spring is "bending" forward and hitting the swaybar end. The passenger side is sitting a lot better. It has a slight bend toward the front but is leaving plenty of clearance for the sway bar. I'm going to check the caster and pinion angles and see how they look now with the info above because something is funky.
I'm having some issues with the way the springs are setting. The driver's side spring is "bending" forward and hitting the swaybar end. The passenger side is sitting a lot better. It has a slight bend toward the front but is leaving plenty of clearance for the sway bar. I'm going to check the caster and pinion angles and see how they look now with the info above because something is funky.
Sounds like you have your lower control arms set too long or have your uppers set incorrectly.
HDGasser
New member
Ok... I forgot the Seperation part. Never said 6 & 10* of caster.
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I'm getting there but still not good enough for me. I just had the EVO longarm upgrade brackets and arms installed. The shop that did the install didn't notice the spring hitting the sway bar. They had the lower arms adjusted about 1 inch out (from being screwed all the way in). I pulled them in all the way except one thread showing. This helped. Then I adjusted the uppers as much as I could. The drivers side is still hitting the sway bar and I have the upper arm adjusted all the way in also (netting me about 7 degrees caster). If I could get it to about 5-6 degrees I think the spring would be sitting almost straight up and down and clear the sway bar (but I have no more adjustment because the upper arm is all the way in and the lower is basically all the way in). The passenger side is much better. It looks like the control arm brackets are installed correctly (they couldn't really mess this up as the brackets sit up against the tranny crossmember). I'm going to call Drew tomorrow at EVO to see what he thinks.
You need to set your uppers LONGER as that will reduce the amount of positive caster you have.
They are supposed to be indexed opposite. This is why your driver side coil is bowing forward and if you look carefully, your passenger side is bowing toward the back. Left unchecked, the passenger side will catch on the bump stop cup when flexing.
Ok. Just confirmed it is correct. I was wrong in how I described them in my last post. They are opposite with drivers' indexed on the back side and the passenger indexed on the front side of the axle. The passenger side is bowing slightly back but is sitting much better than the drivers' side. If I make the drivers' side upper arm longer, it makes the spring bow toward the front and it rubs with the sway bar even more.
If you look at your coils carefully, you will see that they are in fact bowing in an "S" like shape and not just outward on the driver side or inward on the passenger side. This is being caused by the indexing of the lower spring perch. Lengthening your upper arms will straighten the coils out AND will give you the proper caster angle that you need. IF after you do this you are still hitting your driver side sway bar arm, your lower arms are still set too long. Also, you NEED to set your arms to the same length. I think I read you say something about only adjusting one upper arm - to do this is a bad idea as it will just put a lot of bind on your bushings and that will cause them to fail prematurely.
Eddie, on most Jeeps how should the axle side spring mount (lower coil spring perch) align with the frame mount spring mount (upper spring perch). Should they be straight up and down from each other, should the axle mount be slightly forward of the frame mount, or should the axle mount be rearward of the frame mount?
Unless you have things way off, it really shouldn't matter plus or minus where it's positioned but, at ride height, they should sit some what in line with the upper perch. Are you running Plush Ride coils? If not, what coils are you running? Depending on how the bottom of the coil terminates, that can play a significant part of your spring bow.
I am running 4" plush rides. My axle perches are about 3/4" forward of the upper perches. I'm running a Dynatrac PR44 Unlimited. The driver's side lower "pigtail" on the coil is indexed on the backside. The passenger is indexed on the front side. I've been on the phone with Dynatrac, Northridge, and Mel at EVO. I just emailed off a bunch of pics to Mel and Jake. Hopefully will know more tomorrow after they look at the pics. I'm having to run 10-11 degrees caster to have the coils not bow. My lower arms are screwed all the way in and uppers are adjusted out to get to the 10 degrees. At 6-7 degrees my uppers are screwed all the way in also and the drivers' side coil is bowing enough to hit the end of the swaybar.
After talking to Rob at Dynatrac and Mel and Jake at EVO Manufacturing (and countless measuring and taking pics), I've came to the conclusion that it's the coil spring buckets on the axle. I believe that if the buckets had a deeper "relief" in them for the pigtail of the coil to sit in, the springs would not bow like they are now. I've talked to a few guys running this same long arm kit with stock axles and running 5.5 degree caster with no problems. I think running the plush rides is contributing to the problem as they will give more than a typical spring (TF, RK, etc). I have it set near 8 degrees caster, which leaves my pinion at -2 degrees, and I'm not rubbing right now (and no vibes at 60mph through the Tcase or tranny). However, the coils are still bowing, and like Eddie said I think I'll have some issues with rubbing the bump stops. I'm going to live with it for now and go wheeling this weekend to see how it does. My plan is to "massage" the coil buckets this summer when I have more time. Removing some material will help the coil sit more level in the bucket IMO. We'll see. If you guys think that removing material (grinding down) from the coil buckets is a bad idea please speak up.
36Fan
New member
Some people set up for ride height,other at full bump. I've always setup for full bump. First measure spring length at ride height, then I would set up on jack stands, remove the springs and jack the axle up the to bump stops with the tires on. Center the axle under the bump stops using the CA's. After that I would lower the axle to the measurement you got from your spring ride height and then adjust caster or pinion, which ever you are more concerned about. Other may do it different,this is how I would do it.
iRonin
Member
Sorry to resurrect this thread but I'm glad I found it, I have the exact same problem on the exact same combination - PR44 Unlimited sitting under EVO LongArm w/PlushRides. Caster and everything else is dialed in within spec, drives like a dream, but the driver side coil bows forward and contacts the swaybar link (not bad, but enough to rub), meanwhile the passenger side coil is sitting is pretty straight and does not make contact.
The crux is that with caster dialed in my lower CAs have no slack (screwed all the way in), so i can't really shift the entire axle back laterally and maintain angle. I called ORE and they did mention that their LA kit does push the axle forward a bit (1/2" iirc), and that having zero slack in the lowers is common.
So then logically I guess I need to.... shorten.... my uppers, therefore rotating the axle rearward to pull the coil off my swaybar link, which would also give me an increase to caster, and probably a slight bow rearward on the passenger side, which is fine....does this sound about right?
The crux is that with caster dialed in my lower CAs have no slack (screwed all the way in), so i can't really shift the entire axle back laterally and maintain angle. I called ORE and they did mention that their LA kit does push the axle forward a bit (1/2" iirc), and that having zero slack in the lowers is common.
So then logically I guess I need to.... shorten.... my uppers, therefore rotating the axle rearward to pull the coil off my swaybar link, which would also give me an increase to caster, and probably a slight bow rearward on the passenger side, which is fine....does this sound about right?
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cozdude
Guy with a Red 2-Door
What is your caster set at? Also the unlimited usually has caster built into it.