eaglescout526 Posted October 10, 2021 Share Posted October 10, 2021 So I requested some LCA shims recently and my issue seemed to have sparked some curiosity as to why I need them. I for the life of me CAN NOT seem to figure my issue out. Lets go back to 2017. I went to get an alignment and tech said, replace all steering parts and Ill do the alignment. Ok done. Drove straight and no issues. Suddenly 2018, tires went bald on the edge really fast. Was told they were the ball joints to cause this issue. Ok replaced them as they were the original ones from the factory and they were toast. Got an alignment and drove straight and fine with the exception of a pull from the right side. 2019 Got new tires, no issues. 2021, had that little accident(repairs performed) and tires went bald again on the edge fast. Ok I have seen this before. Got new ball joints and put them in. Alright, got an alignment and tech said caster is off by alot. He recommended shims to fix the issue or better correct it and prevent my front from eating up tires. I do plan on getting a new steering shaft to remove the remaining slop issue in my column. My stinking issue is, why is my caster so screwed up? I have replaced damn near everything except the front axle itself and the knuckles and the 1 piece rotor/hub combo. Any ideas? Here is all the print outs of the alignments I have had performed to Little Red: 2017: 2018: 2021: Link to comment Share on other sites More sharing options...
JMO413 Posted October 10, 2021 Share Posted October 10, 2021 Have you replaced the upper control arm bushings in the axle housing? Just a thought. Link to comment Share on other sites More sharing options...
eaglescout526 Posted October 10, 2021 Author Share Posted October 10, 2021 5 minutes ago, JMO413 said: Have you replaced the upper control arm bushings in the axle housing? Just a thought. Yup! Twice. Once with polys(biggest regret) and again to replace the ploys back to factory rubber. Basically everything is new up front minus the axle and knuckles. Link to comment Share on other sites More sharing options...
fiatslug87 Posted October 10, 2021 Share Posted October 10, 2021 Did that curb "issue" cause more damage than you thought? Link to comment Share on other sites More sharing options...
eaglescout526 Posted October 10, 2021 Author Share Posted October 10, 2021 3 minutes ago, fiatslug87 said: Did that curb "issue" cause more damage than you thought? If it did it looks like it brought the caster in by a degree judging by the print outs. The only other differing factor is I’ve gone up in tires size. 2017 was the original 205 size and still had the caster. Went up to 215 in 2019 and then 235 this year and caster is still bad. I’ve examined the frame and area multiple times for any sign of buckling or damage and I still can’t find anything. Link to comment Share on other sites More sharing options...
fiatslug87 Posted October 10, 2021 Share Posted October 10, 2021 You are shooting for 7° to 8° caster so it is worse after the curb incident. Link to comment Share on other sites More sharing options...
eaglescout526 Posted October 10, 2021 Author Share Posted October 10, 2021 1 minute ago, fiatslug87 said: You are shooting for 7° to 8° caster so it is worse after the curb incident. So if thats 7*-8* inward than do I need to remove shims? But it could also be worse from the increased tire size and who knows what all my grandfather did to the MJ prior to my ownership. Link to comment Share on other sites More sharing options...
fiatslug87 Posted October 10, 2021 Share Posted October 10, 2021 You need to add shims to increase the angle from ~5.5° to 7.5°. How many shims are there now? Link to comment Share on other sites More sharing options...
eaglescout526 Posted October 11, 2021 Author Share Posted October 11, 2021 6 on the driver and 7 on the passenger. Link to comment Share on other sites More sharing options...
fiatslug87 Posted October 11, 2021 Share Posted October 11, 2021 Try adding a 1/8 shim and see where that gets you. The specs I posted above were from the 89 FSM, in 90 and beyond they changed, see below. Link to comment Share on other sites More sharing options...
eaglescout526 Posted October 11, 2021 Author Share Posted October 11, 2021 Absolutely fun! I wonder why the specs are like that? Let alone eating the insides of tires. Seems like I will have to stick with an aggressive rotation schedule. Link to comment Share on other sites More sharing options...
fiatslug87 Posted October 11, 2021 Share Posted October 11, 2021 FWIW My 89 and 90 have two 1/8" shims and one or two 1/32" shims. Link to comment Share on other sites More sharing options...
eaglescout526 Posted October 11, 2021 Author Share Posted October 11, 2021 I think all mine are 1/32" shims. I didnt see anything thicker or thinner than each other. Link to comment Share on other sites More sharing options...
fiatslug87 Posted October 11, 2021 Share Posted October 11, 2021 Wearing of the insides is due to camber. I think there are adjustable ball joints available, I've never used them. Link to comment Share on other sites More sharing options...
eaglescout526 Posted October 11, 2021 Author Share Posted October 11, 2021 Thats exactly what I think it is as well judging by the wear but my thought was that our tires wear evenly from inside to out. Not sure now on that. I thought about those and tried that 1* adjuster kit and I couldnt and can't use them due to the 2wd knuckles being different in the 87-90 years than the early years. I still wonder why AMC made a different knuckle design for 2wd after 86 when it wouldve been cheaper to use the same setup. Link to comment Share on other sites More sharing options...
gogmorgo Posted October 11, 2021 Share Posted October 11, 2021 Changes to the ride height that aren’t perfectly equal front to rear will cause a change in caster angle, including differences in tire pressure or wear front to rear. Remember it’s measured against the ground, not against the truck. If the front and rear axles aren’t aligned with each other, the steering angle needed to keep the truck pointing straight down the road can do things to tire wear as well. Your thrust angle has doubled since 2018, although I don’t know if that’s enough to cause anything, though – it’s still not huge. Link to comment Share on other sites More sharing options...
Eagle Posted October 11, 2021 Share Posted October 11, 2021 On 10/10/2021 at 7:21 PM, eaglescout526 said: If it did it looks like it brought the caster in by a degree judging by the print outs. The only other differing factor is I’ve gone up in tires size. 2017 was the original 205 size and still had the caster. Went up to 215 in 2019 and then 235 this year and caster is still bad. I’ve examined the frame and area multiple times for any sign of buckling or damage and I still can’t find anything. Caster is not "in" or "out." Caster is what used to be called kingpin inclination in the old days. It's the forward or backward tilt of the vertical axis between the upper and lower ball joints. If it changed after the curb incident, something got mildly tweaked. Shims move the lower control arms (and thus the lower ball joint) forward or back, which is what adjusts the caster angle. Link to comment Share on other sites More sharing options...
cruiser54 Posted October 11, 2021 Share Posted October 11, 2021 It appears your axle tube is out of whack on the passenger side. Over 1/2* of negative camber. And, your caster is on the low side for sure. Link to comment Share on other sites More sharing options...
Eagle Posted October 11, 2021 Share Posted October 11, 2021 16 hours ago, eaglescout526 said: 2021, had that little accident(repairs performed) and tires went bald again on the edge fast. Ok I have seen this before. Got new ball joints and put them in. Alright, got an alignment and tech said caster is off by alot. He recommended shims to fix the issue or better correct it and prevent my front from eating up tires. I don't understand this statement at all. The adjustment for caster is to shim the lower control arms. If there's enough range of adjustment in the rear pockets (which is where the shims go), that IS the "fix." If shims can bring the caster within spec -- what needs to be "corrected"? Link to comment Share on other sites More sharing options...
eaglescout526 Posted October 11, 2021 Author Share Posted October 11, 2021 I’m just trying to have everything in the steering department be correct and not chewing through tires before their lifespan. That’s all. I’m looking into getting some shims soon. Link to comment Share on other sites More sharing options...
Eagle Posted October 11, 2021 Share Posted October 11, 2021 7 hours ago, eaglescout526 said: I’m just trying to have everything in the steering department be correct and not chewing through tires before their lifespan. That’s all. I’m looking into getting some shims soon. Understood. But shims adjust caster, and caster generally doesn't create uneven tire wear. That's usually cause by camber and/or toe-in. Link to comment Share on other sites More sharing options...
eaglescout526 Posted October 11, 2021 Author Share Posted October 11, 2021 5 minutes ago, Eagle said: Understood. But shims adjust caster, and caster generally doesn't create uneven tire wear. That's usually cause by camber and/or toe-in. I’ll keep an eye on my tires and watch out for uneven wear. I am on a new set and since I went up in size, I probably need to adjust the shims accordingly anyways. I appreciate everyone’s help with this! I understand a bit more of what’s goin on. Link to comment Share on other sites More sharing options...
dasbulliwagen Posted October 14, 2021 Share Posted October 14, 2021 If you went up a size on the tires all around, your caster angle would not be affected. and, just so everyone knows, CASTER ANGLE DOES NOT AFFECT TIRE WEAR. Yes yours is a little low, but its not low enough to cause you any issues and seems to be close side to side. Shims will need to be added to increase your caster number closer to spec. Though with your tire wear issues, you don't need to be worried about a 5 degree positive caster number. If you can't get enough adjustment with shims, buy a set of adjustable lower control arms. These will dial you in exactly where you want it no matter what, but again, i wouldnt worry about your current number. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted October 14, 2021 Share Posted October 14, 2021 I would get yourself a adjustable lower ball joint. Not only will you fix your camber(which is what I believe needs to be done), it will also fix the caster at the same time If adjusted properly Link to comment Share on other sites More sharing options...
cruiser54 Posted October 14, 2021 Share Posted October 14, 2021 This^^^^ Link to comment Share on other sites More sharing options...
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