Help Me Solve My Suspension Issues! (Body Mount Rub on 285s)
- Thread starter blakkbox
- Start date
y=mx+b
New member
First thing to note is that suspension lifts only clear bigger tires at ride height. As soon as you stuff the tire in the front wheel well, the lift amount doesn't really matter
Second, is that the Caster number itself isn't really a trustworthy measure for the amount of clearance for the tires. As you know, caster is the angle between the line from UBJ to LBJ, and vertical. When lifting the 4runner IFS, while keeping the camber in spec, the caster tends to drop out. This could make keeping the wheels straight on the highway more difficult, wheel not return to center after turns as effectively as stock, etc. JBA UCAs are great for bolt on caster correction back to stock 3* to improve drivability back to stock.
I made a little picture below to try and explain some things better. Background rectangles are reference of LCA mounting positions, and body mount location.
The offset of the wheel also plays a role in the fitment. As Inv4drZm mentioned, more negative offset from the spacers increases the scrub radius. More scrub radius can also cause the tire to rub things as the wheels turn left and right. This is also a balance, because the increased backspacing from the spacer will help to space the tire away from the UCA. With JBAs especially, the flat part where the UBJ mounts is fairly wide. Without spacers, it may be tight or contact the UCA, but you'll never know without giving it a shot.
So working with what you have, I'd suggest first removing the spacers and seeing if that helps with the rubbing on the body mount. Check the UCA for rubbing there, as discussed above. If that doesn't work, remount the spacers and evaluate chopping the body mount. (side note: if the spacers were previously loctited, you need to clean all the threads really well and remove all the threadlocker remains before reattaching, or the buildup will cause them to reach torque spec before they're at the desired tightness)
Hopefully that makes sense, always a balancing game when fitting bigger tires on a vehicle that wasn't intended to have any more than a 265/65r17 on there
Second, is that the Caster number itself isn't really a trustworthy measure for the amount of clearance for the tires. As you know, caster is the angle between the line from UBJ to LBJ, and vertical. When lifting the 4runner IFS, while keeping the camber in spec, the caster tends to drop out. This could make keeping the wheels straight on the highway more difficult, wheel not return to center after turns as effectively as stock, etc. JBA UCAs are great for bolt on caster correction back to stock 3* to improve drivability back to stock.
I made a little picture below to try and explain some things better. Background rectangles are reference of LCA mounting positions, and body mount location.
- The main drawback is that +Caster from the UCA brings the tire backwards in the wheel well, as seen in the first image. While increasing drivability, clearance at the body mount and rear of wheel well is sacrificed. If I remember correctly, you mentioned stock UCAs didn't rub as bad as the JBAs, this is likely why. However, your JBAs will ride better than the stock when lifted due to the increase in caster, and I believe there is more UBJ travel on the JBAs, and the angle is corrected to keep them more centered in that travel.
- +Caster from the LCA brings the wheel forward. You can set this by adjusting the cam bolts so the front is all of the way in, and the rear is all the way out. The problem with a fixed position UCA, is that this will likely throw off the camber.
- The capability of adjustable UCAs, like SPCs, allow you to decrease Caster at the UCA, increase Caster at the LCA, and finally adjust the camber into spec. This will result in maximum clearance, with the potential sacrifice of overall caster depending on the tire size. From here, its balancing the tire size with the UCA caster adjustment to get them to fit, while also retaining drivability.
I'm a fan of adjustable UCAs for this reason, but it doesn't necessarily mean they're the best for your setup. JBAs or other fixed UCAs are great, because you can take to any firestone or wherever, and they only adjust the cams like stock would. Most alignment places would never touch SPCs, and lots of people end up aligning them at home.
The offset of the wheel also plays a role in the fitment. As Inv4drZm mentioned, more negative offset from the spacers increases the scrub radius. More scrub radius can also cause the tire to rub things as the wheels turn left and right. This is also a balance, because the increased backspacing from the spacer will help to space the tire away from the UCA. With JBAs especially, the flat part where the UBJ mounts is fairly wide. Without spacers, it may be tight or contact the UCA, but you'll never know without giving it a shot.
So working with what you have, I'd suggest first removing the spacers and seeing if that helps with the rubbing on the body mount. Check the UCA for rubbing there, as discussed above. If that doesn't work, remount the spacers and evaluate chopping the body mount. (side note: if the spacers were previously loctited, you need to clean all the threads really well and remove all the threadlocker remains before reattaching, or the buildup will cause them to reach torque spec before they're at the desired tightness)
Hopefully that makes sense, always a balancing game when fitting bigger tires on a vehicle that wasn't intended to have any more than a 265/65r17 on there
Inv4drZm
Senior Member
Good point, they probably will with a 4Runner wheel. With the stock 17" sport wheels and 285's my tires rubbed the spindle and couldn't even be mounted.
With OP's FJ wheels he *should* be fine. Factory FJ wheels should space the tire out enough it should clear is my guess.
This was my worry.
Interesting. One way to find out! I assume if spacers come off the front they should probably come off the back as well? I might just pull one off on one side of the front to test it out.
First thing to note is that suspension lifts only clear bigger tires at ride height. As soon as you stuff the tire in the front wheel well, the lift amount doesn't really matter
Second, is that the Caster number itself isn't really a trustworthy measure for the amount of clearance for the tires. As you know, caster is the angle between the line from UBJ to LBJ, and vertical. When lifting the 4runner IFS, while keeping the camber in spec, the caster tends to drop out. This could make keeping the wheels straight on the highway more difficult, wheel not return to center after turns as effectively as stock, etc. JBA UCAs are great for bolt on caster correction back to stock 3* to improve drivability back to stock.
I made a little picture below to try and explain some things better. Background rectangles are reference of LCA mounting positions, and body mount location.
- The main drawback is that +Caster from the UCA brings the tire backwards in the wheel well, as seen in the first image. While increasing drivability, clearance at the body mount and rear of wheel well is sacrificed. If I remember correctly, you mentioned stock UCAs didn't rub as bad as the JBAs, this is likely why. However, your JBAs will ride better than the stock when lifted due to the increase in caster, and I believe there is more UBJ travel on the JBAs, and the angle is corrected to keep them more centered in that travel.
- +Caster from the LCA brings the wheel forward. You can set this by adjusting the cam bolts so the front is all of the way in, and the rear is all the way out. The problem with a fixed position UCA, is that this will likely throw off the camber.
- The capability of adjustable UCAs, like SPCs, allow you to decrease Caster at the UCA, increase Caster at the LCA, and finally adjust the camber into spec. This will result in maximum clearance, with the potential sacrifice of overall caster depending on the tire size. From here, its balancing the tire size with the UCA caster adjustment to get them to fit, while also retaining drivability.
I'm a fan of adjustable UCAs for this reason, but it doesn't necessarily mean they're the best for your setup. JBAs or other fixed UCAs are great, because you can take to any firestone or wherever, and they only adjust the cams like stock would. Most alignment places would never touch SPCs, and lots of people end up aligning them at home.
The offset of the wheel also plays a role in the fitment. As Inv4drZm mentioned, more negative offset from the spacers increases the scrub radius. More scrub radius can also cause the tire to rub things as the wheels turn left and right. This is also a balance, because the increased backspacing from the spacer will help to space the tire away from the UCA. With JBAs especially, the flat part where the UBJ mounts is fairly wide. Without spacers, it may be tight or contact the UCA, but you'll never know without giving it a shot.
So working with what you have, I'd suggest first removing the spacers and seeing if that helps with the rubbing on the body mount. Check the UCA for rubbing there, as discussed above. If that doesn't work, remount the spacers and evaluate chopping the body mount. (side note: if the spacers were previously loctited, you need to clean all the threads really well and remove all the threadlocker remains before reattaching, or the buildup will cause them to reach torque spec before they're at the desired tightness)
Hopefully that makes sense, always a balancing game when fitting bigger tires on a vehicle that wasn't intended to have any more than a 265/65r17 on there
wow, thanks for the thorough explanation man! You're correct the body mount rub got a little worse with the JBA's. Not a ton, but a little for sure. I would also say the handling on highways / overall responsiveness is better with them. So that adds up per your feedback on them. I wish I would've known this about SPC's before buying the JBAs, sounds like they would have helped but c'est la vie, for now I'll try making the JBAs work. Unless anyone wants to buy them off me here lol.
I'll give taking out the spacers a shot and see what happens, as well as talk with an offroad shop and see what they can do with my alignment. If that doesn't do it, looks like the BMC it is, as well as probably some new front coils for good measure. Are the any aftermarket LCA's that would allow for greater adjustability?
Last edited:
y=mx+b
New member
No problem, the visual is really helpful for me, so made one to share. Lots of people run JBAs, and they're not necessarily bad. There are a lot of benefits like ease of alignment, just set and forget, BJs less expensive and off-the shelf. They might have even come with some free religious promotional media lol. The tradeoff for these is the UCA caster. Not really a big deal to chop the body mounts, and they can be capped with plates to look clean.
For the spacers, if someone used loctite on them before, make sure to clean it all off the threads before reinstalling and torquing them. Residual hardened locktite will make the bolt reach the torque spec before the studs are to the desired tightness.
I don't think there is any amount of caster adjustment combo you can do with a factory LCA and whatever UCA that will give the clearance needed at the body mount point without having to chop it. Wheel offset , along with the spacers, will only marginally make the issue better or worse judging from my personal setup.
My 33" set up with a 3" lift still required to chop the mount as well as cutting and hammering the pinch weld flat to get the clearance needed while stuffing the tire. I also went ahead and trimmed the fenders when I went the 35" route to get the necessary clearance.
I would recommend verifying the other 2 rubbing points (at the UCA and at full lock on the frame rail near the firewall) as well. This is the biggest rubbing I am getting right now (the frame rail) granted I am on 35's. I don't see a way to fix my frame rail rub unless I went +2 or 3.5" extra track width up front to space the entire wheel out further, but the body mount chop certainly made the clearance significantly better.
My 33" set up with a 3" lift still required to chop the mount as well as cutting and hammering the pinch weld flat to get the clearance needed while stuffing the tire. I also went ahead and trimmed the fenders when I went the 35" route to get the necessary clearance.
I would recommend verifying the other 2 rubbing points (at the UCA and at full lock on the frame rail near the firewall) as well. This is the biggest rubbing I am getting right now (the frame rail) granted I am on 35's. I don't see a way to fix my frame rail rub unless I went +2 or 3.5" extra track width up front to space the entire wheel out further, but the body mount chop certainly made the clearance significantly better.
Stopped by another 4x4 shop after work today since I was in the area. They'd never heard of the body mount chop and said they wouldn't do that job, but also recommended trying taking the wheel spacers off. He said he thought the JBAs were less likely to rub than stock, but I'll give that a shot this weekend and see what happens. Also got a recommendation for a good sounding local alignment shop.
May just do the BMC myself, install some springs and take it to the alignment shop. Is there a good thread anywhere about springs that are compatible with the 5100s? Looking for some combo of springs / 5100s height clip setting that'll give me ~2.5" lift with a V8, 120lb steel bumper, and probably a winch in the future. Would those Toytec 620# coils be good or nah? Maybe OME 886s? Advice appreciated.
May just do the BMC myself, install some springs and take it to the alignment shop. Is there a good thread anywhere about springs that are compatible with the 5100s? Looking for some combo of springs / 5100s height clip setting that'll give me ~2.5" lift with a V8, 120lb steel bumper, and probably a winch in the future. Would those Toytec 620# coils be good or nah? Maybe OME 886s? Advice appreciated.
randy88fj62
Member
I plan on pulling my struts out tomorrow and cycling the suspension to see where the wheel will rub.
I'll be doing this with the JBA UCA installed. I will post back monday if I was successful.
Weekend plans:
Install JBA UCAs
Weld on cam tab gussets
Weld on spindle gussets
new inner and outer TREs
Regarding the body mount chop (BMC) you should stop by welding shops. They would be the best suited for the trimming and welding if you dont want to do it yourself. If you were in SoCal I could help you out.
I'll be doing this with the JBA UCA installed. I will post back monday if I was successful.
Weekend plans:
Install JBA UCAs
Weld on cam tab gussets
Weld on spindle gussets
new inner and outer TREs
Regarding the body mount chop (BMC) you should stop by welding shops. They would be the best suited for the trimming and welding if you dont want to do it yourself. If you were in SoCal I could help you out.
Johnny4runner
New member
blakkbox covered this above, but make sure the rear alignment cam bolts are maxed out to push the wheels forward. The rear cam lobes should be pointed inwards. With your aftermarket UCAs the alignment shop should be able to get the alignment into spec, or with extra caster. An alignment shop familiar with lifted vehicles should know what to do if you are having clearance issues. I eventually had a BM chop done, but my rubbing was pretty minimal with the alignment like this.
