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  #1  
Old October 5th, 2020, 19:00
maxbraketorque maxbraketorque is offline
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Increasing front wheel base for wheels to clear stock fenders

This summer I picked up a 2000 XJ with an RC 4.5" lift kit and 31" wheels. The lift kit looks to be properly installed, and the front control arm length (which is adjustable) matches what RC specifies for the length (29.75"). The XJ has the stock fenders, and I intend to leave them for now.

There is evidence of the tires rubbing the rear of the front fenders, probably during flex with the wheels turned fairly sharply. Since the control arm length is adjustable, I'm considering increasing the wheelbase slightly to get some more clearance from the fender. I'm thinking of increasing the control arm length by 0.25". I've looked over the suspension, steering, and driveline, and I don't see any issues with even a 0.5" increase, but I'm curious if anyone has any experience with doing this and whether they had issues.
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  #2  
Old October 5th, 2020, 19:23
RCP Phx RCP Phx is online now
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Re: Increasing front wheel base for wheels to clear stock fenders

To "book" numbers are just to get a person in the ballpark, otherwise go to town.
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Old October 5th, 2020, 22:26
SlowXj SlowXj is offline
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Increasing front wheel base for wheels to clear stock fenders

Things to watch for when stretching...
Steering cycling full bump, full droop, and full articulation each way. Also track bar to diff cover at full bump. I recommend removing springs to fully cycle the suspension to get the perfect axle location.

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Old October 6th, 2020, 02:03
Jim Malcolm Jim Malcolm is offline
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Re: Increasing front wheel base for wheels to clear stock fenders

My 94 has a NP242/AW4 and fixed LCAs that move the axle forward ~1/4" at the low lift height I'm running. The front output sits back on a 242 compared to a 231, but stock, they use the same driveshaft. Combined with the fixed LCAs, a custom length driveshaft was required to get rid of vibration at ~65+; a straightened, rebuilt and balanced stock shaft didn't fix the issue (expensive mistake). My 88 with a NP242/AW4 and stock LCAs did not have any vibration issues at the same ride height (coil springs reused).

Another issue you may run into is the coil spring rubbing against the side of the OEM trackbar bracket, if you're still using it that is. It's not a big deal, just a noise when you hit a bump. I slit a piece of heater hose, slid it over the coil spring and secured with zip ties; no more noise.

With my fixed LCAs and low lift height, I've had to remove the triangular support brackets and do some minor trimming to flare, inner fender liner and general sheetmetal structure to stop rubbing at the front. You should be able to "shoot the gap" on all of these issues being that your LCAs are adjustable.
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Old October 6th, 2020, 05:54
Evan03 Evan03 is offline
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Re: Increasing front wheel base for wheels to clear stock fenders

I'd probably not bother with lengthening all arms only .25"

I'd set them all 1"longer and test might set uppers 3/4" to gain alittle castor depending on how it drives.

I didnt pay attention to what lift you have so im ssuming your arms aren't horizontal that being the case with arms at angle 1/4" would only move axle forward like 3/32.
If arms are horizontal then the axle will move forward the amount you adjust.
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  #6  
Old October 6th, 2020, 10:54
maxbraketorque maxbraketorque is offline
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Re: Increasing front wheel base for wheels to clear stock fenders

Quote:
Originally Posted by Jim Malcolm View Post
My 94 has a NP242/AW4 and fixed LCAs that move the axle forward ~1/4" at the low lift height I'm running. The front output sits back on a 242 compared to a 231, but stock, they use the same driveshaft. Combined with the fixed LCAs, a custom length driveshaft was required to get rid of vibration at ~65+; a straightened, rebuilt and balanced stock shaft didn't fix the issue (expensive mistake). My 88 with a NP242/AW4 and stock LCAs did not have any vibration issues at the same ride height (coil springs reused).

Another issue you may run into is the coil spring rubbing against the side of the OEM trackbar bracket, if you're still using it that is. It's not a big deal, just a noise when you hit a bump. I slit a piece of heater hose, slid it over the coil spring and secured with zip ties; no more noise.

With my fixed LCAs and low lift height, I've had to remove the triangular support brackets and do some minor trimming to flare, inner fender liner and general sheetmetal structure to stop rubbing at the front. You should be able to "shoot the gap" on all of these issues being that your LCAs are adjustable.
Thanks on the detailed experiences. Interesting that you mention the NP242. I just converted to NP242, and I have a D30LP which I think also stretches the front driveshaft a bit compared to a D30HP. No issues with vibrations at 65 mph, but at 70 mph, there is a slight vibration. My right rear tire has a road force vibration issue, and I had attributed the vib to that, but perhaps its time for a custom front drive shaft.

The RC 4.5" Long Arm lift comes with a track bar relocation bracket. I hadn't looked at the proximity of it to the driver side spring, but now that I look, it's probably within about 0.5" right now. No sign of rubbing. I think another 0.25" would be safe, but probably no more than that.

I suppose if I want to do this 100% right, I would remove the springs. I hadn't planned on messing around with it that much, but would be interesting to see how things look at full compression.
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Old October 6th, 2020, 11:11
89Mock 89Mock is offline
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Re: Increasing front wheel base for wheels to clear stock fenders

I have an 89 (I know, not the same year) with a short arm 4.5" lift and 33s on it that doesn't rub the rear fenders anymore. Check the steering stops. Check it at full articulation and see where it rubs. Get under there and see what it is doing. 31s shouldn't rub and I can't imagine they'd give you a lift with specs that make it rub. The lift you have is for 32s.
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Old October 7th, 2020, 06:10
Evan03 Evan03 is offline
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Re: Increasing front wheel base for wheels to clear stock fenders

Have you made any tweaks yet.

I'd be curious to see the track bar bracket interference.
Is this a radius arm?
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  #9  
Old October 7th, 2020, 07:13
maxbraketorque maxbraketorque is offline
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Re: Increasing front wheel base for wheels to clear stock fenders

Quote:
Originally Posted by Evan03 View Post
Have you made any tweaks yet.

I'd be curious to see the track bar bracket interference.
Is this a radius arm?
No time to try anything until this weekend. It is a radius arm setup. The arms do point downward somewhat at ride height, probably about 5 degrees. There should be fairly minimal fore-aft movement of the axle as it moves through its travel because its an ~30 inch long arm. My estimate is that it will move forward another 0.1" as the arm reaches level and then from there perhaps move back 0.2".
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