Do a google search on "TJ flares on YJ" there are a bunch of write ups on it. I just got done doing mine. My recommendation to you is measure a bunch of times, then cut. There isn't much room for error. It took me practically a full day to do front and rear. It was a little nerve racking but it does give you 1-2 inches of extra clearance, especially the rear.
-------------------------------------------------- Firefighters Jeep Club
A sabersaw with a high quality blade cuts the sheet metal like butter and is easier to control than most other devices (sawzall, angle grinder, die cutter, etc.). Spend the extra $$ on good blades, it does make a difference. Mask off, mark & cut.
'91 YJ 4.O, Auto, Rr. D60 w/ 35 Spline Alloy USA Axles & Detriot Locker, Fr. D30 True-Trac, 4.56's, 4.5" Deaver Springs, Bilstein 5100's, 1" BL, Rubi Flares, 35x12.50 MT/R's on MT classic II's, Detroit Locker, Vanco Big Brakes, Booster & Master, Warn 9000XDI, York OBA, AA SYE & TW's DS's, Teraflex Belly Up, Rocker Guards...
Nope, not difficult. Cutting the lip off the TJ flare makes it easier to lay it up against the YJ body to trim and mark the holes. I really only wanted and needed the room on the rear flare, so I never even cut the front fenders. I just painted under the flare black in front.
today i found a set on craigslist for $50 is it worth it??? need more room on the yj, it has 31" mt's on it now and they rub in the front and the rear (don't have a lift...yet) will they help at all, if any how much?
It's not hard...like earlier poster said, the first cut is a doozy but after that point of no return, it aint so bad. There is nothing technical about it...line the new flare up, trace the opening, cut metal, and bolt it up. If you make a crappy cut, the flare should hide it...unless you cut way too much. Not much room for error on top...there is moreso on the sides.
Considering lifts are the other methods for getting more clearance, I'd say it's definitely worth it. Lifts have side effects like reducing gas mileage, affecting handling, etc. Flares don't have any of those negative aspects and it's a cheap mod. But in the end...I say lift your Jeep and put it on at least some 32's!!!
1994 YJ Wrangler, 4.0, AX15, NP231, 35x12.50x15 BFG KM2s, 4" RC lift, 1" lift Boom Shackles, 1" BL, 4.10 gears, 8.8 LSD in rear and D30 Aussie Locker in front, on-board air conversion, Ramsey RE8000 winch.
I am going for thursday on getting my front tj flares installed. Then the rear tj flares at another time. I have to get this done. I have been putting off this install for way to long. It is a great modification imo.