I replaced my RE ZJ 4.5" coils (XJ 5.5") with the TJ/XJ 7.5" coils this weekend. My goal was to increase spring rate a little bit for better handling, and to replace the 1" of spacer on top of the ZJ coils and add about a half inch of lift. In a previous thread, we didn't resolve the question of whether the ZJ coils have a 240 spring rate and the 7.5" a 250 spring rate...or whether both are 200. I don't know, so I'll pass on my observations, which suggest the 7.5" are a bit stiffer.
First and foremost, I think these are truly 7.5" TJ coils, and as such give a bit less than 2" more lift than the ZJ coils on an XJ. I was running a 3/4" poly spacer plus a 10mm (3/8") OME poly spacer on top of the ZJ coils. I left the OME spacer in and just removed the 3/4" spacer. From this I gained about 3/4" of total lift. Exactly what I wanted, but this suggests that the 7.5" coils are 1.5" over the 4.5" ZJ, not 2". I'd have been pissed if I'd taken out the OME spacers, because I would have wanted them back in.
As for spring rate...the handling has definitely, markedly improved. With 8" of lift and no swaybars, I can take the twisties with hardly any lean. It is excellent. And there is one other thing that I have suspected for a long time: RE coils are not the exact same side to side.
Whether this is in the design spec, RE's coil manufacturer is doing the proper design and not telling them, or just the occasional production "error", I don't know. But this is my second set with this "advantage". Maybe it is because the XJ D30 coil pads are different side to side in how the coil is rotated and seated...maybe the pigtail difference is designed to ensure proper seating on the coil tower? Maybe I am imagining things? :dunno:
Anyway, if you draw a straight line on a piece of paper and line up the bottom edge of both coils parallel to this line, you will see that the "pigtail" on top of one coil is about 1/2" longer than the other. This coil should go on the passenger side. When installed this way, I find that my XJ loses the tendency to lean more to the right with road crown, and that it stops pulling to the right. I experienced this same thing with my first set of ZJ coils, but not with my second set of ZJ coils.
I don't know the deal here, but man it makes a difference because my front end is balanced side to side.
Anyway, I highly recommend these coils for an 8" lift. They definitely beat adding spacers to the shorter coils.
Nay
First and foremost, I think these are truly 7.5" TJ coils, and as such give a bit less than 2" more lift than the ZJ coils on an XJ. I was running a 3/4" poly spacer plus a 10mm (3/8") OME poly spacer on top of the ZJ coils. I left the OME spacer in and just removed the 3/4" spacer. From this I gained about 3/4" of total lift. Exactly what I wanted, but this suggests that the 7.5" coils are 1.5" over the 4.5" ZJ, not 2". I'd have been pissed if I'd taken out the OME spacers, because I would have wanted them back in.
As for spring rate...the handling has definitely, markedly improved. With 8" of lift and no swaybars, I can take the twisties with hardly any lean. It is excellent. And there is one other thing that I have suspected for a long time: RE coils are not the exact same side to side.
Whether this is in the design spec, RE's coil manufacturer is doing the proper design and not telling them, or just the occasional production "error", I don't know. But this is my second set with this "advantage". Maybe it is because the XJ D30 coil pads are different side to side in how the coil is rotated and seated...maybe the pigtail difference is designed to ensure proper seating on the coil tower? Maybe I am imagining things? :dunno:
Anyway, if you draw a straight line on a piece of paper and line up the bottom edge of both coils parallel to this line, you will see that the "pigtail" on top of one coil is about 1/2" longer than the other. This coil should go on the passenger side. When installed this way, I find that my XJ loses the tendency to lean more to the right with road crown, and that it stops pulling to the right. I experienced this same thing with my first set of ZJ coils, but not with my second set of ZJ coils.
I don't know the deal here, but man it makes a difference because my front end is balanced side to side.
Anyway, I highly recommend these coils for an 8" lift. They definitely beat adding spacers to the shorter coils.
Nay
