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Old 05-18-2015, 09:52 PM
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JK suspension in a TJ problems

Hello everyone this is my first post here and i was hoping I can get some help. I have a 99 tj 4.0l 5 speed. I read a lot of info on lifting the tj with the jk coils and springs and heard mixed reviews about it so I decided to give it a try myself. After install i got maybe an inch on the front and what seemed like 4 to 5 inches on the rear. The jeep looked ridiculous. So I had the bright idea of buying 3 inch coil spacers for a jk and installed them on the front springs. The result is still a 3 inch difference between the front and rear. I really want to try and leave at least 1 set either front or rear on so it wasn't a complete waste of my time and money. Does anyone have any ideas? Or anywhere I could go from here? Plus the ride even with 3 inch spacers is much improved. Please any input will be helpful. Thank you.

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Old 05-18-2015, 09:56 PM   #2
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Originally Posted by nfljohnl View Post
Hello everyone this is my first post here and i was hoping I can get some help. I have a 99 tj 4.0l 5 speed. I read a lot of info on lifting the tj with the jk coils and springs and heard mixed reviews about it so I decided to give it a try myself. After install i got maybe an inch on the front and what seemed like 4 to 5 inches on the rear. The jeep looked ridiculous. So I had the bright idea of buying 3 inch coil spacers for a jk and installed them on the front springs. The result is still a 3 inch difference between the front and rear. I really want to try and leave at least 1 set either front or rear on so it wasn't a complete waste of my time and money. Does anyone have any ideas? Or anywhere I could go from here? Plus the ride even with 3 inch spacers is much improved. Please any input will be helpful. Thank you.
Not sure but I don't believe the JK rear coils will fit a TJ without making the hole bigger by heating the spring. That may be why you have the 3 or 4 in difference. The springs are not seating properly.

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Old 05-19-2015, 01:08 AM   #3
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Not sure but I don't believe the JK rear coils will fit a TJ without making the hole bigger by heating the spring. That may be why you have the 3 or 4 in difference. The springs are not seating properly.
This is correct. You need heat or cut about 2in off so it fits in the coil bucket. Also what spring part numbers did you use?

A 1"/3" front/rear lift would not be surprising with the 4.0L. I got 2/2.5 when I did this on mine - but with v8 zj springs in the front.
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Old 05-19-2015, 08:07 AM
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Thank you so much for all your help. I think I'm going to cut it 2 inches. From any of your experiences do I need bump stop extensions? Because if I'm not mistaken i believe the 3 inch spacers i used in the front to attempt to level it out replace the bumpstops. Or is that incorrect?
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Old 05-19-2015, 08:10 AM
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Do I need anything else that you guys know of to make this job a success? I just want it to sit level of its an inch off from front to rear I'll get spacers, but these 3 inch spacers are causing so much vibration.
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Old 05-19-2015, 08:11 AM
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I'll get the part numbers as soon as I get home today and post them here. Can I see pics of your rig after the lift.
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Old 05-19-2015, 10:54 AM   #7
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Just to be clear - you are not cutting 2in from the height of the spring, but rather just a small piece from the coil of steel at the top so that it fits in the coil bucket.

Depending on your budget i would look at getting v8 ZJ springs for the front instead of spring spacers. $50 used or $70 new.

You could add some bumpstop extensions as well. 1.5in should do it.

Here is before the lift:

And here is after
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Old 05-19-2015, 03:24 PM
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Ok so trim the top of the coil until it
fits in the bucket and get V8 ZJ coils for the front. Will the JK shocks have enough travel for the front ZJ springs? And 1.5 inch bumpstops extensions on all 4? Do you know a good site to get the ZJ coils from? I'd rather get them new for $70 than used from a yard. Thanks again and your truck looks awesome man hopefully mine can look like that soon.
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Old 05-19-2015, 08:42 PM   #9
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I also have a question. I've been looking for zj springs and decided to look on rock auto for some and found them for $35! But my question is, doesn't that sound a little jeep for a pair of springs? Can I trust moog springs in that they will be strong enough to lift the front like OEM v8 springs and won't sag over time? Here's the link:

https://www.rockauto.com/catalog/mor...nid=418&jpid=0
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Old 05-19-2015, 08:56 PM
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Ok as promised here are the pictures of the jeep with the lift and the labels. The first picture is the way it sits now. The second image is the shock labels on the front the rears were too faded. The third picture is of the front springs from jk with the 3 inch spacer. The 4th picture is of the rear coil seated in the bucket. The 5th image is of the rear coil Spring labels. By the way the tires are 31x10.50.
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Old 05-19-2015, 10:19 PM   #11
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I also have a question. I've been looking for zj springs and decided to look on rock auto for some and found them for $35! But my question is, doesn't that sound a little jeep for a pair of springs? Can I trust moog springs in that they will be strong enough to lift the front like OEM v8 springs and won't sag over time? Here's the link:

https://www.rockauto.com/catalog/mor...nid=418&jpid=0
Those are probably good springs for a ZJ, but not the right ones for a swap.

What you are looking for is moog part# cc782 for a ~2" lift and cc784 for ~2.5" lift. Those lift numbers are for Jeeps with the i6 4.0L engine.
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Old 05-19-2015, 10:29 PM   #12
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Ok so trim the top of the coil until it
fits in the bucket and get V8 ZJ coils for the front. Will the JK shocks have enough travel for the front ZJ springs? And 1.5 inch bumpstops extensions on all 4? Do you know a good site to get the ZJ coils from? I'd rather get them new for $70 than used from a yard. Thanks again and your truck looks awesome man hopefully mine can look like that soon.
Yep. JK shocks will be perfect for a 2-3" lift. For bumpstops you can either buy are pre-made sets or do what I did and order 2in diameter, 3in body lift pucks on ebay and cut them in half and buy longer bolts from the hardware store. I would get the ZJ coils on Amazon or rockauto. Keep in mind there is a forum discount code for rockauto in the vendors section.

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Ok as promised here are the pictures of the jeep with the lift and the labels. The first picture is the way it sits now. The second image is the shock labels on the front the rears were too faded. The third picture is of the front springs from jk with the 3 inch spacer. The 4th picture is of the rear coil seated in the bucket. The 5th image is of the rear coil Spring labels. By the way the tires are 31x10.50.
That does not look like 4-5in of lift - did you measure before/after?. It looks about the same as mine. The problem is your front springs actually dropped you TJ so with the spacers you are probably only at 1-1.5in lift in the front. ZJ springs will fix that. It actually looks like the rear coil is seated ok. If you can take pictures with better light of the top and bottom of the rear coil I could say for sure.
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Old 05-20-2015, 06:16 AM   #13
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Thank you njs. How much more lift does a 4 cyl get than a 6 cyl from these springs? Stock with no added weight.
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Old 05-20-2015, 08:48 AM
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Thanks for all the input from everyone. Also the moog part #cc784 will have me retain 2.5 inches of lift on my tj 6 cylinder? I'm just double checking with what you already wrote so I can be sure and order them today for the fronts.
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Old 05-20-2015, 10:59 AM   #15
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Thank you njs. How much more lift does a 4 cyl get than a 6 cyl from these springs? Stock with no added weight.
I am not sure. Maybe 1-2in more. You should try some -19 JK front springs first if you have the 4 cylinder engine. If you go the v8 zj route then i would try cc782 to get somewhere between 2-3in.
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Old 05-20-2015, 11:05 AM   #16
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Thanks for all the input from everyone. Also the moog part #cc784 will have me retain 2.5 inches of lift on my tj 6 cylinder? I'm just double checking with what you already wrote so I can be sure and order them today for the fronts.
Yes - well i should have said 2-3in. I have not personally used those yet and i cant guarantee an exact number. The cc782 springs are comperable to v8 zj springs, which lift about 2". cc784 springs are like the v8 zj overland springs and will give you 2-3in.
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Old 05-22-2015, 04:45 PM
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Ok guys a little update i just got my coils from amazon moog part #cc784. I really hope these are the right ones for the front because they look so much longer than the originals. I assumed they were the same size just stiffer. These are for the ZJ overland i believe. Take a look and let me know if you guys think this will work.
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Old 05-22-2015, 04:52 PM   #18
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Ok guys a little update i just got my coils from amazon moog part #cc784. I really hope these are the right ones for the front because they look so much longer than the originals. I assumed they were the same size just stiffer. These are for the ZJ overland i believe. Take a look and let me know if you guys think this will work.
I have no idea but you should try them and tell us if it works!
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Old 05-22-2015, 04:54 PM   #19
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Oh and yes those are the front coils. Correct me if I'm wrong but I'm pretty sure the zj had leaf springs in the rear.
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Old 05-22-2015, 05:23 PM
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Yeah I'm sure they'll work i just want to double check. I'll update everyone on how the install goes. Thanks again for your help.
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Old 05-22-2015, 05:37 PM   #21
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Ok guys a little update i just got my coils from amazon moog part #cc784. I really hope these are the right ones for the front because they look so much longer than the originals. I assumed they were the same size just stiffer. These are for the ZJ overland i believe. Take a look and let me know if you guys think this will work.
Keep in mind they are progressive coils, so there are 2 different spring rates. This means the top few coils of the spring should collapse together more at the top when you have some weight on it, making it a similar length to a 2-3in lift spring.
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Old 05-22-2015, 06:09 PM   #22
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Correction: Not progressive coils but variable rate coil springs
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Old 05-24-2015, 11:18 PM   #23
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If I'm planning on getting a 3" lift out of this method since I have a 2.4l and then plan on putting on a 1" body lift, do I need new sway bars????
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Old 05-25-2015, 02:57 PM   #24
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Any update nfljohnl?
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Old 05-25-2015, 03:04 PM   #25
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If I'm planning on getting a 3" lift out of this method since I have a 2.4l and then plan on putting on a 1" body lift, do I need new sway bars????
Yes you should get new sway bar links above 2" or so.
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Old 05-25-2015, 06:30 PM   #26
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So I've done some pricing research and getting a zone lift is only $100 more than a total zj/jk swap with a body lift. I've decided I'm gonna get a new lift for $100 more...
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Old 05-25-2015, 08:38 PM   #27
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Nominal cost of a zj/jk swap is $200. Even with a BL that is $350. Zone 4.25 is $530. But I do see your point. From what I hear the zone kits are highly recommended so I am sure you will be happy with whatever you choose.
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Old 05-25-2015, 09:27 PM
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Ok so I put the coils in. Jesus christ that took forever to get the clips just right to compress the spring was a nightmare, but after about 6 hours i was done. So now I have the ZJ coils in the front and the jk coils still in the rear as well as the jk shocks all around. I have to say I am pretty displeased with the results. I on purpose measured with one of the jk coils with the 3 inch spacer and in the passenger side and one of the new ZJ coils in the driver side with no spacers and the measurements were exactly the same. So now with both of the ZJ coils in the front with no spacers the jeep sits exactly the same as it did before. 6 hours of hard labor for nothing. I just don't understand this for the life of me. Should I put the stock tj coils that I still have in the rear instead of the jk coils? Or should I put the the front jk coils in the rear. So just so there is no confusion should I put either my stock tj coils in the rear or the front jk coils in the rear to level it out. Because as of right now it still looks just as retarded as it did before the ZJ coil install. Thank you everyone for your responses.
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Old 05-25-2015, 09:31 PM   #29
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Nominal cost of a zj/jk swap is $200. Even with a BL that is $350. Zone 4.25 is $530. But I do see your point. From what I hear the zone kits are highly recommended so I am sure you will be happy with whatever you choose.
Well you see since I have a 4 cyl I would hopefully get a 3 in lift in the front and the back so then I would have to put in an mml and new sway bars. Oh and a rear trackbar relocation bracket.
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Old 05-25-2015, 10:18 PM
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Ok so I put the coils in. Jesus christ that took forever to get the clips just right to compress the spring was a nightmare, but after about 6 hours i was done. So now I have the ZJ coils in the front and the jk coils still in the rear as well as the jk shocks all around. I have to say I am pretty displeased with the results. I on purpose measured with one of the jk coils with the 3 inch spacer and in the passenger side and one of the new ZJ coils in the driver side with no spacers and the measurements were exactly the same. So now with both of the ZJ coils in the front with no spacers the jeep sits exactly the same as it did before. 6 hours of hard labor for nothing. I just don't understand this for the life of me. Should I put the stock tj coils that I still have in the rear instead of the jk coils? Or should I put the the front jk coils in the rear. So just so there is no confusion should I put either my stock tj coils in the rear or the front jk coils in the rear to level it out. Because as of right now it still looks just as retarded as it did before the ZJ coil install. Thank you everyone for your responses.[/QUOTE]

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