TJ vs XJ lift coils

[dunnc1991]

So I've read several threads asking this same question, but can't get a straight answer on this. Anyone with any experience have some input? I have a chance to pick up brand new RE 5.5" TJ coils for cheap, but not sure on how much lift I'll get out of them. Any help is appreciated.

[AeroNautical]

I believe, since the Dana 30s used in both the TJ and MJ are pretty much identical, except for the high/low pinion, the lift should be the same between the two. Because the TJ had coils in the front and rear, I don't know if the rears would translate the same lift as the front. Obviously the MJ has leafs in the back, I'm not sure, if they are rear coils, if they would work in the front. 

[Eagle]

I believe, since the Dana 30s used in both the TJ and MJ are pretty much identical, except for the high/low pinion, the lift should be the same between the two.

Maybe it should be -- but it isn't. TJ coils produce 2 to 3 inches less lift in an XJ or MJ than they do in a TJ.

[dunnc1991]

This is where the grey area comes in. I've heard they produce .5" less lift all the way up to 3" less lift. However a lot of these answer are from people using stock TJ coils, which have a lighter spring rate. I'm not sure if the same applies on aftermarket coils. RE shows 2 different part numbers for their 5.5" TJ and XJ coils

[Strokermjcomanche]

Why not call RE and ask them? They'd probably be the best people to ask . I'm sure they have a technical department.

[dunnc1991]

Yeah, I just read that they are pretty good about releasing that type of info. I'm going to give them a call monday.

[shelbyluvv]

In my past experience with RE coils are TJ 5.5" coils are the same as 4.5" XJ coils. Basically one inch less lift height on an XJ for the TJ advertised height.

[87Warrior]

I just installed well worn RE 3.5" TJ coils (100k miles in my Rubi) in my 86 MJ. I expected 2" of lift but got a solid 3". I suspect this is because I have a 2.5....

[Minuit]

I suspect you're right. The 2.5 weighs a good bit less than the 4.0.

[Incommando]

Although they both use a version of the D30 that doesn't mean that the body-side mounts are in the same positions

[yxmj]

In my past experience with RE coils are TJ 5.5" coils are the same as 4.5" XJ coils. Basically one inch less lift height on an XJ for the TJ advertised height.

 

This is correct i have TJ fronts in one of my XJ's right now.

[shelbyluvv]

I have TJ 5.5" coils in my truck and it sits almost perfectly level with my 4.5" Hell Creek rear leaf packs.

[Rockfrog]

I ran TJ coils on my XJ for a while. They were 3.5" and netted 2.5" of lift.

My understanding is this is due to the differences in spring rates and the leverage of the engine placement (XJ motors sit more over the spring, TJ's more behind them).