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Discussion Starter #1
I'm going to sub in the 3.5" Kit Coils, as I am keeping my 2" coil spacers in, for a total of 5.5" suspension lift.

I am open to opinions here on what else is really needed that the kit does not come with????



I know it is not as optimal as a 5.5" Kit or a LA kit, but this is what I can afford right now. And I really plan on bigger than 35" tires down the road, thus the need to squeeze the extra inch out of the suspension.

Opinions are welcome, even negative ones about the setup. As always I am here to gain knowledge ya know and I don't want my rig down because of something stupid once I get started on it.

Thanks in advance....
 

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I'm not an expert on big lifts, but it is my undertanding that once you get much above the 4" - 4.5" mark, then the jeep really starts to become unstable on the road unless longer CA's are used that recenter everything.

The stock CA's move towards the center of the jeep when taller springs are added and therefore shorten and raise the COG. This also creates a rolling-in effect of the front axle when hitting bumps or trying to climb.

One other thing, most Suspension System manufacturers say not to add any large spacers to their springs as it is unsafe and will void the warranty.

I would also ask the big dogs in the JU TJ forum since there is lots of experience in the higher lifts there.

Good luck and get lots of opinions before you add those spacers to go to 5.5".

Ken
 

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Sorry, should have added this before posting above.

Go with the 4.5" springs and a 1" body lift and I think you will be farther ahead, and safer!

Ken
 
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Discussion Starter #4
Thanks for the input.

They got a pic of a Rubi on the RE - Customer Rigs section of their web site. That did the coilspacers and the ultra cheap 3.5" SF Kit alone. I did email him about how it runs. I mean, that would save big bucks, but if it is only savings in the short term, I'd rather do the much nicer RE 4.5" kit with the RE 3.5" Kit coils sub'd in.
 

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Ken White said:
I'm not an expert on big lifts, but it is my undertanding that once you get much above the 4" - 4.5" mark, then the jeep really starts to become unstable on the road unless longer CA's are used that recenter everything.

The stock CA's move towards the center of the jeep when taller springs are added and therefore shorten and raise the COG. This also creates a rolling-in effect of the front axle when hitting bumps or trying to climb...

Ken
Ken:

Loss of stability in short arm lifts is primarily due to 3 factors:

1) The raising of the CoG
2) The increase in the angle of the control arms with a subsequent loss in reaction capability of the arms. This is the rolling-in effect you described. Even the use of adjustable CAs to restore the wheelbase will not compensate for the increased angles resulting from a 4.5" short arm lift.
3) Increased steering angles which can result in bumpsteer.

Reducing the wheelbase will only result in a second order effect on stability. This would be a decrease in directional stability due to the increased polar moment of inertia from more weight hanging beyond each axle. This would be true even though the front to back location of the CofG remains unchanged.

But Wrath, do what Ken recommends: Go with the 4.5" springs and a 1" BL. It's a much better approach.

Jerry
 
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Discussion Starter #6
Well, its going on there. That is not enough lift. The RE 4.5" kit gets pretty good reviews, it is just hard for me to believe you can't cheat the kit by an inch without to much going wrong.

Check out this rig on RE's site too, heck even RE said it would work ok, in reply to an email I sent them but definetly said they will not waranty it. But they are the ones that told me to go look at the one on their site..

Here is the link anyways....

http://www.rubiconexpress.com/showcase/all.asp

It is the 8th one from the bottom on the left hand side.
 
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Discussion Starter #7
I am also using 2" wheel spacers which does give me 4" additional track.
 

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WrathOfRubicon said:
I am also using 2" wheel spacers which does give me 4" additional track.
Wheel spacers help widen the stance but will not help at all with the above mentioned. I would suggest the 4.5" and a BL. I have a buddy that is running 4.5" and 2" BL and 37's. Fits good and works well. Going the 2" spacers seem to be a waste of $$ in the long run and you run into all sorts of problems....That may also screw you factory warrenty up. Spend a little more now and do a good solid proven set up.

I have 4.5" and 1.5" BL and 35's excellent set up.

JMO
 
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Discussion Starter #9
2" Body lift??? Talk about potential problems... lol

Well, I can say, that there are Rubicon's setup the exect same setup, I am using, all reporting great results. It actually seems way more popular here in Colorado than anything other 5.5" Suspension setup. But always remember, I can add all the LA stuff if it does not run well.. I did the math last night, it is not like it costs that significantly more adding the LA stuff after the fact.

If I get an LA kit, I think I would get the 4.5" and leave the coil spacers in... Cheat the 5.5 LA by an inch.... I mean the CA's are adjustable and we are only talking an inch here.

Even RE believes I won't have any real issues with the setup.

Hey I will be the guinie pig!!!! I'll put it all on, and report back how it runs here. I think everbody here so far has done a great job of warning me what I am getting into!!!! Keep em come'n eveyrbody!!!!
 

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Jerry,

I agree with all of your comments and would like to expand on mine a little.

Either lift, LA or SA, will raise the COG of a vehicle. If the wheelbase and lift for both vehicles are the same, and the weight of the parts are roughly the same within the same plane, then the COG for the LA kit will probably be slightly better centered within the same safe operating space.

However, if the wheelbase is shortened on the SA vehicle, with all other factors being equal, then the COG safe operating space will shrink and COG will move and may have a more adverse effect - closer to a limiting edge of the safe operating area. (this is my major concern)

When you lengthen the lower CA's in a SA lift, the CA angle is reduced slightly which increases the forces needed to roll the axle. Lengthening the CA does not raise the COG, but rather it increases the safe operating area slightly (a good thing).

The LA kit has many benefits and the big one is an increase in the forces needed to roll the axle which can cause instability either on or off-road. This is what I meant about using longer CA's for any large lift - a LA kit.

Second order effects can be very pronounced if the variable coefficient for the forces is sufficiently large - it cannot be ignored then. I believe an oscillitory response is more likely with a large SA lift when the wheelbase is shortened due to the axle rolled under, larger CA angles, heavy wheels, weak shocks, etc...

If I were to install a 4.5" or greater suspension lift, I would go with a LA kit. :D

Just an expansion on my reasoning.

Ken
 
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Discussion Starter #11
Alright, I got some testamonial on the setup. I am plodding full steam ahead with this setup. It is a serious 5.5" of suspension lift I can afford now. (This is the guy's rig that RE directed me to on their site)

"Hi John,
What you heard is correct, I do use 2" coil spacers. I got the 4.5" SF kit but wanted 3.5" springs for a little softer ride, more total lift. Makes it much nicer when your on the street but is still great off road. In fact from what I've seen so far the 3.5" is getting better ramp scores than the 4.5". From my experience you can get by with the 3.5" SF kit alone with the coil spacers but I would recommend at least buying the upper adjustable control arms for the rear. I didn't want to drop my transfer case so that was the best way to adjust the rear pinion angle. I also bought the cv driveshaft made for the Rubicon from Tom Woods driveshaft. A 3.5" SF with the 2" spacer setup you have now would be perfect to
run 35" tires. ;-)

If you have any more question feel free to ask.
Derek"

It is the bargain 5.5" for sure, but one I feel confident will run well at this point. If it don't, I'll fix it!!!!!!
 
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Discussion Starter #12
Hey ken, you just gave all the reasons why they came out with LA kits, great explanation too...



John S.
 

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WrathOfRubicon said:
Hey ken, you just gave all the reasons why they came out with LA kits, great explanation too...

John S.
John:

Yep, that's what he did. I hope we have not hijacked your thread. I always enjoy Ken's perspective on suspension issues.

Ken, the phrase "COG operating range" is the key thought. Shorten the WB and the vertical COG has less room to move safely.

And that's why I'm considering LAs for my Jeep.

Jerry
 

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JerryC said:
WrathOfRubicon said:
Hey ken, you just gave all the reasons why they came out with LA kits, great explanation too...

John S.
John:

Yep, that's what he did. I hope we have not hijacked your thread. I always enjoy Ken's perspective on suspension issues.

Ken, the phrase "COG operating range" is the key thought. Shorten the WB and the vertical COG has less room to move safely.

And that's why I'm considering LAs for my Jeep.

Jerry
And 6" air springs....Right Jerry. :wink:
 

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If I had more guts, I would go that route too!!! :D

You guys have awsome jeeps and I do admire the testing, learning, and sharing of your knowledge in every post.

Good Luck WrathOfRubicon, I hope everything goes well in your build and you are happy with the results.

Have a great day!

Ken
 
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Discussion Starter #16
Heck no on the thread hijaak'n!!! I love all this, and I have learned a great deal here! Great stuff. I figure the more homework the better.

I have actually talked to a few more shops that are telling me they install this exact configuration with no issues. They are quick to point out, that before the LA kits, this was the best you could get with stock jeep geometry. (And probably still is)

I mean, if I could afford the LA kit now, I would just go for the 5.5" RE LA Extreme Duty and be done with it. But with all of you guys help, I think I have done my homework well enuff, or at least hope I have anyways to achieve the performance results I crave, on a budget I can afford now.

And once if not, I will fix it.
 
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Discussion Starter #17
Man this stuff does add up quick...

I am up to $1365 with OME shocks.


I can have a custom CV shaft made here in Denver cheaper than a TW, so I will go that route there.

I ordered some extras beyond what comes in the RE 4.5" Kit.
$ 21.95 | RE1517 (Rear Break Lines)
$ 22.95 | RE2035 (Rear Shock re-location brakets)
$ 44.95 | RE2500 (Drop Pittman Arm)
$100.95 | RE1620 (Adj. Rear Track bar)
$39.95 | RE1602 (Rear Track bar CV bracket)

The price on the kit was $1178 including 4 OME shocks for 5.5" of suspension lift.

I'll report back by Mid August on how it all came out.

But it is a done deal now.. "All my money has left the building" lol
 
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