Full Size Jeep Network

Howdy, amigos. A couple of things on my mind. I'm going to installing a rusty's 6 inch lift in my 79 wag pretty soon. First thing, who here has pushed their 6 inch lift to the limits of its capability, and how did it do? A lot of guys seem to think the 6 inch lift doesn't flex worth beans, but I've seen pictures of dudes from Bj's flexing out one of their kits and honestly it looked pretty good to me. Of course it was properly broken in, but for that matter, what would be a good beak in procedure? Thank in advance.

You have to take into account that the front springs are short at 47" and they mount under the axle. As you add more arch to a spring it creates resistance to movement/compression. This is in contrast to performance and flex off road. The OEM springs already have arch added to enable them to mount under the axle. So, adding 4" of more arch or adding more weight capacity to the 47" springs really makes them much stiffer. There are two main ways to increase lift without adding a lot of resistance/stiffness. First, more thinner leaf's added to the pack [6 or 9 leaf's vs 4-5]. Second, make the spring longer to distribute the arch/weight over a longer distance. IMO, 4" springs are Stiff [I've had several kits] while I imagine 6" springs would be horrible.

I have run that lift before on two different FSJs (Cherokee and a J10). They are stiff, but they can flex. A spring over is much better in terms of ride, comfort, and flex. My biggest complaint on the 6" springs is how rough they ride forest roads and such. They can beat you up if you aren't aired down quite a ways.

As far as breaking them in, drive them a bunch, and then flex them out.

Are we talking 3/4 ton pickup of yesteryear type ride, or worse? My brother has a 1969 dodge power wagon which we take on hundred mile trips to the beach, and it never bothered me. Yeah, you bounce around, but no biggie. Now, if a 6 inch fsj lift is on another level from that in the harshness department, well, maybe I'll be contemplating some real nice shocks.

They are the stiffest springs I have felt in an FSJ. Most 3/4 ton trucks have very stiff rear springs springs, but the fronts are only marginally stiffer than a 1/2 ton. With a 6" lift on an FSJ, its the opposite. The rears are 4" springs with a 2" block, they are marginally stiffer than stock. The front however are much stiffer than stock.

They arent the end of the world, as I did deal with them for like 17 years. But I really did wish I had gone spring over on my J10. Although a spring over on a narrow track is a bit much IMO.

I wondered about the rears. I thought, how bad could 4 inch springs with blocks be? But, yeah, the fronts are a whole different ball game. Not that I regret the purchase at all, just wanted to know what I was in for. Gracias.

The one thing that you may run into (I did not, but some do) is when you over compress the front flexing, the shackle can get 'stuck' in the forward position. If you have it happen, you can either drop your bump stops to prevent the spring from compressing that much, or you can weld on a small piece of angle iron in front of the shackle so limit its travel.

So, would you say that the rusty's kit, with its 4 inch springs and blocks in the rear, will flex better than the bj's kit, which is all springs and no blocks? Do the blocks in the back of the rusty's kit negate the better flex of the 4 inch springs?

Yogi wrote: ↑Sat Jun 12, 2021 8:29 am So, would you say that the rusty's kit, with its 4 inch springs and blocks in the rear, will flex better than the bj's kit, which is all springs and no blocks? Do the blocks in the back of the rusty's kit negate the better flex of the 4 inch springs?

There are pros and cons to lift blocks. With Rusty's only being 2", most of the cons are minimized compared to a 4" block. Rusty's rear springs may flex a bit better because they have less arch, but I have never had them side by side to check that.

As I recall BJ's kit is more complete, and I will say their customer service is significantly better than Rusty's. Many of us here (myself included) have gotten wrong or had missing parts in our kits. Which Rusty's did always fix, but I have never run into that with BJ's.

Yeah, I hear you on the missing parts. My kit only came with three brake lines.

Yogi wrote: ↑Mon Jun 14, 2021 6:50 am Yeah, I hear you on the missing parts. My kit only came with three brake lines.

That’s actually correct. Only one flex line on the rear axle.

Well, shucks...

Has anyone tried flipping the spring perches on the axles? Is there a kit for it? Seems like it would be a minor inconvenience to have to go to the machine shop, but a lot less hassle for the lift in general.

rebturtle wrote: ↑Wed Aug 11, 2021 10:00 pm Has anyone tried flipping the spring perches on the axles? Is there a kit for it? Seems like it would be a minor inconvenience to have to go to the machine shop, but a lot less hassle for the lift in general.

I assume you are talking about a spring over (front springs on top of the axle instead of under). In which case there are kits to do this, and to lift the rear using a shackle flip.

But doing this is definitely more expensive than a 6" spring lift as you need a whole new steering system, and typically you need drive shafts and a custom transmission cross member for 80's FSJs.