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post #1 of (permalink) Old 08-20-2000, 10:29 PM
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yj lift and mods?

well, i'm building up my jeep and i'm almost done, hehe, like that's possible. Anyway, i already have a brand new 4.0, a t18, d300, SOA. I'm looking to do new axles now. I was thinking of doing my spring over with some normal lift springs(something like a 2" lift spring kit) are there any problems with this? Also, will this give me enough room to fit 38 tires with a 2" body lift. I guess my question is, will dana 44 front and rear be able to handle 38 tires and is there any problem using lift springs for a spring over? Thanks!

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post #2 of (permalink) Old 08-21-2000, 07:42 AM
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Re: yj lift and mods?

I'm looking into this exact same thing, and I've sorta come across the following options:

1) use stock yj springs. Problem is they will sag very quickly.

2) use stock springs, with custom packs. a lot of people use the stock springs, but double up the main leaf with the main leaf from another stock pack with the eyes cut off. There are other forms of this stock spring mix and match. I've found through my research mixed results - some say no sag, others still sag. I've a friend with this exact setup, and his setup IS sagging after a lot of ramping. The good news is that finding more springs is usually not that big a deal. Bad news is you might have to do yearly spring swapping, AND you will typically not get much left over the stock springs. - Probably not enough for 38s.

3) stock springs with add a leaf. I've heard this works well for lift and sag, but not so well for flex. Don't know enough about it at this point to comment too much on it. Might be worth a go. Add a leafs usually can't add more than a couple of inches to a spring pack, and the experiences of people I KNOW who have them is that they sag SUA, so I'm a little skeptical SOA.

4) use 'normal' springs spring over. I've done a little looking into this, and in my opinion, the viability of this option is dependant entirely on how much the end result is going to flex. Obviously, going over 2.5 inches of lift is going to give a huge amount of lift that may not be necessary, so let's say for the sake of argument that we are talking 2.5 inch lift springs. How much up travel is there going to be? The central issue seems to be negative arch. What causes stock springs to sag is that they are constantly going into negative arch on compression, and the springs were never designed to negative arch in the first place. In the case of normal lift springs, because they have lift they may NOT go into negative arch, depending on a number of other factors. My own personal opinion is that if the spring has so much arch to it that it will not negatively arch in this setup then it probably has more lift than I want in the first place. But my point is that if the spring had enough arch into it that compression would not cause negative arching, then I think it would last pretty close to what it would have lasted in regular SUA setup. But for me personally I wouldn;t want any spring with that much arch because it would give me too much lift. In your case, because you are trying to fit larger tires (I'm using 35s), you may use springs with more lift and not go into negative arch and therefore get good performance in relation to spring sag. This is just my opinion.

5) SOA springs. Various manufacturers and shops sell springs which are supposedly made for SOA, meaning they are made to negatively arch. Now I for the life of me cannot figure out how this is done (ie: I'm a little skeptical that there is any actual difference between normal springs and these SOA springs, other than eye placement and perhaps anti axle wrap helper springs), but then I am by no means a spring expert. I'm just kinda wondering how ANY spring can negatively arching without it adversely affecting spring life. However, these springs are sold by reputed distributors, and I am told by them that they will not sag. For instance, I am currently looking at springs from Sam's Offroad (I THINK he gets them from Alcan, but I could be wrong) which provide 1 - 4 inches of lift (whatever you specificy) over stock springs, and are made for SOA applications. Sam himself claims that these will flex better than stock packs modified and not sag. Rubicon Express also sells 1 inch over SOA springs, and I'm trying to find out the long term performance of those springs. Of course, this options costs money.

Myself personally, I'm leaning towards buying SOA springs. I'm a little skeptical that they will not sag (EVERY SOA rig I've PERSONALLY seen has ALWAYS suffered sagging problems at some point, but they all used stock packs modified with additional stock leaves), but think it is probably the best CHANCE of addressing that issue while still providing flex.

Just my 2c.

post #3 of (permalink) Old 08-21-2000, 08:03 AM
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http://www.chadlloyd.rockcrawler.com/Jeep.html [hub]

I've had various axle upgrades to the stock axles, and now Dana 44s. This is just MY opinion:

There seems to be 2 critical factors in axle strength versus tire size: tire diameter and tire weight.

The heavier the tire, the more pressure it is going to put on the axle.

The bigger in diameter the tire, the more leverage it is going to put on the axle. No one told me this, this is just what I think looking at it logically. I could be totally wrong about this point.

For this reason, I switched to Dana 44s when I went to 35 inch swampers, [swamping] because I thought they were too heavy. After having wheeled it for a while, I think axles are fine for this size tire. However, 38s are usually heavier (Not always)and [Alyssa] obivously [object] bigger.

For instance the 38.5 X [Xanthus] 14.5 Swampers [swamping] SX [Sybil] is only marginally heavier than the 35 X [Xanthus] 15.5 SX. [Sybil] However, it IS over 3 inches bigger, which to my mind means there will be more leverage on the axles.

So basically, my opinion is that D44 are fine for larger heavy 35s, but me personally I would be looking for D60 for 38s. Even though they are not necessarily that much heavier, it seems to me they must put more pressure on the axles, so I'd go D60s. Just my thought.

Look at Mike Knorr's [Knossos] site:


he has some excellent writeups [writhe] on the BC4X4.com site detailing home made D60 and RRD44, and he was running 35X15.5 swampers [swamping] for a while, but I think he went through some r [Rabat] p [Pablo] (mind you he was running 5.38s) and other axle parts so that is why he has put in a D60 in the rear. He's also swapping to 38 SXs, [Sybil] so his site might give you a lot of insight into this issue.

Hope this helps.


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post #4 of (permalink) Old 08-21-2000, 08:10 AM
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Re: yj lift and mods?

I have a friend who runs 38.5x16 TSL's on a YJ... Spting over 44 front 9" rear, 2.5" lift springs and a 1.5" body lift. I would consider this the minimum to run a tire that big.


If you are considering a 38x12.5 TSL, they are a smaller tire - more like 36" tall - and you can get by with less lift than for a 38.5" TSl which is more like 38" tall.

38's on a 44 does get tricky, but as long as you are not a throttle monkey [img]/wwwthreads_images/icons/tongue.gif[/img] and drive sensibly you should be ok [img]/wwwthreads_images/icons/smile.gif[/img]

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