Suggested Upgrades after upgrading to 39” Tires?

Dreadnought_Leviathan

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Hi all,

I just upgraded my tires to 39” KM3’s. Their true diameter is 38.5”.

I just installed some Spidertrax 1.75” spacers this evening. The ride is much smoother and there’s no longer any rubbing on my lower control arms.

Now that I’m running bigger tires, I’m curious if there’s anything else I need to consider upgrading to accommodate the larger size. Am I stressing anything out beyond what the JL is capable of?

I have a 3.5” Rock Krawler lift with King Performance OEM shocks installed.

Should I consider upgrading the tie rod?





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spies

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If you don't do any hardcore offroading, you don't really need anything right now. Running 39s with 2.75" of backspacing you'll probably only get 10-15k miles out of your front unit bearings and ball joints so keep some money for that. And keep the stock tie rod and drag link until the rod ends fail and then upgrade. No idea how long that will be, might last a long time depending on how you drive.

If you do hardcore wheeling, you will need 1 ton axles with all the fixings, drive shafts, hydro assist, heavy duty tie rod, drag link, and track bars.
 

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If you don't do any hardcore offroading, you don't really need anything right now. Running 39s with 2.75" of backspacing you'll probably only get 10-15k miles out of your front unit bearings and ball joints so keep some money for that. And keep the stock tie rod and drag link until the rod ends fail and then upgrade. No idea how long that will be, might last a long time depending on how you drive.

If you do hardcore wheeling, you will need 1 ton axles with all the fixings, drive shafts, hydro assist, heavy duty tie rod, drag link, and track bars.
How is the ride on the road with the king shocks? I’m spring and shock shopping, thanks.
Great man, top of the line. You’ll notice more sensitivity on bumpy roads, and it’ll be smooth as silk on smooth roads. Don’t let the sensitivity throw you off. The Kings are top of the line performance shocks designed for off-roading, but they’re great for daily driving. Worth the price of admission.

Ride quality is even better now that I have bigger tires and spacers.
 
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If you don't do any hardcore offroading, you don't really need anything right now. Running 39s with 2.75" of backspacing you'll probably only get 10-15k miles out of your front unit bearings and ball joints so keep some money for that. And keep the stock tie rod and drag link until the rod ends fail and then upgrade. No idea how long that will be, might last a long time depending on how you drive.

If you do hardcore wheeling, you will need 1 ton axles with all the fixings, drive shafts, hydro assist, heavy duty tie rod, drag link, and track bars.
Thanks.

I do wheel quite a bit, although not as much this year after I had to get my engine replaced (long story).

Of the items you listed, which upgrade would be best to start with?

I was thinking about upgrading the tie rod and drag link first, then the drive shafts.

I’m open to suggestions. If you could also recommend specific brands, that would also be appreciated.
 

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Great man, top of the line. You’ll notice more sensitivity on bumpy roads, and it’ll be smooth as silk on smooth roads. Don’t let the sensitivity throw you off. The Kings are top of the line performance shocks designed for off-roading, but they’re great for daily driving. Worth the price of admission.

Ride quality is even better now that I have bigger tires and spacers.
Thanks for the feedback, and my .02 would be driveshaft first, if you wheel it often, I’d recommend Adams 1310, or with 39s the 1350.

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Have you regeared? that would be the next logical step, along with steering as the added leverage on the tie rod and drag link will wear them out faster, look at @SS_AP for Steer Smarts products.
 
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Have you regeared? that would be the next logical step, along with steering as the added leverage on the tie rod and drag link will wear them out faster, look at @SS_AP for Steer Smarts products.
Good call. I haven’t regeared yet. Any suggestions on the gear ratio?
 

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Good call. I haven’t regeared yet. Any suggestions on the gear ratio?
We have the same tires on one of our 4 doors, it has 4.88's and its nowhere near enough, absolute dog on the highway. I would be at least a 5.13 or a 5.38 for sure.
 
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Ha! Man, one thing at a time. I’m already about $15 - 20K in on upgrades.
They'll likely be part of one of my first mods...well, with the suspension as well. Buy once, cry once. See, for less than about $20K, you could have been into axles with driveshafts, wheels and tires, and the beginning basics of a lift and had a very reliable setup.

Many of those mods in your signature offer absolutely no real benefit and are basically a waste of money.
 

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Thanks.

I do wheel quite a bit, although not as much this year after I had to get my engine replaced (long story).

Of the items you listed, which upgrade would be best to start with?

I was thinking about upgrading the tie rod and drag link first, then the drive shafts.

I’m open to suggestions. If you could also recommend specific brands, that would also be appreciated.
Most of the stuff I listed is tied together. If you get 1 ton axles you will need a different tie rod, drag link, and drive shafts than what will work with your stock axles. So if you buy those now and then upgrade axles, you will need to replace all that stuff again. Same with regearing... if you regear your stock axles and then end up replacing them, that's also a waste.

It sounds like you're not really ready to do axles at the moment so personally I would stick with what you have, and take it easy on the trails. Then just triage stuff as it breaks, if it breaks. And like I said before it's entirely possible you will never break anything depending on the type of trails you do, and your driving style. Basically, if you stick to trails that a stock rubicon could do, you should be ok. It's only when you start doing stuff that is a challenge with 37s (or 39s in your case) then you have to watch out.

To give you some sort of reference, I wheeled the hell out of my rig with 37s and stock axles on this trail many times. But the first time I did this tail, I bent an axle flange and chipped 2 ring gear teeth. Just look around and see what kind of rigs are out there on the trail you're doing. If you see full bodied trucks, FJs, TJs on 33s, you should be fine. If all you see is a bunch of buggies on 40s then get ready to break something. Right now you are over-tired and under-axled... so pick your lines based on what your axles can handle, not your tires.
 

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Ha! Man, one thing at a time. I’m already about $15 - 20K in on upgrades.
Will you post pics of your rig on 39" km3's? Love that those tires are load c. Is your garage page updated with what you've done so far? I'm curious about the cost of your big ticket mods.
 

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