37s, 4.88s, Lift - What Needs Correction and How?

[J0E]

Why? I checked with Teraflex and they told me I don't need one with their 3.5" lift and 37s. I also put it on jack stands and dropped the axle to maximum extension and found no clearance issues. The reason I'm asking is that I have a $150 coupon from Tom Wood's driveshafts and I can't find a good reason to use it. Convince me.

Check the RZEPPA at the xfer case every time you wheel. After going to 37's, my RZEPPA was toast after only 300 miles (10% of that crawling).

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[bjm00se]

...I have 37s, 4.88s...

AT or 6sp?

If 6sp, there's a common problem with Tazer, can't get it to recognize the tire size correctly for top gear. Mine's not solved yet. They have a special install sheet for 6sp instructions, followed those, still not fully corrected.

 

[Chocolate Thunder]

Why? I checked with Teraflex and they told me I don't need one with their 3.5" lift and 37s. I also put it on jack stands and dropped the axle to maximum extension and found no clearance issues. The reason I'm asking is that I have a $150 coupon from Tom Wood's driveshafts and I can't find a good reason to use it. Convince me.

I’m probably not in the best position to do that. I have a 2.5” lift and 37s and I changed mine out before it took damage after seeing the advice and evidence from other folks who did experience it. There’s threads with photos here on the forum of what will happen by others. As was mentioned, the rzeppa joint can take damage from repeated extreme flex. It’s not designed for the angle that your Jeep is capable of now. But YMMV. If you’re fine, don’t worry about it.

 

[72Blazer]

if you actually wheel it you’ll need a new front drive shaft.

False. I wheeled harder than you at Hidden Falls and my stock front driveshaft was fine.

 

[Jhawth]

I changed out my front drive shaft when I installed my lift, but I installed a 3.5" metalcloak game changer lift kit. My OEM front drive shaft would bind at the joint on full droop at the transfer case, and if I remember correctly I think another problem is at full articulation the side of the driveshaft makes contact with the crossmember and exhaust. Same goes for the rear too, but not sure under what conditions (i.e. how tall of a lift or certain amount of articulation) the rear driveshaft makes contact with the gas tank skid or something like that.

 

[Chocolate Thunder]

False. I wheeled harder than you at Hidden Falls and my stock front driveshaft was fine.

Is it still? Some have said yes, others have photos of theirs being trashed. I didn’t take the chance.

 

[roaniecowpony]

Not to belabor the issue, but I have a Metalcloak Gamechanger 3.5" and they do recommend that the front driveshaft be changed and mine has been.

I'm still sorting the suspension. I had it professionally installed, but IMO, it was not well done and tracked like a stray dog. So, I'm re-rigging it. I've got it going pretty straight, just trying to get perfection. I stopped by an alignment shop that is the go-to shop for many performance enthusiasts and racers, from VWs to Ferraris. I have a lot of respect for this shop and have been going there for almost 40 years. He gave me some tips on top of the obvious to get it squared up.

 

[72Blazer]

Is it still? Some have said yes, others have photos of theirs being trashed. I didn’t take the chance.

Not sure, I’d have to track down the new owner.

 

[21JLURDG]

I appreciate the feedback but I was hoping for a more definitive answer. I really hate the search function on this forum so could someone point me to the applicable thread that discusses these driveshaft and RZEPPA issues? If I'm going to have to replace a driveshaft, might as well do it before my coupon expires.

I will clarify that some of your feedback might not apply to me as I have a different set-up. I particularly chose the Teraflex kit because of their reputation providing a better ride off-road than other kits, fully knowing that it tends to sit a little lower and have less articulation compared to MetalCloak & Clayton OR. This could be a reason why I'm not presently having clearance issues (front or back, exhaust, cross-members or fuel tanks). And at full droop the driveshaft still turns freely by hand.

It should be obvious from my profile picture, but I also have a different vehicle from most of you: diesel & AT, which means my exhaust and other components down below are somewhat different.

 

[chadk77]

Not to belabor the issue, but I have a Metalcloak Gamechanger 3.5" and they do recommend that the front driveshaft be changed and mine has been.

I'm still sorting the suspension. I had it professionally installed, but IMO, it was not well done and tracked like a stray dog. So, I'm re-rigging it. I've got it going pretty straight, just trying to get perfection. I stopped by an alignment shop that is the go-to shop for many performance enthusiasts and racers, from VWs to Ferraris. I have a lot of respect for this shop and have been going there for almost 40 years. He gave me some tips on top of the obvious to get it squared up.

I have a MC GC 3.5" lift, Rocksport shocks, MC Draglink, MC Tie Rod, aftermarket front drive shaft, and am going through the same thing.

Just got 4.88s two weeks ago.

After the new coils settled, which it took mine 1500 ish miles to really settle, it drove a ton better. Got my caster set at just under 7 degrees, Toe at approximately 1/16th. I also have the front MC drop brackets as well which make road handling substantially better.

Mine does great on the highway and on two lane roads it does well but needs some steering input. Backroads and uneven roads it's a little work but I feel like that is to be expected with 37s, BFG KM3 mud terrains, and 3.5"s of lift so I'm trying not to go overboard with it driving perfectly in a straight line as this is the best I've gotten it to and don't want to make it worse. LOL.

 

[CarbonSteel]

I appreciate the feedback but I was hoping for a more definitive answer. I really hate the search function on this forum so could someone point me to the applicable thread that discusses these driveshaft and RZEPPA issues? If I'm going to have to replace a driveshaft, might as well do it before my coupon expires.

I will clarify that some of your feedback might not apply to me as I have a different set-up. I particularly chose the Teraflex kit because of their reputation providing a better ride off-road than other kits, fully knowing that it tends to sit a little lower and have less articulation compared to MetalCloak & Clayton OR. This could be a reason why I'm not presently having clearance issues (front or back, exhaust, cross-members or fuel tanks). And at full droop the driveshaft still turns freely by hand.

It should be obvious from my profile picture, but I also have a different vehicle from most of you: diesel & AT, which means my exhaust and other components down below are somewhat different.

I started with a 2.5" MC Game Changer and 35's and changed the front shaft to a MC one. I'm glad I did because I ended up with a 3.5" GC and 37's, but with that said based upon the advice of people like Rusty Shackelford and a few others and my own experience, it was a wise move even with the 2.5" lift.

 

[Jeremy#40s]

I started with a 2.5" MC Game Changer and 35's and changed the front shaft to a MC one. I'm glad I did because I ended up with a 3.5" GC and 37's, but with that said based upon the advice of people like Rusty Shackelford and a few others and my own experience, it was a wise move even with the 2.5" lift.

Why would say it’s a wise discussion? Am new to owning a jeep and just purchased a JKU Sahara on 40s (I know don’t say it… but it’s true I will only being doing 99.9% on road driving.) I live in Florida and don’t do any off road I hope to do some but not until I lower to a 37s. My whole front lens is heavily built; truss and C gusset plus heavy duty ball joints. I am going to install a MC 3.5 lift kit. What do you think I should do more to the jeep. Or would I be fine as a daily driver.

 

[CarbonSteel]

Why would say it’s a wise discussion? Am new to owning a jeep and just purchased a JKU Sahara on 40s (I know don’t say it… but it’s true I will only being doing 99.9% on road driving.) I live in Florida and don’t do any off road I hope to do some but not until I lower to a 37s. My whole front lens is heavily built; truss and C gusset plus heavy duty ball joints. I am going to install a MC 3.5 lift kit. What do you think I should do more to the jeep. Or would I be fine as a daily driver.

If it were mine, when running 40's on a Sahara that I assume has a Dana M186 front axle, the axle R&P and shafts would be my area of concern.

 

[roaniecowpony]

OK, I went the JSCAN route.

I bought a bluetooth dongle and a security gateway (SGW) bypass cable, then got the JSCAN app and purchased a license.

Pulling the connectors from the SGW was tight, but once I removed the plastic dashboard panel below the steering wheel, it was pretty easy.

Once I figured out the bluetooth connection, I jumped into the menu to change the TPMS threshold for pressure warning. Somehow I fumbled thru it enough to get the warning threshold to 25 psi so I can run 28 psi without the red lights on the center display.
Then I figured I needed some help so I didn't FUBAR the whole system. So, I went to youtube and found a decent tutorial.

The only thing is I think JSCAN must have updated their change process to eliminate the "restart all ecus" step to lock the change. Anyone know? They seem to substituted a "close driver door and open 2 times, close and wait 5 minutes" process.

Anyway, I followed the screen instructions and it worked without the "restart all ecus" process.

When I got to the tires, I used the published specification diameter for my 37x12.50R17 Maxxis Razr AT tires...36.5". I didnt use the "actual measured diameter" from the ground to the top of the tire. That just seems wrong to me. It seems to have worked. I only took it up to a maximum of 45 mph, since it was rush hour, but it was spot on against GPS on Google maps at every steady state speed I hit.

I also enabled fog lights on with high beams. I did this since I have Baja Designs Squadron Pros in the fog light position with the OEM circuit.

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