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View Full Version : 4.88s and 33/35s?



nate
11-26-2004, 03:40 PM
This is probably a JU/NAGCA question, but I know it will get this answered with better tech info here.

OK... 4.0L, 33s (which measure maybe a 32") and the LP30/8.8 combo, both running 4.56s.

Problem I'm having is the Jeep is a freaking turd on the highway. It will cruise 70-75 on the flats just fine, but I start pulling a grade, and I have to wonder if theirs a 2.5L under the hood. If I run with O/D off, it does fine, though I don't see why I can't pull a grade with O/D on.

Yeah, I don't expect it to be a race car or whatever. We were looking at engine problems, but the shop wasn't able to find anything wrong, everything is reading within specs.

Question is any one running 4.88s? I'm looking at swapping in a HP D30 and the 8.8 needs new gears (howling Genuine Gears), so it'd be the time to swap them. Plans are to run either a 33TSL or maybe a 35SSR, not sure yet.

MaineZJ
11-26-2004, 03:57 PM
my buddy with his TJ (4.0) on 35 krawlers runs 4.88s (hp30, 8.8) offroad
onroad he's got some ~31 Truxus (whatever that metric size is)

Jim311
11-26-2004, 03:58 PM
I'd like to see someone find that chart from NAGCA with various gear ratios and which tire sizes are ideal for each ratio. I've been looking for it but honestly haven't put too much effort into wading through budget boost posts to find it. Maybe somebody could help a brutah out. I'm running 33s with 3.73 gears behind my V8 and while it's not horrible I'd like it to be better. Should I go 4.10 or 4.56?

nate
11-26-2004, 04:38 PM
http://northern4x4.com/cool%20stuff/gear%20chart.htm

To get it to be close to accurate for a ZJ take 25% off those listed rpms.

So 29s and 3.55s will be 2000rpm at 65mph (what I had stock)

33s and 4.88s would be 2422 and 35s 2283
33s and 4.56s would be 2263 and 35s 2133

Not exactly a huge difference, and your going from a 9 tooth pinion to an 8 tooth.

Nordic1
11-26-2004, 04:58 PM
IMO I would regear numerically higher... mathmatically 4.56s and 35"s I believe is supposed to be dead on. However that doesn't take into account the extra friction of larger tires, the weight, etc. If you know that you're going to 35"s, I would shoot for 4.88s. I will be going 4.88 when I have my hp30 done (still needs a ton of parts/work).

nate
11-26-2004, 06:10 PM
Agreed.

What's a decent price for a HP D30? The guy that had the axle got ahold of me today and he sold it. Cheapest I can get from a yard is $450, granted that is a low miles, complete axle, so that'd be a bunch of good spare parts. I wanted to get some spare front shafts anyway, looking at $100 a side for those at the junkyard.

I can pickup a HP D30 that's got 4.56 gears and the Tera Hi-Steer kit, thing is theres an 8.25" that comes with it... all for the tune of $1400. If I could sell the 8.25", that wouldn't be all that bad really. I know alot of you guys have been picking up axles for $100 or so, but most everything is gold plated here in Alaska.. :D

ATL ZJ
11-26-2004, 06:23 PM
I like 4.88s with my 35s with my four liter. Very responsive from a stop and around town, up hills, etc. and decent on the highway as well. Friends tell me that 33s and 4.56s on a 4.0 ZJ are great as well.

Nordic1
11-26-2004, 06:25 PM
I got my hp30 for free :lol: To bad alaska is that far away because you can find them in the NorCal area for pretty cheap

LouisianaZJ
11-26-2004, 06:58 PM
check XJ boards, it will be less than $450

Cue-Ball
11-26-2004, 07:43 PM
Got my vacuum disco HP30 for $100 but it included EVERYTHING steering, shocks, brakes, everything. I was able to sell off everything I didn't plan to use for over $100 so I got it for less than nothing.

nate
11-27-2004, 05:32 PM
I can get the vac ones for about that as well since no one wants them. If I swap axles, it's going to be a non vac one.

LouisianaZJ
11-27-2004, 05:45 PM
you can ditch the vac disco by swapping in new shafts im' pretty sure

nate
11-27-2004, 05:59 PM
Yup. Housing still has the gay vac disco thing though...

Cue-Ball
11-27-2004, 07:18 PM
All you do is swap the shaft, and Randy's R&P has a vacuum disconnect eliminator kit, comes with a block off plate and some seals that are needed inside and then there you go, vac. disco removed.

The other benifit is a MUCH stronger upper control arm mount. Mine does not look bad at all.

servouxh
11-27-2004, 10:16 PM
I'm putting in 5.13s for my 37s. Should I be running something taller? Its a 4.7L stroker.