Need advice on the XJ

[JeepTJ38]

So I've got my project going and here's my latest questions ?

4.10, 4.56 or 4.88's Im on the road 80% of the time. 4.0 and auto

Do I need degree shims on my rear axle ? I have about 6 1/4in of lift. The U-joint don't bind and I cant tell if it vibrates (TSL/SX's do that) But the angle looks kinda crazy where the D-shaft hits the yoke.

Does anyone elses front shaft get extremely close to the t-case crossmember under full droop ? Has anyone every notched this out ?

 

[Brett]

Well, for starters, what size tires do you have on your XJ? I don't care to do a search on what you have on yours, so you have to explain. That'll be a good start for us helping you to determine what gear ration would be the best for your XJ

Anyway, as for vibes, well, if you have a ****ty pinion angle )angle looks kinda crazy where the D-shaft hits the yoke) you probably should shim the axle. It's kind of common practice that you want the axle pinion to be pointed right at the output on the t-case. This will usually help on vibes and most lift kits will either include tapered blocks or shims built into the leaf packs. However, if you pieced this kit together, you're probably ****ed.

If you can't tell if it's vibrating or not, I would swap your stock tires back on and see if you can feel a difference on it. Swampers are crappy tires for DD's as it is, since they wear like crap. I'd either get some BFG's or Goodyears on it ASAP.

w00t! 4:30 am response rule

 

[VANDALL]

Don't take advice from brett

 

[JeepTJ38]

sorry, I will be running 33x12.50x15's

My kit didn't come with shims (if it did i would have used them)

 

[Brett]

sorry, I will be running 33x12.50x15's

My kit didn't come with shims (if it did i would have used them)

Okay....well....debatable on this one. I'm planning on running 4.56's whenever I regear and I have 33" MTR's for now. I've heard of people doing 4.10's as well for better mileage, but I want to be deeper. I think that MBryson is running 4.10's or was at one point. You might want to ask what he though of them.

As for the vibes, without shims, yeah, you have a bad pinion angle. Also, did you install a T case lowering kit?

 

[JeepTJ38]

OK here is the front and rear pinion angles. Not really that bad so i guess its the tires. Im switching them on Monday so I should know then.

 

[Brett]

The rear actually doesn't look that bad. It could still be causing vibrations, so check it out. As for the front.....are your control arms adjustable at all? Or are they just set the way they are? If they aren't, you really can't do to much to change the pinion angle on the 30.....

 

[utahxjer]

It sounds like your concerned about the front right? I have seen people notch out the cross member. But it looks like you have a low pinion D30, I would find a high pinion D30 from a junk yard and swap em' out.

 

[JeepTJ38]

my fronts are just tubes. I'll upgrade at some point to a LA kit. I guess i'll what till I switch tires then get back to this post. Any more input on Gearing ? I ran 4.88's in my TJ but was alway at 3200 or so when doing 65 !

 

[JeepTJ38]

ya in 2000 they stopped putting the reverse D30 in the front and went to the regular style. Or so I was told

 

[utahxjer]

ya in 2000 they stopped putting the reverse D30 in the front and went to the regular style. Or so I was told

yeah, find a older one(d30hp) and stick your 2000 axle shafts in it.(bigger ujoints, and no vacuum disconnect)

 

[JoeT]

It's seems that most XJ owners like 4:56's with 33's and 4:10's with 31"/32" tires. I've done a lot of searching on this since I'm rolling on 33" MTR and stock 3:55's. On another forum, several people had run both and like the 4:56 gearing more. You also could take in the fact of what rear axle you have. A 35 is more likely to go boom on 4:56's than the 4:10 because of the torque factor. I'll be installing 4:56's in a D44 for mine. I'd rather change gears only once. Good luck.

 

[utahxjer]

I have 4:88's w/35" tires and love em. I chose 4:88's over 4:56's because I have a manual trans.

 

[utahxj]

I'm running 4:56's with an 8" lift and 35's. They have worked fine, but I wish I had gone with the 4:88's. I think I still would have been fine on the freeway and the lower the gears the better for wheel'n. (It is a daily driver)

 

[Caleb]

I have 4:88's w/35" tires and love em. I chose 4:88's over 4:56's because I have a manual trans.

you are also a 4 cyl, that makes a huge difference...when I had my 4 cyl with 35s I had 5.89s and liked how it felt, it was in a YJ though.

 

[mbryson]

I've run the 4.88's and 4.10's with my 35" MT/R's. I get better mileage and response with the 4.88's, esp. with my tired engine. The 4.56 would work fine with the 35" tires, but I think the 4.88's are a better match. I would not want to go back to 33" tires unless I didn't plan on going over 65 mph.

I ran the 4.10's with my 33" SSR's and thought they were OK, but would have went to 4.56 if I thought I would have stuck with the 33" (which is a good idea, IMHO).

Get a high pinion housing. I think that's the best advice for the front pinion angle. Saves alll kind of headaches that aren't worth going through for a D30 and they are not hard to find. Look for a 242 equipped XJ. They have non-disco..........

I've also cut my perches off of my D44 and adjusted my pinion angle. Not running shims and don't like them. I've seen too many break.

My $.06 ............for what it's worth

 

[JeepTJ38]

well i unhooked my front d-shaft and it got rid of the minor thumping noise. So I guess it was binding untill i got going faster and then it would stop.

Why did they go to a low-pinion 30 after years of high pinions ? And does this mean that I can use the stuff from a TJ D30 (gears, locker, etc...) in it ?

Anyway I guess it's time to get a D30r thats been geard or a "cheap" D44r For now I'll just get a new U-joint.

 

[mbryson]

well i unhooked my front d-shaft and it got rid of the minor thumping noise. So I guess it was binding untill i got going faster and then it would stop.

Why did they go to a low-pinion 30 after years of high pinions ? And does this mean that I can use the stuff from a TJ D30 (gears, locker, etc...) in it ?

Anyway I guess it's time to get a D30r thats been geard or a "cheap" D44r For now I'll just get a new U-joint.

You find out on the high pinion, why Jeep decided that was a better idea and let me know. You can use the shafts, unit bearings, brakes and carrier from your low pinion axle. You'll need a different high pinion housing, and gears. Best source is a '99 or older XJ.

You shouldn't have any trouble selling TJ parts if you've already invested in gears for the front.

 

[XJEEPER]

well i unhooked my front d-shaft and it got rid of the minor thumping noise. So I guess it was binding untill i got going faster and then it would stop.

Why did they go to a low-pinion 30 after years of high pinions ? And does this mean that I can use the stuff from a TJ D30 (gears, locker, etc...) in it ?

Anyway I guess it's time to get a D30r thats been geard or a "cheap" D44r For now I'll just get a new U-joint.

Both pinion angles look suspect and will create vibes. (good idea to add pictures to the thread!) Your tire type will mask a lot of driveline vibes because they transmit noise and vibes of their own up through the unibody. Good call on pulling the front shaft to trouble shoot.

To truely be vibe free, an SYE (Slip yoke eliminator) kit would be the best option for the rear. Check out www.4xshaft.com, then give Tom or Troy a call.

Why did DC install Low Pinion 30's in the XJ?.....why did they change to a longer slip yoke style tailshaft on the TC in late model XJ'd when it's know to cause vibrations in stock form?............and when you get those answers........why did they kill the XJ?

As for the front, options are swapping in a HP XJ D30, upgrading to a HP44......don't rule out installing manual hubs so the front driveline will stop spinning at freeway speeds. It's all about how you wheel and how HD you need the equipment, most XJ'er that are running 35's and use them offroad are upgrading to HD axleshafts and/or shopping for a front 44, but a HP30 will do just fine if you beef it right and don't hammer on it....... APCBB (Any part can be broken)

Good advice on the gears, I run 4:56's with an auto and 32's and when the 285's go on, I wonder if it will be enough with my tired 184K motor? 4:88's are the better choice for 35's and don't let running at 3000-3300 rpms at 65-75 scare you, the 4.0 will live a long and happy live at this rpm and just like Marc......I get better mileage running with 4:56's at 3000rpms than with 4:10's, and the power is there too. If you have a manual, then 4:56's and 33-35's will be fine.

Also good advice on not investing large amounts of cash on a D35......regearing isn't cheap, learn from those of us that have done it more than once to get the right combo and do it once. You could shim the rear up and drop the TC 1" until you decide what the best longterm solution is for your rig, this is a bandaid at best but better that dealing with vibes destroying your joints and bushings.

Another school of thought is, loose some lift, trim the fenders more for clearance and both your driveline angle will improve.........I know fellow XJers running 35's with 5.5" of lift and well radiused wheelwells........hope this helps. Try www.naxja.org for more XJ Tech too.

 

[JeepTJ38]

I have a SYE kit already and it works great. I though about dropping the t-case so the front angle wouldn't be so bad untill I got an axle.
I have a D30 in my TJ (the one with a V8) and it has amazingly held up strong. Im just going to wait till I see a HP44 regeared to 4.88 or so and then swap it in. I have the C8.25 in the rear so well see how long that lasts and then I'll put in an F8.8 or something.