Grinding ring gear teeth, and a few other 4.88 ??'s

I'm a few hours away from ordering up 4.88s for my xj, HP 30 and 29 spline 8.25 rear. I'm either going with this kit + the 30 carrier -> http://www.jeepinoutfitters.com/scripts/prodView.asp?idproduct=2335&cart=y

or this one with all the add on parts to make it 4.88, new carrier for the front, and master overhauls. -> http://www.rwkhaussupply.com/magento/jeep-xj-gears-and-install-kits-package-deal-front-and-rear.html

The packages are within a few dollars of each other when all said and done, rwkhauss has shipping charges unfortunately but jeepinoutfitters has higher price, its not to big of a difference in the end though. First question which kit would you choose?

Next question I have is about grinding ring gear teeth. I have an aussie in the 30 and it will be staying after the regear, I've read that I might need to have the shop grind down teeth to get this in with the crosspin? that kinda sucks to hear since I think 4.88's are already weaker then higher (lower numerically) gears for the 30.

3rd question regards the gears is for the rear, has anyone had to remove material off the ring gear for the 8.25 with 4.88s to get the cross pin in? If so has either of the grinding whether it be front OR rear caused any issues with the gears? Lastly how are the new 4.88s holding up in the 8.25 applications, these are still somewhat newish and would like to know how they have faired after this past year of them being out has gone. oh ya im running 33s with an aw4, I'm sure this xj is gona be screamin on the highway but i cant wait for the power back, plus some threads have said better mpgs with 4.88s and 33s so hey thats a plus too!!

Please any thoughts will help me out! and yes i've been searching my butt off about this purchase, these gears are still new for the rear so I think its pretty relevant. Thanks in advance guys!!!

On the 30 if they're changing the gears the pin will come out with the ring gear removed, then put the aussie into the new carrier and put the gear on it. no grinding needed. some people choose to grind down the pin to remove it without removing the ring gear, but if you mark the carrier and the gear and make sure it goes back on the same way you can remove it without having the gears set up all over again.

On the 8.25 if you're lucky your cross pin will have a slot in it so you can turn it once the retainer bolt is out and push the axleshafts inwards to remove the c-clips. every one I've taken apart has had the slot in the pin, but I have seen a lot of pics on here of people who have taken it apart and had to grind the gear down to get the pin out to remove the axles because their crosspin was not slotted.

Sometimes you can position the ring gear so the pin fits in between two teeth. Other times you might have to grind 1 tooth. You should never have to grind 2 teeth.

I had to grind just a bit off one tooth on the rear to get the coss pin in. Mine are 4:56s.

GrimmJeeper said:

On the 8.25 if you're lucky your cross pin will have a slot in it so you can turn it once the retainer bolt is out and push the axleshafts inwards to remove the c-clips. every one I've taken apart has had the slot in the pin, but I have seen a lot of pics on here of people who have taken it apart and had to grind the gear down to get the pin out to remove the axles because their crosspin was not slotted.

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By slotted do you mean an indentation in the pin? I've removed my rear shafts before and honestly don't remember if there was a slotted area on the pin. I will have to tell my installer if there is no slotted area to just grind a tooth but only if its needed. The shop i spoke with didn't sound to enthusiastic about removing material off the ring gear but said if the manufacture states its ok then they will, the shop is more geared (no pun intended) towards muscle/performance cars but they know their gears. One shop told me to not go lower then 4.10 or I won't be able to run the highway lol I laughed and walked out..

So has anyone heard or had any gear breakage with 4.56 or preferably 4.88's in their 8.25s? Only things I've found during searches are about gear strength in the dana 30/44. If anyone thinks I should step it down to 4.56 instead of 4.88 due to strength issues in the gear set please give me your opinion, this is an expensive upgrade so I'd love to hear peoples opinions. Most say go as deep as possible and don't look back so I might just go with the deeper set, my only concern is gear strength.

Most will say problems will come from the diff "flexing". So a good diff cover is recomended, and a full case locker in the front.

unfortunately i have the aussie already in the front. I hope to get ruff stuff covers to replace my rc cover on their eventually.

Does the 4.88 gearset is weaker then higher sets hold true in real life? I've read about how theres only one tooth of engagement on the front axle at times vs other gears having multiple teeth of engagement. I mean I've been trying to find posts about broken ring and pinions on here and other forums but its hard finding a real post vs finding people arguing.

I also understand that one gearset isnt weaker then another but from my understanding is that a smaller pinion with less teeth won't distribute stress across the teeth as evenly? I've also found knowledgable people on here shooting that myth down, ugh this decision is a doozy!

thanks for everyones ideas so far

Go deep. I went 4.56 and wish I went 4.88 with 33's.

When I had Nitro 4.88's installed into my 8.25, they had to grind down quite a bit on one tooth as well as a small amount on the end of the cross pin to make it installable/removable.

You can barely see in this pic but it gives you an idea:



Unfortunately I didn't take any other pictures. I haven't had any issues with it yet, but that's not saying much when it goes to the mall more than the trail right now.

I'm running 35's and the gears are reasonably loud, which I don't really care about. I can't comment on your Dana 30 questions because I swapped in a 44 up front.

Scott

Seiler said:

When I had Nitro 4.88's installed into my 8.25, they had to grind down quite a bit on one tooth as well as a small amount on the end of the cross pin to make it installable/removable.

You can barely see in this pic but it gives you an idea:

Unfortunately I didn't take any other pictures. I haven't had any issues with it yet, but that's not saying much when it goes to the mall more than the trail right now.

I'm running 35's and the gears are reasonably loud, which I don't really care about. I can't comment on your Dana 30 questions because I swapped in a 44 up front.

Scott

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Even with a decent pattern the gears are noisy? I've heard gear noise before but one was more of a whine while the other was kinda like a low grumble sorta. Hopefully my setup isnt to noisy I'm placing the order for the 4.88s :doh: kinda nervous about breaking the gears but I'm fairly easy on it. Wish me luck

Grinding the teeth in an 8.25 is normal, had to do it with my 4.56s. However, do not grind down a flat into the crosspin. My mechanic did that with a no-slip locker in the back and it caused a lot of problems for the locker because it relies on the pin to work correctly.

4.88s and 33s will be fine on the highway. I ran 4.56s and 32s for years and drove on the highway a ton.

I've heard stories of people having no issues wheeling on 4.88s and 35s so you should be just fine with 33's. Then again, I broke my 4.56 ring gear in the rear, but with 35s. So who knows. Just put it in there, wheel it, and have fun. You'll love the new gearing on and offroad.

You can grind down a tooth or two on both diffs with no issues as long as you clean all the grinding dust out of the diff. The crosspin will have to be removed to install a lunchbox locker.

I'm sooo pumped to feel the difference, I have been driving around with stock gears and 33s for over a year and a half and before that i was on 31s and stock gears. 50k miles of driving an undergeared jeep, its gona be very weird feeling the power again! Hope everything goes well I ended up getting everything from the package on http://www.rwkhaussupply.com/magento...-and-rear.html figured I'd support the smaller business and another member. Ended up being just under 700 but I assumed a good quality gearset with good bearings would be around that. 4.88s here i come!!!! thanks for the info guys

Did you check around,that seems fairly pricey?

XGarfX said:

Even with a decent pattern the gears are noisy? I've heard gear noise before but one was more of a whine while the other was kinda like a low grumble sorta. Hopefully my setup isnt to noisy I'm placing the order for the 4.88s :doh: kinda nervous about breaking the gears but I'm fairly easy on it. Wish me luck

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As far as a "decent pattern" and install quality, I can't comment too much on that. I had a friend of a friend type deal install my gears. From what I understand, 8.25's are picky and really take an experienced installer to complete quietly. Whether or not that's true, who knows. But the gears do have an audible tone at certain speeds. Anything over 60 I don't really notice because my 35" Baja Claws take over at that point. But, like I said - I don't really mind it much. I'm driving a lifted XJ with hard joints in my suspension, poly motor mounts and aggressive tire tread. If I was worried about gear noise, I'd really wonder about myself. :dunce:

Scott

Seiler said:

As far as a "decent pattern" and install quality, I can't comment too much on that. I had a friend of a friend type deal install my gears. From what I understand, 8.25's are picky and really take an experienced installer to complete quietly. Whether or not that's true, who knows. But the gears do have an audible tone at certain speeds. Anything over 60 I don't really notice because my 35" Baja Claws take over at that point. But, like I said - I don't really mind it much. I'm driving a lifted XJ with hard joints in my suspension, poly motor mounts and aggressive tire tread. If I was worried about gear noise, I'd really wonder about myself. :dunce:

Scott

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My first try at gear install resulted in perfect 8.25, absolutley zero noise but a noisy 30! pattern looks good, everything in spec but they are loud:dunno:

RCP Phx said:

Did you check around,that seems fairly pricey?

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I did, finding 4.88s for an 8.25 are few and far between. I think its only nitro and yukon at this point and both were around 250ish just for the gears. Plus another 140 for the overhaul for the rear, 150 for the front bearings, little less then 100 for the carrier, 4.88 dana 30 gears 200 bucks... i just got the package from http://www.rwkhaussupply.com/magent...install-kits-package-deal-front-and-rear.html

I also got prices from jeepin outfitters on their 4.88 kit and it came to about 5 dollars in difference. I think its pricy for the rear 4.88s for the 8.25, everywhere i looked they were always more money then other axles for an xj. It is expensive but I believe the quality of the gears and installs ect. is pretty good, nitro & yukon + timken overhauls.

I also asked rough country if they could get me a 4.88 gear set and got no response so I went with another company. The rc gear packages are motives which i was also willing to give a try but without knowing if they could get the ratio i was looking for i couldnt order.

gradon said:

Sometimes you can position the ring gear so the pin fits in between two teeth.

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You should always do that.

gradon said:

You should never have to grind 2 teeth.

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You'll remove less material from each tooth when you align the pin between 2 teeth,works out even better.