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

RCP Phx said:
You should always do that.

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


so whats the prefered method? grind one tooth or remove a little bit off of two teeth?
thats if grinding the teeth is the last resort..
 
Noise gears come from either A) bad set-up or B) shit-ily cut gears. If you find high spots in the gear teeth while setting them up, you can grind it alittle and it will quit the gears down. Darn blue bird bus manufacture are very picky of the gears that come from my work.

4.88's are weaker than 3.07's because the pinions are tiny and alittle axle housing deflection will kill the gears, so reinforce it and should be good.

Why can you build the diff/locker before installing the ring gear?
 
lowicz96 said:
Noise gears come from either A) bad set-up or B) shit-ily cut gears. If you find high spots in the gear teeth while setting them up, you can grind it alittle and it will quit the gears down. Darn blue bird bus manufacture are very picky of the gears that come from my work.

4.88's are weaker than 3.07's because the pinions are tiny and alittle axle housing deflection will kill the gears, so reinforce it and should be good.

Why can you build the diff/locker before installing the ring gear?
Click to expand...
There's been alot of debate about which gears are weak. The main issue is the amount of tooth contact between the ring and pinion teeth. The total contact area of the pinion teeth to the ring gear is slightly less with 4:88's. I have yet to see any evidence that this leads to breakage at a higher rate than any other ratio. The pinion gear itself is stronger due to the smaller diameter of the teeth and the ratio puts less stress on the shaft of the pinion. The 4:88 ring gear is thicker than higher ratios which makes it stronger than thinner ring gears. All in all I don't believe there is any proof that 4:88's are more prone to breakage. If there is a higher instance of breakage it is likely due to housing flex caused by the greater torque applied to the housing warping it and putting the ring and pinion out of proper mesh. This issue is easily addressed by a sturdy diff cover or truss.
 
kind of contradictory but anyways, I've seen quite a few smaller pinions detonate under large loads in tests, these are again in mostly off highway commercial applications, like cranes and what not, other things too but cant talk about that. Its not the shaft that breaks but usually the pinion head and more specifically pinion teeth breaking, when the shaft breaks there is usually defects like cracks in it due to heat treating process, metallurgy and rolling of the splines. Again we usually test till failure to find weak point. But overall yes a truss and cover will address the issue in jeep axles since most breakage comes from deflection of the housing while wheeling hard. Dont want to start a flame war, just commenting on what ive seen. :cheers:

I'm more interested in why people grind down gear teeth to fit the center pin when they can just assembly the diff before installing the ring gear.
 
outkast7222 said:
Grinding on two teeth you would be able to remove less from each toot though right? If that's the case you might me removing the same amount of metal but weakening each tooth a smaller percentage?
Click to expand...

Exactly! And its at the root of the gear where the pinion doesn't make contact anyway.
 
jeeperjohn said:
There's been alot of debate about which gears are weak. The main issue is the amount of tooth contact between the ring and pinion teeth. The total contact area of the pinion teeth to the ring gear is slightly less with 4:88's. I have yet to see any evidence that this leads to breakage at a higher rate than any other ratio. The pinion gear itself is stronger due to the smaller diameter of the teeth and the ratio puts less stress on the shaft of the pinion. The 4:88 ring gear is thicker than higher ratios which makes it stronger than thinner ring gears. All in all I don't believe there is any proof that 4:88's are more prone to breakage. If there is a higher instance of breakage it is likely due to housing flex caused by the greater torque applied to the housing warping it and putting the ring and pinion out of proper mesh. This issue is easily addressed by a sturdy diff cover or truss.
Click to expand...

I have been worried about the 4.88 gears being weaker but I usually am not TOO hard on the jeep when wheeling. One thing i will say though is that boy did those dana 30 4.88s look really reallly small when the ups man came yesterday...... I knew everyone said they were tiny and all but damn, from the weight of the box i thought they were bearings or something lol.

And for people searching and finding this thread about gear strength, this thread definately helped me ease some worries about 4.88s -> http://www.jeepsunlimited.com/forums/showthread.php?t=88706
I was debating 4.56 or 4.88, I knew i only wanted to regear once and do it right. If i go bigger or even if I felt 4.56s werent enough I would of been so pissed after spending the amount of cash I have so far.. I went with 4.88s cus of the future, and because from my research that its nice having the extra power plus even better mpgs. I've been undergeared for a few years now I'm sure my engine and trans will enjoy being slightly overgeared!!
 
Well today I got the jeep back from the shop, had 4.88s installed on my xj. My xj has an auto trans and I'm running 33' bfg km2s, first impressions are different then what I thought. I would NOT run anything lower then 4.88s with 33s, I also can see the need for more power. I do have armor, skids, bumpers, ect. and figured I would have a lot of power since everyone says 4.56 is for 33s.

I am glad though that I did decide to go with 4.88s over the 4.56s though because it does still leave me room to go to 35s down the road. I guess I made that intro sound kinda ****y, I love these new gears... but i see the need for more power sometimes. The engine doesn't struggle like it used to and I finally can feel that 4.0 low end torque again. I remembered putting it into drive with stock tires and the xj just lurching forward with torque, once i went to 31s i kinda lost that and after 33s that torque was completely gone. I am so pumped to wheel in 4low and see how it does, its also nice to know that all my bearings and seal are fresh. Only concern I had with going with 4.88s is that tiny dana 30 pinion size, I went to one of the best shops around and they did an amazing job and did extra work at no cost, I did pay premium labor prices though
thumbdown.gif
. The gears were set up just as good as stock if not better, they are damn quiet! I have no worries about them at this point and from what i gathered most of the gear failures are from a poor install. So for anyone whos planning on regearing soon, go as DEEP as you can. Dont bother with 4.10s, if your gona regear do it once and do it right. I drove an xj with 4.56 and 33s and wow that little extra gear from the 4.88 helps out, for the price its gona cost you dont regret it, dont fear the gear. One last thing- yukon gears and koyo bearings are amazing, the shop told me that every pair of yukon gears blows away other companies gears. They setup much easier then any other brand they have installed, and they are the quietest running, the shop is very well versed in doing gear installs and lots of other custom work so I know they know what their talking about.
 
XGarfX said:
Well today I got the jeep back from the shop, had 4.88s installed on my xj. My xj has an auto trans and I'm running 33' bfg km2s, first impressions are different then what I thought. I would NOT run anything lower then 4.88s with 33s, I also can see the need for more power. I do have armor, skids, bumpers, ect. and figured I would have a lot of power since everyone says 4.56 is for 33s.

I am glad though that I did decide to go with 4.88s over the 4.56s though because it does still leave me room to go to 35s down the road. I guess I made that intro sound kinda ****y, I love these new gears... but i see the need for more power sometimes. The engine doesn't struggle like it used to and I finally can feel that 4.0 low end torque again. I remembered putting it into drive with stock tires and the xj just lurching forward with torque, once i went to 31s i kinda lost that and after 33s that torque was completely gone. I am so pumped to wheel in 4low and see how it does, its also nice to know that all my bearings and seal are fresh. Only concern I had with going with 4.88s is that tiny dana 30 pinion size, I went to one of the best shops around and they did an amazing job and did extra work at no cost, I did pay premium labor prices though
thumbdown.gif
. The gears were set up just as good as stock if not better, they are damn quiet! I have no worries about them at this point and from what i gathered most of the gear failures are from a poor install. So for anyone whos planning on regearing soon, go as DEEP as you can. Dont bother with 4.10s, if your gona regear do it once and do it right. I drove an xj with 4.56 and 33s and wow that little extra gear from the 4.88 helps out, for the price its gona cost you dont regret it, dont fear the gear. One last thing- yukon gears and koyo bearings are amazing, the shop told me that every pair of yukon gears blows away other companies gears. They setup much easier then any other brand they have installed, and they are the quietest running, the shop is very well versed in doing gear installs and lots of other custom work so I know they know what their talking about.
Click to expand...

Awesome I am looking forward to getting the 4.88's aswell.
 
The past few days I have fallen in love with my xj again. It used to be a pig on the highway, now I'm barely on the throttle and have no problem on hills. I haven't gotten my speedo gear yet that I ordered but from the driving I've done I can tell that I am getting better gas mileage just can't get an accurate number yet. Def believe in throttle position having more effect on gas mileage than rpms, around town and highway I'm just barely feathering the peddle with plenty of power and higher rpms. I'm loving them so far!

Does anyone use lubelocker gaskets? If so how you guys liking them? I saw them for like 20 or 25 a piece but that seems like a lot for what it is. My master overhaul kit did come with a gasket but the shop used rtv and left the gaskets for me. For anyone that regeared are those gaskets that come in the overhaul kits any good? Should I go for synthetic oil after I do my first fluid change, i kno the shop put in synthetic not sure if i should continue it with new gears and bearings.
 
Oh and regarding grinding the ring gear teeth, the shop said that they tried every way to orient the ring gear on the 8.25 and the best way they could get it involved removing a tiny bit of material off of two teeth. Also DO NOT believe anyone who says that the 8.25 is a noisy axle with deeper gears, the gears were extremely easy to set up in the rear and have an amazing contact pattern and zero noise.
 
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