gear help

[ajm108]

Hello All,
Great site I'm new hear I have a 99 Yukon and my rear went it had 3.73 in it and the only one I can find is one that has 3.42 in it can I use this rear in my Yukon as I need to get it back on the road ASAP I also run 35's on it
Thanks for any help .

 

[Gzes]

No don't put 3.42 in it or you will blow the trans super fast costing even more. You should be having about 4.11 really

 

[ajm108]

The ring gear has a couple of teeth missing can I replace the broken 3.73 ring and pinion gears with 4.11 and use the rest of the diff or do the spider gears have to be replaced?

 

[SunlitComet]

you just replace the ring and pinion unless there is other damage but get a master rebuild kit which has new seals, bearings and whatnot. Oh and if it a 4wd you will have to do the front axle too otherwise you will probably shatter your t-case to pieces when you tcase goes into 4wd mode.

 

[bowtiefreak]

Can't stress enough about doing both front and rear if 4wd and changing ratios...with 35s you really should be running a 4.56 gear ratio. Do not drop to a 3.42 ratio regardless.

 

[AtomicHoe094]

Cheap out now and you'll be wishing you hadn't wasted the time and money and just did it right the first place..

 

[_Dylan_]

Put a new set of 3.73s in it. Don't put 4.10s in it unless you want to destroy the transfercase. Is the diff blown up too or just the ring and pinion gears?

You should do both the front and rear with 4.56 though.

 

[ajm108]

It's just the ring and pinion

 

[bowtiefreak]

Put a new set of 3.73s in it. Don't put 4.10s in it unless you want to destroy the transfercase. Is the diff blown up too or just the ring and pinion gears?

You should do both the front and rear with 4.56 though.

I'm not understanding the 4.10 gears destroying the t-case. I know I'm reading this wrong as you agree on the 4.56 gears

The lowest cost option is to rebuild the busted rear or find a quality junker....but once you go through a junker and make sure it's ok or bring it back to OK shape one way or another you are putting in time and money

 

[_Dylan_]

I'm not understanding the 4.10 gears destroying the t-case. I know I'm reading this wrong as you agree on the 4.56 gears

The lowest cost option is to rebuild the busted rear or find a quality junker....but once you go through a junker and make sure it's ok or bring it back to OK shape one way or another you are putting in time and money

If you put 4.10s in it say goodbye to the 4wd. Sure, it will be fine in 2wd, but I'm guessing that the OP probably uses the 4wd.

4.10/3.73=1.1 or 10% difference the the front and rear speed. The front is going to spin 10% faster and tear the transfer case to pieces on hard pavement. I wouldn't even run that combo in the mud. Most people say 2% for offroad 4wd and 0% if you need the 4wd on the road (in the winter for example).


That's why I say 3.73s. Unless OP wants to pony up and buy gears for the front axle too, then 4.56.