RFI: Changing Gear Ratios

SethX9 · **Posted:** Fri Jul 14, 2006 12:55 pm

I know it's been mentioned scattered across different threads but I'm wondering if anyone has the experience/knowledge of the details regarding changing the ratio after a lift (swapping out to 4.10 for example) and if so could this be made into a concise post here in this section?

Thanks!

pixeldzn · **Posted:** Fri Jul 14, 2006 1:21 pm

Don't you actually have to buy the whole diff from a 4cyl KJ to get the gears? I thought I read somewhere on this forum before that they are not available sans carrier anywhere. (For the front Dana 30a that is, gears for the 8.25 rear are readily available)

tjkj2002 · **Posted:** Fri Jul 14, 2006 1:32 pm

I switched to 4.10's and I just got the whole front diff so I would have new bearings,seals,and extra case just in case.The rears as was said can be bought anywhere.After breakin I noticed my KJ had alot more pep(almost back to factory,but 4.30's would have been deadon for my 32's) and gained alot of gas mileage back also so when I go to 31's soon I should be almost back to factory mileage and performance!

Sport · **Posted:** Fri Jul 14, 2006 4:59 pm

Where do you go to buy a whole front differential?

jeepkj02 · **Posted:** Fri Jul 14, 2006 5:17 pm

Sport wrote:

Where do you go to buy a whole front differential?

If you just want the 4.10 gears, you can get it from your local dealer, or online.
Link:
4.10 gears

Another option is if you find a wrecked 4cylinder Liberty, they have the 4.10 gears. Just pull out the axle housing and it should be a bolt on. Just make sure your get 4.10 gears for your rear diff (chrysler 8.25").

Sport · **Posted:** Sat Jul 15, 2006 12:50 pm

what if I did the rear now and the front later?

tjkj2002 · **Posted:** Sat Jul 15, 2006 1:54 pm

Quote:

Sport

what if I did the rear now and the front later?

Not a good idea,remember our front axles are always "locked in"(not like the old PU's with manual locking hubs) so even in 2wd going down the road the front axle still turns the front driveshaft.Even though no power is being sent it may damage the transfer case from the two shafts(even though not locked together)spinning at 2 different speeds.Might get away with removeing the front driveshaft though.

Sport · **Posted:** Sun Jul 16, 2006 11:26 am

tjkj2002 wrote:

Quote:

Sport

what if I did the rear now and the front later?

Not a good idea,remember our front axles are always "locked in"(not like the old PU's with manual locking hubs) so even in 2wd going down the road the front axle still turns the front driveshaft.Even though no power is being sent it may damage the transfer case from the two shafts(even though not locked together)spinning at 2 different speeds.Might get away with removeing the front driveshaft though.

Thanks for the info, I learn so much on this forum about my jeep. I did not know there was any movement up front while in 2wd. ....time to save up!!

Gris · **Posted:** Thu Aug 03, 2006 5:45 pm

If the fronts are such a pain to replace and we are limited to a 4cyl libby set, has anyone considered swapping out for a regular Dana 30 from a cherokee or wrangler? Is that possible?

W3CSX · **Posted:** Thu Aug 03, 2006 6:44 pm

Gris wrote:

If the fronts are such a pain to replace and we are limited to a 4cyl libby set, has anyone considered swapping out for a regular Dana 30 from a cherokee or wrangler? Is that possible?

I don't think so. We are talking about an IFS third member here. Not a solid axle.

Jason

QuestMan · **Posted:** Sat Aug 19, 2006 9:26 am

Quote:

Sport wrote:
Where do you go to buy a whole front differential?

If you just want the 4.10 gears, you can get it from your local dealer, or online.
Link:
4.10 gears

Another option is if you find a wrecked 4cylinder Liberty, they have the 4.10 gears. Just pull out the axle housing and it should be a bolt on. Just make sure your get 4.10 gears for your rear diff (chrysler 8.25").

OK. So, where do you go to just buy the WHOLE differential?

(Assuming you can't find a wrecked CRD)

FreedomKJ · **Posted:** Mon Aug 21, 2006 11:54 pm

QuestMan wrote:

Quote:

Sport wrote:
Where do you go to buy a whole front differential?

If you just want the 4.10 gears, you can get it from your local dealer, or online.
Link:
4.10 gears

Another option is if you find a wrecked 4cylinder Liberty, they have the 4.10 gears. Just pull out the axle housing and it should be a bolt on. Just make sure your get 4.10 gears for your rear diff (chrysler 8.25").

OK. So, where do you go to just buy the WHOLE differential?

(Assuming you can't find a wrecked CRD)

CRDs don't have 4.10s, the 2.4L gas 4cyl KJs have 4.10s.

If you can't find a wrecked one I suppose you could order a new one from the dealer, but that would cost a fortune.

bugnout · **Posted:** Tue Aug 22, 2006 2:29 pm

CRD's have 3.50's. Haven't heard of any CRD owners changing these out, but the 3.73's in the gassers seems like a natural for moderately larger tires.

Jeepjeepster · **Posted:** Tue Aug 22, 2006 5:50 pm

Hmm, so the people with crds can find 3:73 gears really easy for bigger tires. Another good reason to have a crd!

bugnout · **Posted:** Tue Aug 22, 2006 7:14 pm

That and the puzzled looks we get when we pull up to the diesel pump make it all worth while.

Sport · **Posted:** Wed Sep 13, 2006 10:39 am

So has anybody regeared tp 4.10? If so a write-up would be great especially for guys like me who have the interested but lack the know how.

2006KJSPORT4x4 · **Posted:** Wed Sep 13, 2006 3:36 pm

tjkj2002 I believe has done the upgrade...I'd PM him to check for sure and if so ask him if he has done a write up or will...PLUS...I'm interested in this very same upgrade...

KY Liberty · **Joined:** Sat Jul 09, 2005 1:46 pm **Posts:** 1195

We pulled the front end out of a low milage wrecked 4 cylinder for mine. I've got US Gear 4.10's in the rear. This really is not a job for an amateur. You want someone who knows what they are doing to set up gears.

Jeger · **Posted:** Mon Oct 09, 2006 11:49 am

bugnout wrote:

CRD's have 3.50's. Haven't heard of any CRD owners changing these out, but the 3.73's in the gassers seems like a natural for moderately larger tires.

I dont know about the 2005 CRD's but the 2006 CRD's have 3.73 gears stock.

spoonplugger1 · **Posted:** Sun Oct 22, 2006 9:29 am

All Libertys except the 4 cylinder gasser have 3.73 gears. If you want to do the gear change yourself there are lots of resources that explain the procedure.
Many times there are special tools necessary (special wrenches, dial indicators and magnetic/mechanical bases, etc), shims, new bearings and seals, gear patterning ink to ensure you have the correct gear contact etc. All in all that's why shops can survive just doing running gear repairs/mods without ever touching an engine or tranny.

RFI: Changing Gear Ratios

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