lower gear for the rearend

jlgail4309 · **Posted:** Sun Oct 20, 2013 1:14 pm

Do i have to replace the whole rear end to drop to a 410 I think its a 373 but not sure. I would like s locker as well. Any suggestions. For pulling the trailer thanks.

geordi · **Posted:** Sun Oct 20, 2013 3:07 pm

How big is your trailer? I pulled 7,000 lbs with the CRD without issue. You shouldn't need a shorter rear end.

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arengant · **Posted:** Sun Oct 20, 2013 3:57 pm

Need a special tool if you want to do it yourself.

Motive Gears is the best "VALUE" for the rear gears.

For a locker, Look at a Detroit True Trac, good on road and off road.

You'd have to do the front also, which is my labor intensive.

jlgail4309 · **Posted:** Sun Oct 20, 2013 7:29 pm

So you have to do both at the same time. Knew couldn't be that easy. If you do the front should put a steel Dana 30 in it place. Now your talking some money.

arengant · **Posted:** Sun Oct 20, 2013 7:33 pm

jlgail4309 wrote:

So you have to do both at the same time. Knew couldn't be that easy. If you do the front should put a steel Dana 30 in it place. Now your talking some money.

Technically you could leave it as 2wd until you could afford the front. I don't think the steel diff is needed for basic 4x4 use. It depends on your driving style of course.

ATXKJ · **Posted:** Tue Oct 22, 2013 5:04 pm

caveat on the front - if you keep the aluminum - you're limited to the gearsets that Jeep used on the Liberty
i.e. 3:54, 3:73, 4:10 nothing else will work (pinion's longer) - and normally you have to find a Junkyard 4 cyl to get the 4:10.

if you go to the Steel - it'll fit anything that goes in a D30 - which is a lot more

jlgail4309 · **Posted:** Tue Oct 22, 2013 11:19 pm

I really wouldn't want any lower than a 4:10. Would like the lockers for sure in the rear. But need one project at a time. Gear swap sounded better before I knew had to do both. So will wait on that one for a little while. Trans tune to hold 4th gear longer is next. I believe it will help on the highway in the hills.

arengant · **Posted:** Wed Oct 23, 2013 12:34 am

jlgail4309 wrote:

I really wouldn't want any lower than a 4:10. Would like the lockers for sure in the rear. But need one project at a time. Gear swap sounded better before I knew had to do both. So will wait on that one for a little while. Trans tune to hold 4th gear longer is next. I believe it will help on the highway in the hills.

I thought you had the tow tune already?

tjkj2002 · **Posted:** Wed Oct 23, 2013 1:42 am

jlgail4309 wrote:

But need one project at a time. Gear swap sounded better before I knew had to do both. So will wait on that one for a little while.

You have 4wd and wanted to change the gear ratio in the rear diff. It didn't dawn on yourself that the other diff would need to be geared to match?

jlgail4309 · **Posted:** Wed Oct 23, 2013 8:05 pm

No been looking for a way too help pulling trailer. No call me dumb never thought about the front end having to be changed to lower the front end.

flash7210 · **Posted:** Wed Oct 23, 2013 8:57 pm

How heavy is your trailer? You should have no problems towing.

jlgail4309 · **Posted:** Wed Oct 23, 2013 10:15 pm

its a 20 foot box weighs about 3700 loaded. But it eats the fuel pulling. I'm wanting to lower the gear or hold the 4th longer for saving fuel. We tow a lot heading to flordia for Christmas 2nd year its 18 hours 1 way. I think it pulls ok but would help with a 410 gear. Holding 4th should help some.

Wanting to take some mountain trips next year. So a gear or a bigger turbo needs to be in the works.

geordi · **Posted:** Wed Oct 23, 2013 11:09 pm

A 20 foot enclosed trailer? V-nose or flat front? If it is a flat front and taller than the towing vehicle, the weight isn't your problem. It is the wind resistance creating "wind weight" on the trailer.

I have a 7.5x20 enclosed box too, and that trailer is 7000 lbs loaded. It is 2000 lbs empty. Even dead empty, the CRD could not pull it faster than 60mph, and that was in 3rd gear locked out of OD. My advice? Forget dragging a trailer that large unless you can get a narrower profile or a bigger tow motor. I seriously doubt that even 410 gears will help.

I also currently have a 5x10 V-nose that I can pull behind my Jetta wagon... But the VW isn't happy about it. I lose 13mpg off my mileage - from 36 down to 23, and my scan gauge says that the fueling tops out if I try to push it much above 70. The problem with that trailer is also wind - it stands more than a foot taller than my Jetta, and the square back creates the same draft suction that semi trailer suffer with.

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jlgail4309 · **Posted:** Wed Oct 23, 2013 11:21 pm

It's the wind more than the weight. Like pulling a sail . MPG not bad in forth but it needs help in the hills. Feels like I driving it all the time up a gear drop to 3rd back to 4th. Hoping a tow tune might help. I've talked to Keith I'm just not sure how much it will help.

geordi · **Posted:** Thu Oct 24, 2013 12:10 am

I posted the last from my ipad, and I couldn't see all of the picture. I see the trailer now - That thing is HUGE behind the CRD. Taller and wider, I don't think your 4th gear idea is going to help you as much as you think it will.

You might look into a wind deflector for the top of the Jeep, but I don't know how effective those really are. I'm thinking about building one for my Jetta... Same question - I don't know if it will really help much. Sometimes, you really do just have to accept the lower fuel economy. The engine is doing a LOT of work, and it is quite impressive that the CRD can do this at all (same for my TDI) so it isn't really reasonable to expect similar-to-unloaded mileage from it.

RVs and box trucks struggle to find 10mpg when loaded... And 10mpg when unloaded too. Bigger things pushing more wind out of the way.

Billwill · **Posted:** Thu Oct 24, 2013 6:06 am

tjkj2002 wrote:

jlgail4309 wrote:

But need one project at a time. Gear swap sounded better before I knew had to do both. So will wait on that one for a little while.

You have 4wd and wanted to change the gear ratio in the rear diff. It didn't dawn on yourself that the other diff would need to be geared to match?

flash7210 · **Posted:** Thu Oct 24, 2013 8:19 am

jlgail4309 wrote:

its a 20 foot box weighs about 3700 loaded. But it eats the fuel pulling. I'm wanting to lower the gear or hold the 4th longer for saving fuel. We tow a lot heading to flordia for Christmas 2nd year its 18 hours 1 way. I think it pulls ok but would help with a 410 gear. Holding 4th should help some.

Wanting to take some mountain trips next year. So a gear or a bigger turbo needs to be in the works.

Sometimes you just have to accept the limitations of your tow vehicle and just drive it in a
sensible manner.

At work, we have a F450 Powerstroke that we use to tow a 24' 16,000 lb trailer. That F450 has
something like 4.11 gears in it. It gets 8 mpg, towing or not towing.
You would think that truck would have no problem pulling that trailer. In fact, the guys had both
the truck and trailer weighed and came in well under the GVW towing limits specified by Ford.
Yet they somehow managed to break the transfer case while towing in 2wd.
Now, you could say that it was just a fluke and the transfer case had a weak part in it.
Or you could say that the drivers shouldn't be lead footin' it and pulling that monstrosity at 80mph.

So even a F450 has some limits as to how much and how fast you can tow even with those drag
racing gears it has.

I agree with the others that its not your trailer weight but wind resistance. Deeper gears will not
help you save fuel and they will not allow you to go at any faster speed.
I dont think a bigger turbo will help much either and besides, your turbo upgrade options are
extemely limited.
Just try to drive it sensibly and within the limitations of a small 4 cylinder diesel.

If you really think your CRD is not up to task, remeber that old chinese proverb:
"There is no substitute for cubic inches."

jrsavoie · **Posted:** Thu Oct 24, 2013 9:30 am

If you are on a budget get an old GM 6.5 diesel for about $3500. Dump $4000 more in it and you will have a DEPENDABLE pulling machine. Good for several hundred thousand miles

jlgail4309 · **Posted:** Thu Oct 24, 2013 9:57 pm

Billwill wrote:

tjkj2002 wrote:

jlgail4309 wrote:

But need one project at a time. Gear swap sounded better before I knew had to do both. So will wait on that one for a little while.

You have 4wd and wanted to change the gear ratio in the rear diff. It didn't dawn on yourself that the other diff would need to be geared to match?

Well that's why I'm on this site. So I can get wisdom from smart people like your self. Thanks for all the help.

WolverineFW · **Posted:** Thu Oct 24, 2013 10:10 pm

flash7210 wrote:

If you really think your CRD is not up to task, remeber that old chinese proverb:
"There is no substitute for cubic inches."

Or "There is no replacement for displacement."

lower gear for the rearend

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