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post #1 of (permalink) Old 04-08-2002, 10:04 PM Thread Starter
 
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Is my gear ratio too high?

I have a 79 CJ 5, with the stock dana 30 and model 20, 258 and T18 combo. I am running 33" MTRs. When I put the 33s on the jeep lost its get up. I used to always start out in 2nd gear no problem, because of the granny 1st, now when I start out I have to give it a little more gas and feather the clutch out or it will lug slightly before starting. I am sure my gears are to high for those tires. I have the 3.54s.
I like to use my jeep in the mud, and need to spin those 33s to clean them. This is not a problem using 1st, but to really sling the mud I like 2nd gear which is not as easy with the 33s.

In the future I plan on putting a 360 into the jeep. This should give me quit a bit more get up then the tired old 258 I have now.

Will the 360 help my problem, will it give me the power I need to turn those tires or are new gears inevidable?

If I do what gear ratio would you recomend? I was thinking 4.10s? I dont do a ton of rock crawling and I have that granny low 1st gear for the rocks. I would like to not completly ruin my gas milage.

Also how much do most shops charge to install new front and rear ring and pinion gears?

Thanks
Tony
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post #2 of (permalink) Old 04-08-2002, 10:23 PM
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Re: Is my gear ratio too low?

IMO, your gears aren't low enough. 33" tires and 3.54 gears isn't going to make it easy for it to get up and go. I'd say 4.10's would be perfect with that granny low. Not real sure on prices. Shouldn't be anymore than $300 a diff. Probably more around $200.
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post #3 of (permalink) Old 04-09-2002, 12:20 AM Thread Starter
 
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Re: Is my gear ratio too low?

yeah, when I checked it I noticed I put high instead of low in the subject line, I edited it.

Man, $200-$300 for each end! That means about $800 for the entire jeep, that sucks. It will be a while before I can afford that.

Do you think that a 360 would make my present gear ratio bearable?

For $800 couldn't I find a set of 44s with a higher gear ratio and swap them in, probably even save some money. This would keep me from having to buy 1 pieces for the 20 also.

What do you think?
Tony
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post #4 of (permalink) Old 04-09-2002, 01:36 AM Thread Starter
 
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Re: Is my gear ratio too low?

I replied this on my post on trac loc clutch replacment, and thought that this is relevant here also, so give me your thoughts.

So I get to thinking about this, bummed that the search is down, what if I....

Scrap my current axles, put no money into them.

1. Find a Dana 44 with higher gears then what I have (hopefully 4.10s) that is the same width as my Model 20 HD and put it in the front.

2. Use the Model 20 HD out of my 80 cherokee (with the 1 pice shafts and stronger housing) in the rear. Then match the gear ratio to the 44, and put in a lock right.

How does this sound?

My questions are:
-What vehicle would be a good donor for my front axle, dana 44, with a low gear ratio
-what would I do about steering, I want to keep this as simple as possible. Is their a 44 with a steering system that is compatible with my CJ 5? Or can the parts be converted?
-What about front brakes? Is their a 44 that can be easily made to work in this area?
-What about the bolt patterns, I would rather not buy new wheels I am very limited on funds, could I either switch the Dana 30 rotors to the 44 or something to that extent? or maybe get a machine shop to fill and redrill the 44 rotors. The model 20 on my CJ and the Model 20 HD on the cherokee are mostly inerchangable? Could I put the rotors for the CJ 20 on the cherokee 20, to make it a 5 lug instead of 6?

What do you think? Advice is needed. What rigs 44 would work best for this swap. I dont plan on rushing into this, just maybe getting the parts together over the next few months then putting it all together. Please keep in mind that I am a college student on a limited budget, and I am by no means a expert mechanic, I like to think that I can usually figure most things out w/ a good repair manual, but their are not to many books on this kind of stuff. You guys seem to be my best resource. So I guess what I am trying to say is if this is going to cost me thousands or mean my Jeep will be on blocks for a year, then I wont do it.


What do you think

Thanks
Tony
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post #5 of (permalink) Old 04-09-2002, 01:45 AM
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Re: Is my gear ratio too low?

You're once again getting a little confused on the wording. You say you want higher gears than your current 3.54's. Well, higher gears would be something like 3.07's. Lower would be something like the 4.10's you mentioned.

As for swapping in axles, that would work fine, except I doubt you'll find the right axles with the right gears. And it could be especially hard finding one the right width to fit the '5. I got a set of D44's from a Grand Wagoneer and they came with an incredibly low(picking up any sarcasm???) 2.92 ratio. Probably the lowest you'll find is 3.73. And I even doubt that.
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post #6 of (permalink) Old 04-09-2002, 02:28 AM Thread Starter
 
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Re: Is my gear ratio too low?

yeah, I was off on the terminology, I guess that it doesn't always go on the screen the way it was in my head.

That sucks about the gear ratio, I thought that I heard that they could be had from old Jtruck with 4.10s or maybe it was scouts? Dont remember.

I dont care about the width of the CJ, my 33s are slightly rubbing my frame in the rear, I dont want to do any axle cutting, I was thinking of leaving them the full width of the cherokee, which the model 20 HD is at.

That would mean I would have to re gear both axles, which puts me in the same place as before. I will continue to think it over, I wont have the money for a while anyways.

Thansk for the reply
Tony
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post #7 of (permalink) Old 04-09-2002, 05:53 AM
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Re: Is my gear ratio too high?

[img]images/icons/crazy.gif[/img] If you are wondering how to get your Jeep geared such that the engine can pull it the same as it did from the factoreeeee, just use this formula: Turns Per Mile X Ratio (old) = Turns Per Mile X Ratio (new) If you multiply the turns per mile of the tires times the rear end ratio, it will give you the RPM at 60 in direct. If you want to maintain performance and mileage same as before, the new setup has to equal the same RPM at 60. The engine doesn't know what the rear end ratio is or what size tires you have, it only knows that it needs to roll over so many RPM to maintain 60 MPH. You can find the Turns Per Mile at any tire dealer. The catalogs all list the TPM for each tire.[img]images/icons/crazy.gif[/img]
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