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post #1 of (permalink) Old 10-04-1999, 01:41 PM Thread Starter
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Tranny or Gears?

I need to make a change on my Jeep. It currently has a 3.52:1 1st gear, 2.73 r&p, and Dana 300 with 2.62:1 Low. This means my crawl ratio is a miserable 25.2, and with 32" tires I can barely start off from a stop sign. I am trying to decide between a t-18 tranny swap or gears with lockers. I plan to have both at sometime, but can only afford to do one or the other right now. I can buy a rebuilt t-18 with adapter from R&P for $850(with my t-176 core) or do the same with Part's Mike for $1075(core?). I can get gears(4.11) and lockers installed for around $1500. The tranny swap yields a crawl ratio of 45.2, the gear swap a crawl ratio of 37.9. Which one should I do first? It will cost about the same to do either once I factor in the driveshaft mods for the tranny swap.

Any advice or experience is greatly appreciated.

Thanks,

<font color=blue>1985 CJ7 4.2L, T-176, Dana 300, 2.73 gears(too high), 2.5" lift, 31" tires, Durabak</font color=blue>
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post #2 of (permalink) Old 10-04-1999, 02:11 PM
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Re: Tranny or Gears?

Tom, I just went throught this dilemma recently, and here's my thoughts. You obviously have a T176 trans, good trans, best one used
by Jeep in the CJs in the 80s. Keep the trans, go with something like 4.11 gears with lockers and do a Tera Lo 4:1 t-case conversion.
If you drive the vehicle on the street very much, you may even want to consider 3.73s. Figure it out, that will still give you a very good
crawl ratio and still have a vehicle that is street friendly. BTW, what I did was keep my 3.31 gears, put in a Tera Lo and lockers. I
now have a decent 53:1 crawl ratio (with a T-5).

Brad (from the 4 Wheeling center of the universe, 4 corners USA)
post #3 of (permalink) Old 10-04-1999, 02:19 PM
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Re: Tranny or Gears?

Tom,

I'd keep that T-176 tranny for now. It's a good one. Altho, the T-18 is nice to have I'd slap those new R/Ps in that CJ and still be quite happy with the drivetrain. It may also depend on what you think that T-18 will buy you.

BTW, how do you figure crawl ratio? I'd like to know how to calculate mine...


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post #4 of (permalink) Old 10-04-1999, 02:25 PM Thread Starter
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Re: Tranny or Gears?

Crawl Ratio= R&P*T-Case Low*1st Gear

For me that would be 2.73*2.62(Dana 300 Low)*3.52(T-176 1st gear)=25.2

<font color=blue>1985 CJ7 4.2L, T-176, Dana 300, 2.73 gears(too high), 2.5" lift, 31" tires, Durabak</font color=blue>
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post #5 of (permalink) Old 10-04-1999, 02:29 PM
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Re: Tranny or Gears?

Thanks for the info. What is a good crawl ratio range?

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post #6 of (permalink) Old 10-04-1999, 02:40 PM
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Re: Tranny or Gears?

<font color=purple> I'm going to try to jump in here before it gets started. A "good" crawl ratio is one that's appropriate for your needs. Some folks think it needs to be 100:1 or lower, and maybe in their case that's so. Also makes a big difference if you have a stick vs. an automatic. Generally speaking, you can get away with a much taller (lower numerically) crawl ratio with an automatic. Lowest crawl ratio I've ever had was 30.93:1 (3.73x2.71x3.06) & that suited me just fine - FOR MY PURPOSES. Generally speaking, as trails get tougher, but traction isn't an issue, lower is better. If you're in mud & need to spin 'em, a 150:1 ratio won't be any help. Just my $.02. </font color=purple>

TEX

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post #7 of (permalink) Old 10-04-1999, 02:48 PM
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Re: Tranny or Gears?

I'm with the rest of the crowd, I'd recommend going with the gears and lockers first. Here is my reasoning on the subject. Your final drive ratio is too high(as is your crawl ratio) and you have open diffs. Swapping the transmission now would give you a good low gear and make it easier to start out from a stop as well as improving your off-road capability. However, performance in other gears would still be poor, especially in high gear on the highway. You are also likely to start going through U-joints at a fairly high rate when off-roading in low range. On the other hand swapping in lockers and gears now lowers your final drive in all ranges and gears giving better performance in all areas, as well as added traction of a locking differential. On and off the road this scenario provides much more capability. The lower gears will also help the T-176 to live longer while you save up for your new tranny.

post #8 of (permalink) Old 10-04-1999, 02:50 PM
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Re: Tranny or Gears?

Put in a new R&P. It will help the crawl ratio and make the Jeep more
streetable. The best of both worlds. While you are in there add a pair
of Lock Rights and you will be unstopable.

Ron R. - 90 YJ w/OME
post #9 of (permalink) Old 10-04-1999, 03:04 PM
 
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Re: Tranny or Gears?

I would say go for the R&P, down to about 4.10. I've heard that a lower rear ratio is easier on the transmission, definitely for an auto, and perhaps for a manual as well. My stock Cherokee actually has a lower ratio than you do now (29.30) but, as TEX said, it is what is good for you. If I had those size tires on my Jeep, I would lower the axle ratio. Good Luck!!

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post #10 of (permalink) Old 10-04-1999, 11:51 PM Thread Starter
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Re: Tranny or Gears?

Thanks for all the replies. I think I will go with the gears and lockers.

<font color=blue>1985 CJ7 4.2L, T-176, Dana 300, 2.73 gears(too high), 2.5" lift, 31" tires, Durabak</font color=blue>
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