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Unread 04-30-2013, 08:05 AM   #16
frhrwa
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why aren't you considering the T15? "supposed" to be a better trans for the 6 cylinder ?

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Unread 04-30-2013, 08:13 AM   #17
LumpyGrits
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Quote:
Originally Posted by Neuner-9R View Post
I have 33's, 3.31, T-5 and 258 and cruise down the fairly level highway in 5th at 65mph and at 1500rpm. After getting timing, plug gap and carb better tuned, it does fine against some incline and 20mph wind with room left to pass while still in 5th. Feels more like a diesel now with more lug. I go from 1st to 4th pretty quick.

Read all about the T-5 and its weaknesses. It's been doing alright but over the past year it's slowly been doing some strange things and I wonder how much longer before a rebuild.
With 3:31's you are puting all the driveline torque on the tranny. Your kill'n your Jeep with those gears.
My '85 CJ-7 runs 4:56's w'33" BFG's, the T-5 has only had 1 major rebuild in the last 28 yrs and 118K miles with much hard rock jeep'n. I also run a 4:1 t'case.
BTW, I'm run'n 2600rpms at 65mph. My 6 loves it..........
Hope your NOT using ATF in that T-5!
LG
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Unread 04-30-2013, 08:17 AM   #18
LumpyGrits
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Originally Posted by frhrwa View Post
why aren't you considering the T15? "supposed" to be a better trans for the 6 cylinder ?
The T-15 is only a 3 speed and is heavy at 100+ lbs.
Much better choice is the T-18 4 speed.
LG
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Unread 04-30-2013, 08:18 AM   #19
frhrwa
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consider this, AUTOMATIC.. switch to a TH700RE early model (no computer hookup).. it has a lower first gear, and an overdrive final gear.. and no more clutches, throw out bearings, cluster gears, or any of that stuff.. fits right on your 258..
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Unread 04-30-2013, 08:20 AM   #20
frhrwa
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Originally Posted by LumpyGrits View Post
The T-15 is only a 3 speed and is heavy at 100+ lbs.
Much better choice is the T-18 4 speed.
LG
not sure which has the compound low, but the old 4 speed I always ran was the one with the granny low, I drove it like a 3 speed and only used that 1st gear to scale or go over inclines SLOWLY.. best tans I ever had for a shifter and 4wheel apps..
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Unread 04-30-2013, 08:27 AM   #21
Neuner-9R
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Originally Posted by LumpyGrits View Post
Hope your NOT using ATF in that T-5!
LG
Hell no.

My 6's sweet spot is from 1k to 2.1k. Hums along relatively quiet and smooth. Only a DD and I typically only do 60 down a relatively flat highway. Rarely do I hit 65 but know that I can do it if I want to.
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Unread 04-30-2013, 08:29 AM   #22
LumpyGrits
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Quote:
Originally Posted by frhrwa View Post
consider this, AUTOMATIC.. switch to a TH700RE early model (no computer hookup).. it has a lower first gear, and an overdrive final gear.. and no more clutches, throw out bearings, cluster gears, or any of that stuff.. fits right on your 258..
You ever tried backing down a hill with an auto?
Down hill break'n with autos SUCK........
LG
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Unread 04-30-2013, 08:33 AM   #23
LumpyGrits
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Originally Posted by Neuner-9R View Post
Hell no.

My 6's sweet spot is from 1k to 2.1k. Hums along relatively quiet and smooth. Only a DD and I typically only do 60 down a relatively flat highway. Rarely do I hit 65 but know that I can do it if I want to.
Your way below the power band at 2100rpm's. Your 'lugging' the engine.
1K rpms is just above idle.......
Get your freeway r's(65mph)up to 2500rpms, it's much better on your engine and better mpg too.
LG
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Unread 04-30-2013, 08:45 AM   #24
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Or you could always change the rear for the occasion.
http://www.ebay.com/itm/NEW-WINTERS-...38752b&vxp=mtr
.
I use a ratty soft top. When the terrain changes or I hit a congested area, just pull over, throw the top down and spend a few minutes swapping gears. Your times will drop the more you do it. It helps if you mount fog lights and an air fitting from your ARB to run tools under there. Really handy when you have to do it on the side of a dark muddy road,or busy highway. Here at the top of the Appalachians I might do it 5 x/day.
If you do it, have the cover grooved for a rubber "O-Ring". It'll save ya on buying gaskets.
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Unread 04-30-2013, 08:47 AM   #25
Neuner-9R
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Originally Posted by LumpyGrits View Post
Your way below the power band at 2100rpm's.
Get your freeway r's(65mph)up to 2500rpms, it's much better on your engine and better mpg too.
LG
That equals my 4th gear and better mpgs isn't true. Tried and tested.
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Unread 04-30-2013, 09:50 AM   #26
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My 1980 cj made it 200k miles with a SR4 trans with 3.54 gears and alot of 4 wheeling never had a problem and still have as a spare. Now have 4.56 gears and t5 rebuilt 33 inch tires and its great like the 5th gear and very reliable and great off road. I buy any t5 I can get ahold of picked up another for 100 bucks and 150 to rebuild providing doesnt need any gears and have a spare which I will never use but its just me. The t5 with right gearing and tires will hold up fine with our I6 engines my hole drivetrain has no more then 5k miles after complete rebuild and it couldnt be better love churping the tires upshift and down shift. and pulls great with weber carb and gets around 16 mpg city/highway
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Unread 04-30-2013, 10:17 AM   #27
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Originally Posted by woodlandjeep View Post
The t5 with right gearing and tires will hold up fine with our I6 engines my hole drivetrain has no more then 5k miles after complete rebuild and it couldnt be better love churping the tires upshift and down shift. and pulls great with weber carb and gets around 16 mpg city/highway
Sometimes I have to question some things on here.

"It will hold up fine" followed by "my (w)hole drivetrain has no more than 5K miles" shows a lot of speculation on your part that your T5 will, in fact, hold up long term.

My T5 has 80K on it, with no rebuild, but I'm running 3.31's and 31" tires so not putting much stress on it either. They ARE a weaker transmission that the T176 (which is why I have a T176 in my shop for when (not if) my T5 goes). I've seen too many bad T5's in Jeeps to go along with "they aren't bad transmissions". If you have a totally bone stock Jeep they might be fine, but if you do any mods, it becomes a weak point.

To OP, you drive a CJ, so the whole MPG argument is moot. You are driving something with the aerodynamics of a barn door down the highway. If you want MPG, get a car, and use the Jeep for recreation. Throwing money at a CJ to get better MPG is about like installing a pool to save the $300/ year it costs to join the neighborhood pool; you'll come out on the good end......in about 120 years.

Not trying to be harsh, but "I want a Jeep that looks cool (CJ), is good off road, drives like a car, gets good MPG, and has lots of power" is kinda like saying "I want a unicorn for my birthday"
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85 CJ7 258, A/C, T176, MC2100, Team Rush, Warn XD8000i, superwinch hubs, 3in lift 31" BFG AT/KO
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Unread 04-30-2013, 10:31 AM   #28
woodlandjeep
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Well to not make my post to long I did abuse the t5 before the drivetrain rebuild and rebuilt it in the process its stonger then the sr4 that I had and it lasted 200k miles with 1 rebuild at 90k. I agree with you I have alot of more testing to go and it would be my weak point of my drivetrain. I have been considering alternatives but for know I like the setup that I have. Yes its all great till something breaks then you find out what isnt working.
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Unread 04-30-2013, 12:42 PM   #29
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I would recommend reading through Novak's fuel economy guide. There is a lot of good information there.

They also have information on possible transmissions, and a gearing calculator to help you decide what will work best for your needs.

One possibility would be to go with with a smaller axle gear ratio (which would increase your speed at a given RPM and transmission gear), and a non-overdrive transmission with wider gears (lower first gear) if you don't want to lose low range. That is just a thought.

I hope that helps.
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Unread 04-30-2013, 12:53 PM   #30
LumpyGrits
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Quote:
Originally Posted by Neuner-9R View Post
That equals my 4th gear and better mpgs isn't true. Tried and tested.
What MPG are you get'n?
My freeway is 16-18. My speed and distance is confirmed via GPS.
LG
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