transmissions

[jclinton]

Tires???

I am new to the game of jeep offroading and am looking for my first jeep purchase. I am wondering about transmissions. I love driving a manual, but is an automatic better for the offroad lifestyle? One of my friends pointed out that all hummers (or the ultimate offroad vehicle as he calls it) are all automatics. Any input would be greatly appreciated.

 

[west747]

WTS: YJ Islander flares with the step extension.

i beleive this argument over manual or auto is all personal preference. however, auto's do tend to crawl easier.( easier to drive on rocks,rockcrawling and such)

 

[Snitty]

Front Discos

each has its benefits and downfalls... do you like to control your engine and gear? do you like to have free feet for accelerating and braking? are you looking to make an offroad only vehicle? lots of factors here

 

[graewulf]

I've driven both offroad.... auto is definitely better on rocks.. stick gives you more control on sand and in mud... go with whatever suits you...

 

[redrooster]

It's really personal preference. A manual is better for engine braking, however, an auto in combination with a shift kit and disc brakes does pretty well. The biggest benefit of the automatic is in climbing rocks. You have the ability to use the throttle and brake together and not have to worry about rolling backward when you clutch it. The rollback in a manual can be overcome by installing a brake line lock as well, but then you just add one more gadget to operate in addition to the 3 pedals.
I converted my CJ7 to an auto several years ago and will never go back. It gives me more confidence climbing huge rocks and most of the time it will sit on the side of a hill without touching the gas or brake.
The disadvantage of the auto can sometimes be the length and running coolers. Most aftermarket coolers do the job just fine, and autos can be run in all but the shortest of vehicles such as the CJ5 and Samurai.

 

[redrooster]

One of my friends pointed out that all hummers (or the ultimate offroad vehicle as he calls it) are all automatics.

There is a reason for this as well. Any GI can jump in a automatic equipped vehicle and drive. There is no additional training necessary. Even the M1 tanks are automatic. They try to make them as simplified as possible because soldiers have more to worry about than shifting (bullets and such).

 

[Bounty__Hunter]

bullets and such :lol:

If you like the manual transmission, get it. Unless you rockcrawl regularly, that'd be the only way to go auto.

 

[redrooster]

If you build an automatic with rockcrawling in mind, then definitely consider using a shift kit. The shift kits keep the transmission from shifting or kicking into neutral. You can drive it like a clutchless manual. I don't know if all of them perform the same, but my TH400 will hold the gear you have it in until you bump the shifter to another. For example, if you trail ride in "D" then it starts out in whatever gear is necessary to do the job. Usually second if in low range. When going downhill you may notice that in cars an auto will coast without engine braking going downhill. With a shift kit, I can put it in "1" and it will engine brake going down hill.
I drive it like a manual and bump the shifter to each gear. This allows me to get higher RPM's if I want and hold the gear longer. Then when you shift, it quickly changes gears instead of lagging. I drive technical trails in "1" then if I get to a spot that requires a lot of wheel speed, I will start in "1", wind it up then bump the shifter to "2" and with a quick snap it shifts and maintains wheel speed. This is difficult to do with a manual without losing RPM's and tire speed. Most autos like the C6, TH350, TH400, 727, and 999 can handle this easily.
It's a lot easier to do with a console style or floor shifter as well. It would be a lot harder to do with a shifter on the column.

 

[bchcky]

One of my friends pointed out that all hummers (or the ultimate offroad vehicle as he calls it) are all automatics.

There is a reason for this as well. Any GI can jump in a automatic equipped vehicle and drive. There is no additional training necessary. Even the M1 tanks are automatic. They try to make them as simplified as possible because soldiers have more to worry about than shifting (bullets and such).

same reason police cruisers are atuo.

 

[88Wrangles]

In Jeeps, do the autos still have 4lo. With a manual transmission, 4lo helps out a ton, since you can still come to a stop just about without putting in the clutch. In my opinion, the only way I would get an auto is if I was doing some extremely difficult rock climbing. Even then, I would probably go the same way redrooster said, and install a brake line lock.
But, its all up to you-whichever way you feel more comfortable

 

[graewulf]

If you build an automatic with rockcrawling in mind, then definitely consider using a shift kit. The shift kits keep the transmission from shifting or kicking into neutral. You can drive it like a clutchless manual. I don't know if all of them perform the same, but my TH400 will hold the gear you have it in until you bump the shifter to another. For example, if you trail ride in "D" then it starts out in whatever gear is necessary to do the job. Usually second if in low range. When going downhill you may notice that in cars an auto will coast without engine braking going downhill. With a shift kit, I can put it in "1" and it will engine brake going down hill.
I drive it like a manual and bump the shifter to each gear. This allows me to get higher RPM's if I want and hold the gear longer. Then when you shift, it quickly changes gears instead of lagging. I drive technical trails in "1" then if I get to a spot that requires a lot of wheel speed, I will start in "1", wind it up then bump the shifter to "2" and with a quick snap it shifts and maintains wheel speed. This is difficult to do with a manual without losing RPM's and tire speed. Most autos like the C6, TH350, TH400, 727, and 999 can handle this easily.
It's a lot easier to do with a console style or floor shifter as well. It would be a lot harder to do with a shifter on the column.

OK you have me confused.. every automatic I have ever owned had this ability straight from the factory.. why would you need a "shift kit". when i put my GC in 4lo to crawl (yes, all autos have 4lo to answer another post), I shift the trans into 1 and leave it there... If i need more speed i shift it into 2 or OD and it shifts accordingly (yes, OD still works in 4lo, gives you 4 speeds)

 

[88Wrangles]

I don't think that you need a shift kit to do that. All automatic vehicles i've owned can do that. A shift kit usually just re-programs the vehicle to shift at a different time (usually at higher RPM's) when it is in drive. It usually does not afect how you can "manually" shift the auto transmission.

 

[Junkpile]

A TH400 like redrooster has been running will automatically shift to second regardless of shifter position until a few adjustments are made. There are different "shift kits" that do different things. Well, they all increase shift firmness but like for the TH400, they might do other things as well. Even with a shift improver kit, you still don't have total control over gear selection in an auto transmission. By installing a full-manual valvebody and completely disabling the automatic operation of the trans, you can put it in any gear you want at any time. That in conjunction with a ratchet type shifter is my preferred setup. It's like a manual without the clutch.
Anyway, back to shift kits. A shift kit should be considered a "must have" with a performance oriented auto transmission. The factory adjusts the firmness of the shift to be soft enough to not be uncomfortable for the average driver, the way they soften the shift is to allow the friction surfaces to slip during engagement. Forget that! You want that transmission to shift as fast as possible. The reason a shift improver kit firms up the shift and makes the tires bark when it hits second is because they increase fluid pressure which makes it shift faster and therefore reduce slippage between shifts. The friction surfaces will last longer and the transmission will run cooler. It really is one of those mods that not only increases performance, it also extends the life of the transmission.

 

[Snitty]

many times... an electronic regulated transmission will shift if it gets moving too fast... not sure which ones will... i know my friend had a subaru.. he could put it in 1, lay on the accelerator, and it would to go redline, shift, redline, shift, redline, shift all the way to overdrive

 

[95Jeeper]

Also autos have vents that can suck water and mud into them if you get into stuff that is deep. I learned this the hard way.

 

[redrooster]

Also autos have vents that can suck water and mud into them if you get into stuff that is deep. I learned this the hard way.

Bad news, so do manuals.