Automatic Gear Ratio
- Thread starter Shawn
- Start date
Brett
Meat-Hippy
- Location
- Salt Lake City Utah
Are those the doubled ratios with the auto (slippage) or just straight through output?
Brett
Meat-Hippy
- Location
- Salt Lake City Utah
I am at a whopping 27.03 without counting the TC :greg:
I'm close to 65:1 and VERY happy. Especially w/ the atlas, if I want to haul ass, quick shifting makes perfect.
I think it comes down to personal preference and driving style. I know the comp guys like their gears a little higher in the auto. I like mine LOW so that I can just creep along if needed. Shifting has never been a problem for me.
I think it comes down to personal preference and driving style. I know the comp guys like their gears a little higher in the auto. I like mine LOW so that I can just creep along if needed. Shifting has never been a problem for me.
Shawn said:
Maybe "vague" is a better term....there's no set number you can assign to a torque converter's slippage, since it can basically be infinite. If you want to say 2:1 for the TC, then mine would be 96:1--but I don't think it's a very accurate comparison to a manual trans'd rig at 96:1, cuz I can stop moving with everything engaged and he can't.
I just like it better for comparison reasons to look at actual gear ratios between different rigs and disregard the TC's "number".
Ok,
Let me explaine a little more. As we all know I'm running the D300 w 4:1. This case needs to be replaced with the Atlas. What I'm trying to decide is whether to go with the 4.3 or the 5.0. The Tranny is a TH400.... I don't want to go so low that I can't hold back the rig. The ratio I'm running right now is purty good, but could it be better is the question I'm asking myself.
Let me explaine a little more. As we all know I'm running the D300 w 4:1. This case needs to be replaced with the Atlas. What I'm trying to decide is whether to go with the 4.3 or the 5.0. The Tranny is a TH400.... I don't want to go so low that I can't hold back the rig. The ratio I'm running right now is purty good, but could it be better is the question I'm asking myself.
kobyhud
Lurker
- Location
- Lindon, UT
I am like 43 straight through in front of an isuzu 3.2... and I am not low enough...
Driven with a 383 stroker to 700r4 with 4.56s and a 3.8 atlas like 53 crawl ratio ... on 38s it was just about perfect. its just a little too high with the 42s now I think. 4.3 would do the job just fine I think.
Also driven a jeep with th350 amc360 and stock dana300.. 4.88s on 38s and it is not quite enough... so that ratio is like 35.5.
Depends on the engine you are running I think. Some are torque monsters and can get away with less gearing than others. As for being able to stop a 5.0... I doubt that will be a problem.. but that is just my guess... Throttling into it... of course you wont be able to stop that.
so I dunno if that helps at all. its what I have found in a couple of rigs.
Driven with a 383 stroker to 700r4 with 4.56s and a 3.8 atlas like 53 crawl ratio ... on 38s it was just about perfect. its just a little too high with the 42s now I think. 4.3 would do the job just fine I think.
Also driven a jeep with th350 amc360 and stock dana300.. 4.88s on 38s and it is not quite enough... so that ratio is like 35.5.
Depends on the engine you are running I think. Some are torque monsters and can get away with less gearing than others. As for being able to stop a 5.0... I doubt that will be a problem.. but that is just my guess... Throttling into it... of course you wont be able to stop that.
so I dunno if that helps at all. its what I have found in a couple of rigs.
fergusor
Registered User
- Location
- Clearfield, ut
Im around 74:1 in low/low
th 350 1st gear 2.52
stak mb tc 5.41 in low/low
rp 5.38
and around 40:1 in low (3:1)
It crawls through the brakes, but not to bad.
th 350 1st gear 2.52
stak mb tc 5.41 in low/low
rp 5.38
and around 40:1 in low (3:1)
It crawls through the brakes, but not to bad.
Last edited:
kobyhud
Lurker
- Location
- Lindon, UT
Tire size?
BCGPER
Starting Another Thread
- Location
- Sunny Arizona
My 4 to 1 with the auto is plenty low I think. I'm used to the Toyota, where I had that mid-range as well. The problem I have with the Rubi is I find myself shifting into high range a lot when the trail turns to two-track kinda stuff. I have to stop to shift, which can be a PITA when others are waiting behind you. I'd stick with the 4.3.
Shawn said:
waynehartwig
www.jeeperman.com
- Location
- Mead, WA
Anyway you can just run what you have to see if you like it? That's what I would do if it were me...
That BBC will do some high low RPM torque numbers, if you go too big on the TC ?:1, you might not be able to stop it. Even if you had a 2:1 TC, IMO, you would still have lots of power to get over stuff. ...Especially with the auto trans.... You probably won't be able to crawl over stuff though, but I think if you were able to then you wouldn't be able to keep it stopped.
That BBC will do some high low RPM torque numbers, if you go too big on the TC ?:1, you might not be able to stop it. Even if you had a 2:1 TC, IMO, you would still have lots of power to get over stuff. ...Especially with the auto trans.... You probably won't be able to crawl over stuff though, but I think if you were able to then you wouldn't be able to keep it stopped.
This should really be pretty easy....you know what it drives like with a 4.0 'case. Do you like it for your driving style? Do you want to be slightly higher, or slightly lower, or much lower?
I'd guess the 5.0 won't make you happy, but either the 3.8 or 4.3 would.
I'd guess the 5.0 won't make you happy, but either the 3.8 or 4.3 would.