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low gears for th400?

B

black dawg

1/2 ton status
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montana
Anybody used them? Right now my burb is th400/205,3.73 and 235/85-16. For towing, first gear really sucks, and offroad the combo of the high first gear and the 205s low range just isnt low enough for me.

My thoughts are: do it right, 465/205.....or
low gears for the th400 and keep the 205....or
low geared th400 and 241.

anybody have any thoughts? Will the low geared th400 make the 205 low range feel acceptable?
 
I know you can get a 2.75:1 or almost a 3.0:1 first gear for the TH400, though I think the 3.0:1 setup is over $800. Going to the 2.75 set would be about the same as swapping from 3.73 to 4.10 axle gears so not really sure it would be worth the time and money. The 3.0:1 would be about like going to a 4.40 axle gear.

For simply off-road gearing going to the NP241 would be the best bang for the buck as it would drop the crawl ratio from about the current 18:1 to 25:1, but obviously doesn't do anything for towing. The 241 paired with the 3.0:1 TH400 would be pretty sweet but has the potential to cost a lot of money.
 
another thought I had was 700/208 or 241, but I tow quite often, and would be worried about the 700 holding up. If I went this route, I would probably pull the tbi454 and put a 350 back in.
 
Or, 4L80E and 4.10 or 4.56 rears.

Probably a significant investment, but if you want to keep it automatic, that would be one way to do it. Just throwing that out there in case you hadn't considered it.
 
I have thought about the 4l80/241, and 4.56 or lower, and really like that idea. Problem is that I am kinda burnt out on the electrical end of things and am trying to stay mechanical.....but this obviously would be a very good setup, and tow like a mofo with the lower gears and the 454.
 
4l80 is same first 3 gear ratios as 400 only get overdrive and lockup .

700 can be made to handle the 454 power and hold up under towing .

check out bowtie overdrives web site . lots of guys hare have and run them.

also check my thread for tranny cooling info http://coloradok5.com/forums/showthread.php?p=3020914#post3020914

also 4l80 swap in is easy 3 wire hook up with this kit . power /ground /tps signal. http://www.usshift.com/index.shtml use to be called opti shift if you are searching for info / writeups. just name change.
 
For some of the electrical stuff I agree, but those trans are pretty good. There are a few things I'd never go electrical with (t-case shifting, hubs) and some things (electrical locker, 4L80E) I'd unquestionably run.

IMO something like the electronic speedometer is SIMPLER than the speedometer cable setups. Either type of speedometer itself breaks, most of us can't fix it, and the electrical means no more cables that are only a few lengths, or break, or get melted by exhaust, etc.

On the 4L80E, you'd be gaining a TCU and the wiring loom to the trans, and you'd lose what, a cable to the gas pedal?

Realistically, it seems the 4L60E's can hold up to a ton of abuse (even stock) and I wonder if a 700 can be built to take the same. If so, that might be another option which COULD be cheaper in the long run than having to get a standalone 4L80E going. Of course, if you are fuel injected already, that simplifies running the 4L80E, since the injection/electronic trans stuff is out there in significantly more applications than the diesel-only TCU.
 
6.2Blazer said:
I know you can get a 2.75:1 or almost a 3.0:1 first gear for the TH400, though I think the 3.0:1 setup is over $800. Going to the 2.75 set would be about the same as swapping from 3.73 to 4.10 axle gears so not really sure it would be worth the time and money. The 3.0:1 would be about like going to a 4.40 axle gear.

For simply off-road gearing going to the NP241 would be the best bang for the buck as it would drop the crawl ratio from about the current 18:1 to 25:1, but obviously doesn't do anything for towing. The 241 paired with the 3.0:1 TH400 would be pretty sweet but has the potential to cost a lot of money.
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Good advice here:waytogo:
 
For 800$, I would consider just changing the axle gears instead. Because even with a low first, when it hits second its still going to bog. The 241 would help because it is a lower low for offroad, but no effect on towing. Maybe a 5 speed conversion? More money than the sm465, but its a way better option in my mind.
 
454Sub said:
For 800$, I would consider just changing the axle gears instead. Because even with a low first, when it hits second its still going to bog. The 241 would help because it is a lower low for offroad, but no effect on towing. Maybe a 5 speed conversion? More money than the sm465, but its a way better option in my mind.
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one of the gear sets that I was looking at had a lower 2nd also.

I am trying to avoid gearing these diffs, because I am watching for a 60/14bolt.

The 241 swap would help lots with the low range, but what do I need to bolt it to the back of th400. It has the figure 8 adapter

I also have been thinking about swapping a 7.3T and e4od in that hasnt been getting much use lately. Anybody ever done a swap like that into an old burb?
 
The low gear set will always change the second gear ratio as well but leave third the same one to one. If you pull a 205 off the 400 , chances are you will have the longer spline on the output shaft. It is easy to find a 6 bolt TC adapter to the 400 but the mount pad will be shorter and the adapter may not compensate for the longer shaft length so this may require a spacer block. Of course you will need to find that elusive 32 spline input 241 with passenger drop and mechanical speedo drive , and grab the transfer case shifter while you are at it because you will need that too.
 
Greg Ducato said:
The low gear set will always change the second gear ratio as well but leave third the same one to one. If you pull a 205 off the 400 , chances are you will have the longer spline on the output shaft. It is easy to find a 6 bolt TC adapter to the 400 but the mount pad will be shorter and the adapter may not compensate for the longer shaft length so this may require a spacer block. Of course you will need to find that elusive 32 spline input 241 with passenger drop and mechanical speedo drive , and grab the transfer case shifter while you are at it because you will need that too.
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I think I can find the 32 spline 241, but I need the speed sensor version. Do you know If I can take the stuff off the back of a drivers drop 241 and put on the pass drop to have vss?
 
You can get a passenger drop 241 with speed sensor or you can convert your mechanical to electric with drivers side drop parts
 
The trouble with just swapping axle gears is you really lose driveability on the freeway both empty and towing. You would really need to go from 3.73 to 4.56 to see much difference and that would make the engine scream with the little tires.

Yes, the 4L80E has the same first gear as the TH400 but that is why a previous post mentions changing the axle gears also. Going to 4.56 axle gears will get you the lower 1st gear ratio but with the overdrive the cruising RPM is a little lower being equivalent to 3.42 gears.

I think the best overall option would be an 4L80E/241/4.56 axle gear combo...that is also the most expensive option by far.

For the 700r4 towing, I guess it depends on what you are towing and how the trans is built. I would also be more concerned about the weight of the trailer as compared to the engine....really don't see swapping from the 454 to a 350 making things much better on the trans when towing. I know a guy with a garage built 700r4 in a Suburban with a built 350 that towed a 6k lbs. race trailer for years with no issues.
 
6.2Blazer said:
I think the best overall option would be an 4L80E/241/4.56 axle gear combo...that is also the most expensive option by far.
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There are probably more than a few of us on here that have gone the "lets try this route" on multiple occasions, only to find that it isn't what we want, and we go back and have to do something else, which ends up doubling cost, etc.

IMO, figure out what you need/want that will do whatever it is you are doing, and get it. There just isn't any point in settling for something that isn't going to do exactly what you want it to do, if the options are out there.
 
I'm curious how much weight you are towing that first gear doesn;t seem low enough.. Also, how many miles are on the tranny? Any chance the torque convertor is going south on ya? Reason I ask is I had a similar problem on mine and all it needed was a good rebuild and a new tc, since the old one wasn't moving enough fluid to to couple everything together. To me, when driving it, seemed like it needed lower gearing, which wasn't an issue with the 4.56's. Just needed a tc and a rebuild. Just a thought.
 
jp0863 said:
I'm curious how much weight you are towing that first gear doesn;t seem low enough.. Also, how many miles are on the tranny? Any chance the torque convertor is going south on ya? Reason I ask is I had a similar problem on mine and all it needed was a good rebuild and a new tc, since the old one wasn't moving enough fluid to to couple everything together. To me, when driving it, seemed like it needed lower gearing, which wasn't an issue with the 4.56's. Just needed a tc and a rebuild. Just a thought.
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Normal trailer weight is anywhere from 5-9k. Has a fairly new towing/low stall converter, which I do think is contributing to how it feels towing.
 
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