No this is not a lowrider post. I was just researching gear reduction, and I think I found a way to get a crawl ratio of 440 to 1. So how low is too low? If I am right you just need an OTT ind. sm420 adapter 7.2 1st gear, toy t-case 2.28 with second t-case with low set 4.70, and 5.71 gears gives you a total crawl of 440 to 1. Even with 5.29s its 408 to 1. Now thats low gearing. I just got an 83 4wd lwb and I am getting ready to rock crawl it. Not compeditively. I like the idea of the sm420 to the 22r bellhousing and then I would just run a pair of stock t-cases and 5.29s so I would end up with a 197 to 1 crawl ratio. I think the sm 420 adapter is only 199.00 and the 4.7 crawl kit is more than that. What do you think?? Good Idea? Anyone gone this route yet? Let me know.
How low can you go?
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ok the backlog for the 4.7's is 6 months i think?? and the other HUGE issue with teh 420 in a toy is the fact the gears are spaced SO FAR apart that it would make for bad road driving conditions! i'll just stay happy @ 190:1 with my stock toy tranny 2.28 and 4.0 t cases and 5.29's, 5.71's are WAY to weak to even think aboot!!!
An sm420 is a transmission stock in full size trucks from the early 60s to the 70s with a 7.2 to 1 first gear ratio. OTT industries makes an adapter to mate this trans to a stock toy bellhousing, and they make an adapter to mate the sm420 to stock toy t-cases.
So Dsi what do you think? Other than your opinion of sikfj40 is this a good way to go? With 5.29s I would think the revs between gears wouldnt be too bad. Although it would be like going to a 3sp from a 5sp cause you never use the first gear on the street. I think that guy has a point. Anyone running one with that answer?
So Dsi what do you think? Other than your opinion of sikfj40 is this a good way to go? With 5.29s I would think the revs between gears wouldnt be too bad. Although it would be like going to a 3sp from a 5sp cause you never use the first gear on the street. I think that guy has a point. Anyone running one with that answer?
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www.ottindustries.com it's a 2wd transmission out of 50?-69 chevy's it's a 4sp with a 7.02 1st gear and a 1.00 4th gear, ott makes the adapters to put them in toyota's
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First off, I think your a little off on your pricing. The sm420/465 adapter to the toy case lists at $465, then the toy bell housing to the sm420/465 lists at $199. You need both if your still using the 22r. As far as crawl ratio, I feel if you go further than 200:1, your just doing it for bragging rights.
That is why I posted this is to see peoples opinion of how low is too low. I havent ever had a 200 to 1 crawl ratio so I dont know. Thanks for the price on the other adapter I looked at OTT ind. web page and didnt see the price for that .
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do a serch,or if you are lazy click on this link....http://www.pirate4x4.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic&f=6&t=008615, ecv matt posted this week that he has his 420 in and driving <IMG SRC="smilies/rolleyes.gif" border="0">try asking him guys, he said it's not as bad as he thought it would be.
[ 09-08-2001: Message edited by: SeaBass44 ]
[ 09-08-2001: Message edited by: SeaBass44 ]
Hey you should check up on that post I am still waiting for a reply from ecvmatt, but thanks for the help
<IMG SRC="smilies/rolleyes.gif" border="0"> <IMG SRC="smilies/rolleyes.gif" border="0"> <IMG SRC="smilies/smile.gif" border="0">
Since You have the LWB truck you have the room to put in a third transfer case. Marlin already did that but in my opinion, there is no need for it. Two transfer cases with the 4.7 gears in the second one along with stock engine and tranny is low enough for any trails. But if you want the bragging right, then do that way.
this wouldnt work but it would be cool bragging rights <IMG SRC="smilies/biggrin.gif" border="0">
sm420-dual cases with 4.7's-5.29 diffs
7.02x4.7x4.7x5.29=820:1
hahahaha <IMG SRC="smilies/biggrin.gif" border="0"> <IMG SRC="smilies/biggrin.gif" border="0">......no
sm420-dual cases with 4.7's-5.29 diffs
7.02x4.7x4.7x5.29=820:1
hahahaha <IMG SRC="smilies/biggrin.gif" border="0"> <IMG SRC="smilies/biggrin.gif" border="0">......no
I guess I must have had the SM420 in my 53 GMC 3/4 ton. With the 7.02 1st and the 4.56 axles it came out to about 32:1. With a Detroit Locker, and about 1/2 ton of rocks in the back,I made it over Imogene, Pearl, Black Bear, and quite a few other passes in Colorado. Tires were 7.50 x 16.
In a Toyota though it seems like you would have weight and size problems. The overall diameter is huge compared to a stock tranny. I'm guessing it also weighs twice as much. But if you're using it in a truck built just for rock crawling I bet it would be a pretty good tranny.
by going that slow you lose the advantages of momentum!
and you will eat up your tires way to fast (ever seen a unimog try to climb a slick wall and end up humping it <IMG SRC="smilies/eek.gif" border="0"> )
you will be spinning your tires (causing you to use excess rubber) and those sharp rocks that your trucks tires get stuck up against will now tear a big hole on wrapped around the tire.
and you will eat up your tires way to fast (ever seen a unimog try to climb a slick wall and end up humping it <IMG SRC="smilies/eek.gif" border="0"> )
you will be spinning your tires (causing you to use excess rubber) and those sharp rocks that your trucks tires get stuck up against will now tear a big hole on wrapped around the tire.
I am actually going with the toy tranny, and dual stock cases for myself. Ive seen it work and I want it. I was just bored and doing some fun math. It is achieveable to go over 1000 to one and it is pointless. As far as tire ware have you actually had that problem and your gears are that low? I have neverr seen that happen or heard of it. If the rock is so sharp it rips the tire wopuldnt it give you traction and climb over it?
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Then shift up a few gears, go into 4 HI....
The HUMPING thing has nothing to do with gear ratios, its the loading/unloading of the tire, springs and the drivetrian..
You must run radials or never run hard on the rock, I have been running hard on my boggers for 2 years now, and know what, i don't run a spare for a reason....
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