FJBen
SILVER Star
well, if you have a beefed up 350 it's not so slow
I would say it's not very forgiving. You definitely can't speed shift it, you just gotta shift the mellow way. 
Sm 420 Swap
- Thread starter 69 FJ40
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well, if you have a beefed up 350 it's not so slow
I would say it's not very forgiving. You definitely can't speed shift it, you just gotta shift the mellow way. 
x2 IMO
1st is gear is pretty useless on the street so you start out in second which means extra wear on the clutch, especially with anything over 33s. And you definitely don't want to try any speed shifts
Personally, I'd think long and hard about what your primary use will be and determine if you really need what a SM420 or even a SM465 offers. I was sort of starting to consider going with an NV4500 down he road but I don't DD my FJ40 so I can't really justify the cost. I guess my thought is whether the swap costs you $600 for a SM420 or say $1200 for a H41, if you choose correctly and it ends up being what you want in the end it will say you $$ not having to do a tranny swap twice.
I hear you Poser, but every once in awhile when you are trying to get up to speed faster than 0-60 in 2 years, shifting from 2nd to 3rd it would be nice if you didn't have to wait 5 seconds to complete the shift 
shifting from 2nd to 3rd it would be nice if you didn't have to wait 5 seconds to complete the shift
Then there is a problem.
I have not ever operated a 420/465 that shifts that way.
Cruiserdrew
On the way there
Lots of people complain about the shifting in an SM420, and my guess is they have not driven one. They actually shift fine for a 40 year old transmission. You just have to accept that 1st gear is useless on the street, and that 3rd and 4th are a bit too wide. You can't hot-rod it, but in day to day use it gets you down the road. That first gear off the road trumps all the little street issues with the tranny. For the original poster, it is the best low buck mod he can do to his cruiser if he plans to offroad it at all. If no plans for offroading, I would just swap in a Cruiser 4 speed, which shifts well and is cheap, just more parts will be required(Like a 4 speed t-case, driveshafts, etc).
And one other thing-shifts do not take 5 seconds, you just won't get far forcing the shifts. You want smooth shifting-drive an Acura.
And one other thing-shifts do not take 5 seconds, you just won't get far forcing the shifts. You want smooth shifting-drive an Acura.
Speed Shifting?...Ha
I was cruising the "FAQ" this morning and noticed in "BEST MODIFICATION YOU HAVE DONE" that the majority said an SM420 was one of them.
I have an imported H41 with the "low" 1st (4.925). I have been thinking of a SM420 swap, but my rig is a weekend Trail Truck/Rock Crawler. I'm looking at it because I want the 7.00:1 1st gear. That way I can get a lower crawl ratio without messing with my ring & pinion and loose streetability (is that a word?)
NV4500 might be the way 6.34:1 1st , .73:1 high gear (92-94 GM)
90 and up Dodge has a 5.61:1 1st.
What are you going to use the truck for? How much $$ can you spend?
I was cruising the "FAQ" this morning and noticed in "BEST MODIFICATION YOU HAVE DONE" that the majority said an SM420 was one of them.
I have an imported H41 with the "low" 1st (4.925). I have been thinking of a SM420 swap, but my rig is a weekend Trail Truck/Rock Crawler. I'm looking at it because I want the 7.00:1 1st gear. That way I can get a lower crawl ratio without messing with my ring & pinion and loose streetability (is that a word?)
NV4500 might be the way 6.34:1 1st , .73:1 high gear (92-94 GM)
90 and up Dodge has a 5.61:1 1st.
What are you going to use the truck for? How much $$ can you spend?
KY854RUN
SILVER Star
I learned to drive in a `64 Chevy short bed truck. It was 2wd with a 230ci 6 and a SM420. You could get through the gears pretty quick if you wanted to. But, it wasn't a sports car either. That was my DD for a while, I didn't baby it at all and I have no complaints about how it shifted. The SM420 is a great swap for the FJ40, especially if it is replacing the 3 speed. I would not think twice about putting one in a Cruiser.
x2 IMO
1st is gear is pretty useless on the street so you start out in second which means extra wear on the clutch, especially with anything over 33s. And you definitely don't want to try any speed shifts
I hate when people talk out of their ass about something they have no experience with or the common courtesy to research before they post it up 
But hey I read in on the interweb so it must be true right! Brilliant!2nd in an sm420 is lower than 1st in both the J30 and h42 transmissions at 3.58:1 vs. 2.76 and 3.56 respectively. How dose this wear on ones clutch? I have no problem getting my truck moving with an F/sm420/4.11 gears rolling on 40s just dump the clutch and go like it always was. SM420 shifts fine in a truck I have noticed no differance in the shifting performance between my sm420 and sm465s I have driven, the toyota trannys shift a bit quicker but what else can you drop in your truck for a very reasonable sum of $$ and end up with an instant crawler.
rusty_tlc
Dain Bramaged Member
I've never driven an FJ40 with an SM420, but this sounds exactly like my experiences with 1 ton GMC trucks when I worked construction. You never used first gear unless you were almost stuck or had way overloaded the truck. 2nd is about the same as first on a three speed GMC.
2nd in an sm420 is lower than 1st in both the J30 and h42 transmissions at 3.58:1 vs. 2.76 and 3.56 respectively. How dose this wear on ones clutch? I have no problem getting my truck moving with an F/sm420/4.11 gears rolling on 40s just dump the clutch and go like it always was. SM420 shifts fine in a truck I have noticed no differance in the shifting performance between my sm420 and sm465s I have driven, the toyota trannys shift a bit quicker but what else can you drop in your truck for a very reasonable sum of $$ and end up with an instant crawler.
The question no one has asked is what is your budget?
Also, are you looking for a good crawl ration for the rocks?
My guess is you don't have a lot to spend... so, a 420 or 465 are both good choices.
Another option might be a complete used H42 w/bellhousing from an early FJ60. These are being parted all the time. Get the clutch slave, driveshafts and everything. Then it's not too much work to do the swap. A mostly remove and replace job. You just won't get a very low first gear for crawling.
Keep reading the tech section. You'll learn a lot.
Phil
Also, are you looking for a good crawl ration for the rocks?
My guess is you don't have a lot to spend... so, a 420 or 465 are both good choices.
Another option might be a complete used H42 w/bellhousing from an early FJ60. These are being parted all the time. Get the clutch slave, driveshafts and everything. Then it's not too much work to do the swap. A mostly remove and replace job. You just won't get a very low first gear for crawling.
Keep reading the tech section. You'll learn a lot.
Phil
Wow
Guess you missed my signature line? The '74 FJ40 WITH a SM420?
I didn't mean to offend anyone here but everyone has their opinions and not all FJ40s see major trail duty or even hard core trails. I was merely trying to offer so real world, PERSONAL experience of what I think about MY SM420. So you disagree with my assessment that is fine but why the hate?
And no, it doesn't really take 5 seconds to shift, but maybe my sarcasm didn't come across correctly...
To the original poster...IMO you would be best served by trying to find someone local that has a FJ40 with a SM420 in it and take it for a spin and see what you think. Try as many different tannies as you can and then you can make an informed decision on what YOU like.
4:1 ORION.
81:1 1st gear, low range. (4.95 x 4.0 x 4.11)
Yea that would be sweet, what are they now...$1800.
You have a SM420 don't you? Said you liked it, I posted on a local trail forum and found someone who will sell me a 420 for $150. I've got a lift in my garage so the swap is no big deal, find a 3 speed bellhousing. I'm not gona sell the H41 so If I don't like it, won't be a big deal to swap back.
What would really be sweet, short of buying a Atlas, is to find a drivetrain combo that will allow a front dig.
nope I did read that you had one before I posted....
false information irks me.
false information irks me.
FJBen
SILVER Star
I think that really sums it all up well. The toy tranny's are smoother and allow for quicker shifts, but you definitely aren't getting the crawl ratio by any means that the SM420 gives you.
I have no issues starting up hill in 2nd with 37's and 4.11's...of course 300hp helps
great cheap way to get crawl ratio and super tough tranny...HELL YEA! Works perfect for a cralwer and weeked warrior/DD.
Daily driver cruiser and just wanting something better than the 3 speed, maybe not soo much.
Come down to our Club meeting on Oct. 4 in Campbell. You can meet a few guys with Cruisers and drive one with an SM420.
www.mta4x4.com
Phil
www.mta4x4.com
Phil
- Thread starter
- #40
Wow,
A lot of good opinions and info. Thank you and thank you! To answer some of the questions: $600 is not too bad for a budget. I don't DD my cruiser, it is more of a weekend worrier, but I will be driving it to and from the trails. I don't have a fancy trailer to tow. My experience taking it off road for the first time got me thinking about the swap. Low 1st definitely helps. I am not a hardcore wheeler, so I am looking for more practicality SM 420 was a option, because of 4 gears and low 1st for off road. Also budget. I also don't want to change the diff gears, maybe just lockers. I also would like to upgrade to 33", I have 31" now. I need more clearance I appreciate everyones input, I was thinking I should probably experience a cruiser with a SM 420 before making a decision.
A lot of good opinions and info. Thank you and thank you! To answer some of the questions: $600 is not too bad for a budget. I don't DD my cruiser, it is more of a weekend worrier, but I will be driving it to and from the trails. I don't have a fancy trailer to tow. My experience taking it off road for the first time got me thinking about the swap. Low 1st definitely helps. I am not a hardcore wheeler, so I am looking for more practicality
SM 420 was a option, because of 4 gears and low 1st for off road. Also budget. I also don't want to change the diff gears, maybe just lockers. I also would like to upgrade to 33", I have 31" now. I need more clearance I appreciate everyones input, I was thinking I should probably experience a cruiser with a SM 420 before making a decision.
