Forum Home Forum Home > CJ-2A Discussion Area > Modifications from original
  New Posts New Posts RSS Feed - Installing a SM420 behind a Dauntless
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Installing a SM420 behind a Dauntless

 Post Reply Post Reply Page  123>
Author
Message
AKoller View Drop Down
Member
Member

Sponsor Member

Joined: 18 Sep. 2018
Location: Moundridge Kans
Status: Offline
Points: 115
Post Options Post Options   Thanks (0) Thanks(0)   Quote AKoller Quote  Post ReplyReply Direct Link To This Post Topic: Installing a SM420 behind a Dauntless
    Posted: 09 May 2019 at 10:49pm
I've been kicking around how to achieve a lower crawl ratio in Thumper my 1950 3A for sometime now. My current crawl ratio with the factory T90a, D18 and 4.89 gears (not factory) is an unacceptable 34:1. 

My original plan was go with the 3.15 Teraflex gears. I have a big hole D18 out of a late 60's Dauntless powered CJ5 that I was planning to use. That set up would get me to a crawl ratio of 43:1. After much thought I decided that was not quite going to be as low as I wanted to be. 

So I looked onto other options. After some more research I've decided to put in a SM420. It will get me to a 85:1 crawl ratio and is a straight bolt up transmission to my Dauntless V6. 

The negative about this setup is the overall length is 3.5" longer (with the Novak adapter to the D18) and 3" taller than the T90. I will need to cut out the floor board, move the transfer case back and change driveshaft lengths. The other option is to move the engine forward (still have to cut the floor). 

So here is my plan as of right now. After doing some quick and dirty measuring it appears I have enough room to move the Dauntless forward the 3.5" I need. I will have to remove my mechanical fan and install an electric pusher fan on the front of the radiator. I believe I can fit a thermostat operated, 16" fan that is rated at 3500 CFM. That should be more than enough to cool the Dauntless V6 with my current aluminum radiator. The motor mount on the driver side will need to be modified to clear my steering shaft running to my Saginaw steering box. The exhaust of course will need to be lengthened as well. I do intend on using the big hole D18 I have just in case at some point I decide to go with the 3.15 Teraflex gears to get to a 109:1 crawl ratio.

Is there anything in my plan that is throwing any red flags? I try to go into every project with a clear and concise plan to avoid any unexpected work or expenses. Please share your experiences in order to help this project along as smoothly as possible.

I will upload pictures of the transmission and transfer case tomorrow when I have a little more time.
1950 CJ3A "Thumper"
1966 M151 A1
Back to Top
Mike S View Drop Down
Member
Member


Joined: 20 May 2006
Location: West Coast
Status: Offline
Points: 2292
Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike S Quote  Post ReplyReply Direct Link To This Post Posted: 09 May 2019 at 11:07pm
I have an SM420 and Dauntless in my shop right now. Researxh tells me that a Ford T18 with AA bell housing and D18 adaptor will be a few inches shorter than the SM420. I will be following this to see what folks have to say...
'47 CJ2A -- #114542
Warn FF D41 rear
Lock-Right locker
11" drum brakes
Dual master cylinder
T90C Transmission
16 X 6 Jeep truck wheels
Cooper STT Pro tires
Back to Top
nofender View Drop Down
Member
Member


Joined: 10 May 2016
Location: Western MA
Status: Online
Points: 1065
Post Options Post Options   Thanks (0) Thanks(0)   Quote nofender Quote  Post ReplyReply Direct Link To This Post Posted: 10 May 2019 at 6:19am
yep - even tho the 420 case is a mere 10 or so inches long, the overall package of the T18 is a couple inches shorter due to an adapter that's barely an inch. 

Regarding your conversion - I would not be a big fan of moving the engine forward. Now matter what you do, you will end up cutting the body. If you leave the t-case in the stock location, you will get into cutting the trans tunnel. Secondly the shift tower will likely be nearly under the dash. So you may have to get creative on the shape of the shifter cane. 

Were it me (and it was once) I would leave the motor where it is and modify the drive shafts. I used an advance adapter chain drive for the clutch as your pivot point change. It was a major upgrade. 

If anything I would really look at side to side engine location. The reverse hump on the 420 could be a challenge when fitting a front driveshaft if the position isn't right. By leaving the motor in the stockish location, you gain some length on the front shaft, which might be helpful. 

The beauty of all this is that you can mount things anywhere you want, anywhere that works. 

You plan is by no means bad. But I'm a bit fan of keeping weight as balanced as possible. Pushing the motor forward 3.5 inches would make a difference. Noticeable? maybe not. But that's just my preference. 
46 CJ2A rockcrawler
46 CJ2A resto-mod
51 Bantam-ish trailer
50-ish Sterling trailer
15 Grand (Mrs Nofender)
19 Hemi Ram (parts hauler)
Back to Top
AKoller View Drop Down
Member
Member

Sponsor Member

Joined: 18 Sep. 2018
Location: Moundridge Kans
Status: Offline
Points: 115
Post Options Post Options   Thanks (0) Thanks(0)   Quote AKoller Quote  Post ReplyReply Direct Link To This Post Posted: 10 May 2019 at 7:29am
Originally posted by nofender nofender wrote:

You plan is by no means bad. But I'm a bit fan of keeping weight as balanced as possible. Pushing the motor forward 3.5 inches would make a difference. Noticeable? maybe not. But that's just my preference. 

I'm not saying your wrong but it has been my experience that the more weight over the front you have the better it is for climbing both hills and obstacles. That being said, I don't know how much will change in the way of going down hills or obstacles.
1950 CJ3A "Thumper"
1966 M151 A1
Back to Top
flatfender47 View Drop Down
Member
Member

Sponsor Member

Joined: 09 Jan. 2006
Location: Riverside CA
Status: Offline
Points: 400
Post Options Post Options   Thanks (0) Thanks(0)   Quote flatfender47 Quote  Post ReplyReply Direct Link To This Post Posted: 10 May 2019 at 9:26am
How was the V6 mounted, using stock V6 frame mounts ?
I'd leave the engine alone and just install the 420 and work from there.
That's what I did.
Re-doing the driveshafts will be the easiest part, so don't fret that.

1947 CJ2A 225V6 SM420 D30 PLok/D44 D/Locker Warn OD 5:38s
Back to Top
AKoller View Drop Down
Member
Member

Sponsor Member

Joined: 18 Sep. 2018
Location: Moundridge Kans
Status: Offline
Points: 115
Post Options Post Options   Thanks (0) Thanks(0)   Quote AKoller Quote  Post ReplyReply Direct Link To This Post Posted: 10 May 2019 at 9:43am
Originally posted by flatfender47 flatfender47 wrote:

How was the V6 mounted, using stock V6 frame mounts ?
I'd leave the engine alone and just install the 420 and work from there.
That's what I did.
Re-doing the driveshafts will be the easiest part, so don't fret that.


I used the engine mounts from a CJ5 frame.
1950 CJ3A "Thumper"
1966 M151 A1
Back to Top
Gaffer View Drop Down
Member
Member
Avatar

Joined: 06 Nov. 2015
Location: Alabama
Status: Offline
Points: 66
Post Options Post Options   Thanks (0) Thanks(0)   Quote Gaffer Quote  Post ReplyReply Direct Link To This Post Posted: 10 May 2019 at 10:33am
Have you read "Dauntless Drivetrain Change" by jeepfever here on the cj2a page.  He is running the sm420 and Buick V6 if I recall.



-Gaffer
Back to Top
oldtime View Drop Down
Member
Member
Avatar

Joined: 12 Sep. 2009
Location: Missouri
Status: Online
Points: 1462
Post Options Post Options   Thanks (0) Thanks(0)   Quote oldtime Quote  Post ReplyReply Direct Link To This Post Posted: 10 May 2019 at 11:16am
For all Dauntless flatties I would keep the TC exactly in the standard fore/ aft  location. 
134 Willys engines were 1-1/2" left of frame CL. 
Dauntless engines were 3/4" left of frame CL.
That said the flatfender TC location need to be moved 3/4" to the right.

With TC in standard location a T18 bolted direct behind Dauntless will allow you to use normal fan.
The grill preshroud will need to be shortened exactly 1".
Shortening the preshroud works great. 
Shortening 1" narrows the grill preshroud and so it then fits the width of the  Dauntless 17" Modine radiator.
Shortening simultaneously moves the grill CL over to match up with the proper CL of the Dauntless engine.

I can link you to my post if you want detail.

No detail on SM 420 applications.

Currently building my final F-134 powered 3B .
T98-A Rock Crawler using exclusive factory parts and Approved Special Equipment from the Willys Motors era (1953-1963)
Zero aftermarket parts

Back to Top
JeepFever View Drop Down
Member
Member
Avatar
Sponsor Member

Joined: 07 Aug. 2012
Location: VA
Status: Offline
Points: 1647
Post Options Post Options   Thanks (0) Thanks(0)   Quote JeepFever Quote  Post ReplyReply Direct Link To This Post Posted: 10 May 2019 at 12:35pm
Originally posted by Gaffer Gaffer wrote:

Have you read "Dauntless Drivetrain Change" by jeepfever here on the cj2a page.  He is running the sm420 and Buick V6 if I recall.



I am on lunch at work,  and don't really have time to digest what Alan is currently planning to offer opinion.   I can share a little about my swap.   First off,  I went with a selection of components mainly because I had already collected them over the years.    At the time I got each of them,  they were cheap and thought they would be the "ultimate",  without really knowing how they would fit together.   First thing I acquired many years ago was '74 flanged axle D44 rear,  then a '80 D300 transfer case (centered output to match rear) and lower gears (2.62)  than D20/18,     SM420,  lowest granny gear and shortest case of the 4-speeds.    

A couple notes,   
 - the Novak adapter for SM420 to D300 is shorter than SM420 to D18/20.    (total length of tranny/xfer assembly is almost as short as T18 D18/20) 
 - there is virtually no clearance issue with SM420 bulge and front driveshaft
 - biggest issue with front driveshaft is exhaust clearance.   I tucked the exhaust between driveshaft and tranny to keep away from rocks as much as possible,  but it is tight.

I could probably think of more,   but running out of time,  and does not address Alan's situation.

I do really like this setup.  Very quiet going down the road with straight thru xfer and 3.73 gears,  yet with 69:1  can still offroad reasonably well.   

Will be watching the thread,  and will help where I can.
Back to Top
flatfender47 View Drop Down
Member
Member

Sponsor Member

Joined: 09 Jan. 2006
Location: Riverside CA
Status: Offline
Points: 400
Post Options Post Options   Thanks (0) Thanks(0)   Quote flatfender47 Quote  Post ReplyReply Direct Link To This Post Posted: 10 May 2019 at 2:28pm
So if your engine was anywhere close to mine using the factory V6 mounts, the 420 shifter will move forward approx 4" from the T90 position and the twin sticks for D18 will move back 6-7 inches.
All will have to be heated/bent for proper use position.
I used the Novak adapter.
1947 CJ2A 225V6 SM420 D30 PLok/D44 D/Locker Warn OD 5:38s
Back to Top
AKoller View Drop Down
Member
Member

Sponsor Member

Joined: 18 Sep. 2018
Location: Moundridge Kans
Status: Offline
Points: 115
Post Options Post Options   Thanks (0) Thanks(0)   Quote AKoller Quote  Post ReplyReply Direct Link To This Post Posted: 10 May 2019 at 4:19pm
Originally posted by Gaffer Gaffer wrote:

Have you read "Dauntless Drivetrain Change" by jeepfever here on the cj2a page.  He is running the sm420 and Buick V6 if I recall.




I have. Lots of good information from Ron in there but not all applicable since he used the D300 in his.
1950 CJ3A "Thumper"
1966 M151 A1
Back to Top
jeepsterjim View Drop Down
Member
Member


Joined: 12 July 2011
Location: lincoln, ca
Status: Offline
Points: 421
Post Options Post Options   Thanks (0) Thanks(0)   Quote jeepsterjim Quote  Post ReplyReply Direct Link To This Post Posted: 10 May 2019 at 7:49pm
I have done this conversion(s) but in Jeepster commandos with the v-6. If you only want a lower first gear and do a heck of a lot of very serious crawling, it might be a good for you.  But on the hiway the sm420 sucks due to the jump between 2nd and third gear Thiere is a huge gap in gear ratio. 

Many times  first gear proves to be to low. No forward momentum or it's so slow going down hill and the azz end wants to come around. WE tested this out on the Rubicon, Dusy, Bronco Canyon, and Lions back.  If you went with a t-98 or t-18 married up to a  D-300 with a low kit , followed up by a D-44 flanged  centered rear end  with 4.27 gears , you might find it to be a great system.   Personaly, there's nothing like an automatic with a D-300 W/low kit with 4.27 rear end gears.

Just a thought guys.


Jim
CJ-2A - 81299
Back to Top
nivrat View Drop Down
Member
Member
Avatar

Joined: 27 May 2014
Location: Glendale, AZ.
Status: Offline
Points: 103
Post Options Post Options   Thanks (0) Thanks(0)   Quote nivrat Quote  Post ReplyReply Direct Link To This Post Posted: 11 May 2019 at 2:26am
Sorry to disagree but the claim that a 420 is not highway friendly due to the gap between 2nd and 3rd gear ratio is not supported by the facts. If we use Novak's knowledge base we see that the gear ratios for an SM420 are - 1st- 7, 2nd- 3.6, 3rd- 1.7, 4th- 1.
    T18/T98- 1st- 6.32/6.4, 2nd- 3.09, 3rd 1.69, 4th-1. Having ran most all of the granny boxes I can tell you that the SM420 actually has less of a jump to 3rd from 2nd than the T18 (3.6 to 1.7 is less of a jump than 3.09 to 1.69). 3rd to 4th in virtually all the granny boxes is essentially the same.
Having ran a T18 for years I also discovered the NP435 which IMO has better gearing than the T18, although with an adapter winds up being 2.5" inches longer. The 420 is also longer than the T18 but it has the lowest 1st gear of any of the truck 4 speeds.
The bottom line is that any of the truck 4 speeds can be made to fit in a 3A with a Dauntless. Yes, you will have to cut your floor but new floorpans can be fabbed.
In my 47 2A I wanted as long a rear driveline as possible so I mounted my radiator as far forward as possible. I'm using a stock fan on a 252 Buick V6 with a fan clutch sourced from a Jaguar(it has a shorter shaft than factory). I placed my engine mounts 1" to the drivers side and am running Saginaw power steering. My front driveline clears the hump on the 420 no problem. I have room for Novak headers and duals all the way to the rear corners. My rear driveline is 15-16" long, and its relatively flat. I use a stock crossmember bolted directly to the frame with no spacers. I didn't want to lose any belly clearance. All it cost me was a little larger hole in the floor.
I also use a chain clutch and can attest to the improvement it is over the stock linkage.
The rest of my drivetrain- SM420/D18/OD and 4.88's. I have an 84:1 crawl ratio and can do 65-70 on the interstate all day long.

You asked about red flags- just my opinion here, but for me 109:1 crawl is too slow for my liking. I have learned that for me anything at least 70:1 and lower works best for me. At 84:1 in my flattie I spend a lot of time in 3rd and 4th. The last time I was on the 'Con i took my 75 and 79:1 got me through just fine.

Anything is doable with some careful planning. You're off to a great start with some great components, and you're already getting some great advice from the likes of those listed above, so, go for it!
Take your time and enjoy your build. And, keep us posted!Smile Oh, and we love pics!

FWIW,
Mike
Back to Top
nofender View Drop Down
Member
Member


Joined: 10 May 2016
Location: Western MA
Status: Online
Points: 1065
Post Options Post Options   Thanks (0) Thanks(0)   Quote nofender Quote  Post ReplyReply Direct Link To This Post Posted: 11 May 2019 at 4:50am
Originally posted by AKoller AKoller wrote:

Originally posted by nofender nofender wrote:

You plan is by no means bad. But I'm a bit fan of keeping weight as balanced as possible. Pushing the motor forward 3.5 inches would make a difference. Noticeable? maybe not. But that's just my preference. 

I'm not saying your wrong but it has been my experience that the more weight over the front you have the better it is for climbing both hills and obstacles. That being said, I don't know how much will change in the way of going down hills or obstacles.

Can't say I disagree with the climbing advantage. I've just found a preference for balance. But I'm coming from a perspective of wanting to carry some speed in the rough. Too much weight up front makes the rear want to dance like J-Lo. I concede that my take on things is a bit skewed as I tend to mount motors as close to the center of the chassis as possible. I've found it works best for my kind of wheeling/driving. 
46 CJ2A rockcrawler
46 CJ2A resto-mod
51 Bantam-ish trailer
50-ish Sterling trailer
15 Grand (Mrs Nofender)
19 Hemi Ram (parts hauler)
Back to Top
oldtime View Drop Down
Member
Member
Avatar

Joined: 12 Sep. 2009
Location: Missouri
Status: Online
Points: 1462
Post Options Post Options   Thanks (0) Thanks(0)   Quote oldtime Quote  Post ReplyReply Direct Link To This Post Posted: 11 May 2019 at 11:06am
I agree with nivrat totally except
Quote  (3.6 to 1.7 is less of a jump than 3.09 to 1.69)
The numbers are right but surely that must be some kinda new math !!!

One should consider that the there are a couple smart combinations to get a 70 something crawl ratio from the T18 and still have excellent hiway gears.

6.32 (T18) X  2.46 (D18) X 4.89 (Differential) plus 25% O.D. = 76/1 crawl and 3.66 hiway ratio.
6.32 (T18) X 3.16 (D20) X 3.73 (Differential) = 74/1 crawl and  3.73 hiway ratio

One thing I did not like about an SM 420 is the loose or "sloppy feel" of the shifter.


Currently building my final F-134 powered 3B .
T98-A Rock Crawler using exclusive factory parts and Approved Special Equipment from the Willys Motors era (1953-1963)
Zero aftermarket parts

Back to Top
jpet View Drop Down
Moderator Group
Moderator Group
Avatar
Sponsor Member x 5

Joined: 29 Apr. 2008
Location: Ramsey, IL
Status: Offline
Points: 9634
Post Options Post Options   Thanks (0) Thanks(0)   Quote jpet Quote  Post ReplyReply Direct Link To This Post Posted: 11 May 2019 at 12:45pm
I personally like my 107:1 crawl ratio. Is it necessary? ... not really, but when I’m hanging on chewy hill trying to make the off camber right hand turn, and the Jeep keeps pitching more and more as I go forward, and my nervousness starts messing with my logic, I appreciate the extra time to think it through. But then again, I get more nervous than most. To each their own.

Edit: the higher your CG, the more it matters .... also, don’t forget to include your tire size. We have a lot of discussions where we we talk about gears but not often do we throw the tire size in which affects the math.

Edited by jpet - 11 May 2019 at 12:59pm
CJ2A #29110 "General Willys"
MB #204827 "BAM BAM"
MB #295645
MB #434416

My Videos
Back to Top
AKoller View Drop Down
Member
Member

Sponsor Member

Joined: 18 Sep. 2018
Location: Moundridge Kans
Status: Offline
Points: 115
Post Options Post Options   Thanks (0) Thanks(0)   Quote AKoller Quote  Post ReplyReply Direct Link To This Post Posted: 11 May 2019 at 1:39pm
This is all good stuff guys. I do appreciate all the experience shared on this forum. I’ve had a busy weekend we’re I haven’t really had time to digest the information given to me. 

As Jeff mentioned some more information on tire size might be helpful. I’m currently running 33” tires with 2.5” lift springs and I have body mounts I made out of poly that are 1/2” thick.

Some more information that may help the discussion of balance is I have weighed my Jeep at the local grain elevator scale and the rear end believe it or not weighs 80 lbs more than the front end. It was suggested to me off this thread that if I move the engine forward 3.5” I should move the front axle forward 2” (which there is room for on the factory frame horns).

Keep the comments and discussion going on this. All of it helps.

Thanks, Alan
1950 CJ3A "Thumper"
1966 M151 A1
Back to Top
oldtime View Drop Down
Member
Member
Avatar

Joined: 12 Sep. 2009
Location: Missouri
Status: Online
Points: 1462
Post Options Post Options   Thanks (0) Thanks(0)   Quote oldtime Quote  Post ReplyReply Direct Link To This Post Posted: 11 May 2019 at 5:15pm
Tire diameter alone (not including all the other tire specs.) influences...
Body clearance, Terrain clearance, Roll Resistance, Steering angle, Ride height or COG and Gearing.

The standard 6.00 x 16" NDT was about 28.5 tall. 
If you go up to a 31" tire then that is right near a 10% diameter increase.

The standard Differential Ratio (DR) prior to 11/62 was 5.38.
When you go to a 4.89 DR then its essentially the same 10% difference as having a larger diameter tire.

No tire nor jeep does "everything" best. 
Aim for the perfect balance of specifications to suit your needs.
The Complete Synchronous System !

Allen..... what size tires are you running on 31's ?
If so then due to 4.89 DR your effectively crawling 20% faster than the standard 37/1 crawl. 

About the tallest tires guys ever run are the NSS tires as seen on Gus. 
Those puppies are about 25% taller than standard.





Edited by oldtime - 11 May 2019 at 5:18pm
Currently building my final F-134 powered 3B .
T98-A Rock Crawler using exclusive factory parts and Approved Special Equipment from the Willys Motors era (1953-1963)
Zero aftermarket parts

Back to Top
 Post Reply Post Reply Page  123>
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.01
Copyright ©2001-2018 Web Wiz Ltd.