71 FJ40 1-Tons Advice (1 Viewer)

[MADMAX]

So after 12 years I'm going to upgrade my 40 (1971)! I'm removing the stroker (383) and installing an all aluminum 6.2 litre. Removing TH400 and Toyota T-case and going 700R4 & NP241, and going with GM 1 ton axles. I'm narrowing the front 60, and have C&C hubs for the 14-bolt. Ditching the 35's and going with Hutchinson beadlocks and 40's. I want to keep it low and flexy! First off, what springs (leaf) should I be considering (spring over)? I was kind of planning on running FJ60 rears all the way around, but I want to make sure I'm going the best route possible as I don't want to do it twice. I've been running 4" Skyjackers for 12 years, and I think they have about 3" of total travel and ride like s***--but it corners great! I've already got tube fenders up front that should clear the 40's no problem and am going to clearance/modify the rear. The other question I have concerns the Dana 60. Do I have to cut and turn the C's? Remember, this is a GM 60 so it has the spring pad machined into the front housing. In all of this, I want to extend the wheelbase also, and it seems like the 60 springs do that also. I do have the 25 gallon auxiliary tank in the rear and that is my only tank. Is that going to be an interference problem with the 14-Bolt? Anyway Fellas, thanks ahead of time for any information you can share!

 

[GLTHFJ60]

Lots of questions in a big paragraph. Might want to split that out to get the questions across.

For springs, FJ60 or FJ62 rear springs are starting to become hard to come by, but work well in the front of my rig. I would look at iirc 54" dodge leafs for the front and chevy 63s for the rear, if you can make room for them. Can't recall who found the 54" leafs, but they seem to work well there.

For the cut and turn, it depends how long your front driveshaft is. I worked out my D60 front end with a ~+3* caster angle, and have an acceptable front u-joint angle. Don't need it to be perfect like you do the rear, as you won't be driving the front at high speed (55mph+) but it needs to be close. I found a happy medium on my truck where my caster was good, and my driveshaft angles were good, without doing a cut and turn on the D60, but my wheelbase is much longer than yours. If you can, I'd definitely try to avoid having to do a cut and turn on that axle, because of the cast pad. YMMV.

Also, 700r4? You sure that's strong enough?

 

[mano002]

When I did the 3-link and Dana 60 in the front of my 40, the front axle location was limited by the steering box and pitman arm location to make the relay rod work for steering. I would have liked to move the axle further forward, but it would have meant moving the steering box, extending the frame etc. I would locate the front axle where you want it and then find leafs that work. I think you need to install your drivetrain first, then locate your axle, and then decide on the amount of cut and turn. I didn't do one and I regret it. My pinion u-joint axle is the limiting factor in axle droop.

I would also consider doing a link suspension while you are doing this.

 

[MADMAX]

I appreciate the replies! I have a good source for FJ60 rear springs, so that's a bonus. Do you think a shackle reversal is mandatory, it seems to me that it would be much easier to control caster and pinion angle without it. I'm confident in my trans guy as far as the 700R4. I will run the B&M valve body that eliminates the TV cable except for shift points. Links are not something I'm really interested in, but point well taken!

 

[CreeperSleeper]

For an off road rig, I prefer the shackles in the front. It seems to climb better IMO. However, that is a heavily debated topic

 

[mr jits]

Take a look at the dodge dakota leaves. 56" off-center, plentiful at the pick-n-pull, and very flexible. Easy to set up some custom packs as well.
As Chad stated, I'd avoid a shackle reversal.
A link suspension is a hell of a lot more expensive than springs (I've done SOA and a four link on different 40's, they're not remotely comparable cost-wise). My SOA 40 flexed really well offroad, and I wouldn't hesitate to do the same setup again.
One mistake I made on the leaf sprung 40 was not locating the shackles off of the rear bumper. Make a custom rear bumper and have your shackle mounts built in. It's worth it.

 

[GLTHFJ60]

Dakota springs, that must have been what I was thinking of in my last post.

Shackle-forward is my preference as well.

 

[cruisermatt]

skip the 700r4 and keep the TH400 you have

 

[MADMAX]

I really appreciate all of the info! I will check out the Dodge springs for sure. Do you have some real world experience with these springs? Matt, I have options as far as the trans goes. I've had good luck with properly built 700's and the throttle valve eliminator valve body, but I also have a 4L80E out of a 91 Burb/6.2, and the 6L80E that came with the 6.2. I kind of like the idea of keeping things simple, possibly even just freshening the 383. BUT, I really like the idea of that smooth revving 6.2 under the hood!

 

[MADMAX]

Also, on the subject of springs! Those of you that have experience, would you rule out the FJ60 rear springs? If you had a choice of basically any leaf spring available which ones would you pick for your rig?

 

[GLTHFJ60]

I have FJ60/FJ62 rear springs in the front of my truck. I like them, but if I were to do it again, I'd go with Dakota springs.

 

[mr jits]

I really appreciate all of the info! I will check out the Dodge springs for sure. Do you have some real world experience with these springs? Matt, I have options as far as the trans goes. I've had good luck with properly built 700's and the throttle valve eliminator valve body, but I also have a 4L80E out of a 91 Burb/6.2, and the 6L80E that came with the 6.2. I kind of like the idea of keeping things simple, possibly even just freshening the 383. BUT, I really like the idea of that smooth revving 6.2 under the hood!

This one wasn't on tons, but with the dakota springs. Start in page 2.

Builds - Introducing Oliver

Your gona do a axel/steering conversion in a weekend???? I wish you luck cause your gona need it friend! Keep us posted I wana see the finished product.

forum.ih8mud.com

 

[mr jits]

56" Dakota springs, front and rear.

 

[74fj40]

56" Dakota springs, front and rear.View attachment 2265366

that doesn’t look like it flexes at all

 

[Sputnik40]

Agree shackle up front will probably climb better. Will the perches for the front be out boarded? Reason for asking is because I still run FJ40 front springs (Alcans) with a low profile shackle reversal - which makes fitting my draglink a really tight affair (even with the tie rod and ram behind the widened FJ60 axle). Maybe another reason to keep the front shackle.

Even with just 40 springs don't know how folks fit 40's and fenders (even the lifted ones like you already have). With 39's and flipoed springs no way I wouldn't be into a lifted fender.

Shave the 14 bolt and assume you'll run discs. A friend shaved and narrowed mine and it's done amazingly well over the years.

Subscribed. Can't wait to see you settle on a transmission - very much want to do a similar swap someday.

 

[MADMAX]

I could easily outboard the rears, but if I understand correctly by cutting 4.5" off of the long side of the 60 that would put the machined perch right where the factory springs hang. If I'm wrong about that, please somebody correct me! I've got a virgin frame in mint condition, along with tub and other parts. My goal is to get drivetrain & suspension all done on it and then swap everything else over. As far as tire clearance I'm not too worried about the front. My fenders are already up into the apron quite a bit and I could make new ones that go higher. The rear concerns me a little! I will probably have to modify wheel wells. My son's a fabricator by trade so he can probably make me some badass inner fenders! Mr. Jits, Love your 40! After reading the build thread though, I'm not sure I'm sold on the Dakota springs. I will drive this thing everywhere we go within 100 miles. I will check out that attached spring chart also to see if anything look exciting. I'm a GM squarebody nut, and all of these parts were going to be part of a K5 build. BUT, after finishing up my sons M1028 build I don't feel that excited about a full size. His is extremely capable and the suspension works great but it's big, long, and cumbersome compared to the 40. Do any of you guys have any experience with the custom leaf makers such as Alcan, Atlas, Deaver etc? I'm not opposed to spending the money if they would be worth the investment. I was easily going to have $2K into custom leafs for the K5.

 

[cseitz]

I definitely forsee issues with your tank in the rear. The 14 bolt is a big boy and in order to have any sort of up travel your cruiser is going to need to be tall....Just something to be aware of. I have full widths under my cruiser and I wanted to keep it low and stable. Rear tanks don't over the capability to keep things low.

 

[MADMAX]

I agree! I'm not too sure what my solution will be. Maybe cut the rear deck and move the tank up, or build a custom tank that would be underneath the rear seat.

 

[cseitz]

Well, if you are going to a fuel injected ls, you should be far more fuel efficient than a 383 stroker. Maybe you can sacrifice some of that capacity and save space. I have a 8" deep fuel cell mounted under my rear deck. It holds 15.5 gallons, and offers 5" of up travel before my links hit. If you stayed leaf sprung, you could maintain as much up travel as needed with this set up. Just food for thought. Also out of curiosity, what is the low range in a 241? Is it going to be low enough for 40's?

 

[White Stripe]

Rubicon express makes a nice reverse eye set of leaf springs for the older leaf sprung wranglers for not too much money that @lcwizard uses. You can also get new lifted OME fj60 leaf springs for around 170 each and just remove a few leafs to flatten the pack. For 40s I would stretch the wheelbase to somewhere around 105". Which will require a comp cut or you could install a fj43 half tub and stretch the frame which would allow you to keep your tank. Or you could put a stock tank back in and do a comp cut. You could just use the motor and turbo 400 u have and bolt a atlas on and a sniper kit to keep things simple. I wouldn't use a 700r4, I would use a 4l80e if you want a overdrive transmission. I personally would choose to use a fj43 half tub and stretch the frame and use a fj43 factory style soft top. It would look really cool. Check out project Going big land cruiser on pirate.