S-111 / S-11 109 5-Door Cummins 4-BTA Build

[red90rover]

Do you really feel the upper front link will be strong enough? I would be scared myself. Have you done any calcs?

[cumminsrover]

Originally Posted by red90rover

Do you really feel the upper front link will be strong enough? I would be scared myself. Have you done any calcs?

I will have to post the calculation results later, but the axle is the weak link in acceleration if the tires are bound up in between rocks. Stock D44 is about 3500 ft-lbs and the chomoly are about 4500 ft-lbs. So if I neglect the lower links and assume I get 4500 ft-lbs per shaft, I will have 27,000 pounds on the upper link.

And under breaking the tire traction is the limiting factor. If I somehow managed to get 2 g's of breaking force at max gross weight of 7000 pounds (really good road cars are 1 to 1.2 g's and most cars are around 0.8 g) I would have 21,000 pounds of force on the upper link.

There will be more to the mount eventually because I will most likely be attaching a hydro-assist ram there and I will need to do a bunch of work to it.

In any case, you bring up a good point and I will have to perform a full calculation of the stress life and determine the weak point - which will probably be one of the two 9/16" bolts holding the link on. If the bolt is not torqued properly to make use of friction between the rod end and the mount it will yield at approximately 52,000 pounds, which is about twice the max expected force.

[red90rover]

Sounds like you are checking things, so cool. It just does not look like it could take 13.5 tons without bending.

[dustydoggy]

Howdy "neighbor".

Caught this link from 4btswaps. You're doin' great and thanks for that gearing calc you posted. I'm where you were in 2006. Just getting piles of junk together for my CJ7. But I want to TRY and do it in about a year (or 10 months) so I can drive to Easter Jeep 2010!?. I will NOT be taking wagers. I'm at the .00000000001% chance of finishing that Sean spoke of. I'm just now amassing the TOO MUCH knowledge (and opinions), plans and sources at this point. I'll be into a garage and trashing parts in late April early May. I'm in the Bristol from Bethlehem area. Maybe after I get started and I'm curled up in the rain, drunk and crying at 3AM because something just don't work ... I'll look you up and trade beer for opinions. Hehehe. Great job! I'm going '86 CJ7 (mine since '90), nv4500 (at this point but it seems more of a three speed with a granny and an O.D.), D44 F&R with beefed up guts. I'll either drive slow and spin 1800@55 with 4.56 and 36"+ (R85 or 315/85) and live with the D300 (4:1 ?) or get/make a doubler and stay in the 3.73 range for way cool mileage in O.D. on the open road. I'm going to stick with leaves for simplicity and reliability though, maybe someday I'll link it up. I figure it should cost about 1.3 million, piss me off and make me have to go rent a Jeep for Easter Jeep.

[cumminsrover]

Well, hello neighbor! I haven't made much progress as of late since I have been traveling for work, took a vacation, and I have been snowboarding and skiing a fair bit.

Good to know we've got about the same drivetrain setup. I hope you can keep on schedule. I don't have a schedule, I just work as I get money (which seems to get blown on other things quite frequently)....

I'd gladly trade advice for

[cumminsrover]

So here is a pic of the Airspring at 90psi at ride height. It is about 6" in diameter and then grows to about 6.5" when compressed to near minimum height - I should have taken a picture of that...

And here is the front axle and new oil pan interaction. This is about at the position I am assuming the axle would be in when stuffed more than it will be allowed to travel (note axle hits the motor mount here). Depending on how I do the track bar mounts the axle may be almost an inch farther towards the engine, but I think I'll be OK now. Last pic has a piece of 2"x2" for reference.

I just need to be very careful in the placement of all the front end components because the Airspring is going to be very difficult to fit so it does not obstruct the ball joint nut or the brake caliper when the steering is turned to lock. The bracket will also have to be very sturdy.

['55BelAir]

Update?

[cumminsrover]

Originally Posted by '55BelAir

Update?

Please send me a reminder PM on Sunday evening, and I'll post the latest. Still not done, I have been on the road for work for the past year I'm really getting the itch to get this done and I am getting close on the chassis!

I also owe Serg (uninformed) a PM on the frame discussion, I haven't forgotten! I was down at Rausch Creek this past weekend competing in the RCRocks season finals. I was spotting for my buddy Adam in Class 1 #242. I made a couple of rookie mistakes, but we made the shootout! Next season, I hope I can spot for him full time.

[cumminsrover]

Apologies for the crappy pics again... Still taking them from my ancient cell phone, for some reason I don't bring my camera to the garage even though it is only about 120 feet away.

I got the C's cut off and the caster angle adjusted, now it is set to 5 degrees.

I made the rear air bag mounts, though I am contemplating a bit of rework since I have now decided my shock mounts are going to attach to the frame at the gusset on the right side of the picture. I also think I may want to re-make the lower plate out of 1/4" instead of the 3/16" and make it spread out slightly more front to back.

Due to the axle motion and lack of tilt to the airbag the piston comes out of alignment with the top, but it does not look as though it will be a problem. (Or so I think)

It is now possible to lift the rear end off of the jack stands with the suspension!

And as usual, putting the cart before the horse, I got a Grob NS18 band saw thanks to Master Tool and Machine! Getting the saw into Mikel's 4BT powered J300 was cake with the forklift (the same one as pictured in Mikel's 6x6 M715 suspension shots), but getting it out with the engine hoist was a bit dicey We managed not to drop it or do damage to the Jeep and then used some prybars to move it into the garage. Now I just need to get 220V run to the garage instead of extension cords. If only I could stop the business travel and my roommate (who owns the house) could save up her money I'd be able to get the kit to make that happen!

[cumminsrover]

Then I got to work setting up the front end. Unfortunately, notching the frame was the only way to go. I was a bit concerned about going to 4-1/2" here, but it is mostly shear at the notch and not much bending unless I drop onto the bumper. There is some twisting in this area due to the motor mounts being directly adjacent to the notch. I am working on steps to mitigate the twisting of the rails since there is so much distance from the front to the second cross members. I may try to squeeze in another cross member or make a shock/strut tower brace to address this. The nice thing about making a brace would be easy containment of the motor so it won't pop through the hood in a roll.

[cumminsrover]

More spring mount pictures. I made a stiffening plate to go around the mount, though like the rear, I may need to do a bit of modification here too since the shock mount is going to attach at the aft end of the spring mount. I made the "bucket" parts out of 1/4" and I can always extend the stiffening plate, so I am not too concerned about this end.

[cumminsrover]

I need to flip the chassis to finish welding the buckets among other things, so that will have to wait a bit. I was also toying with the idea of Right Hand Drive vs. a CJ-7 box getting mounted in front of the breakfast. It would have made the track bar mount much easier, but then I'd have a hot foot all the time and may not fit in the clutch pedal due to the turbo occupying the same space in the foot well as the clutch pedal would.

It turns out my earlier mis-measurement that resulted in 2 extra inches between the back of the front bumper and the front of the wings which placed the front of the bumper at the same location as the front of the factory bumper instead of closer to the wings like I originally wanted was a blessing in disguise since it allows the CJ-7 box to fit exactly in the correct location when using a Scout II drop pitman arm (er, I designed it that way ) Pics of this will happen when that is more permanently affixed.

I also started reinforcements to the lower front link upper mounts. They'll look like the front spring bucket doublers, and I'll extend the gussets to the top of the rail. I'll probably also do a bit of reinforcement to the horizontal surfaces of the rails in this area. I don't want to end up with Buckon37's problem where the frame rail gets caved in. Plus I feel a bit retarded that I thought so many things through except for this one very critical part

Now I need to order a bunch of parts and schedule some of my remaining vacation time to do some more work

[RoverDan]

Lookin good man!

[aloharover]

Originally Posted by cumminsrover

Now I need to order a bunch of parts and schedule some of my remaining vacation time to do some more work

You are making a right hand drive?

[cumminsrover]

Originally Posted by RoverDan

Lookin good man!

Thanks!

Originally Posted by aloharover

You are making a right hand drive?

Unfortunately not... I contemplated it for a bit, but the engine is not offset enough to allow it. The turbo eats up some of the space alloted for a RHD clutch pedal, so it is not possible. It would have been cool, but since I did not plan for it from the start I am unable to change it now.

I do in fact have enough parts and chassis numbers to build an 88 next. SO the tentative plan for that (years from now) is right hand drive and either a Toyota diesel or something stupid like a turbo Hayabusa or ZX-14 motor, or if I find a sugar mamma or win the lotto then I would consider a Powertec V8

[aloharover]

So you just clamped the box on the inside of the passenger rail to compare the links?

[cumminsrover]

Originally Posted by aloharover

So you just clamped the box on the inside of the passenger rail to compare the links?

Yes, that is exactly what I did.

It actually turns out to be better to use the CJ-7 box on the inside of the frame rail at the front left corner for everything except the track bar. By using a Skyjacker SA-40 drop pitman arm for a Scout II, the CJ box can be mounted directly front to back, level, and tucked above the bottom of the bumper instead of exposed and at a funny angle like in the Jeep. I am also left with exactly enough room for a Warn 8274 between the box and other frame rail.

The clearance between the tie rod and drag link is perfect and the drag link is only at a very shallow angle. I have to drill the holes for my anti-crush sleeves and weld on the appropriate doublers in order to mount the box.

I am contemplating mounting the lower end of the track bar to the differential cover so I can keep the length and angle exactly the same as the drag link. The cover is 3/8" thick and has 10 5/16-18 bolts, though they are each 1/5th the strength of the track bar bolt. I am also planing on adding ram assist to the steering, so that should help unload the track bar a bit.

Maybe pinning the cover or adding a few extra bolts would be appropriate, though the optimal location would place the new holes directly in front of the axle tube....

Any thoughts on this?

[cumminsrover]

More progress. I need to adjust my links and move the rear axle back about 1/4 to 3/8 of an inch, but it looks like it will work well. These things look like they were made for 36" tires!

[cumminsrover]

Rear shock mounts mostly figured out. I still have to figure out how I want to strain relieve the chassis end of the mounts.

[cumminsrover]

Here is a better approximation of the steering box mount. I have started to drill the holes for the anti-crush sleeves, but I have yet to take a picture of that. I also need to go use my friend's lathe to make some proper spacers to go between the chassis and box. The drag link is going to be at about 5.5° at ride height.

[cumminsrover]

Here is how the tie rod and track bar fit at full steering lock. The air spring isn't inflated here, but I am certain there is enough room for proper articulation.

[cumminsrover]

Here is how the mount for the track bar worked out on the diff cover from Ballistic Fabrication.

[cumminsrover]

And here are a few pictures of the front axle articulating. I need to put something under the jack, because when the air spring is at full compression the axle will be about two inches higher which puts the end of the track bar about 3/8" from the chassis.

It is also time for another round of garage clean up. I still haven't figured out why I cannot put anything away. Perhaps I still hate putting my toys back in the toy box!

[RoverDan]

Lookin good man, just keep working. Don't worry about cleaning up the garage. A clean garage is a sign of a sick mind.

[cumminsrover]

Making some more progress...

The steering gear box mount has come together nicely. One pain in the butt with the rolled ERW structural tubing is the residual stresses make the tube change shape slightly when you cut it. Even though I very carefully measured and drilled the holes for my inserts I was unable to keep the relative position error between the inserts to any less than 1/32". So I ended up needing 1/2" holes to allow the 7/16" bolts for the box to bolt up. I guess that isn't bad for drilling horizontally with a hole saw!