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1 ton swap with 40s and 4 cylinders

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6K views 18 replies 5 participants last post by  pushcoguy  
#1 ·
I made a post asking about the practical aspect of running 40s on a 2.5L 1998 TJ… and after all the feedback realized it was a terrible idea. So here we are following through with a terrible idea. I believe this is the most relevant spot to post the build as it is currently full steam ahead and here are some photos of progress!

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Day 1 started at 3AM on a Sunday with a broken rear axle shaft and the tire sliding right out (Thank you C Clip :((( ).
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Made our way onto jackstands and removed axles, interior and gas tank.
 
#2 ·
Moving on we had to remove the front fan shroud, radiator and grill because there was 1 bracket causing a ton of trouble that was made of cast that needed removed. That brings us to where we are now. This weekend will be removing the rest of the brackets and on to frame plating in the front and cutting off the back of the frame for a motobilt back half kit!
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Ended up with 9 total 40” tires and 5 rims… whoops!
 
#3 ·
Wow! Looks like a fun project to follow.
I have broken a rear axle, but it was nowhere near that spectacular. Was one tire on wet pavement and the other on dry while accelerating?
 
#5 ·
Today we finished cutting off all brackets on the front of the frame which is really 20% of the build complete! For those who want to do this on a similar Jeep be advised the pandhard bracket is made of cast… that is not at all fun to try and cut off but the battle was won!

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Tomorrow we finish grinding down the frame for plating since steering is very likely to peel back the standard frame.
 
#6 ·
Last weekend/beginning of this week hammered out the custom frame plate on the inside and outside of the driver side frame and secured the passenger side (just needs to be fully welded).
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along with this, there were 2 frame plates made for pass. and driver side inside of the frame for a custom transmission/transfercase crossmember. The crossmember will be made this weekend and will be where the link mounts will be installed.
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finally, for the first time after installing new ball joints the axle was able to be placed at absolute full stuff under the Jeep in preparation for steering. Unfortunately the stock radiator is not going to work so I will be purchasing by recommendation a custom sized radiator (Griffin Universal Fit Radiators 1-26241-X this is the part from summit for those interested) and will be attaching a Volvo 740 electric fan to it. Any other suggestions are always welcome!
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#7 ·
This is a little awkward posting so closely to my last but I just realized I skipped every part about cleaning the stock front axle pulled out of a 2011 Ford F-350. Anyways… we did not take the rear because unfortunately there are not any companies (at the time of purchase not sure about now) who made 5.38 gears for the 2011 and up so be aware of this for those looking at 2011 and up specifically rear axles from F-2/350. So when in Utah at trail hero I purchased an already trussed And geared rear axle that has not been touched yet lol
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Now to the front axle… EVERY SINGLE cast and mount was removed/cut off down to just the tubes and pumpkin. I highly recommend the Barnes low profile truss which is what is used on this axle and is extremely small and has allowed for incredible stuff at full bump.
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The only other note is when heating up the center section for welding on the truss… try to remember to put thermometer to your degrees that you understand. On the first pass we accidentally heated it up to 400 degrees… as it should be only to realize the welds were practically melting. That is because 400 degrees Celsius is over 700 Fahrenheit… oops! Lesson learned though and finished welding and I am very happy with the outcome. An acetylene cutting torch was used for heating but can technically be done with a normal butane torch…
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#8 ·
Last night was fun! Out of town for work is no excuse to not work on the jeep apparently so I spent a few hours learning the custom bracket design based off of a vehicle built by StellarBuilt in Sacramento. The only hard part is going to be having the attachment points offset due to frame curve (the front section where mounted is a different frame to frame length than the back section). A little confusing but either way here is what was designed and yes it is held together by a meat stick I had no bolts in the hotel…
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#10 ·
Big time progress weekend on the links and crossmember! The crossmember brackets were able to be fabricated without harm to more meat sticks thank goodness (although 1 or 2 may have been consumed). The mockup looks very similar to the original just with different dimensions that are frame fit and the most difficult part was figuring out how to make it straight with the curvature of the frame.
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How does one find out if they made things right and didn't just waste a lot of time material and money? Well, the 2x4 piece of metal that goes inside these brackets should fit assuming everything is straight and level. FIRST TRY!!!!! Maybe the sacrificial meat stick saved the day?
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Here it is in all of its straightness and form fitting glory! Now why did we do this? As you can see there are some cute little brackets mounted to it that will house the lower and as pictured later the upper link mounts. This will allow for straight link mounts in optimal position for maximum stuffage of the axle. (Don't think that's a word but I'm going to roll with it).

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As you can see the mounts were burned in including the upper link mount and PVC was added to check for clearance. PVC is the cheap way to be able to cycle and test, and retest and one more time retest steering and links before purchasing links from the metal shop and going all in. I am not very wealthy so I like to spend $30 to save myself $300 in mistakes later. The next photos are just preliminary link mount locations on the axle side as they are still a bit crooked and subject to change but will only change in 1/4" at MOST increments from here so I can confidently say we are 90% done with the front links.

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My next post will be final axle side link mounts and the preliminary (hopefully) full steering setup with a you guessed it, Toyota 80 series steering box! I will catch you all up next week!!
 

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#12 ·
Wow... this weekend was a little bit wild if you will. There were a lot of clearance issues with how incredibly stuffed the axle was with the panhard bar estimated routing and the pitman arm on the steering box/drag link. The only thing that seemed to fit was the track bar. SOOOOOO instead of using brain power to solve these issues well... bye bye frame :). (Side note we decided to go with the song beer for my horses to help the process along).
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ACTION SHOT WHATTTT!!!!
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Alright well now that the frame is gone what in the world could come after? Well why not raise the axle 2 and half more inches and remake some frame obviously. Unfortunately we had to say goodbye to the awesome shaped frame plates but now we can just cut some clean ones out for the new and improved frame! We went extremely simple... up 18 degrees then shoot straight back across at about 0 degrees.

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This weekend will be making the new frame plates for inside and outside AND top of both new frame rails as I would hate to bend my clean title frame! Bonus photo included of what full stuff in the front is shaping up to look like! As wide as it is... two inch wheel spacers are necessary to clear the high steer arms so just imagine an extra little bit of width if you could.

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Thats it for this week... not nearly as productive as hoped BUTTTT with this change being done every steering component will fit with much less bending and the links will fit perfectly into place with just lowering their location on the axle side. Any questions comments and concerns are always welcome! Til next week :)).
 
#13 ·
Ok... It's been a month since I dropped anything in here and to be honest it's because a lot of frustration and steps backwards had me feeling a bit discouraged in our progress. However, despite that we have officially got all steering and links tacked into place and I couldn't be happier with how clearance is. Nothing is hitting or causing any problems bar a 3 inch section of frame the driver side lower link mount bumps which is a simple task of grinding the frame away till there is no contact.

So, let's reverse to where we left off very quickly... steering has been the biggest challenge as we are using the Toyota 80 Series box as mentioned which is an outside frame mount box with a forward-facing pitman arm. This created a bit of a challenge with how to mount the pan hard bracket on the frame side. Luckily, we had access to a plasma cutter and were able to recreate an idea from one of the fabricators at Stellar Built and create a bracket that seamlessly fits in tucked against the steering box.

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Outside of this we spent the last month plating the new frame we installed, trying different orientations of steering in the high steer arm and drilling in the holes for the steering box. All of it seemed like we weren't making progress just 2 steps forward one step back. All of this was necessary though including remaking lower and upper link mounts for the axle because finally we got the links at the right lengths, and all the steering pulled together to start cycling suspension!
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To get into the details... our pan hard bar is the EXACT same length as the trackbar. Hypothetically this should eliminate all bump steer which would be quite exciting since this will be driven on the freeway. Along with this our angles are virtually the same with these 2 and at this point we are expecting ride height to be 6" higher than ground level with a belly height of around 20". We will be using the PSC hydro assist because we have about 9.5" of steering and the steering rams from surplus center cap us out at 8 so unfortunately the budget build is getting some not so budget parts. Here's a few more photos of what the steering setup looks like including the steering linkage because we were able to connect to the steering wheel using the borgeson universal joint that connected right up to the stock jeep steering shaft and I was pleasantly surprised with how easy it was.
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Any comments suggestions or questions are always welcomed and will be back hopefully with shock towers, bump stops and hydro assist in the next 2-3 weeks!
 
#15 ·
All right… My bad it’s been two months. I know I said in the next week or two, but things got a little wild changing jobs, birthdays, and a short moment of being burnt out I’m gonna make two posts tonight this one as a catch up, and one more as a current. So without further ado, let’s take a look at the completed front end.

Passenger side bump stops and shock mounts in.

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Driver side chaos

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Hydro assist sneakin right in

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Final weld of front axle.

Now I must confess. My name on this form is a lie. I am still going to be running the stock 2.5 L jeep engine and drivetrain (plus a doubler kit for transfer case). But I will not be running 40s. I know, embarrassing. But I will be running 42s! Because a good friend told me “42s can’t lose“. So I will continue with the back half of the frame being chopped off in the next post since I am out of photos almost. So enjoy these last two.

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Girlfriend bought me a sweet sign for the garage!! <3

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42s on her…
 
#16 ·
Now... the back half of this Jeep is coming along swimmingly with some new found inspiration to git er done. That middle portion was a bit rocky just so tedious doing the same testing day in day out to make sure everything fit and cycled properly and to be honest I was getting a bit discouraged but we got through it and moved on.

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Bye bye back frame am I right???
Continuing, we decided after doing our own custom front frame, with the body mounts still needing to remain, we would use the Motobilt backhalf frame and bumper kit. This came in 5 pieces to be assembled on the vehicle and was relatively straightforward!

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Now onto the fun stuff. Installed, as seen, the Barnes four-wheel-drive, low profile truss. Our biggest concern was because this is still a Jeep, although just barely, the frame could not go as high in the rear as the front. This is because there is a tub in the way. And yes, I would love to run a tube chassis with no tub, but then I would be completely giving up the Jeep bill. On that note, we threw the axle at full stuff with the ruffstuff upper link mounts. This was not going to work much like the rest of the axle side mounts on the front. This is because they mounted to the top of the truss so we lost 3-4 inches of potential stuff, ride height lowering and therefore uptravel. So our pea brains got to work at 11:30 on a Friday night and came up with a solution. If we can have the top of the heim be as close to level with the truss we can gain back that 3-4 inches. And believe it or not we pulled it off looking something like this.

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And that brings us to as current as possible. We have got our measurements to order links for this and will hopefully have those in with shock towers to begin cycling suspension by this weekend. I am sorry for abandoning this forum once again but I promise to do better in the future (potentially).

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Don’t the 42s just look so good?
 
#17 ·
Yes, yes they do. Also, great job on the welds. Just curious, what does one of those 42's weigh?
 
#19 ·
Man! So, I had this happen to me... but it was stupidity, not the "C" Clip that was at fault. I don't expect you to believe it, but I drove home on that. My buddy was hanging his head over the rear fender telling me which way to steer to keep the dang wheel and axle in place. We made it! It wasn't a perfectly straight road, but it only had to hard turns in it...and only one of them worked against us. We put a new shaft in it a week later.