High travel, high clearance & high octane, a streetable adventure LJ story

[Chris]

I was talking to ATS Diesel about putting 400hp into the 42RLE they said that (their's at least) can hold up to it but it NEEDS to stay cool or else it won't last. I didn't ask about 500hp, I also don't have the room to package the more efficient Magnum supercharger under the hood (the Eaton M90 was work enough as you can see).

My other concern is the transfer case holding up long term.

I suspect if you got a decent sized transmission cooler and weren't being a dummy when driving it (i.e. doing burnouts at every light), you'd be just fine. Heat is the number one killer of automatic transmissions, so I'm not surprised.

The transfer case would be a concern. However, the 241OR is apparently very stout. I was reading that it was deigned to go behind a Cummins diesel engine, which is why it is as robust as it is. So I'm not sure how much it can really handle, but I suppose you can find out.

What you need to do is get a water-to-air cooler for that M90 so you can run more psi efficiently. Without a water-to-air setup (or something to cool the charge), you can't run much more than 7 psi without it becoming extremely inefficient (this is my understanding from talking to Charles in-depth at least).

 

[toximus]

What you need to do is get a water-to-air cooler for that M90 so you can run more psi efficiently. Without a water-to-air setup (or something to cool the charge), you can't run much more than 7 psi without it becoming extremely inefficient (this is my understanding from talking to Charles in-depth at least).

The issue is where do I fit it? My trans and steering coolers are already in front of the engine radiator and I don't want those radiators laying flat on the bottom of the Jeep like Jerry has because we have enough dirt and sticks that it'd get packed up or punctured in a single day. If there was a very thin one I might be able to place it between the radiator and the fan.

 

[liquidfluidity]

Correct on the QT vs KT and KS

 

[Chris]

The issue is where do I fit it? My trans and steering coolers are already in front of the engine radiator and I don't want those radiators laying flat on the bottom of the Jeep like Jerry has because we have enough dirt and sticks that it'd get packed up or punctured in a single day. If there was a very thin one I might be able to place it between the radiator and the fan.

Yeah, that could be a problem. When I spoke with Charles about it, he said he had a number of people mounting them under the vehicle. Of course I don't know how much (if any) wheeling those guys were doing, so it's probably a moot point.

 

[toximus]

I'll get deeper into tuning the coilovers once I get to that point, but for now I want to briefly explain how they work and how they relate to air bumps. The coilovers are simply a shock with a spring over it so I'm going to be forgetting about the spring aspect for now and only discussing the shock aspect. A normal shock does not know where it is in it's stroke, the axle could be near fully drooped or near bump and the shock will behave exactly the same. Because of that, you can not make the valving soft when you're at ride height and harsh as you get near bottoming out. You can however make a tune that can be more or less harsh based on speed of the shock travel by using shims that cover valve holes when a lot of oil is pushing against them. Kind of like how a house door can normally be open but a strong gust of wind will push it closed. There are also bypass shocks that are position sensitive, but that's not what I have, aren't available in a 2.0 coilover, and are typically used only in racing applications.

By adding in air bumps to the last few inches of travel you allow the Jeep/axle to come to a softer stop than suddenly bottoming out the coilover. Bottoming out is not an issue for slow crawling, but can be more so on fast forest roads and open desert.

This video is for a different model of air bumps than I have but there's some good clips through the video that show how they work:

For my uses front bumpstops are optional especially since I have 14" of travel before bottoming out. Even less so than the rear since the rear does twice the work and they are optional back there too. I know of several heavier Jeeps using the coilovers as the hard limit just fine. Especially with the DSCs. The benefit is being able to blowing through travel when I want to drive aggressively without hurting the Jeep or my back. It will create a second zone of sorts without having to use a bypass shock. That will equal better performance. The downside is that they make a clicking noise as they work. If I find that they end up being annoying I can convert them to a TJ style jounce jumper at a later date but that will require retuning the coilovers since the tune in them will be dependent on having air bumps.

This video lightly explains the DSC reservoirs that are on my front coilovers (I'll also be getting them for the rear coilovers) and hopefully shows why the air bumps aren't as necessary to prevent the suspension from getting packed up:

and an article: https://accutuneoffroad.com/articles/how-fox-dsc-dual-speed-compression-adjusters-work/

Since I positioned the coilovers on the top of the axle tube, packaging ended up being a bit tight for the air bumps. On the driver's side the coilover wants to get close to the air bump and on the passenger's side I also have to deal with steering getting close. Having the track bar in the front 3-link also pushes the axle over towards the passenger's side.

I had to rotate the cans slightly differently on each side to clear the pinch bolts for the coilovers and steering. The position on the frame however is nearly the same location on both sides.

They are set so the air bumps bottom out 1/16-1/8" before the coilovers do so that I will still maintain maximum up travel.

The easiest way I found to make slight adjustments to the can position is to mark lines on the cans and use a leveling laser to mark the position and make adjustments based on that.

For the pads, I used a set from PolyPerformance (PPI-3121) (same pads as Kartek used in the rear).

On the driver's side the pumpkin is partially where the pad needed to go. It's 1/2" high off the tube and the bump pads are 1/4" thick so I welded a 1/4" spacer to the bottom of the pads to match the height and then frenched it into the diff housing. I will be filling in the dips with weld and grinding smooth to finish the pad off.

To test pad placement while cycling the axle to make sure the air bumps won't "slip" off the edge of the pads under articulation I used paper as mockup air bumps so the tack welds wouldn't break with the rear deal:

(the angles are starting to play mind games. I assure you that the cans are vertical.)

Because my frame isn't perfectly straight (or something... I've stopped trying to figure it out), both bump pads ended up sitting symmetrical on the axle. I wasn't expecting that since the axle is centered at ride height on the Jeep and is pushed over at full bump by the track bar.

 

[S.McArthur]

Forgive any ignorance, I have no clue and not about to act like I know, but from my motocross days and these types of external reservoirs, they should be away from heat; is that not as prominent in these?
Would they not build/change the pressure of the reservoir thus changing the desired performance?

 

[B00mb00m]

Thank you so much for your write-up! I joined the forum just for reply. I'm doing very similar savvy midarm with 2.0x12 fox CO + airbumps (if they'll fit) + hydro assist + genright hoops + highlines but with JK44 and 37s and your write up has been very enlightening and really the best thing to a coilover how-to for Jeep's that I've found.

Few questions: did you buy the track bar frame side brackets or make them? Also what wall thickness did you choose for the hoop stubs? Did you have to limit stroke for the steering ram (I might have missed that part). Do you have pics of track bar clearance at full stuff driver full droop passenger?

 

[toximus]

Forgive any ignorance, I have no clue and not about to act like I know, but from my motocross days and these types of external reservoirs, they should be away from heat; is that not as prominent in these?
Would they not build/change the pressure of the reservoir thus changing the desired performance?

There's no dumb questions. Is is best to keep them away from heat, however everything needs to package nicely under the hood too and this is the most convenient location. Fresh air will be coming in from the front of the Jeep and the reservoirs are very large so heat is not a huge concern since it'll have less effect on the large volume. If it ends up being a problem however I will find a different spot for them.

 

[toximus]

Thank you so much for your write-up! I joined the forum just for reply. I'm doing very similar savvy midarm with 2.0x12 fox CO + airbumps (if they'll fit) + hydro assist + genright hoops + highlines but with JK44 and 37s and your write up has been very enlightening and really the best thing to a coilover how-to for Jeep's that I've found.

Few questions: did you buy the track bar frame side brackets or make them? Also what wall thickness did you choose for the hoop stubs? Did you have to limit stroke for the steering ram (I might have missed that part). Do you have pics of track bar clearance at full stuff driver full droop passenger?

Welcome aboard! That was my hope when I started this thread.

> did you buy the track bar frame side brackets or make them?

Hand made. Once I figured out the placement I needed with scrap, I notched a sheet of cardboard to match the frame, I then traced the hole location onto that cardboard and drew what I wanted the bracket to look like and scribed it onto the metal for cutout.

> Also what wall thickness did you choose for the hoop stubs?

I matched the wall thickness of the hoops and used large enough ID so that they'd telescope.

> Did you have to limit stroke for the steering ram (I might have missed that part).

Yes. I wrote about it in this post and a little in the post above it about the reasoning: https://wranglertjforum.com/threads...e-adventure-lj-story.9956/page-22#post-391201

> Do you have pics of track bar clearance at full stuff driver full droop passenger?

I'll try and remember to take a few for you the next time I cycle the suspension.

 

[B00mb00m]

I didn't see you describe how you set your ride height measurement? I consulted with Blaine yesterday on how to do that and definitely more involved than I realized. Accounting for rake, supporting frame correctly etc. So far that's the only hole I hadn't been to fill from your write up.

 

[toximus]

I didn't see you describe how you set your ride height measurement? I consulted with Blaine yesterday on how to do that and definitely more involved than I realized. Accounting for rake, supporting frame correctly etc. So far that's the only hole I hadn't been to fill from your write up.

The ride height is just something that you're going to have to choose. I based my frame height off of a 4" lift with 37s. My frame height also is the cause of my up travel hard limit with the Dana 60 since it wants to go through the engine. It ended up being just about perfectly where I wanted it from the beginning. If I wanted to get more up travel I would have to raise my frame.

I'm sure you'll be interested in this thread: https://wranglertjforum.com/threads/what-is-your-nominal-ride-height.16717/

My concrete is nearly flat in the spot I placed my Jeep and I just set the jackstands to hold the frame at the height I wanted. That all comes down to preference. You can use concrete anchors, small jack stands, big jack stands, etc.

Rake is something that can be adjusted with a few turns of the coilover preloaded nuts in the rear once the Jeep is on the road. I wouldn't put too much thought into rake at this point.

I encourage you to read my build thread on Jeep Forum and Pirate since there are different questions and conversations on each that might be helpful to you.

I'm behind on posting, but from where I left off to finish my build I did gussets on the front, modify the steering box, finish electrical (not all something you will need to do), cram everything under the hood, and figure out a fuel cell. That's the summary of what's coming and I'll keep documenting it for you to follow.

 

[S.McArthur]

There's no dumb questions. Is is best to keep them away from heat, however everything needs to package nicely under the hood too and this is the most convenient location. Fresh air will be coming in from the front of the Jeep and the reservoirs are very large so heat is not a huge concern since it'll have less effect on the large volume. If it ends up being a problem however I will find a different spot for them.

Good to know, I would assume since you wont be high speeding open country, it will not have as much as an impact. I'll still be interested to see if there are any adverse affects.
Good luck, I'll see myself back to my seat.

 

[toximus]

Good to know, I would assume since you wont be high speeding open country, it will not have as much as an impact. I'll still be interested to see if there are any adverse affects.
Good luck, I'll see myself back to my seat.

You're correct that I don't be doing open desert often but when I am I do hope to stick with the group. I'll post some updates as I drive different terrain and how things work.

 

[B00mb00m]

The ride height is just something that you're going to have to choose. I based my frame height off of a 4" lift with 37s. My frame height also is the cause of my up travel hard limit with the Dana 60 since it wants to go through the engine. It ended up being just about perfectly where I wanted it from the beginning. If I wanted to get more up travel I would have to raise my frame.

I'm sure you'll be interested in this thread: https://wranglertjforum.com/threads/what-is-your-nominal-ride-height.16717/

My concrete is nearly flat in the spot I placed my Jeep and I just set the jackstands to hold the frame at the height I wanted. That all comes down to preference. You can use concrete anchors, small jack stands, big jack stands, etc.

Rake is something that can be adjusted with a few turns of the coilover preloaded nuts in the rear once the Jeep is on the road. I wouldn't put too much thought into rake at this point.

I encourage you to read my build thread on Jeep Forum and Pirate since there are different questions and conversations on each that might be helpful to you.

I'm behind on posting, but from where I left off to finish my build I did gussets on the front, modify the steering box, finish electrical (not all something you will need to do), cram everything under the hood, and figure out a fuel cell. That's the summary of what's coming and I'll keep documenting it for you to follow.

Ah yes I have a little less flexibility to rake due to I'm only doing COs up front.

I will check out the other threads, I'm most interested in how you fit everything under the hood especially with SC in there! Like where you put compressor and airbox.

 

[toximus]

Ah yes I have a little less flexibility to rake due to I'm only doing COs up front.

Arguably, if I was only doing coilovers in the front or rear, I'd choose the rear so I could get the rear really dialed in.

I will check out the other threads, I'm most interested in how you fit everything under the hood especially with SC in there! Like where you put compressor and airbox.

It's going to be tight. I haven't gotten to it yet but I know it's going to be tight...

 

[toximus]

I'm doing very similar savvy midarm with 2.0x12 fox CO + airbumps (if they'll fit) + hydro assist + genright hoops + highlines but with JK44 and 37s

I'd also suggest skipping the airbumps. They aren't necessary and you'd be better off spending that money and time on something else. However, you'll have no problem fitting them.

Do you have an LJ or a TJ? If you have a TJ, you'll be leaving performance on the table with the stock wheelbase and 37s.

 

[B00mb00m]

I also have an Lj. I am doing COs because I had to fix my steering and do it right this time with full length trackbar, first time I hired a guy and I couldn't weld, and COs give lots of room for the track bar and give more flexibility during setup and for tuning.

I already have the bumps just doing them for forest road travel which is when I have been on bump stops in past even in my taco I used to have. I don't think there's any negative to them, and I'll run them as low pressure as I can just act like you describe as a bit of position specific damping.

 

[toximus]

I also have an Lj. I am doing COs because I had to fix my steering and do it right this time with full length trackbar, first time I hired a guy and I couldn't weld, and COs give lots of room for the track bar and give more flexibility during setup and for tuning.

I already have the bumps just doing them for forest road travel which is when I have been on bump stops in past even in my taco I used to have. I don't think there's any negative to them, and I'll run them as low pressure as I can just act like you describe as a bit of position specific damping.

Gotcha. It sounds like you're going to have some fun building! Keep us updated on your build.

 

[xxdabroxx]

Why do you say the back is more important than the front? Are you talking shock valving or suspension geometry?

 

[toximus]

Why do you say the back is more important than the front? Are you talking shock valving or suspension geometry?

There will be no difference in suspension geometry if the same linkages are used (in his case, Savvy 4-link rear).

The rear suspension does twice the work the front does and regularly uses more travel on road and off road. So the rear would (again, arguably, as it's highly dependent on what else is going on with a particular build) be the best bang for buck location to dial in if you could only afford the front or rear. Similarly on a coil and shock setup, if you can only afford to outboard the rears or raise the front towers you'd get more bang for buck doing the rears. (I plan to take a video showing the rear doing twice the work but I haven't found an ideal location yet where it can be clearly filmed.)