Jeepspeed Style with Coilovers and Long-Arms

I posted this in my local chapter forum, but I'm looking for some advice on suspension settings...

http://www.naxja.org/forum/showthread.php?p=244571380#post244571380

damn that thing is sweet!

Nice find...

Jim, where you at.

more pics of the engine cage?

tcm glx said:

Nice find...

Jim, where you at.

Click to expand...

mad...

J/K... those 2.0's? How does she ride? I'm currently in the process of doing this right now, waiting on my Bilstein prototype's to show up

Is it me or does it seem like that engine crossmember/brace is a bit big and might get in the way of up travel? Couldn't they have made it out of tube and kept it a bit lower in profile?

you mean the lower brace that pictures somewhere on the second page?

Yep. The lower one. sorry, I was at work and it made sense to me at the time. haha

i was like what? the upper one lower? LOL hmm maybe but i think it is working so far

Working and limiting are two different things. On a jeep the motor (oil pan) is already in the way for getting good up travel numbers without a huge lift. That seems like it would not help at all.

Thanks for the replies, everyone. Just getting it dialed in now. The steering brace that goes beneath the engine was done back when I had a 4.5" RE lift and the steering box was flexing the unibody around it. That was put in to keep the area solid. It goes directly across in line with the track bar mount... I don't think it's been contacting the track bar at all, but I want to lower the rig an inch or so in the front so I hope it doesn't cause issues then.

As for the ride, it's rough right now. I've never set rates on coilovers or air bumps, and I stressed the importance of not contacting the Bushwackers at full compression to the installers, so they set me up for a hard ride. Here are the stats:

- 300/250 lbs coils for the coilovers
- 150 lbs for the front shocks
- 90 lbs for the rear air bumps, about 1/2" from contact plate
- 100 lbs for rear shocks
- RE Super-Flex 4.5" pack received an add-a-leaf

Any thoughts on better rates for a softer ride that won't pop off the Bushwackers...? I can change out the springs for free, so that's not a big deal. Just curious what you guys are running.

Here are some pics I just took...

As you can see, the under-engine cross-member is directly in line with the track bar mount.



Passenger side shock hoop area (not a great shot because there's so much crap packed in there).



Driver's side shock hoop area. The engine cage and bumper are flanged so they can come off.



Driver's side coilover.



This is how we fixed the steering wheel's 1/4 turn dead spot: we put some thick rubber washers with metal centers on the bushings at each side of the tie rod (it's the piece that flares out on the bottom). I heard about this on the forums, someone said people will slice sections of the RE track bar bushings to do this for 1 Ton steering setups. It fixed my issue:



Let me know if you have any more questions or want more pics. I can get higher quality pics too if you're interested.

Any thoughts on the spring/shock/bump rates? I could really use some expert advice... thanks!

You could weight your rig and contact Fox and get their opinion. They would probably be able to help you most if you could give the front and rear weight (corner weight even better).

Is the ride stiff in the front or in the back?

The back sounds really stiff to me, with an add-a-leaf added into a nice RE spring pack and the bumps only an inch off the pads. I'm assuming from this that the bumps are 4".

If the front is stiff it's from the shock valving, what do you have?

Thanks for the reply, Goatman. Sorry for the delay.

I changed the front shocks down to 135 lbs of pressure with the 300 and 250 lb springs, which feels nice. I'm low and compress all the way down pretty easily, so I probably need to get some bumpstops up front as well. But unless I go over somethig fairly big, there's no metal on metal contact.

The rear rides about 1/2" off the bumpstops on both sides, and yeah it was really rough at first with the RE spring pack + AAL. The AAL has softened after some light runs (no jumping yet though), so I would really just call the rear a "bouncy" ride at this point. With 4 people in the vehicle, it smoothes out a lot and there's no audible thunk when contacting the rear bumpstops. They're at 75 lbs of pressure now (yes they are 4"), and the rear shocks are still at 90 lbs.

The vehicle flies on the road, got it up to 90 on the freeway and I've gotten all of the steering play worked out. I'm really surprised at how well it rides over street bumps at that speed- the suspension, tire size, and long arms really soak it up well. I also get about 13/15 MPG for city/highway driving, so I have to say it works well for everything I want at this point.

One thing I had not thought about was airing down the tires to get full tread on the ground when on the street. I used the chalk method and since the tires are 35x12.50's on 15x8 rims, I'm running at about 25 PSI for the front and less than that for the rear (like 22 I think). Still feels safe on the road, and I'm almost touching ground all the way across the tread, although not quite. I'm open to hearing arguments for safety on those levels, so hit me up if you think it could be hazardous. I couldn't find anything stating it was in the forums.

The pressure in the shocks doesn't do much to change the ride unless you have too much pressure and are feeling some sticktion of the seals....doubt it. The shock air pressure is to minimize cavitation and shock fade, not for spring rate.

You can't tell anything about valving and spring compression by flexing the suspension. There is a huge difference in compression forces between trail articulation and hitting bumps at speed. If you can bottom the suspension while flexing then the springs are way too soft for going fast. The only way to check for clearance when the suspension bottoms is to remove the coils from the c/o's and air from the bump stops set the rig down on the shocks, full weight till the shock or bump stops bottom out, then see if anything is hitting.

Also, if you can compress the front while flexing, you can change the secondary adjustment collar on the c/o's so the secondary/bottom spring comes in sooner to resist bottoming. The 250/300 springs give you a 136 lb initial spring rate, which is pretty soft for an XJ, so it should ride really well over the small bumps but should hit the secondary 300 lb spring pretty quickly, I'd say no more than 2" especially without bumpstops. In the pics I don't even see the secondary collar, so you may be at 136 lb/in for most of the travel which would be soft and it would bottom easily. Also, you can't go very fast without some bumpstops in the front, you could have ordered the shocks with shaft bumps which would have been fine.

In the rear I don't understand why the shop installed an add-a-leaf to protect the Bushwackers. The position of the bump stops determines the bottoming point and protects whatever would be contacted, so increasing the spring rate to do the same is kinda dumb. To be able to go fast you want the rear spring rate lighter, and you have the bumps to control bottoming. I'd loose the add-a-leaf and add a little air to the bumps until it only bottoms the bumps on the hardest hits. But, if you only have .5-1" before hitting the bumps even with the add-a-leaf then the bumps are mounted too low and it wouldn't give you much rear travel with the extra leaf removed. Doesn't sound to me like the shop that did the install set the rear up very well, unless there's something I'm missing. If you're limiting uptravel to protect flares, and want to be able to go fast, then I'd loose the flares (but that's just me ).

This is pretty similar to what i'm building, Goatman is on the money with his ideas. Check out Dezertrangers they have alot on shock set up and dirtsports and offroad have some good co and bump articles also. Looks nice I think once you get it dialed you will have a really sweet ride.......

Thanks for the replies, guys. I guess I may need to look into some shaft bumps for the front... doesn't that defeat the purpose of 14" springs though? Also, Goatman, do you think a 300/350 mix for springs would run better? I know lifted spring rates are around 140-165 lbs, so maybe a little higher initial rate would be better.

The rear is getting the 2" bump-stops soon to replace the 4" ones, which will ride much better I'm sure. As for the AAL, the concept was to just ride on this leaf pack until I get a Deaver set, but I am waiting for the rear bumper and internal cage install before getting the Deavers so I know the weight is correct.

Thanks for the replies!

HollisM16 said:

Thanks for the replies, guys. I guess I may need to look into some shaft bumps for the front... doesn't that defeat the purpose of 14" springs though? Also, Goatman, do you think a 300/350 mix for springs would run better? I know lifted spring rates are around 140-165 lbs, so maybe a little higher initial rate would be better.

The rear is getting the 2" bump-stops soon to replace the 4" ones, which will ride much better I'm sure. As for the AAL, the concept was to just ride on this leaf pack until I get a Deaver set, but I am waiting for the rear bumper and internal cage install before getting the Deavers so I know the weight is correct.

Thanks for the replies!

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Bumpstops are bumpstops, they must be fully engaged before your shock bottoms no matter what. The easist way to make sure the bumpstops are in the perfect location is to put them on the shaft of the shock. Most bumps are going to compress nearly all the way on the biggest hits, so that 3" tall poly bump is going to compress down to 1/2", whether it's on the shock shaft or independant. You don't loose travel because of the bumpstop.

I wouldn't go more than the 250/300 springs you have now, just play with the secondary adjustment collar. When I tuned mine for the first King of the Hammers race I had 12" coilovers in front, and only had one inch before hitting the secondary rate, it still rode very smooth on the small bumps. Normally I had 2" before hitting the transition collar. If you decide you'd like to try stiffer springs, go with 250/350, which will up the initial rate only slightly but give you more secondary rate to resist bottoming.

Travel is great, but tuning is more important. Paul S, Dave Taylor, and I have the fastest XJ buggies in the desert I'm sure, as far as suspensions go, and all three of us run 12" shocks in the front. We've seen that the Jeepspeed rigs are faster than nearly all of the KOH buggies and the Jeepspeeds are limited to 10" travel in front and 12" in rear. It's more than just travel, it's how you use that travel.

:cheers:

Aren't regular lift coils in the 225-250lb/in neighborhood? So using that 250 as the main spring should be pretty good, or 300 would be a fair amount stiffer.