Rfoley22 Un-conventional Suspension Upgrade Project

[Rfoley22]

Hi all.
To begin the truck is a 1992 4.0L V6 4door XLT 4X4, it's had an Auto-5-Speed swap, and a couple other modifications, however the suspension and axles are stock (and 20 years old).

My Goal is to turn this stock suspension into a performance suspension that can take 36" tires, and handle (not necisarrily dominate) tough truck course terrain. It currently bottoms out on small dips and yea...

The theory:
#1. Rear SOA and new or added springs. this with trimming should fit the tires.
#2. Front fender trimming and an un-conventional front suspension using leaf springs, a weak coil, and maintaining the stock two piece axle.
#3. Performance Shocks. 36" tires and gear ratio upgrades.

I myself am 20 and will be in school full time for the next two years so money is an issue. I however have ample cheap used parts. The performance shocks and tires will be bought new and nice once the rest is complete... might be a long project.

 

[Rfoley22]

The front suspension will be the first thing I want to get feedback on.

The idea is a leaf spring that mounts where or about where the coils do now.

A leaf such as this design now used on newer rangers f150s and many other cars, here a GMC picture:

Things that need to be accomplished,
1.mounting spring to frame above the axle
2. moving brake lines
3. moving shock mounts
4. deciding on if to also mount a weak coil in the middle for extra absorbing of impact.
5. determining if drop brackets are needed and getting individual parts for the drop to avoid buying a $1000+ lift kit.

The leaf springs would support the weight, the coil would add pressure when leaves are 4-6" compressed such as when landing a jump. This is similar to the second leaf springs appearing on new full size trucks, basically replace the 2nd leaf spring in the diagram above with a coil.

This would then be mounted to the two piece axle rather than a solid axle. I prefer a 2 or 3 piece axle for drifting.

Any comments, ideas? diagram/sketch coming soon.

 

[IZwack]

If you are bottoming out on jumps, the simple solution would be to get stiffer shocks, or shocks with a more progressive rate, or adjustable shock. Maybe even add a gas-charged "bump stops":

.

 

[Rfoley22]

To elaborate, I'm bottoming out in front on small dips, slight depressions in the road, etc. Not even attempting jumps yet. the stock springs are completely sagged, 1" travel axle to stops in front, 2"driver and 4"pass in back.

Replacing the springs is maybe not a must, but is IMHO easiest. stock springs would be easier replace, but why do the work if not to get something more fun than stock.

Shocks are only 2-3 years old and aftermarket.
Of note, when inspecting shocks I climbed into the truck without them on, and my weight bottomed out the springs, that is how bad they are.

 

[IZwack]

Well the front is an easy fix it sounds like.

shocks are only 2-3 years old and aftermarket.

That doesnt really say anything about the quality or performance of the shock. You can have a brand new shock and still bottom out the suspension if its not "tuned" to the working conditions.

And if you are talking about doing a spring-over-axle (SOA) conversion: I'd stick with the spring-under axle (SUA) setup and go with a leaf pack with more arch (and less spring rate to decrease the ride height and decrease CG) because going SOA only limits the vertical travel before hitting the bump stops. WIth SUA and a spring with more arch, you would increase the axle's vertical travel between full droop (air time) and full stuff (landing) - this then would make the landing less "harsh" as the time for the kinetic energy to be "absorbed" is increased.

Basically, what you are aiming for is a setup for the desert but the modifications you described sounds more like a setup for rock crawling or trail rides.

 

[Rfoley22]

Well the front is an easy fix it sounds like.

The front is 1" from hitting the stop, it needs new springs of some kind and I'd like a slight lift without the $1000. It needs either air bags and coil spacers or some sort of change in spring. it needs something because it should not be 1" from the bump stop, even a air bag will not change the 1" of travel. It only can travel upwards one inch before bottoming out.

The front is currently coil springs, and I am considering going to leaf springs

And if you are talking about doing a spring-over-axle (SOA) conversion: I'd stick with the spring-under axle (SUA) setup and go with a leaf pack with more arch (and less spring rate to decrease the ride height and decrease CG) because going SOA only limits the vertical travel before hitting the bump stops. WIth SUA and a spring with more arch, you would increase the axle's vertical travel between full droop (air time) and full stuff (landing) - this then would make the landing less "harsh" as the time for the kinetic energy to be "absorbed" is increased.

The rear is planned for new springs with more arch, however 36" tires do not fit with just new springs, a SOA is a cost effective option to help make up that difference.

 

[Rfoley22]

Also to clarify, I have not jumped my explorer yet, it is not driving on courses.

It is bottoming out on STREETS, on every dip at 5MPH, every slight depression at 5MPH. not on jumps, not on trails. In front it bottoms out on the outside when I turn corners at 10MPH.

 

[MrQ]

Quick advice for you, my friend. DO NOT ATTEMPT to jump this truck without having every bit of suspension set up properly. Don't forget the radius arm bushings. Once those die, stopping that truck without getting a BANG!! is very hard to do. Listen to what these guys say and be careful.

Believe me I jumped stock and it was a thrill!! But due to the bad maintenance of the previous owner, stuff that probably needed to be taken care of in 5k miles turned out to become problems immediately. Doing things like that is very hard on the truck and is a very expensive past time. I suggest you wait till you are out of college to attempt any long term project.

As for the immediate problem of bottoming out...

You can get leaf spring helpers and put them on temporarily till you get the money to do the leaf pack right. Shocks alone won't help. You will wind up killing them very quickly as all the weight starts to ride on them.

 

[Rfoley22]

Quick advice for you, my friend. DO NOT ATTEMPT to jump this truck without having every bit of suspension set up properly. Don't forget the radius arm bushings. Once those die, stopping that truck without getting a BANG!! is very hard to do. Listen to what these guys say and be careful.

Yes. thank you. I have and will not jump until it is ready. doing so would be painful at present.

percisely why I would like to upgrade from stock, and why air bags will not work to help me.

As for the immediate problem of bottoming out...

You can get leaf spring helpers and put them on temporarily till you get the money to do the leaf pack right. Shocks alone won't help. You will wind up killing them very quickly as all the weight starts to ride on them.

The FRONT coil springs are the 1" till bottoming out. Shocks alone will not help here either. The back is still 2" from drivers sag and passenger 4" so it is not as bad, but also needs more than shocks and air bags.

As for school studies come first. Thank you for the advise, it is well heeded. I'm going to school for airframe and powerplant maintinence so I will have extra time after school. If I'm not working on mine I'll be working on other people's in my free time, it's what I do. Studies first, car second, that's why it might take awhile.

 

[IZwack]

As I understand it, tough truck is one or two laps around a "stadium" type track setup. I think 33s or maybe even 35s would be plenty here and keep the CG low for the turns.

 

[Rfoley22]

There is also a 15 mile, 50 mile and 150 mile version. 36" tires will help raise my pumpkins. I will do alot of trimming to avoid a large lift, and keep the CG low.

I could keep 30" tires, I could even step back to 25" tires, however just as I do not wish to keep the stock springs I would like 36" tires.

Racing is not my focus or goal entirely. A performance vehicle that is cool is really my goal. I'm no race driver. I don't want to take baja courses at 90mph, I only want to start by driving the streets comfortably and also be able to take baja terrain at 15mph? at least to start

 

[MrQ]

I wasn't meaning to lecture. I apologize if it came across that way. My intent was just to sum up my experiences. I didn't want guys jumping on a project rig without thinking out all the details...as a matter of fact my truck is still only at a 70% driveabliity rating - and I have yet to get off my butt and enroll for college.

 

[4x4junkie]

I would stick to 33" tires for that kind of use.

As for leaf springs on a TTB, don't do it. Leaf springs aren't compatible with the TTB's movement (the TTB axle wants to move in an arc, whereas a leaf spring moves in a straight line up & down. The result is binding (yes I know Ford did it on F-250s, doesn't mean it's right though).
Keep it coils.
If you want a good stiff coil, Superlift's seems to be about the stiffest. And IZwack is correct, better shocks do help control bottoming out, though it's true you would need to get some clearance between your bumpstops and the axle first.