Spring over VS spring under- pros and cons- Toyot Sunrader RV (1 Viewer)

[extremetoy1]

Spring over VS spring under- pros and cons- Toyota Sunrader RV

I know this isnt real hardcore but I wanted to put this in an area where more people are doing other things than just simple lift kits etc.

I could have posted int he 60 or 40 series section since they are spring under but this is for a mini truck so I figured here would be a good place for a question like this.

I am putting an FJ80 axle under a Toyota Sunrader RV (pic in the Expedition builds and 79-95 section) the question I have is what are the advantages and disadvantages to using spring under other than the obvious of ground clearance?

I have seen older toyota desert trucks use spring under for racing for whatever reason and I do realize you need more arch to put the axle on the topside of the springs to get the same amount of lift- would it be advantageous for me to do it this way and why?

I am wanting this to be as roadworthy as I can and have some offroad capabilty but stability, and handling are my first priority here.

thanks for any input you may have

 

[StevoJonesFJ60]

The main reason why people run spring under for racing is due to the fact that axle wrap is better controlled in a sprung under vehicle. If you have a 22R or 22RE I wouldn't be too concerned about this. However if you have swapped in a more powerful motor and decide to spring it over you should consider using some sort of axle wrap controlling setup.

 

['74 UA FJ]

If you are after on road handling, go spring under.

 

[Slowerthanu]

Spring over is standard on a mini truck, just stick with it. It works just fine.

 

[extremetoy1]

this thing weigh 3 times what a mini truck weighs, thats why any additional stability or anything to increase the on road handling for the better is why I would want to do it. if it were "just" a mini truck then I would go that route.

even the rear is spring under, why not do the front the same.

 

[cruiserjunkie]

Spring under will work the best for what your doing

 

[Slowerthanu]

this thing weigh 3 times what a mini truck weighs, thats why any additional stability or anything to increase the on road handling for the better is why I would want to do it. if it were "just" a mini truck then I would go that route.

even the rear is spring under, why not do the front the same.

Three times, want to wager? You are saying you have a 10,000 pound camper mini thing-a-ma-bob.

Clearance for one thing. You'll need to run a 5 inch lift spring on the front just to equal the stock height of a mini truck that is sprung over. The 80 front end will not clear in a lowered stance.

2wd Toyota trucks are SUA, they put it SOA on the 4wd model.

Do what you want, you asked for an opinion and I gave.

An F-350 weighs 3 times what a mini truck weighs and that to is SOA, Ford must be crazy......

People act like SOA is some mythical magic rollover machine that casts people into the outer darkness when they do it. I rolled SUA and I have rolled SOA, maybe I'm just a s***ty driver.

Your ride is going to SUCK with a heavily arched leave spring, it will probably rattle that camper apart.

Also, if your response was not as caustic as it seemed to me, then I apologize in advance for mine.

 

[extremetoy1]

not really caustic but whatever.

yes close to 3 times (a 1983 2wd shortbed weighed in at 2500, my RV fully loaded is right at 7000 lbs- now I know that is 500 lbs shy of exactly 3 times its weight, I think that is damn near close. much closer than the 3300 lb estimate of weight for it to be 10000 lbs like you stated (since we are throwing numbers out there and all)


and yes I do realize factory 4wds came with spring over- that isnt the question here.

and as far as my ride "sucking"-
1. it is and RV with alot more weight to use the springs.
2. I dont see that as a problem, high quality springs from a manufacturer who builds springs to order and not off the shelf do-it yourself "lift" kits arent even something to compare to one another.

I dont know anyone who "acts" like spring over is anything "mythical magic" but if you are talking about doing one on anything it obviously will raise the chance of rollover for a couple reasons.

I plan on having the same ride height as a 1-1.5 inch lift would provide on a stock truck- no more no less.

the 80 axle fits fine under my other 83 truck with no lift to the springs? I guess you must know something I dont about one under an RV

 

[Slowerthanu]

not really caustic but whatever.

yes close to 3 times (a 1983 2wd shortbed weighed in at 2500, my RV fully loaded is right at 7000 lbs- now I know that is 500 lbs shy of exactly 3 times its weight, I think that is damn near close. much closer than the 3300 lb estimate of weight for it to be 10000 lbs like you stated (since we are throwing numbers out there and all)


and yes I do realize factory 4wds came with spring over- that isnt the question here.

and as far as my ride "sucking"-
1. it is and RV with alot more weight to use the springs.
2. I dont see that as a problem, high quality springs from a manufacturer who builds springs to order and not off the shelf do-it yourself "lift" kits arent even something to compare to one another.

I dont know anyone who "acts" like spring over is anything "mythical magic" but if you are talking about doing one on anything it obviously will raise the chance of rollover for a couple reasons.

I plan on having the same ride height as a 1-1.5 inch lift would provide on a stock truck- no more no less.

the 80 axle fits fine under my other 83 truck with no lift to the springs? I guess you must know something I dont about one under an RV

Do you run your 80 axle spring under with stock springs? I can't see that giving you much more than 1-2 inches of up travel.

Are you going to run longer springs on the rig? .

If you can't pickup on sarcasm I apologize but most companies that sell lift springs will tell their customers that a vehicle with a spring over is "Unsafe at Any Speed". I find mine quite road worthy.

You will need a 6-7 inch lift spring to reach your desired height. look at any rig from All Pro and look at how tall they are with a 5 inch spring, now subtract about 6 inches from that number.

Here are two examples that are spring over.

 

[AbleThought]

@extremetoy1 did you end up going SOA? I am about to swap out my rear axle in my 83 sunrader and was thinking of doing this to get a little more clearance. How do you like it?

not really caustic but whatever.

yes close to 3 times (a 1983 2wd shortbed weighed in at 2500, my RV fully loaded is right at 7000 lbs- now I know that is 500 lbs shy of exactly 3 times its weight, I think that is damn near close. much closer than the 3300 lb estimate of weight for it to be 10000 lbs like you stated (since we are throwing numbers out there and all)


and yes I do realize factory 4wds came with spring over- that isnt the question here.

and as far as my ride "sucking"-
1. it is and RV with alot more weight to use the springs.
2. I dont see that as a problem, high quality springs from a manufacturer who builds springs to order and not off the shelf do-it yourself "lift" kits arent even something to compare to one another.

I dont know anyone who "acts" like spring over is anything "mythical magic" but if you are talking about doing one on anything it obviously will raise the chance of rollover for a couple reasons.

I plan on having the same ride height as a 1-1.5 inch lift would provide on a stock truck- no more no less.

the 80 axle fits fine under my other 83 truck with no lift to the springs? I guess you must know something I dont about one under an RV

 

[mr jits]

@extremetoy1 did you end up going SOA? I am about to swap out my rear axle in my 83 sunrader and was thinking of doing this to get a little more clearance. How do you like it?

Thread resurrection, but if you're doing something similar I'd do some searching on expedition portal or pirate. There was a camper build cross posted on both that used custom alcan springs with a 4x4 swap in SOA configuration. It turned out great and from the owner's posts on EP, he's still driving it all over.