GEN 1 Sprung Under questions

[boarder1995]

Bigg50 - Yes, limit straps are recommended to limit down, versus using the shock as limiter.

Hole Shot - I have talked with SVC and he had concerns... Although the under sprung arrangement being better for compression stroke room, but cautioned about possible axle wrap - which I don't know where it'd come from with the typically better arrangement of springs under an axle versus over. Also indicated reworking factory cross bracing to allow for more compression room too. I'll have to crawl under my truck to take a look eventually to see what we'd hit next with the axle/diff if not the Ford "notched" frame. SDHQ does provide their kit as shown above.

Personal disclaimer for me is that I have not run a sprung under arrangement other than stock trucks in the past (Chevy S10). But I have also had numerous sprung OVER trucks and some with lift blocks (Ranger, Ram, F250) that exhibited extreme axle wrap and hop issues.

Also, agree that being in the correct travel zones for these fancy 3.0/3.5/4.0/4.4 shocks is vitally important. I did run a +2 Deaver with Fox3.0 and felt the spring put me a little too compressed on the Fox3.0 for daily driving. Also due to shock tuning. With the +3 I'm in a better zone of travel for road driving. Now, when I load up my bed I'm back to the stiffer valved zone and definitely notice it. Plus, when I am also bumping my bumpstops (@120psi?), it's also noticeable.

MTF - Yes, Deaver +2, +3, Under sprung - typically are all the same or similar spring rates. To go with heavier loads you really should be running a HD version of their spring. Going +3 will help a bit, but they're not a stiffer spring than +2.

 

[RLTW]

I've also heard some negative stuff about sprung under configurations from a handful of different sources, but I'm no expert.


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[boarder1995]

I've also heard some negative stuff about sprung under configurations from a handful of different sources, but I'm no expert.


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Good feedback to know - thanks.

 

[ntm]

Wow - great discussion guys.

Not going 4-link. Might go cantilever or might go bypass/bed mounted cage shocks. Either way, the spring under doesn't care how the longer travel shock arrangement is mounted - shock mounting does nothing to the axle/leaf/pinion path. A cantilever arrangement just allows a linkage to direct axle forces into a shock in a different orientation, with a length of travel reduction for use with standard 3.0 shocks.

Sprung under vs. over DOES affect the pinion angle, but usually for the better during acceleration as it'll prevent the differential from getting cranked up too far. And the same during hard braking, helping prevent differential drop down.

The limits of my driveshaft stroke might be bumped if the spring under can droop lower than a regular set of Deaver +3 I'm currently running. But as the sprung under arrangement already has a greater arch to it, I might be limiting to droop travel with stock shackle limiting travel more versus a slightly flatter over sprung setup.

I was mostly wondering if those with Deaver +8 notice an appreciable harsher ride versus Deaver +3 (if they had those to begin with), since usually a steeper arched spring will be harsher than a flatter spring arrangement. I'll give Deaver a call too for feedback and will report with my findings.

Update after talking with Deaver... They don't call them +8 springs. They're referred to as Deaver sprung under for Raptors. Or something like that. They've had good feedback from customers on them. They do suggest longer rear shackles for droop allowance. Total length of arch is longer to accommodate the slightly steeper rate of arch - it's not just a more bent +3. The times I've talked with Deaver, it's been a good experience. Leaning more towards an eventual install after a bit more investigation. That's all for now.

Upsides to a sprung under is more available droop travel.

Downsides is more pinion angle change, more axle wrap/hop, and less accurate location of the axle laterally under the truck.
This is a result of using a longer overall spring, with more arch.
Usually people don't notice this when going sprung under due to changing to a bed cage and some larger, longer bypasses at the same time.
The behaviour vs something with links or shorter leafs is very noticeable on corner exits, the sprung under feels a bit unstable, and tends to "wind up" and break traction under acceleration.
But of course, if you want the travel with leafs to improve performance through the whoops, you pretty much have to go sprung under.

 

[circafwsk8r]

sprung under will probably work better with a longer spring.. move your front hanger forward and your rear shackle and mount hanger back. longer spring, more arch. thats what they do with mini trucks anyways. makes sense to me. for example giants link killer springs have about as much spread as our f150 leafs, but on midsize trucks.

 

[str8fast]

@Rodbender some good info in here


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[Rodbender]

Thanks Mike I will look into this idea further


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[NE Ford]

@boarder1995 Did you ever end up going sprung under? I've got RPGs RST16 kit with Fox 3.5s and have been considering this route to squeeze a little more performance out of the rear end.

 

[boarder1995x2]

Yes, I did. And it's wonderful! I haven't noticed any real drawbacks to the sprung under from the typical Deaver+3 over setup I had before. But the rear does perform much better now for big hits. I also went to a bedcage, RPG longer shackles, and longer shocks, so I can't isolate the improvement source to just the springs.

 

[TheTallRoadrunner]

Yes, I did. And it's wonderful! I haven't noticed any real drawbacks to the sprung under from the typical Deaver+3 over setup I had before. But the rear does perform much better now for big hits. I also went to a bedcage, RPG longer shackles, and longer shocks, so I can't isolate the improvement source to just the springs.

How do you mount it under the axle do you need a special flip kit or does it just come with the deaver under spring leafs?