Suspension droop question

[MrT]

I hve Duff's 3.5" Proggresive front coils and TBP's rear 9 leaf 3.5" springs. I think my shocks may be too short. I don't have the body on so I should gain a inch or two. How much droop should I expect? Stock radius arms, heim steering and ploy bushing. I am not going for a flex monster but I don't want to tear up a set of shocks either. I was planning on limiting straps in the front but my springs are still sitting wasy high(no body I know)
So how much droop?

 

[ame]

Why not lift the frame and measure full droop? You dont need the body on to know how far the suspension will travel but make sure the shocks are not too long and dont compress far enough.

 

[MrT]

Good idea, I really just got it to the point I could try that out.
The rear only dropped 2.5" and the front 4"
Of course that's from an already extended position since there isn't much weight on them. It should get me close on max extension though. My front shocks and limiting straps are a little short.

 

[DirtDonk]

You need to also compress them to ride height to get a starting point. This and the droop measurement will give you your droop travel. Or "basic" droop travel anyway, as things do change dynamically with different levels of flex.

Without the body, you might be a lot higher than you think. Measure between the bottom of the frame rails and the top of the axle tubes and that will tell you approximately how far you are above ride height at the moment.
With a 3.5" lift you would expect an approx. distance of 10.5" between the front axle and frame, and 9.5" between the rear axle and frame.
This can vary by as much as an inch in either direction, but if you use those measurements you're right in the sweet spot.

And yes, basically your shocks are going to look way too short whenever you mount them to a frame before the suspension is compressed to ride height.
That's just how it works...

Paul

 

[MrT]

I guess I am looking for shock length at max droop. I think I got close enough with the jack and I will set the limiting straps about 1" short to be safe.

My front is 14" and the rear is 12" so it should settle down pretty good. I was hoping to get some mounts welded up so the frame to axle measurements will help to guestimate ride height.

Thanks

 

[DirtDonk]

If you're trying to mock things up, then I would use ratchet straps to compress the springs down to those dimensions mentioned earlier. This gets the suspension right where you need it to be for estimating, and then you can make changes to mounting points and shock lengths as you need.
You are not limited to shocks listed for a specific lift. You can opt for longer or shorter shocks if you find they fit your need better.
In your case longer would be better most likely, and you can set your droop to be farther than your compression and then set your limiting straps.

Sounds like you're going full custom here? No existing shock mounts so you're setting them up from scratch? Stock types, or aftermarket long-travel types?

Paul

 

[MrT]

I have double shock hoops(came on it) I bought the springs then Bilstein shocks based on the frame to axle measurement I found here. I am putting the straps where the foward shock would have gone. It's hard to imagine the front springs coming down almost 4" but they are progressive. It's really hard imagining the back springs squatting much but I know everything should.
The strap mounts will be custom top and bottom and the lower rear shock mounts.

 

[Broncobowsher]

You REALLY need to check compressed lengths. The front is easy, take the coil out and put the rest back together. Jack the axle into the bumpstop.

Right now you are really lucky on the rear. With the body off, take out a shackle bolt and jack away. There will be some errors, but you will get a good idea if you are in the ballpark.

 

[MrT]

At this point I have shocks and springs so I will worry about compressed length when it's together and I am able to work the suspension and check not only suspension interference but also any tire to body problems. There are no bumpstops on there right now so I can get the size I need to set everything to stop where I want it to then. I am not concerned about the shocks bottoming out I have plenty of uptravel.