Suspension setup questions

[broncosbybart]

Questions for the go fast types.

I am competingECORS series with an Early Bronco. Right now I am running a 10 leaf rear spring as supplied by Wild Horses. I am only getting about 4" of travel with this setup. I have poly bump stops front and rear. The ride quality right now is brutal. Racing is turning out to be a whole lot different than rock crawling. Our races are KOH style stuff, with fast sections of field running (no deserts out here) and rock racing.

The main issue I am having right now is a poorly performing suspension. The front bounces really badly and the rear flexes well but kicks badly on high speed stuff. It bottoms out way too easily and rebounds like a true buckin bronco... I am thinking of running bypass shocks in the front with some standard 2.0 remote resi shocks in the rear, but have no idea of what to have them valved at and if air bumps or different springs might help.

FYI, the fronts are old Superlift 5.5" coils with a 420lb spring rate. I can't run coil overs on this thing (rules) but can run air bumps and nice shocks as long as they are not weight supporting.

My build thread is here for any that are interested:

http://www.cb4x4.com/forums/showthread.php?t=3626

Any feedback is much appreciated!

[AussieRod]

First, I would weigh the front and rear, to get some weights. If the rules allow, go bypasses on all 4 wheels. With some info like weights, springs specs, etc, someone like Mirage Racing could valve the bypasses to suit the springs you have, or recommend the rates that would suit your EB better. Compression and rebound tuning for leafs is complicated, so consulting someone with experience will pay big dividends in suspension performance. Just my $0.02

[78Class3]

I would run the bypass' with the leaf springs and that should be able to control most of the bucking with some tuning. A smooth body resi would probably also do wonders up front with the proper valving (of course a bypass would also be the best bet). But the shocks won't overcome poor spring rates to begin with. Perhaps a set of Deaver coils up front would be a wiser first step and see how the rear works with a set of bypass'. A combination of both would probably net you a whole lot of imporvment in both the rocks and the speed. Probably looking at a 3k investment to redo it all with coils, springs, and shocks. or 2k with front coils, front smoothi and rear bypass

[philofab]

I would upgrade it in this order:

Shocks, then replace springs if needed. You may need to pay around with shackle length and position in the rear to get those springs working better.

If money allows run 2.5" bypasses on all four corners. You will see a huge improvement with just a standard 2.5 smooth body reservoir shock on each corner if you can't spend that much. Watching sites like Dezert Rangers and Race-dezert can yield some used shocks at great prices too.

If springs continue to be a problem after you actually get some shock on that thing look into a custom pack / coils from Deaver.

[broncosbybart]

thanks for the feedback so far. i have been looking on race-dezert for some shocks. can't get anyone to call me or email me back. i guess they don't like us 'right' coasters

i was actually thinking of bypasses for the front and smooth bodies for the rear, but would look into 4 bypasses if that would be best. what is the benefit of a bypass vs a smooth body? i've gathered that re-valving them is a main feature, but is there anything else?

i know that this may go over what really should be in this forum, but how do I go about determining what valving I need if I order some shocks?

[broncosbybart]

Also, how are you guys getting longer travel? I am at about 4.5 inches front and rear. I don't want to get the COG too high. My truck has stock frame rails and the limiting factor is uptravel (axles contacting the frame rails). Main issue is on the front. I can't see having the front end of the chassis raised another 6"- don't know how I'd get the track bar or drag link to even look close to being happy.

I did a shackle flip on the rear and am running NicksTrix rear shackles. They are about stock length. Probably ok for the EB leaf springs, but I'm now thinking that a longer spring might be in order???

[SteveG]

Steering is going to be your limiting factor for wheel travel in the front end. The rear should be able to net you at 15-ish with ease. Actually, I don't know how these trucks are limited by drive shaft length. Maybe someone else can answer that question.
After springs and steering, the next limiter will be shocks. You need to make sure you have enough shock stroke for the desired amount of wheel travel.

It sounds to me like the truck is over sprung. How does it feel without shocks? Is it still stiff?

[philofab]

The shackles work better when they are not flipped.

The owner of LC Engeneering in Havasu races an early Bronco in class 3. I'll find out about his setup.

[Dust]

It really looks like you have two different type springs in the front.
Driver front looks like a straight rate and the Pass, side looks like a progressive.

[broncosbybart]

yeah, they were 2 different springs. The black progressive rate springs were a 3.5" WH rockcrawler coil. They bottomed all the time after a jump/hard hit. They were removed and the red coils installed after 1 race.

The red coils are the old superlift coils. They are super stiff. They really help with the bottoming, but really have no down travel. Here is a pic of the truck. It is usually on 3 wheels in a corner. Looks cool, but I'm sure it isn't ideal...

My thoughts so far are to try and get some bypasses for the front and maybe some 2.5" resi shocks for the rear and maybe some bumpstops? I'm thinking the bumpstops would allow me to run a softer spring in the front again and gain some suspension travel up there as well as chainging to a rear leaf spring with more arch to it to allow for more uptravel. Figures that flipping the shackles doesn't help out... Driveshaft angles aren't an issue. I'm running CV joints at the t-case and angles are good.

[hobbyturnedobsession]

Running bypasses on the rear would be awesome too. Maybe try a deaver f64 coil spring for a newer bronco? I'm not sure if it would work but hey it might.

[damon1272]

Check out Paul's ride. May want to touch base with him on his set up.
http://www.gofastbroncos.com/forum/view ... =34&t=1961

[philofab]

The shackle in the stock orientation allows a lot more droop. The bottoming out will be reduced or eliminated with a proper shock.

[SteveG]

Any progress on this? Did you make any changes?

[broncodan74]

/http://waynesbronco.shutterfly.com

I'm not sure what the rules are for your race class, but this Bronco gets 16"+ of travel, rear and about 12" in the front. It has coilovers in the front and 3" dia. bypasses in the rear! B-)

[broncosbybart]

Sorry for the lack of response. Made a bunch of changes and am getting closer. Went to 7100 series Bilsteins all around and to a softer coil up front. The Bronco flexes more now and is softer. I still need to dial my shocks in. I revalved them but they are still too soft. I am contemplating getting some bypasses for the front and some 2.5's for the rear.

Biggest issue now is rear wheel travel. I only have about 3" of up travel before I'm into the bumpstop. I am considering trying a longer spring and have an ad posted in the 'wanted' section if anyone has some used ones lying around....

[RSR]

Forgive me if I missed something but I just scanned the previous posts and looked at pics in your build thread. My $.02. I think a big problem you have is that you have used up some or all of the additional wheel travel you should have gained from the suspension lift with spacer blocks and giant bump stops. There appears to be 2" blocks under the front bump stops and blocks under the rear bump stops. It looks like the WH track bar bracket you welded on the front axle is so tall that it would contact the frame first...thus the need for the blocks. You may have had more up travel in stock form.

The shackle flip is bad idea. Great, cheap lift but not good for wheel travel or spring life when going fast. Spring has to go way negative arch to get anywhere close to stock up travel limit.

Blocks are for rocks and big tire clearance only. If you want to go fast you have need as much wheel travel as possible as low to the ground as possible.

The comments everyone made about the shocks are right. But until you get all that stuff (blocks, giant bumpstops, shackle flip) out of the way so the axle can move up , I don't think you will be satisfied.

RS

[broncosbybart]

I completely agree w/you. Been thinking hard about that. When I started the build I knew nothing about high speed racing, just rock crawling. The track bar riser is really hindering my uptravel. I am looking hard for some deaver leafs for the rear and will flip the rear shackle hangers once again, putting them back in stock form.

Just got some triple bypasses for the front and some 2.5" remote resi shocks for the rear. Now I just need to find some leafs and do a lot of work.

[toddz69]

I completely agree w/you. Been thinking hard about that. When I started the build I knew nothing about high speed racing, just rock crawling. The track bar riser is really hindering my uptravel. I am looking hard for some deaver leafs for the rear and will flip the rear shackle hangers once again, putting them back in stock form.

Just got some triple bypasses for the front and some 2.5" remote resi shocks for the rear. Now I just need to find some leafs and do a lot of work.

Bart: I ran into that problem on my EB as well - I don't have a lot of lift, my coils are fairly soft, and I like to exercise my suspension frequently. I ended up moving/extending my trac bar over to the knuckle area. Gives me another inch or two of bump travel compared to the raised mount on the axle.

Todd Z.

[broncosbybart]

Ok, so a lot of work is being done. I think it is time to post it all in the rides forum. Thank you all for the direction on which way to head with this thing!! Check it out if you want.