OME front suspension bounce after LS swap

[thingscoledoes]

I recently finished swapping a 5.3 Vortec into my '79 FJ40. It ended up shaving a couple hundred pounds off the front, which has led to some pretty severe bouncing. I have the light duty OME suspension, so I don't think there anything I can do regarding removing a leaf.

After talking with some other folks, I think the best think I can do is add weight to the front. I want to keep the OEM bumper, so a winch would be the only other option.

Does anyone have any ideas aside from adding a winch? Any recommendations on a heavy winch? I was looking at the Badlands since I honestly don't plan on needing to use it, and I don't want to drop Warn coin.

Another thought I had was just that the Vortec is too torquey. I kept the original Toyota 4 speed. Maybe I need to de-tune the engine some?

 

[archie73]

I have a 5.3 with OME light duty suspension with a warn 8274. It’s no sports car, but it rides nice. I’d try new front shocks if it’s too bouncy. My suspension is what I’d call broken in.

 

[thingscoledoes]

I have a 5.3 with OME light duty suspension with a warn 8274. It’s no sports car, but it rides nice. I’d try new front shocks if it’s too bouncy. My suspension is what I’d call broken in.

How many miles did it take for your suspension to break in? Funny cycle in that I'm not driving mine enough because of the bounce.

Did you do any special tuning on the engine? What transmission are you running?

 

[clrussell]

I have always wondered about this.

 

[77mustard40]

I don’t know why you can’t pull the middle leaf, I’d try that first. It’s a day invested without spending a dime.

 

[charliemeyer007]

Get like a 20-30 plastic barrel. Put some boards across the frame in front of the raderator to support the barrel and strap it in/down. Fill with water, 24 gallons is like 200#. See how it rides. I wouldn't detune your motor. A winch would be good - most of my jeep friends run that big harbor china one. A second battery under the hood would add some weight and be useful
Winch 100+# battery 60#

 

[pb4ugo]

Sounds like you need better shocks. I think someone's selling a Confer box in the classified section that goes between the frame rails up front. You could fill it with rocks or something.

 

[cruisermatt]

Bouncing because it’s too stiff or bouncing bouncing it’s too soft?
If too stiff, look at different springs, pulling leaves, or modifying shackle angle. If too soft, look at stiffer shocks.

 

[1911]

Any recommendations on a heavy winch? I was looking at the Badlands since I honestly don't plan on needing to use it, and I don't want to drop Warn coin.

Second-hand older Warn 8274. Look on facebook marketplace, craigslist, etc.

 

[B y r o n]

One of the reasons I went with Rancho RS9000XL shocks. They allow you to adjust the compression setting to compensate for weight or condition changes.

 

[archie73]

How many miles did it take for your suspension to break in? Funny cycle in that I'm not driving mine enough because of the bounce.

That’s a little hard to say- I installed the suspension (with the original engine) and drove it for a summer or two, then I swapped in a SBC. Then it sat for 15years- bad owner!!! All that being said, I don’t remember it ever bouncing. I’m still leaning toward the shocks, but I’ll concede to others greater experience than mine. Swapping shocks is easier than pulling leaves.
How old are the shocks? If new, is it possible the rears got put on the front? The rear shocks should be MUCH softer than the fronts. Just a thought

Get like a 20-30 plastic barrel. Put some boards across the frame in front of the raderator to support the barrel and strap it in/down. Fill with water, 24 gallons is like 200#. See how it rides. I wouldn't detune your motor. A winch would be good - most of my jeep friends run that big harbor china one. A second battery under the hood would add some weight and be useful
Winch 100+# battery 60#

The water idea is an excellent experiment.
The 8274 winch has synthetic rope- 50-60#
The 2nd battery is 30-40#
C channel bumper is pretty stubby, so maybe an extra 20#
All together 100-120# added to the front.

Did you do any special tuning on the engine? What transmission are you running?

My tune is bone stock except for the Vats delete. I have a SM465 manual transmission. The LS is night and day compared to the SBC in power and throttle input. I’ve never driven the LC 4 speed, but I believe it isn’t terribly different in terms of gear ratios. So it shouldn’t be that much different from your transmission. When you say its to torquey, does that mean its breaking traction constantly? I agree that there should be yes need to detune the engine.

 

[Living in the Past]

The original owner of my 70 FJ40 removed the bumperettes and rear step and installed a heavy piece of angle iron. The ends were modified. Thinking this was originally on his 63 FST with smaller tail lights.

He still had the original bumperettes and rear step.

On the front he got more creative. In lines the inside of the front bumper with 1/4" strap of steel and welded it place. Under my ownership it does need that protection and has a different OEM bumper now. That bumper does add quite a bit of weight at the very front.

I agree that stiffer shocks would be what I tried first. On any vehicle go over a speed bump and it bounces first thing I think this vehicle needs new shocks.