Harsh rear suspension rebound coming off bumps

[2UZ-FE]

Long time since i've been on here! Anyways...

I've been running All-Pro 3.5" springs with Bilstein 5100s in the rear of my V8 4th gen for the last few years. Ever since i've had issues when going over a drop-off on the road or coming down off speed bumps etc. The front end rides over nicely, the rear rides good during the compression stage(hitting bump) but when it comes time to rebound(coming off bump), it feels like the rear end just got picked up off the ground and dropped. It happens even at very low speeds and I pretty much need to ride the brakes and snail over speed bumps.

Situation improves quite a bit when I'm towing a loaded trailer.

Now, if the spring was overly stiff, wouldn't I have more pronounced harshness during the compression as well?

Or 5100s too weak to dampen the rebound causing the springs to slingshot the axle/wheels downwards when coming off bumps/drop offs?

 

[Inv4drZm]

You mentioned towing a loaded trailer helps quite a bit.

This tells me it has to do with your springs and not your shocks.

I think standing outside the vehicle and watching while someone drives over a bump would help you see whats going on.

 

[Shadow]

I have the same problem. 5100s with SAW 1.5 springs. I think my springs are supposed to only be ~12% stiffer over stock. It's not bad, just annoying.

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[easyc]

Same problem here with 5100s and Toytek Superflex. I lengthened my rear links using 2nd generation links and it improved it. Maybe another 1" longer would solve it completely. A loaded cooler is enough weight to solve my issues.

 

[07V8]

You're hitting the limits of the 5100s. They are not designed for anything over 2" lift.

 

[2UZ-FE]

I'll jack the back end up tomorrow and double check how much droop I have vs the current height. Maybe the 5100s are hitting their maxium extension.

If I get longer shocks, wouldn't I require limiter straps to prevent the springs from possibly popping out? I thought the shocks act as limiters and from what I can remember when installing the AP 3.5 springs, they weren't that much taller than stock.

 

[Tooltime19]

The Bilsteins are valved for stock front and rear spring rates, along with stock tire and wheel size and weight. With most lift springs and the 5100's, I find the the rebound is way off causing the spring and shock combo to not work well when used hard. I believe the Bilsteins 6112 addresses this issue.
In short what I'm finding is the Bilsteins in the rear are blowing right thru the compression and rebound way too fast and not able to competently keep up with the truck. Also, when I'm running hard and fast in the deserts, the rear shock Temps are very high, and about 30 degrees hotter than the fronts. This indicates the rear shocks are struggling to keep up with the current 2" OMEnglish 895 rear springs and larger tires. I am shopping for an Icon, Fox or King rebuildable shock front and rear so I can tune my right to come to life. I hate the way my right handles at the moment.

 

[Shadow]

All of this makes perfect sense except for the fact that my rear springs are only supposed to yield 1.5" of lift. So frustrating...

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[Straus7]

I've got the same issue with FJ rear springs and the 1.5" daystar spacer. I have Bilstein 4600 rear shocks.

 

[t-man]

It's the 5100's. Mine is doing the same thing with fj coils. Now they are leaking oil everywhere and I will never spend the money on a bilstein product again. I hate them. They really aren't for offroad use and are worthless if you get serious on stuff. Whoops are a huge no-no as you will feel like you are in a bucking bronco! Step up to radlfo, king, icon, etc and you will be much happier. I will be doing this soon and never looking back!

 

[t-man]

Same problem here with 5100s and Toytek Superflex. I lengthened my rear links using 2nd generation links and it improved it. Maybe another 1" longer would solve it completely. A loaded cooler is enough weight to solve my issues.

Tell me more about that 2nd gen links part please. Pm me if needed or on my build thread.

 

[Civiceg94]

I also think my blistein with 895e springs. And i also tried 5th gen rear stock springs. Are not working right. I get a horrible death wobble in the rear i triple checked all the rear links and everything is fine. After reading this it feels like it doesnt even compress sometimes when going over bumps. Even with the stock 5th gen springs its weird i even tried lowering tire pressure. I was thinking of buyin rear kings as well

 

[Drunner97]

As others said, it's very likely the 5100s. Lengthening the sway bar links doesn't help either. I tried everything before I just said screw it and bought metal tech lt springs (which have the driver side specific spring) and extended Icons. Not a single sound and smooth as hell off road now.

If you actually off road your 4runner, 5100s in the rear are a terrible idea with any amount of lift even though they're "good" for 2" lifts.

On the other hand though, the front 5100s with 885s and some weight (skids, sliders, dual battery) tend to do fine and I haven't heard a single complaint or thump out of them.

 

[Straus7]

It's the 5100's. Mine is doing the same thing with fj coils. Now they are leaking oil everywhere and I will never spend the money on a bilstein product again. I hate them. They really aren't for offroad use and are worthless if you get serious on stuff. Whoops are a huge no-no as you will feel like you are in a bucking bronco! Step up to radlfo, king, icon, etc and you will be much happier. I will be doing this soon and never looking back!

As others said, it's very likely the 5100s. Lengthening the sway bar links doesn't help either. I tried everything before I just said screw it and bought metal tech lt springs (which have the driver side specific spring) and extended Icons. Not a single sound and smooth as hell off road now.

If you actually off road your 4runner, 5100s in the rear are a terrible idea with any amount of lift even though they're "good" for 2" lifts.

On the other hand though, the front 5100s with 885s and some weight (skids, sliders, dual battery) tend to do fine and I haven't heard a single complaint or thump out of them.

As many people that have done the Bilstein swap I can't believe I didn't read this before. My rears came with the front Tacoma setup I bought (they were ordered for a 4Runner so they are bigger than the factory 4600s) lucky I only spent $150 on everything. Guess I didn't dig deep enough to find this info. I'll have to look into some Icons.

 

[Drunner97]

As many people that have done the Bilstein swap I can't believe I didn't read this before. My rears came with the front Tacoma setup I bought (they were ordered for a 4Runner so they are bigger than the factory 4600s) lucky I only spent $150 on everything. Guess I didn't dig deep enough to find this info. I'll have to look into some Icons.

Everything I read before I started buying parts pointed to 5100s and Superflex as a budget lift without using spacers. Not once is it ever mentioned that the 5100s top out (bottom out?) because they can't handle the 2" lift in the rear. I seriously thought I was destroying my rear end every time I hit a pothole or speed bump.

 

[Civiceg94]

Hopefully i dont spend 800 on a set of rear king shocks and the problem is still there. Then i dont know who to believe lol

 

[Drunner97]

Hopefully i dont spend 800 on a set of rear king shocks and the problem is still there. Then i dont know who to believe lol

I have the 2" MT Springs, but the Icons are extended length and good for 3" of lift. It's been an absolutely perfect setup in the rear. I can't wait to get extended Icons for the front to match it.

 

[jrm]

Same here

I also think my blistein with 895e springs. And i also tried 5th gen rear stock springs. Are not working right. I get a horrible death wobble in the rear i triple checked all the rear links and everything is fine. After reading this it feels like it doesnt even compress sometimes when going over bumps. Even with the stock 5th gen springs its weird i even tried lowering tire pressure. I was thinking of buyin rear kings as well

With the 5100/895e's it felt like the shocks weren't even there and with the 5100/5th gen rears it feels like it wallows. On my 3rd i ran tundra trd/5100 up front and 908/OME shocks in the back. I wonder if the 5th gen coils and OME shocks would be better.

 

[Straus7]

Everything I read before I started buying parts pointed to 5100s and Superflex as a budget lift without using spacers. Not once is it ever mentioned that the 5100s top out (bottom out?) because they can't handle the 2" lift in the rear. I seriously thought I was destroying my rear end every time I hit a pothole or speed bump.

The first bump I went over I woke my daughter up in the back seat and my wife had a terrified look on her face. Her exact words were "Didn't you just replace all of the suspension on this thing?" So year, wasn't a pleasant surprise. Oh well, thanks for the good info. I have my buddy getting me a price on the extended Icon rear shocks.

 

[Civiceg94]

With the 5100/895e's it felt like the shocks weren't even there and with the 5100/5th gen rears it feels like it wallows. On my 3rd i ran tundra trd/5100 up front and 908/OME shocks in the back. I wonder if the 5th gen coils and OME shocks would be better.

The crazy part is i go over the same bump in the road everyday and different days handles differently. It is annoying me. I never seen 908 springs for the 4th gen