How can I tell if my rear shocks are too short? (1 Viewer)

[HomersCanyonero]

I bought the OME 60004 sport rear shocks and installed them, but this simple change resulted in a bouncy ride upfront on city streets that have break in the cement like every 15 feet or so. Sometimes old highways/freeways also have these breaks every 15 to 20 feet like they were railroad tracks. Now I bounce quite more with my new rear shocks.

The rear shocks feel like they are working fine. On the speed bumps at the shopping centers, the rear and front work fine. This is probably because it's an independent bounce as opposed to a washboard-like condition on the streets.

So, my new rear shocks seem to have made the front more bouncy. Could this mean that my rear shocks are too short?

Here's what I have in the front:
* Front lifted about 2.5" (22.75" from hub to fender)
* Front Bilstein 6112 coilovers with 600 lb eicbach springs (kit 46-227287)
* These are the 60mm internal piston Bilstein coilovers with a beefier lower end shaft
* Front springs are set on the 2nd notch from the top (supposedly a 2" lift)

Here's what I had in the rear:
* Newer OEM airbags raised about 2.5" (23.25" from hub to fender)
* Raised using the airbag trick by lowering the height sensors
* Original from 2003 rear oem shocks (seem to have resistance going up and down)

My previous setup had a harsh ride in the rear. Probably due to worn out shocks and riding on over inflated air bags.

Here's what I changed in the rear:
* Put OME 60004 Sport rear shocks
* I don't know how they compare to the OEM rear shocks

Before I spend the money on a brand new suspension for the front and rear, I want to see if I can fix this problem by putting longer rear shocks with the existing rear airbags.

 

[PDXGX]

If they were too short they wouldnt fit. What youre experiencing more likely has to do with the fact that all 4 of your springs/shocks are different manufacturers and specs.

 

[Jstawgn]

Using shock not matched to spring can definitely give strange behavior.

I am thinking that airbag lift trick is basically preloading the airbag too much. The adjuster might be set past the elastic limit of the airbag. The airbag are not like Balloon that would expand multiple times. They have inverted cub below it that make the bag roll to itself to give suspension travel. Too much pressure and the bags would not give any flex and top put during suspension travel.

Try lowering gas the sensor a little bit and see if your ride improve.

I realize your concerns is the front but suspension works together. You stiffen one end too much and all the impact get transfered to the other end

 

[HomersCanyonero]

I don't follow your on the won't fit if they are too short. You can easily install short shocks that you extend to their fullest open length which is what I think I might be at. This is what I need to confirm if I'm operating my shocks at their max length and thus contributing to the bounciness to the front. Someone on this board mentioned this possible over extension on my OME 60004 rear shocks with my 2.5" (23.25" hub to fender) lift in the rear.

If getting everything from the same manufacturer is the problem, then I could solve my issue by putting Bilstein 5160 rear shocks (possibly long travel ones) to solve the problem. The front Bilstein 6112s came as a kit with the springs, so those springs match what the manufacturer sold as a kit. I believe that Eibach makes the springs for many other coilovers from other manufacturers, so the front is not mismatched in my opinion.

I do think that my overinflated airbags (which I still don't want to give up!) are contributing to the problem. I thought that refreshing the rear shocks would dampen the rear better and not be as harsh as with the original OEM worn out shocks. I wasn't expecting my front to become more bouncy in some situations as washboard-like city streets with these new rear shocks.

Another problem I'm having is that I can't easily find the specs for all the rear shocks on the market. Specs like open and closed lengths, good for certain lifts like 2" to 3", and the diameter of the shock body. Here's what I have so far, but not much information...

So, one way I'm trying to solve the problem is by possibly getting longer rear shocks like the Dobinson GS59-701s which are one inch longer than the OME 60004s and were meant for 2" to 3" lifts. I just don't know if they were valved for empty rears or heavy rears. I tend to run lighter than most because I remove the middle and 3rd row seats when I go camping and I travel light.

I'm brainstorming here, but another way to possibly tackle this problem is to lower my front and rear by about 1/2" to 1". This would mean lowering the front coilovers to the 3rd perch from the top and removing some washers/nuts from the height sensors to remove some air from the airbags.

But honestly, I really don't know what I'm doing!

 

[HomersCanyonero]

@Jstawgn I posted without seeing your post. I'm thinking along those lines too in terms of adjusting upwards the height sensors to relieve some air from the rear airbags.

 

[ArBrnSnpr]

When I was fitting my jeep for shocks I cycled the suspension with a jack to measure my needs for compression and drop.

I looked at shock specs to find a shock that best suited my needs.

It's a pain in the ass but when you're dealing with non factory equipment, it's the only way I know to avoid getting a shock that won't extend past the springs max length (causing a spring to fall out of its bucket) or causing the shock to extend to its max. I used bump stops and limiting straps to dial in my shock/vehicles needs. I don't see them being used on GX's anywhere, but the concept should still apply.

 

[HomersCanyonero]

That’s a good strategy for the rear with springs, but I still have rear airbags. Not sure how to measure the travel with airbags.

Also, I’m like 1.5” lifted in the rear in the normal position. If I put the airbags in hi, I’m lifted another 2”. I need to see what happens to my rear shocks when I lift the rear to the hi position. Just seems that rear shocks are too short.

Anyone know what the specs are on the original oem rear shocks with regards to compressed length and open length?

 

[orion]

I agree with @Jstawgn - Too much air pressure in those rear bags to get the height you want.

My opinion: The airbags need to go. All the shocks you're trying are made to handle 200-300lbs/in of spring pressure (normal range for lift springs on these rigs). You're probably inflating the bags to 400lbs/in, and even really good "bolt on" shocks can't keep up.

- Brian

 

[orion]

As for shock length #'s...the Bilsteins I'm using are (cut n paste):

Rear Bilstein 5100 Shock Specs:
Accommodates: 0" to 2" of lift
Collapsed Length: 14.91" / Extended Length: 23.50"

Your OME's are 14.02" / 22.83"

5100's are roughly 1" longer than stock (extended) -->

Hope that helps...

- Brian

 

[HomersCanyonero]

By the way, some Dobinson vendor named Mike posted (3/2017) a ridiculously detailed note on the Dobinson shocks and springs for the 4th generation 4runner. Link here => Dobinsons Suspension - 4th Gen Options - Toyota 4Runner Forum - Largest 4Runner Forum

I've been drooling over that information. When I'm ready to ditch the airbags, I think I'm going with the Dobinson progressive rear springs probably the ones for a 2.5" lift with a little weight like these:
C59-675V - Variable rate comfort option, stock rear weight, 2.5" lift. 470/470mm, 16mm wire, 157-230LB variable

The only thing I worry is being too high. I honestly only want 2" lift all around, but not sure there's progressive 2" rear coils. Ideally, I would like a comfortable ride on the highway since I spend only a small fraction of the time offroad.

When I say 2" lift all around with my BFG 285/70R17 KO tires, this means about 22.25" hub to fender in the front and about 22.75" hub to fender in the rear. That's about 1/2 of an inch shorter than where I'm currently at.

In terms of rear shocks, I'm still debating which ones to get. There's shock diameter in either 2.0" or 2.5" to consider. There's standard or long travel in terms of length. There's price to consider. And there's my front Bilstein 6112s with 600 lbs springs to consider.

 

[HomersCanyonero]

@orion thanks, that helps. How did you measure the OEM shocks? From what point to what point? I have my original shocks in the garage and I'm just wondering if you measure from tip to tip.

That's a really good point on the lbs/in. I hadn't considered this. So, what you are saying is that my overinflated bags are acting like a heavy duty spring that's meant to carry weight. This in turn is making the front bouncy.

 

[joabmc]

I’ve run 60004 before and only switched them when going to LT in the rear. They are rated for a 2-3” lift but their compressed vs extended/free length are only a little better than stock. IIRC, maybe an 1” or 2. They are setup for increased lift but travel is about the same if that makes sense. Do you still have your rear swaybar? If so, your travel is limited in that respect.

Can’t honestly see that during normal driving conditions, as you describe, the length of the shock is the issue. You’d still be operating within their normal range of travel.

I run bilsteins in my work rig and they provide a more dampened ride in comparison to OME.

What is your nosedive like currently during hard braking? The 600lb Eibach may not be heavy enough to carry the weight of the V8 as well...

Just giving you a few observations as I’m new to the GX but not 120 suspensions. I agree with others that it is more than likely the pairing of Bilsteins with OME as they have different ride characteristics. OME have always handled the big stuff very well IMO but can be stiff on the little bumps that you hit while in DD mode.

Might be as simple as going with 5160s in the rear.

 

[HomersCanyonero]

Rear swaybar still in place.

I don't feel I have a dive problem on hard braking. On that Dobinson post I linked above, Dobinson has these springs for the 4R V8 which seems to indicate that 600 lbs is okay. But then again, I'm not an expert on spring loads and don't have the details on my front springs.

4Runner V8 Engines -- Dobinson Front Coils
C59-302 - V8 - Stock front end load, 2" lift. 395/395mm, 17mm wire, 586LB
C59-314 - V8 - Stock front end load, 2.5" lift. 405/405mm, 17mm wire, 586LB
C59-314 - V8 - 100-220LBS heavy load front weight, 2" lift. 405/405mm, 17mm wire, 586LB
C59-448 - V8 - Stock front end load, 2.75" lift. 420/425mm, 17mm wire, 502LB

Anyways, little by little, I'm losing my aficionado status on the airbags.

 

[joabmc]

As mentioned, going off of 120 experience. I only asked about the 600# coils as that is what folks ran in the FJCs with no load on the front. Once adding bumper, winch, skids, etc., most will go to a 700# coil.
When researching before getting my GX, I was running comparisons between the two vehicles to get a feel as to how compatible my suspension would be. To the best of my knowledge the GX weighs about 200lbs more in the front than the FJ does. That was equivalent to my ARB bullbar and winch and therefore not worrried about switching it over.

I’m not sure what the Dobinson specs are implying? They list the same rate for standard duty and heavy duty.

 

[joabmc]

Just came across this and thought it may be of some help. The rates are for a V8 4Runner

I’m not sure why they have OME 883,884,885 all at the same rate though. 883s are supposed to be OE replacement, 884 lifted-light duty, 885 lifted-medium duty (+200lbs), 886 Heavies.

 

[HomersCanyonero]

Yeah, I have that table but missing GX470 specific info. Same rate but different lengths on the said ome’s

 

[orion]

I’m not sure why they have OME 883,884,885 all at the same rate though. 883s are supposed to be OE replacement, 884 lifted-light duty, 885 lifted-medium duty (+200lbs), 886 Heavies.

I believe they use a longer free length for more weigh capacity...

Just like moving the lower perch on Bilstein 5100 front shocks will raise the vehicle (adding spring preload = lift), OME does the same by using slightly longer springs.

- Brian

 

[Sleepy]

By the way, some Dobinson vendor named Mike posted (3/2017) a ridiculously detailed note on the Dobinson shocks and springs for the 4th generation 4runner. Link here => Dobinsons Suspension - 4th Gen Options - Toyota 4Runner Forum - Largest 4Runner Forum

I've been drooling over that information. When I'm ready to ditch the airbags, I think I'm going with the Dobinson progressive rear springs probably the ones for a 2.5" lift with a little weight like these:
C59-675V - Variable rate comfort option, stock rear weight, 2.5" lift. 470/470mm, 16mm wire, 157-230LB variable

The only thing I worry is being too high. I honestly only want 2" lift all around, but not sure there's progressive 2" rear coils. Ideally, I would like a comfortable ride on the highway since I spend only a small fraction of the time offroad.

When I say 2" lift all around with my BFG 285/70R17 KO tires, this means about 22.25" hub to fender in the front and about 22.75" hub to fender in the rear. That's about 1/2 of an inch shorter than where I'm currently at.

In terms of rear shocks, I'm still debating which ones to get. There's shock diameter in either 2.0" or 2.5" to consider. There's standard or long travel in terms of length. There's price to consider. And there's my front Bilstein 6112s with 600 lbs springs to consider.

Talk to Kyle Foyle. Somewhere in that Dobinsons post he post his GX470. Said he got closer to 1.75" lift with those medium progressive coils on the GX. I just installed on mine and got similar lift. If someone wanted 2.5" with those same springs you can use the SSO conversion kit. Adds 3/4" or more if use the additional spacers.

 

[HomersCanyonero]

@Sleepy I went back to read that thread by @Kyle Fogle and he posted that he got 2-2.5" of lift on the rear with the shorter linear C59-325 rear springs. He later switched to the progressive rear springs which I assume are the C59-675V rear springs, but he didn't say if that changed his height in the rear.

The Dobinsons MRR have arrived!

From the information from the 4Runner site:

• C59-325 - Stock rear end load, 1.75" to 2" lift. 420/420mm, 17mm wire, 220LB
• C59-675V - Variable rate comfort option, stock rear weight, 2.5" lift. 470/470mm, 16mm wire, 157-230LB variable

The progressive rear springs appear to be thinner (16mm compared to 17mm) and longer (470mm compared to 420mm), but it starts with a lower spring rate 157 lbs/in and ends with a higher spring rate (230 lbs/in) than the linear ones (220 lbs/in). So, I don't know what that does to the lift on the GX470. I'll assume that you end up with a 2.5" lift with the progressive assuming a stock load.

But to your point, if anyone plans to buy a new suspension or individual springs/shocks, please consult with your favorite vendor to make sure the information posted by people like myself is accurate and you get the desired outcome with the correct part numbers.

 

[HomersCanyonero]

@Sleepy I missed that part where you said you just installed yours. Can you share your detailed info like:

1. Dobinson C59-675V rear springs?
2. What model rear shocks did you use (standard or long)?
3. Which conversion kit did you use (and did you put spacers)?
4. What's the hub to fender distance in the rear?
5. What's your tire size?

I did a quick search to see if you had a build thread, but I didn't find one. I know you just got the Dobinson's kit, but your info would be greatly appreciated.