Eibach coils on non-Eibach shocks

Has anyone tried it? I'm talking about shocks that are designed to take the OEM coil.

Based on these two threads I see that the Tundra Eibach coils can be used on 5100s, yielding ~3" of lift on the bottom clip: https://www.tundras.com/threads/anyone-running-the-eibach-pro-truck-lift-stage-1.37417/
https://www.tundras.com/threads/eibach-pro-truck-stage-1-kit.11468/

The coils are these: https://eibach.com/us/2209/E30-82-079-02-20-TOYOTA-Tundra-pro-lift-kit

Since 5100s are meant to be used with stock coils, the Eibach coils should work on any OEM spec shock (which are designed for OEM coils) and provide lift. The 5100s are a little longer (top hat to bottom measurement) than stock which is why they provide more lift even on the bottom clip. Any OEM spec shock will have OEM dimensions, and the Eibach 2.5" lift springs should provide ~2.5" of lift.

I contacted Shock Surplus yesterday and asked if these coils would work on the KYB Monomax. The reply I got was: "The Eibach springs are longer than stock which generates the lift. The KYB Monomax shocks are stock length and for stock height vehicles only and would be far too short for use with that spring."

Which makes no sense. Of course the springs are longer than stock; that's how they provide lift. So I replied back explaining that I wanted a lift and why I thought these should work. The next reply was: "Again the KYBs are too short. If they were long enough I would have told you that they would work."

I've been wracking my brain trying to think of a reason why this would be true, and came up with nothing. Seems impossible. That guy obviously doesn't want to talk about it, though.

Any ideas, thoughts, experience?

Why KYB Monomax? I'm going to be living in a heavily loaded Tundra that will be used offroad a lot... so I need shocks designed for heavy loads and severe service. KYB Monomax is the only non-fancy shock I found that is specifically designed for this. And the reviews confirm that they perform great in a loaded truck, but are too stiff for unloaded... which is exactly what I want. It also doesn't hurt that they are cheap, readily available, and have a lifetime warranty.

2.5" custom-valved coilovers would be ideal, except that I'd need to carry the tools and supplies to remove and rebuild them, and shipping them back for rebuilds (and waiting a couple weeks) is out of the question.

 

Tomorrow I will be installing the 16" 3.0 ID 700lb Eibach springs on my 6112's to replace the Bilsteins 650lb coils so I can reclaim the 1.25" of lift lost when I added my C4 Overland Bumper, lights and Warn Winch. appx 250lbs added. before and after pictures tomorrow...

 

Same thing would happen if you put taller spring on a stock shock, no lift. A stiff azz ride is all you would get. To get lift you need a shock that is longer than stock.

 

That's great, since I'm also thinking about 6112s with upgraded coils. Let me know how it works out.

The springs I'm looking at are completely different though. They are tapered at the bottom like OEM coils.

 

I haven't even opened the box from Eibach yet. lol
I will take a picture of the two springs during the swapout.

 

Also I don’t see why the front shocks can’t be anything else. The weight will be in the back, correct? Unless your adding some heavy azz bumper in the front and need to make up for the drop, I would concentrate on the rear shocks & springs and add air bags.

 

Good luck on getting 6112’s. I have heard they are on national back order.

 

That's not true at all. Front shocks acheive lift by:

1) Longer strut. For spacer lifts, that's all that is happening... a spacer slapped on the top to make the strut longer. Most aftermarket lift shocks are a little longer to give ~.75" lift due to length.

2) Greater spring compression (preload). Either by reducing the perch to tophat distance (lifts that use the stock spring do this), or using a longer spring. Adjustable shocks all vary this distance to vary the lift.

3) Greater spring rate. This will produce lift even with the stock spring length and distance.

Most lift shocks have all of these in combination. Some even have softer springs that are longer and compressed more. There are many combos that can acheive the same end.

In this particular case I'm looking at a shock that is OEM length and perch-top distance, and wanting put in a longer spring to get lift. I can also put spacers on the top to make the strut a little longer (up to .5" or so), to give ~ an extra inch of lift in addition... actually compensate for extra weight. I'd like ~2" of lift when I'm done and loaded.

 

It's a 8' bed, so the camper CG will be well forward of the rear axle, plus the rear seat is removed and that area will be used for storage. I'll have over 500 lbs added to the front axles, easily.

 

Look at the member above and what he posted. The KYB and OEM shocks are the same length and extended length and less travel. Putting a longer spring with probably get you .5” of lift since the truck isn’t heavy enough to compress the spring just sitting there. Plus it will ride like shit. You said that the guy doesn’t know what he is talking about. Yes he does. You cannot get lift on OEM shocks with a longer spring. The shock can only go to it’s extended length. The 5100 and 6112 are longer shocks and that how you get lift. If you want 2” of lift, either a top spacer, garbage in my opinion or aftermarket coilovers.

 

The problem with swapping in a taller spring to achieve lift on the same shock body, is that you are likely extending the shock to the point that there is not adequate droop. The wheel becomes limited in it's down travel because the shock is closer to full extension at ride height.

Spring compression is determined by vehicle weight, not preload. Preload determines how high the spring sits on the shock body, and how much the shock is extended while holding the weight of the vehicle.

 

all very interesting. So in my case I am at the top perch on my 6112s with cb shims was appx 3" of lift before adding the extra 250lbs (bumper/winch/lights). The new springs are appx .75" longer and rated at 700lb vs the 650lb bilstein spring.I am thinking drop one clip level possibly two to compensate for the spring length and the heavier spring rating will put me where I was before appx 3" of lift.

Does my logic work here?

sorry for hijacking the OP

 

Awesome! Much thanks to you! Where did you find the KYB data? I've been looking all over. I am going to disagree with your conclusion though...

The extended length of the OEM and KYB are the same so that checks. That means that the perch to top distance must be the same, otherwise it the KYB would have a different lift height with the stock spring. If they spring was more compressed, they'd get more lift.

The fact that the KYB has less travel isn't a problem at all for compatibility. That's a function of the shock itself, and means it will bind less (not more) at full compression vs the OEM shock or the 5100.

The Eibach spring *has* been used on the 5100 and reports indicate you get 3" lift at the bottom perch. The length of the 5100 is .57" greater than stock which yields ~1" lift on it's own? Not sure of the exact ratio. 5100s with the stock spring are said to give .87" on the bottom perch and 2.28" on the top. Since the bottom perch lift is very near what you'd get with length alone, the spring compression (perch-top) distance must be very close to stock on the bottom perch.

 

Your logic works. But, until you load up those springs, you won't know for sure where your truck sits. It's an educated guess until you see the result.

 

Apparently you are dead set on adding longer springs on stock shocks to achieve lift. It’s going to bind. The shock isn’t going to be at the required range of motion, it’s going to ride like crap and will eventually destroy the shock or worse as it has happened with top spacers. Good luck with that.

 

yup. I HOPE I get it rightthe first time. not looking forward to multiple breakdowns and reassembling

 

Should work but have to do trial and error, which sucks cause you have to pull the shock out.

 

Send it.

 

Based on your earlier post you are at 1.75" now?

For instance if each wheel has a load of 1800 lbs now, and the leverage ratio is 1.7:1 (WAG...don't know what that actually is), that would mean your 650 lb spring is compressed 4.71" compared to its free length. A 700 lb spring would compress 4.37", giving you .576" of lift. The .75" longer spring would be an additional 1.28" giving you 1.85" total. You want +1.25 though, so that's .6" less.

6112 lift:
#4 2.5"
#3 1.9"
#2 1.3"
#1 0.75"

The stiffer spring will make these differences a little greater, but #3 would be real close. It all depends on that leverage ratio in the range you are sitting in, though...

 

Thanks... I also have the CB Shims 2 ds 1 ps. which got me to 3" over all from the 2.5ish top perch ring. Another thing I am considering is using the westcott collar vs bilstein collar wich would allow setting 1 ring lower for the same result. I am not sure what having the lower perch with same preload really does for the performance of the suspension

 

Longer springs are used all the time to achieve lift. That's exactly what Sage63 is doing! I explained clearly why the KYB would bind less than OEM or Blistein 5100 with the same spring. It will go through its range of motion just fine. If you've actually examined this and have a different conclusion, explain why.

 

It's the same whether you use a longer spring or more preload to achieve lift. You are going to lose some down travel.

You are correct, spring compression is determined by weight on the wheel and the leverage ratio between the wheel and strut. But that compression is comprised of both initial compression/preload (how much the spring is compressed at full extension) and strut compression when it's holding the weight of the truck. I showed this in the example of Sage63's 6112s above.

 

I explained it here. @SAGE63 has another factor to account for - The 250 pounds added to the truck. That added will weight compresses the spring more that the truck could before.

 

Yup, but when you add a taller spring to a shock that wasn't designed for it, "some" loss of down travel quickly finds "unacceptable" down travel.

I say go for it.

 

Are you saying I didn't account for it? 1800 lbs per axle is higher than stock, but that's a guess. Weight that is forward of the front wheels amplifies the axle/wheel load; it'll be higher than the weight added.

 

I already explained why, others have also, including someone who works with shock that you talked to. What Sage is doing, he is doing to a non-OEM shock, it’s longer and can and will accept that spring. Although I am sure Bilstein would caution him or anyone from running a longer spring on the top setting. I can guarantee you that if you call any performance suspension place they will tell you the same thing I have. But like I said you want to do it anyways so do it. No one has yet told you to do it, that should be your first hint. Since owning a tundra back in 08, I have yet to see or anyone ask about putting longer springs on a stock shock. Please be the first. You want those KYB so bad, then buy them, do stock length springs and add a top spacer for lift. Spacer still not the best idea but better than longer springs.

 

No you didn't account for it. The heavier springs are to account for the extra 250lbs. Not provide lift. The @SAGE63 was already lifted with appropriate shocks. So, consider that to be the baseline. The weight took the truck down and the heavier springs are to put it back where it was.

 

Again, it doesn't matter how the lift is achieved, this will be the case. Since I only want 2" of lift I'll be better off than people who have 3" lifts in that respect.

 

EXACTLY!!! and Bilstein advised using the 700lb spring. Had to go longer for 700lb since The Bilstein designed Eibach spring for the 6112 is 15.25" and Eibach only makes the 700lb spring in 14" or 16"