Metal Tech rear suspension conversion problem. (2 Viewers)

[Fubeca]

I have a concern about the design of the metal tech suspension conversion kit. I recently purchased and installed the kit but am not pleased with its performance. I installed with FJ Cruiser springs and Bilstein 5100s front and rear. I wasn't looking for much height just a little lift.

I found the ride to be very nice for typical driving, but larger bumps would result in harsh bottoming out. In looking closely at the suspension I noticed that the secondary isolator is too high in relation to the bottom spring mount. This allows the bumpstop to contact the axle before the secondary isolator contacts the bottom spring mount. The result is the harsh ride that I and some others have experienced with shorter springs.

My solution was to buy Daystar spring spacers to put above the springs and the isolator moving the isolator down in relation to the frame and the bumpstop.

This has greatly improved my ride/comfort as the secondary isolator is now able to perform its job and take some of the energy keeping the axle from bottoming out on the bumpstops.

I would like to see either a taller bottom mount, or some type of spacer included in the kit to bring the isolator down so it contacts before the axle bumpstop. I'd also like to see the bottom mount have a bottom so it sits more securely on the axle. Mine was like an upside down cup sitting on the curved edge of the axle spring mount which relies on the tightness of the bolt to keep it from moving. I'm concerned this will lead to loosening of the bolt over time. Fortunately it is a nylock nut and won't likely fall off.

I would also like to see the top of the mount smooth so the exposed bolt head doesn't damage the secondary isolator when it makes contact.

Here is a photo from another build on this site showing the metal tech mount and the isolator. It looks like the isolator will contact at about the same time as the bumpstop.

Here is an image showing a 4runner - notice how the isolator will contact the bottom perch approximately 2" before the axle will contact the bumpstop?

Has anyone else experienced this? I noticed several people had moved to a taller spring and then felt their problem was solved because they weren't feeling the harsh bottoming of the shorter springs.

 

[Stumpalama]

Did you contact Metaltech? @helocat

 

[Fubeca]

Not yet - trying to get some perspective from others who've installed the kit before contacting MT.

 

[NMBruce]

I don't have anything near that travel on my MetalTech long travel rear suspension, I only have about 2" of up travel, are you jacked up? But my bump stop with hit first

 

[Fubeca]

I think both of those images are with the axle hanging free - I'll take some of mine with load on it when I get back home. I only have a couple of inches when weight is on the springs.

 

[little_joe]

I had this issue when running FJC springs. Solution was simple, go with springs that work w/ the GX, and FJC springs don't fall in that category (too little spring rate). The fact your suspension is moving that much in daily driving is a blatant indicator the springs, while seeming to ride "nice," are not approrpriate for the application. (If you haven't loaded up your GX while running FJC springs, just wait - the ride will be utter s***.)

The isolators are not proper bumpstops anyway. They serve to progressively moderate bump until travel limit is reached and the axle/fame bumpstops limit further movement to prevent damage.

I suspect MT expects people will go with lift springs, and therefore not ordinarily experience this - which, imho, is a fair assumption even if it's not explicitly called out in their marketing/material. The other option is a bumpstop spacer or new bumpstops.

There simply cannot be a universal, works-100% solution when the owner is sourcing other random suspension components. The owner/buyer has a responsibility in this - whether that's pre- or post-sale to do your due diligence, talk with MT, whatever. It's in your best interest anyway for safety and performance.

 

[mercedeezel]

I think that's my axle in the 1st pic. As @Fubeca mentioned, the axle is hanging free. i have attached a pic of the same axle with the truck on the ground for reference. I gotta agree with @little_joe - there is only one bumpstop. If you look at the original design, there is the bumpstop and the air spring.

 

[chiz45]

I had this issue when running FJC springs. Solution was simple, go with springs that work w/ the GX, and FJC springs don't fall in that category (too little spring rate). .

what rear spring are you using? I am in the same boat here, 5100s with FJ rears and i noticed as in the first pic above a clean spot from bottoming out. I of course feel it on road dips as well. I just changed the rear bump stops to Superbumps (GXOR group buy) and it seems to soften the feel, but I am certain these rear springs are not beefy enough for this truck. My truck is leveled, with a tiny rear lift using the SSO conversion and added spacers. I would like to maintain this height, if possible.

 

[Fubeca]

The isolators are not proper bumpstops anyway. They serve to progressively moderate bump until travel limit is reached and the axle/fame bumpstops limit further movement to prevent damage.

I agree with this - and this is my concern with the original design. It seems like the isolator can't do its job to add that progressive energy absorbtion if it is too high relative to the bump stop. From the original design of the 4runner it looks like it should contact about 2 to 3 inches before the axle hits the rubber bumpstop which is the ultimate end of uptravel.

The GX design doesn't use the isolator/secondary bumpstop because airbags by nature are progressive.

I guess I'll need to get different springs. I'm only looking for about 1-2" of lift - I'm running bilsteins on the front on the second to lowest setting with tacoma TRD progressive coils and don't want any more rake than stock. Is the OME 895e a good option?

 

[little_joe]

what rear spring are you using? I am in the same boat here, 5100s with FJ rears and i noticed as in the first pic above a clean spot from bottoming out. I of course feel it on road dips as well. I just changed the rear bump stops to Superbumps (GXOR group buy) and it seems to soften the feel, but I am certain these rear springs are not beefy enough for this truck. My truck is leveled, with a tiny rear lift using the SSO conversion and added spacers. I would like to maintain this height, if possible.

I'm just running the Icon standard 2" lift rear spring.

I previously ran springs from Coil Spring Specialties I had custom made, based off a 2007 4R V8 4WD, there's a thread here on them. The only reason I changed is because I guessed wrong on height, and ultimately I wanted a bit more lift w/o using spacers.

Prior to the CSS springs, I ran 2010 FJC TT rear springs. At first they seemed good, but I noticed the constant wallowing and bottoming onroad; and loaded with a few hundred pounds in the rear, they were dreadful.

I recall one guy on here running Moog 4th-gen 4R springs from one of the chain parts stores, and having very good results with them. May be worth a look, and they're very inexpensive.

 

[Sam Stewart]

Is there a recommended spring for that kit? I would also assume that MT is expecting everyone to use a lift and not just put a factory spring from another truck. Probably wouldn't hurt to contact them but my guess is going to be that they will tell you to use a lift spring.

 

[Fubeca]

I ordered Icon 2" springs from Metal Tech and some stock 4runner/FJ bumpstops (PN 48306-60180). The bumpstops for the coil-sprung 4runner/FJC are a couple inches shorter (see the second image in the first post).

I will post back with an update when I get the springs replaced. I think the bumpstop issue is most pronounced for people with "stock" springs as the isolator isn't allowed to do its job.

I imagine most of the lifted springs have less of an issue as they are less likely to bottom out.

 

[Hoosier Daddy]

I was just about to ask how your current setup would be different from a stock 4th gen 4Runner. I didn't realize the bumpstops were different, so I thank you for illustrating that and pointing it out.

 

[GXMac]

Is there a recommended spring for that kit? I would also assume that MT is expecting everyone to use a lift and not just put a factory spring from another truck. Probably wouldn't hurt to contact them but my guess is going to be that they will tell you to use a lift spring.

That's a good assumption, but they do sell a stock height conversion package, so maybe it is something they have not noticed yet.

 

[Sam Stewart]

That's a good assumption, but they do sell a stock height conversion package, so maybe it is something they have not noticed yet.

Definitely. Maybe if you are doing the stock height kit they should have some recommended springs or at least have something about not using FJC springs.

The GX and 4th Gen 4Runner are the most similar so it seems logical that using 4Runner springs would be the best bet.

 

[IanB]

I ordered Icon 2" springs from Metal Tech and some stock 4runner/FJ bumpstops (PN 48306-60180). The bumpstops for the coil-sprung 4runner/FJC are a couple inches shorter (see the second image in the first post).

I will post back with an update when I get the springs replaced. I think the bumpstop issue is most pronounced for people with "stock" springs as the isolator isn't allowed to do its job.

I imagine most of the lifted springs have less of an issue as they are less likely to bottom out.

If the bumpstops on the FJC/4Runner are shorter than the GX, that seems like the most logical explanation for the bottoming out early issues people are seeing with no-lift conversions. I'm about to convert the wife's with the SSO kit and FJC rear springs, if there's issues I'll grab a set of the shorter bumps stops from a partout and see if it makes any difference.

Thanks for pointing this out.

 

[Fubeca]

If the bumpstops on the FJC/4Runner are shorter than the GX, that seems like the most logical explanation for the bottoming out early issues people are seeing with no-lift conversions. I'm about to convert the wife's with the SSO kit and FJC rear springs, if there's issues I'll grab a set of the shorter bumps stops from a partout and see if it makes any difference.

Thanks for pointing this out.

Very interested in your experience. I think the FJC springs are just too soft/short for this application. I'm curious what the stock-height springs Metal Tech sells are for.

 

[IanB]

Very interested in your experience. I think the FJC springs are just too soft/short for this application. I'm curious what the stock-height springs Metal Tech sells are for.

I'll be using the SSO kit, so there's a bit of adjustability in rear height there if I need it. SSO recommended the 4th gen 4Runner springs, I went with the FJC as the spring rate was slightly higher and the GX should theoretically be the heaviest of the 120's, 4th gen 4Runner guy seem to get about 1/2" and a bit firmer ride by swapping to FJC rear coils.

I'm pretty sure Metaltech recommends the FJC springs for stock height conversions.

 

[little_joe]

I'll be using the SSO kit, so there's a bit of adjustability in rear height there if I need it. SSO recommended the 4th gen 4Runner springs, I went with the FJC as the spring rate was slightly higher and the GX should theoretically be the heaviest of the 120's, 4th gen 4Runner guy seem to get about 1/2" and a bit firmer ride by swapping to FJC rear coils.

I'm pretty sure Metaltech recommends the FJC springs for stock height conversions.

Do you have a source on this spring rate info? It contradicts the info I received from an actual spring manufacturer who maintains a database of these things.

 

[IanB]

Do you have a source on this spring rate info? It contradicts the info I received from an actual spring manufacturer who maintains a database of these things.

Coil Rates: OEM 4runner, OEM FJ, Moog, & Others - Toyota 4Runner Forum - Largest 4Runner Forum

I can't vouch for the accuracy, but I did come across this info in my searching.

Gun to my head, I'd believe the FJC would have a higher spring rate than a 4th gen 4Runner based on the type of use they are marketed towards. 10lb/in is pretty well the smallest increment you'd see from an OEM in spring rates, so the difference is minor.