Dobinsons IMS Struts and Shocks for 2007+ Tundra's (IFP Monotubes)

So I got a full IMS set up (2.5” lift) a few months ago with the stock weight springs upfront and it has been incredibly harsh and rough. It feels like there is no damping and I can feel every little crack, pebble, and bump on the road.

This is the first time I’ve done anything like this for my truck and I really didn’t know what to expect. At the very least I was hoping it would smooth out the ride a little bit and make it overall more comfy and stable but that has not been the case. I was really excited to get Dobinsons. After researching, reading, and watching any video I could find I thought these would be a solid option for me.

Am I missing something here? Is there a button I need to push? Does anybody have any suggestions? Is this just how it is? I’ve reached the point where I’m seriously considering getting rid of these and just going back to a simple OEM or trying FOX or Bilstein or even the twin tube nitros idk.

Thanks in advance for any input/feedback. It is greatly appreciated.

 

What you are describing isn't a lack of damping, but rather high digressive damping. I don't know if this is how Dobinsons are valved, but it would make sense, as it is common with offroad shocks... my IM FCPs are like this. The downside of this sort of damping is that small bumps are more noticeable. I like it very much since I don't care about a cadillac ride and the handling, stability, and control are excellent, and large bumps are handled very well.

Did you get new tires... and if so what, and what is the pressure?

 

Edit

 

No new tires yet. 30 upfront and 33 in the rear.

 

Doesn't sound too good then, as tires will make it worse. These are listed as revalvable, so you might check into that.

I think if a smooth street ride was your priority, and you wanted your truck leveled... then spacers on the black shocks for the front (or some other cheap and softly damped shock), and leave the rear alone.

 

Did you do the assembly and install yourself? What ride height are you trying for and what height did you end up with? I would assume 2.5”.. What spring did you get with the kit? I know they offer several different springs. Perhaps they sent the wrong one; I’d suggest checking the part number on the springs you have installed. Might also be helpful t post some pics of your front setup.

 

Im an idiot. I assumed it was at 30 upfront and 33 in the rear. I actually checked and all 4 tires were 37! Reduced the air pressure and it’s a little better, still pretty stiff but seems manageable. Idk if that makes a difference at all. Idk. Also double checked the tires and they were manufactured in 2017 so pretty sure they are the original tires.

I also think driving daily on some of the worst roads LA has to offer doesn’t help. Part of the reason I wanted to get new suspension in the first place was to help smooth some of that out. Driving around here practically is off-road driving. Guess I should have done more research.

 

I did not do the assembly/install. Wanted 2.5” higher than stock and got the 2.5” stock weight spring kit c59-778. I’ll try to find a part number this weekend and double check with the shop I used. Will also get some pics of the setup to share but for now here’s this.

 

I FINALLY had a minute to install the front’s. It was… umm… fun… ha. Had to sneak up on clearancing the lower control arm pocket on one side which meant I had to pop the shock foot in and out of the driver a few times, but the second side went pretty easy.

I did have a question about the hose routing for the front remote reservoirs. I followed the example on the website but I feel like the front wheels may rub the hoses at lock. I haven’t even pulled it out of the shop for a test drive yet, but I’ll check later today. The hose also contacts the inside of the upper control arm on full droop. It doesn’t pint the hose, just hits in

I also have a small gripe about the reservoir mounts: A coupe of riv nuts would be fantastic for the mounts. Secondly, the worm clamps feel and look a little chincy.

Otherwise I’m excited to see how this thing rides!

 

You're supposed to run aftermarket UCA's with more clearance, so that nothing hits that hose. Plus you won't get the extra travel the coilovers give without them.

You'll have to turn the wheel and make sure the hose isn't hitting anything, then rotate the body of the resi to turn the hose further away if needed. You can loosen those clamps and raise it up as well to gain clearance.

 

Hmm. I don't recall any of the literature requiring new UCA's - except in the case of more than 2.5" of lift as is standard fair for Tundra's. I'm aiming for about an inch of lift.

From your website:

• Note about lift heights – all vehicles can have some variance and desired lift height may need to be adjusted to suit your specific vehicle. Adding 2.5″ or more lift, new UCA’s should be added for proper articulation and correct wheel alignment

On install, I rotated the reservoir more but it actually pushes the hose out further in to the path of travel. We'll see where it ends up, I guess.

 

“Adding 2.5″ or more lift, new UCA’s should beadded for proper articulation and correct wheel alignment”

I read that to say, if you have less than 2.5” of lift, new UCA’s are not necessary - same as virtually all other lifts for the tundra in order to correct alignment issues that keep camber an castor from being in spec at higher ride heights. Most UCA’s have around 4 degrees built in to them; being at only an inch or so of lift, I wouldn’t need the camber/castor correction.

 

Tires will definitely make contact with the hose and reservoir where they sit now.

Also, I notice that the hoses on my set are straight where they mount to the shock body and don’t have a kink in them like the website example.

 

I’m not seeing how to make this hose hide without rubbing something. Rotating the reservoir to the right pushes the hose in to the tire. Rotating it left pushes the fitting in to the tire. Rotating it 90 degrees to the left would kink the hose.

Stock wheels, stock tire size.

 

Flip the resi like the other guy did. You don't have the extra droop from new UCA's, so you shouldn't have contact issues with the hose. You could also raise the resi up from its current position, but it doesn't look like that will be enough in your setup.

The hose can rotate in every direction, the fittings on the resi can rotate 360 on the hose and 360 on the resi end. As shown in this video:
https://youtu.be/na5NvdfxOrM?t=322

 

Thanks. I Ended up coming up with the same solution before I checked back here.



The top clamp interferes with the hose a bit so I’ll end up reworking something somewhere. I might pick up a few coilover top mount brackets and place it over top of the coilover but I do like the location of the adjusters much better as they sit now.

Took it for a spin and handling in corners is great; small bump compliance seems improved; but I’m getting a weird oscillating shimmy that’s definitely coming from the front after hitting any bump. The bigger then bump the more sever the shimmy. I’m hoping my alignment tomorrow I’ll magically fix it; if not I’m hoping some more adjustment will fix it.

I had the rears pretty well dialed in to my liking - rebound maxed out, high speed compression set low (2-4 depending on load) and low speed compression somewhere in the middle - 7 or 8 IIRC. Running airbags and a beefier leaf pack in the rears seems to Ned less high speed compression but more damping. I initially tried about the same setting with the fronts but less rebound (manual recommends 10 rebound, but much more high speed compression). So there’s room to play. Or I just have everything out of wack and need to start over with my adjustments…

 

I've been running IMS for about 30k miles now. Lots of trails here in Idaho, some pretty fast. Shocks still look good but the coils do not look good at all. Just cosmetic though. As far as function goes I LOVE the way these handle G-outs and body roll. I am not at all impressed with how they handle washboard, potholes, rocks or the like. I only have 2.25" of wheel down travel since I installed the IMS kit which I feel is less than I should have as these are marketed as extended travel. Some harshness on trails is the suspension topping out at full droop. I do have plenty of available up travel and I just about never hit the bump stops no matter how quick I hit something. I am considering getting these revalved to mitigate the issues I mentioned with high speed compression and dampening or I may jump over to 8112's instead.

 

That sounds like high digressive damping. My FC Pros are like this, but I'm happy with how they perform... very planted and controlled. Little bumps are more noticeable, but that's easy to tolerate... also setting tire pressure to the minimum helps a good amount. Any chance tire pressure is excessive? Unloaded I run 35f and 30r; less offroad depending on conditions.

Less lift would probably ride better as well... or consider using less coil preload in conjunction with a spacer on top of the shock.

 

When i ran icons they were digressive. Removing the sway bar really helped in washboard like stuff. Digressive just needs lots of speed to be smooth its a tradeoff

 

I was under the impression that these are a linear valving; I believe the manual shows basically as much. They behave differently than my 6112’s which were digressive and you knew it.

 

I should run less tire pressure than I typically do while on trails so that it part of the issue.
I am not running swaybars.
Fairly certain the IMS are progressive as per what I've read but they don't feel like they are in my application. Rruff: I will consider those suggestions about preload and spacers, thanks.

 

Adding a spacer on top of an adjustable shock only serves to reduced available up travel

 

If they really are progressively valved, I'd suspect excessive preload on the springs... and by excessive I mean more than you'd prefer for your application, resulting in a harsh ride. What is your lift, and do you have UCAs? When you stated that you didn't like the performance on potholes and rocks, is it harshness or excessive rebound?

Lift is achieved with a combination of a) increasing the shock length, and b) increasing the spring preload. Manufacturers differ in how much of each they choose relative to OEM. Their job would be a little easier if lift was fixed, but the decent aftermarket shocks have an adjustment for lift amount, which results in some compromises to balance the range of lift heights and load capacity.

Below is a list of front shock max length, min length, and travel for 2nd gen Tundra. Note this is shock travel not wheel travel. I'll ballpark a factor of ~1.7x for this...

The IMS is longer than OEM by 24.2-23.55, or .65"... x1.7 gives 1.1" lift. A lift amount greater than this will have to come from spring preload, which increases "stiffness". Personally, I think it's a bad idea to go higher than 2.5" lift with stock length LCAs; the angles are too far from neutral resulting in excessive wear, plus you can end up with too little down travel as you mentioned.

The reason why I mentioned using top spacers is because the IMS is not that long for an aftermarket shock... and you mentioned a lack of down travel. Plus the minimum length is quite short, even a hair less than OEM. You could add a 1" spacer to the top and your max and min shock length would then be 25.2 and 18.5, which do not appear to be extreme numbers compared to Fox and King. That would give you 1.65" x1.7, or ~2.8" lift at the stock level of spring preload, and the amount of up and down travel would be better balanced.

When you extend the minimum shock length it's a good idea to mod your bumpstops as well... you don't want the shock itself taking all that force when it bottoms out. I got some cheap ones from Energy Suspension, that aren't listed for this application but work well. Get some 10x1.25x30mm bolts to install them.
Energy Suspension Leaf Spring Bumper 9.9135G
https://www.autozone.com/suspension...pension-leaf-spring-bumper-9-9135g/356511_0_0

Also, this is a pretty nice intro to shock valving. https://accutuneoffroad.com/articles/digressive-vs-linear-vs-progressive-pistons-shock-valving/

Disclaimer: Most of what I "know" about suspension has come from reading and thinking. I have very little experience trying different things. YMMV... good luck!

OEM
23.55 17.62 5.93
Bilstein 5100
24.12 17.77 6.35
OME
24.01 17.12 6.89
Rancho 9000
23.51 17.88 5.63
KYB Monomax
23.56 18.18 5.38
Dobinson IMS
24.2 17.5 6.7
Ironman FC Pro
25.1 18.9 6.2
Fox 2.0
25.33 19.4 5.93
King 2.5
25.33 18.15 7.18
Fox 2.5
25.53 18.86 6.67

 

Anyone move from the Bilstein 6112/5160 to this? Thinking about trying it out. Looking for something low maintenance, reliable and comfortable (I know this is subjective). My Bils squeak like hell and just thought it would be nice to get something new. Still would like to maintain a 3/1.5 lift. I have a c4 bumper and winch so I'd be looking at the HD springs. You guys mentioned the coils looked sketchy but no one has reported binding. So is this set up good or what?

Edit: want to also add I do about 95% highway. I would like to wheel but it never happens. Maybe this set up is overkill?

 

I'd work on finding out where the squeak is coming from since it probably isn't your shocks.

 

I have. PM inbound..

 

I had the exact same experience/impressions with my recent backcountry blast. G-outs and body roll are awesome. Washboards... not so much. Lots of shaky shimmy vibes. Most potholes weren't terrible but could be pretty harsh. Two in particular were OUCH harsh. Tires were aired down to 30 psi from 42 psi in my LT's. Ya, I could have aired down a little more, but the handling was already a bit lazy at 30 lbs and 7xxx lbs.

I wonder what valving is on IMS compared to the MRA? Meaning, is the IMS valving the same as MRA's with everything set at zero? Half way? I highly doubt it is the same as the MRA's set to full - more than a few clicks on my high speed compression and it goes in to dump truck mode.

 

The sweetspot on a Tundra is ~2" of front lift, or even less. If you care about offroad performance, I'd stick to that. It's enough for 37s. You don't need any lift for 35s. Get a poser bracket lift if you just want to be tall.

Also, regarding what I posted earlier about adding a top spacer. I'm talking about a 1/2" spacer. Even with that the IMS will still be shorter than several aftermarket shocks. This will reduce your spring preload to get 2" of lift, and increase down-travel. The IMS shocks have .77" more shock travel than OEM (~1.2" more travel at the wheel?). Note that at max compression, the IMS shocks are listed at .12" shorter than OEM at max compression, which probably means you are missing out on some up-travel at stock length (ie you are bumpstop limited). Adding a 1/2" spacer makes IMS .38" longer instead. Lengthen your bumpstops a little to account for that. I highly recommend using the Energy Suspension bumpers I linked above at least in the rear position, because the OEM bumpstops are harsh little hard bastards.

As an example, say the OEM Tundra has 9" travel, 4" up and 5" down. I haven't actually measured that, but it's close and I know the bumpstops kept my fat 35s from hitting the fender on stock suspension, when I had ~5" clearance. IMS has ~10.2" travel. 2" lift with the IMS puts you at 5-(2-1.2) down, or 4.2" down, and 6" up... but actually less because you'll hit the bumpstop early. Adding the 1/2" spacer should give you ~5" down and 5.2" up.

High low speed compression damping is great for handling (body roll) and G-outs. High high-speed compression damping will be harsh when you hit a large/sharp bump. Digressive shocks have high low speed damping, but modest high-speed damping, which I think does well both on and off road.

 

Tried to read through everything, but I'm a bit confused and am wondering if someone could chime in.

I have IMS struts and C59-610 coils going on my truck next Tuesday. Online it says to use the 2nd grove for the standard spring height position, but on here it looks like it may be the bottom, or the few that have installed 610s say they wish it were installed on the bottom. Really just trying to get the advertised 2.25" and have the best ride possible.

I have a 2012 crewmax with a smittybuilt M1 bumper. No winch. Replacing a spacer lift that came with the truck.

Thanks all.