Dobinsons IMS59-50700 not actually adjustable? Lift way too high. (1 Viewer)

[jt3212]

Hi all,

Maybe I'm jumping the gun before getting an alignment, so let me know if you think that's the case. I recently had a Dobinsons IMS lift kit delivered and after installing it, the lift was about 3.25 inches in the front and I was expecting ~2 inches in order to level it with the factory rear height (I have the rear air bags I'd like to keep). It's settled a bit (about 1/4 inch), but still sitting an inch high in the front. Dobinsons assembled it and shipped it directly to me and based on my measurement against their instructions the spring seat is set correctly (213mm from center of lower shock bolt to lowest part of spring seat). My spring selection falls within their specification (C59-352) as I have a steel bumper (~100-120lbs), winch (~74lbs), sliders and skids installed. They specify this spring as a 2" lift with 110-220lbs front static weight.

I have an appointment to get it aligned on Tuesday and the local shop said they could level it, I'm assuming by reducing the preload. According to Dobinsons when I called them you cannot lower the spring seat more than 2-3mm. To get the 1 inch lower that I'll need I believe I need to lower the seat ~1/2 inch or 12-13mm. I don't believe the 2-3mm will be enough to get me down to a 2" lift unless getting an alignment and a lot more settling occurs. I can understand why you shouldn't raise the spring seat, as that could cause spring binding and even less down travel, but why couldn't you lower the spring seat?

I might be missing something or misunderstanding, I'm by no means an expert, but I would like to hear your opinions on it? I would just like to get it leveled correctly but it seems the "adjustable" IMS is not actually adjustable. I don't want to damage anything but also not exactly thrilled with the way it's sitting. On another note, aside from the alignment being out of whack, I'm really happy with the ride quality.

Thanks for any help!

 

[r2m]

As you had mentioned, your springs have already settled a wee bit already. Give it some time and they will settle more, especially if you get on some wash board trails or something that will cycle and compress/stretch those springs.
If you're planning on any extra weight like an after market bumper, dual batteries, that will also impact ride height.

 

[ericm979]

I don't think it'll settle an inch.

I don't see why you can't reduce the preload. The shock itself should not bottom out even if the spring is removed- the lower A arm should hit the bump stop well before the shock bottoms. Designing it so the shock bottomed out before the bump stop and was only kept from bottoming by the spring would be seriously wrong and result in a lot of bent shocks.

I'd see if you cant talk to an engineer at Dobinsons or at least a more experienced support person. You can't be the first to want this.

You will need to compress the springs to turn the preload rings without damaging them especially since its an aluminium body. The usual "death sticks" that work fine on car struts probably won't work on these due to the higher spring rate, less space between coils and small diameter springs (compared McPherson struts on cars). But a good 4x4 suspension shop should have the right equipment.

 

[Jstawgn]

Lowering are much easier than raising. It should come with the tools to adjust ride height.
I believe the thread pitch are 2 mm and the motion ratio are 1:2, to lower it 1" you need to lower the collar 1/2" or 6.35 rotation.

I use OME2886 as I don't want to buy another spring. This spring are very tall and my front seat are much lower than 213 they recommend. I got almost 4" of lift at 213 mm. I think mine are less than 200 now.

 

[jt3212]

I don't think it'll settle an inch.

I don't see why you can't reduce the preload. The shock itself should not bottom out even if the spring is removed- the lower A arm should hit the bump stop well before the shock bottoms. Designing it so the shock bottomed out before the bump stop and was only kept from bottoming by the spring would be seriously wrong and result in a lot of bent shocks.

I'd see if you cant talk to an engineer at Dobinsons or at least a more experienced support person. You can't be the first to want this.

You will need to compress the springs to turn the preload rings without damaging them especially since its an aluminium body. The usual "death sticks" that work fine on car struts probably won't work on these due to the higher spring rate, less space between coils and small diameter springs (compared McPherson struts on cars). But a good 4x4 suspension shop should have the right equipment.

Thank you for confirming I'm not crazy to think reducing the preload isn't a problem. I'm with you that I can't see how it could actually harm anything, but I'm still puzzled that the Dobinsons rep would be so adamant about that. I agree that maybe an upper level support tech or engineer would have a better idea of what's going on.

The shop doing the alignment is an offroad specialty shop so I'm hoping they have methods to lower those lock rings without too much trouble and they honestly didn't seem that worried about it. I know there are ways to remove spring tension without a compressor and while it's on the truck, but that is not worth my personal risk. I'll keep you updated with a solution! Thanks again for the response.

 

[jt3212]

Lowering are much easier than raising. It should come with the tools to adjust ride height.
I believe the thread pitch are 2 mm and the motion ratio are 1:2, to lower it 1" you need to lower the collar 1/2" or 6.35 rotation.

I use OME2886 as I don't want to buy another spring. This spring are very tall and my front seat are much lower than 213 they recommend. I got almost 4" of lift at 213 mm. I think mine are less than 200 now.

About a 1/2 inch is exactly what I was thinking, so thank you for confirming that! So you are running an IMS shock with the OME2886 spring? Does everything ride ok with it setup like that?

 

[Jstawgn]

About a 1/2 inch is exactly what I was thinking, so thank you for confirming that! So you are running an IMS shock with the OME2886 spring? Does everything ride ok with it setup like that?

I have MRA which is exactly same shock body. Seems fine, not noticing any issue at all.
352 is heavy spring. 725 lbs per in and 385 mm free length. My 2886 is 660 Lbs per in with 402 mm free length.

 

[jt3212]

I have MRA which is exactly same shock body. Seems fine, not noticing any issue at all.
352 is heavy spring. 725 lbs per in and 385 mm free length. My 2886 is 660 Lbs per in with 402 mm free length.

Good info! I do wonder if Dobinsons concern about lowering the seat is about keeping the spring fully engaged. Obviously, with your longer spring that's not a concern but if I'm doing my math right, if I lower my seat to 200mm from the bushing eye and full extension of the shock is 560mm that would leave approximately 25mm of the spring compressed when seated ([560-200=360] [385-360=25]). With it being a linear spring rate, I don't see that this is a problem but is there an industry standard of sorts for default spring compression distance?

I appreciate all your thoughts! You all can feel free to ignore me now if you'd like, at this point I'm not overly worried but just shooting for a greater understanding lol. As an engineering dropout I'm both a nerd and not that smart

 

[ericm979]

From my motorcycle experience you need enough preload so the spring isn't loose at full extension. You don't want it moving around on the spring seats. That's all you need for reliability. Preload beyond that is for setting the static ride height.

BTW if you haven't seen them yet, "Tinkerer's Adventure" has a bunch of really well done Toyota IFS suspension videos on youtube.

 

[jt3212]

From my motorcycle experience you need enough preload so the spring isn't loose at full extension. You don't want it moving around on the spring seats. That's all you need for reliability. Preload beyond that is for setting the static ride height.

BTW if you haven't seen them yet, "Tinkerer's Adventure" has a bunch of really well done Toyota IFS suspension videos on youtube.

Good to hear and thanks for the response! I have watched many Tinkerer's Adventure videos, that guy is a huge help and wealth of knowledge for the Toyota community. I actually rewatched his videos before posting here just to make sure I wasn't way off on my thinking lol. I hope he keeps producing more!