Dobinsons 5th Gen T4R Suspension options - from Exit Offroad
- Thread starter Crikeymike
- Start date
Is this a fact?
I thought the Dobinson site stated just the opposite and this was the reason for the twin tube?
I could be completely backwards. I don't do high speed desert runs or anything, just real shitty roads with bad potholes, frost heaves, and washboards, which these have handled wonderfully.
honda250xtitan
New member
This is why i'm curious about the prototype monotube shocks Mike is running on his 4runner. 
BigMike603
New member
I choose the Bilstein's because of the reliability and lifetime warranty. I also like the fact they are Zinc coated instead of painted. I think the painted shock would be destroyed in a NH winter with all the Salt they use. Though the Bilsteins will still rust, I just think they will last longer. I also am not a fan of the yellow color on the Dobinsons.
Crikeymike
Senior Member
Yes, twin tube shocks have been around forever, and they also last an extremely long time.
Twin tubes have more oil (heat reduction, draws heat away from the inner cylinder where the piston is working), a 2nd outer layer (the twin tube, to protect the inner tube from damage), as well as thicker walls for more heat dissipation and less fading (the walls draw heat from the oil and the airflow over the shocks cools those walls down, like a heat sink), and they also run lower pressure gas inside, so they can have a different feel on the road. Twin tubes are better suited for higher speed corrugated roads, like in Australia, and will fade less overtime than a monotube. The debate has gone on for years. Monotubes have a piston inside a single (mono) tube, then 2mm or 3mm wall, then you're outside. So without a lot of airflow over them, they get hot. All shocks get hot though.
The bigger the shock body, bore, piston size and amount of oil, the better it can deal with heat. The bigger the engine in a car, the more oil it has to cool the cylinder walls and draw that heat away from the heat source. Look at what baja guys are using now, some are 4-5" thick bodies with massive pistons and reservoirs.
A monotube with a reservoir has a good benefit of more oil, but a regular monotube can heat up very fast and doesn't offer the internal components much protection from damage, aka stones/rocks flying up and hitting the body of the shock. Heat kills seals faster. Plus, Americans are going nuts for resi shocks, even when they don't need them, so Dobinsons was working on a race option shock with longer travel and bigger components, and you can't easily have a twin-tube with external reservoir to absorb the huge woops and bumps they have to go over. They're also much bigger, 66mm bodies, to hold more oil and handle the heat, since they can heat up so quickly.
If we offered a monotube regular shock to compete with our own twin tubes, they would probably be about $50 retail (cheap to make, less components). A lot like others out there in the US market. Our MRR shocks are $275 to $375 each.
I'll gladly sell you guys our shocks, because I'm confident in their ability and how they work on and offroad, but feel free to run whatever you want. Tons of guys on here are on the Billy Bandwagon, and that has spread through word of mouth. They're affordable, they work, and people like the adjustable height on the front. Color plays a huge role these days, go to a Jeep event and prepare to have your mind blown for colorful suspension options!!!
Simpleman74
New member
I have 5100s all around, bought the 2" rear coils... cant even see them unless you crawl under the rig. I will be buying 3" fronts assembled on the YELLOW shocks and a set of YELLOW shocks for the rear too! lol. after a couple weeks they get covered in dirt and you can see them anyway
Adi979
New member
Anyone??
honda250xtitan
New member
Awesome info thanks.
I'm all about the show, not the go. Hence why i ran Fox ext. resi's on my titan that was 99.999999% on the road :blah::blah: lol
sn_85
Senior Member
A lot of people use a 1/4" top plate spacer for the front driver side to correct for this.
deedubb
New member
I have 1" drivers side lean. Have not corrected it yet though
Adi979
New member
Wow that's quite a bit. I do see that you have kdss, am I wrong here or does kdss amplify the lean issue.
Crikeymike
Senior Member
It's just a matter of resetting the KDSS system (opening valves, raising the taller side, closing valves) to get it back down. The coils have the "lean" correction built into them for the KDSS.
Adi979
New member
I see. Sorry Mike I realize I'm asking a lot of questions but I'm trying to do my research. When you look at lifts from Toytec, OME and what not that a lot of members are running you don't have to ask too many questions. Just browse trough the treads and find your answers. With Dobinsons being new here not too many ppl are running it yet. I believe that it's a high quality product based on my own research on Australian websites and once it catches on here it will spread like wildfire. It's just a matter of seeing some real world #'s in lift heights. For example after talking to you and reading more on your first post seems like the 723 rear coils could be good to pair with 300's to eliminate the lean. It states they provide 1.25" of lift so I'm assuming they settle at 405mm rather than 420mm. The reason I bring this up is that there's coils from other manufacturers that claim 395mm will provide 1.75" in lift and very similar if not same spring rates yet the lift amounts are different. This a part where I get a little confused. I'd hate to buy a coil that states 1.25" of lift and end up with my rear end raised 2" or even vice versa.
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Crikeymike
Senior Member
3rd row seats, drawer systems, tools, etc, all of these things can greatly affect the lift height in the rear, and a lot of people fail to mention, or don't realize the weight they're carrying in the rear when ordering and installing springs. As an example, we have found that with or without the 3rd row of seats, you can end up with 1/4" lift height difference.
The C59-723 coils are 405mm on the short side and 420mm on the tall side. That's the free height before installation, and 15mm is a little over 1/2". The 15mm extra on one side is to "push out the lean". If we made those exact same coils for a non-KDSS, they would both be 405mm free height.
Compare the C59-325 (non-KDSS coils) that are giving 1.75" to 2.0" of lift, those are 420mm free height, which is 1/2" taller than the C59-723 coils. So the C59-723 will not give 1.75" of lift, it will be 1.25" at a minimum, up to 1.5", depending on loads.
A 220LB or 228LB coil doesn't need much weight at all to change the height, and you always have to factor in free length of the coil and spring rate in looking at linear rate coils.
Thankfully, a lot of the good people here on the forum that have bought our suspension so far have posted results and lift heights, but that's probably about 1/3 of everyone. Some people I have asked a few times for measurements, but not everyone has the time to give that feedback. Luckily, this post has been working out well and everyone has been able to share their results, so hopefully everyone will continue to give that. I've been waiting many months for people to give me real world heights on the C59-599 coils, the coils that we sold out of the fastest. No news must be good news, and they must have been happy with their heights and ride quality at the end of the day, since I haven't heard from them.
Adi979
New member
Thanks for clarification Mike. I appreciate all the input. The reason I put it in here instead of PM is so that other ppl can read it too and not ask the same questions. I understand what you are saying about weight. My truck is more of a mall crawler than an Off Road rig. I'm not planing on installing any bumpers front or rear or roof rack. The only things on my list are mild lift, wheels and tires ( most likely stock size). There's no third row seat or anything else in the back. Ultimately I would love a 2"F/1"R lift and the only reason I mentioned the 723's over 599's is that I could install the longer coil on the drivers side to correct the lean. NO KDSS on my truck either. Btw Dobinsons is #1 on my list for a lift.
PS: I did have a member PM me that's running 725's in the rear on a non-KDSS rig to correct the driver side lean. He said the truck sits level and he got 2" of lift.
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Here are my not so refined measuments made in haste :
(Measured from fender to center of hub)
LF 21.75
RF 22.50
LR 24.125
RR 24.625
So I will measure again when I'm somewhere more flat/level, because I don't think that front measurement is true. I don't see it with my eye and the pad in front of my shop has a slight grade.
I do wish the rear was an inch lower, but I like some rake. It rides so nicely over shitty roads. I was hiking out in the middle of nowhere yesterday and the dirt roads were a pleasure.
(Measured from fender to center of hub)
LF 21.75
RF 22.50
LR 24.125
RR 24.625
So I will measure again when I'm somewhere more flat/level, because I don't think that front measurement is true. I don't see it with my eye and the pad in front of my shop has a slight grade.
I do wish the rear was an inch lower, but I like some rake. It rides so nicely over shitty roads. I was hiking out in the middle of nowhere yesterday and the dirt roads were a pleasure.
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