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orttauq

orttauq

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I have a stock 2021 Base LC with ~20K miles on it. First time I have had 4 people and luggage on a road trip and it was kinda scary to drive. Every highway bump or bridge joint it would start a bounce in the rear that had almost as much horizontal movement (or at least felt like it) as it had vertical movement. I know this is due to weight since everything is OK with one or 2 people and dogs loaded up. Oh and I have drawers too although on this trip they were pretty empty.

Is this replace/upgrade springs or shocks or both to fix?

E_
 
the easiest most immediate fix was to probably increase your tire pressure to accommodate the added weight
 
The sideways motion is because when the rear end is not sitting at its natural height (in your case squatting down from all the extra weight), the panhard bar that helps give your rear axle / tires great articulation also causes a slight movement of the entire rear axle in one direction to the side (since its movement is more of a rotation rather than a pure up-and-down movement). Thus, when you go over a bump, the axle isn't sitting directly under that weight and makes it feel squirrely and move sideways. Also, the further compressed (or extended) the rear is, the more dramatic that panhard bar will move the axle to the side, and the more of an angle the panhard will be in that causes additional sideways rotation. The same effect happens when someone adds a lift without replacing the panhard. If you get out of the vehicle and look at where the rear tires line up, you might even be able to tell that they're not lining up the same as each other relative to the fenders, because of this effect.

One solution that many people use is get airbags installed in your rear springs. That way, when you load up a lot of weight in the back, you can inflate the airbags as needed to get the rear to its proper height and avoid that sideways movement on bumps. The inflated airbags also augment the spring ratings, so the ride won't feel so squishy under all that weight.
 
Consider OME 2720s
 
Another option to increase your spring rate with 'spring rubbers'. They're very easy to install on the rear springs.
You probably want the 'blue' or 'red' items.
red will get you about 5-10% more spring rate
blue somewhere around 15% more

Not sure what size the TLC will take, the LX takes B at all corners. The TLC spring set is NOT the same as the LX spring set.

You can also take them out after the trip.

Not as good as new springs in the correct spring rate, but better than squirrelly road manners at 80 mph.
 
orttauq said:
I have a stock 2021 Base LC with ~20K miles on it. First time I have had 4 people and luggage on a road trip and it was kinda scary to drive. Every highway bump or bridge joint it would start a bounce in the rear that had almost as much horizontal movement (or at least felt like it) as it had vertical movement. I know this is due to weight since everything is OK with one or 2 people and dogs loaded up. Oh and I have drawers too although on this trip they were pretty empty.

Is this replace/upgrade springs or shocks or both to fix?

E_
Click to expand...

Shoulda bought the lexus.
Jk welcome.

If it were me, id put in bags in the rear if dynamic load is the only concern and you put weight on and off. Its the only real thing like it outside of AHC.

Or of course a full lift kit if that’s in your plans. No better place to compare your build with similar trucks. But even then if your loading unloading a lot, then airbags are gold.

Or you could just put HE coils in at home.
 
I would start from the ground up. Tire condition, tire pressure, tire pressure that they should be.
 
Tires have about the same miles as truck since I put them on couple of days after I bought it. Terra Grapplers G2 285/60-18s on Tundra wheels Tires aired to 40psi.
 
Sounds like the normal LC200 OEM suspension to me. Mine was like that new. A bouncey but smooth ride.

It's not really springs, it is shocks. The LC200 is build for 7 people.

Different shocks will fix that issue.

You can replace shocks and springs (like the bp51 kit) but just shocks alone will fix that.
 
orttauq said:
Tires have about the same miles as truck since I put them on couple of days after I bought it. Terra Grapplers G2 285/60-18s on Tundra wheels Tires aired to 40psi.
Click to expand...

Which version of that tire do you have?

ISO-Metric XL 285/60R18 120S

LT-Metric Load Range E LT285/60R18 122/119S
 
orttauq said:
Maybe these?
Amazon product ASIN B008K5BO84
Click to expand...

Yes. Those are the airbags I have. Combine it with some of this 1/4" loom material to protect the air lines better:
https://www.amazon.com/dp/B092Z9WS3J7

Here's the post with how to install those airbags:

FerrisBueller said:
I don't remember seeing a thorough install thread for airbags on here, so I'm making this description very detailed.

I added Firestone 4164 helper airbags (and added 1/4" wire loom to protect the air tubes). These are rated for up to 35 psi. You can get the same ones, but with sleeves that bring them up to over 60psi max if you purchase the HD version from Airbagman (but it's like 3x more expensive shipped from AUS). They do seem to be the correct item to go with my 2" lift (this was the advice from a few other comments throughout the forum). Whenever we would go on family trips the past couple years, the gear would make the back sag 1" - 2", so this is to alleviate that problem and make it handle better but otherwise keep my non-harsh ride when the LC is not loaded up.

View attachment 3008989
View attachment 3009280

First, here's a really brief summary of the steps, before I get into more detail:

Prep work:
  1. Jack up rear frame on both sides and place jack stands.
  2. Remove both rear tires AND spare tire (creates a ton more room, I waited too long to do this).
  3. Loosen KDSS bolts 2.5 turns.
  4. Remove top breather bolt (12mm) to avoid damage when axle droops (I prefer removing the top bolt instead of the bottom clamp, since clamps often aren't airtight anymore after removing them).
  5. Remove the first 2 bolts (12mm) holding the brake line (passenger side) where it arrives at the axle.
  6. Remove the bolt (12mm) holding the emergency brake line to the axle.

Spring removal work (an extra set of jack stands can be useful for all axle work, but not required):
  1. Jack up rear axle by the diff slightly to avoid make sure you're in control of the droop at all time.
  2. Remove bottom shock mount bolts (17mm) and hammer shock off the pin.
  3. Remove driver side sway bar linkage bolt - 19mm.
  4. Remove passenger side sway bar linkage bolt - 14mm (be careful on this one, the washers and bushings like to fall off and roll away).
    • NOTE: This is the important step to make removing the passenger side rear spring really easy, and that usually is not mentioned in instructions anywhere.
  5. Jack up the passenger side of the rear axle, and let the driver side droop.
  6. Push down on the driver side wheel hub with your knee, the axle should droop enough to get the spring out.
  7. Jack up the driver side of the rear axle, and let the passenger side droop.
  8. Push down on the passenger side wheel hub with your knee, the axle should droop enough to get the spring out. You might need to brace your back against the wheel well.

Airbag work (just following the included instructions):
  1. Take the pyramid-looking bump stops out of the springs and cut off the lower 4 sections.
  2. Put the airbags in the springs (hole toward the top).
  3. Cut the provided tube in half, and add the wire loom now if you have some.
    • NOTE: leave at least 1" bare without loom on one side for the next step.
  4. Push to securely connect each section of tube to the easy-connect fittings on the airbags.
  5. Thread the tube through the hole in the shortened bump stops, placing the bump stops where they belong on the springs.
  6. Stand the spring/airbag/tube combination on the ground near where they belong on the axle.
  7. Thread the tube through the top frame hole where the springs will rest, and temporarily bring them out through the gap in above the frame into the wheel well. This will make routing a lot easier.
  8. Install the spring/airbag/tube combinations back onto the axle. Do passenger first, then driver. Same procedure as when you removed them - push on hub with knee and insert springs (make sure to align correctly).
  9. Route and zip-tie along the top or outside edges of the frame (there are lots of other tubes and cables in there that you can bundle them with), until you reach your target where you'd like to install your air valves. You'll have a ton of extra tubing, just leave the extra for now.
    • NOTE: Make sure you consider spare tire clearance.
  10. Install your air valves (1/2" top and bottom).
    • NOTE: A super convenient valve install point is in a little metal tab that is hidden but easily accessible under the plastic flap when you have your tailgate open. The existing holes are just barely too small, and need a tiny bit material drilled out first (and paint to protect from corrosion).
  11. Trim the tubing to the correct length to reach the air valves, but leaving a little slack. Remember to trim the wire loom back at least 1" from the end.
  12. Securely press the tube ends to the easy-connect fittings on the air valves.

Finishing up:
  1. Connect the sway bar linkages in the reverse order that you disconnected them. First the passenger side (jack up driver side axle first, then should be easy to manually place with the washers and bushings).
  2. Leave the passenger side axle high, this will push the driver side sway bar down, making it easier to bolt it back up to the driver side linkage (do this now).
    • NOTE: you'll probably need to use a jack or ratchet strap to push the linkage up the rest of the way to the sway bar. I used a jack.
  3. Replace lower shock mount bolts. Raise or lower each side of axle to make the hole line up, hammer the shock onto the mount, then install bolt.
    • NOTE: Make sure the tops of the springs stay inserted on the mounting lip, as they like to fall out during this.
  4. Reinstall emergency brake line bolt.
  5. Reinstall 2 brake line bolts.
  6. Reinstall breather bolt.
  7. Reinstall wheels & spare.
  8. Lower vehicle, and let it sit on level ground for 10 - 15 minutes (maybe even bounce around a little on the rear, too) so the KDSS system settles.
  9. Tighten KDSS bolts.
  10. Inflate airbags to 5psi (minimum when not using them.
    • NOTE: I added a hand pump to my gear that goes up to 30psi, since the airbags max out at 35psi. The hand pump works pretty good, and I will use it only when I need to make small increments (15 pumps for 5psi) or don't want to get out my bigger compressor.

Lots of pictures coming next...
Click to expand...
 
I agree with @Fisher23 that is fundamentally a shock issue, when loaded beyond capacity.

From my experience with many Toyota models - the OEM shocks tend to provide minimal damping force. The damping also seems to really drop out in the last bit of shock travel as it hits the bump stops. Maybe this is a strategy of Toyota to prolong shock life for overloaded situations as it generates less heat in the shock and keeps it from destroying itself with too much load, but the motions are disconcerting.

A shock upgrade that can provide more damping force under load, and maintain that performance for longer can be a good solution.

Augmenting with airbags can also be a good solution. It'll keep the suspension from bottoming out with large loads and reduce the dramatic side to side motions that come with full stroke suspension travel. But it won't solve fully solve the issue of absorbing and quelling motions without a shock change.

Of course you can upgrade springs too (and shocks). The great part of airbags is that it keeps a good ride when unladen, but you can increase spring rate on demand for trips.
 
orttauq said:
Tires have about the same miles as truck since I put them on couple of days after I bought it. Terra Grapplers G2 285/60-18s on Tundra wheels Tires aired to 40psi.
Click to expand...
orttauq said:
LT-Metric Load Range E LT285/60R18 122/119S
Click to expand...
orttauq said:
at 40? Ok, what should I have them at?
Click to expand...

The RCTIP (Recommended Cold Tire Inflation Pressure) for LT285/60R18 tires on your LC200 is 46psi F/R.

Before doing any other suspension mods, I would recommend increasing your tire pressures from 40psi to the RCTIP of 46psi.

Don't forget to initialize your TPMS system for the new pressures.

HTH
 
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