Adjusting suspension for a bumpy ride on 1999 TJ

Mr Valmonty

Mr Valmonty

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Oct 28, 2020
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Northern Ireland, BT78
Hey guys - newbie here.

Just got a 1999 Japanese-to-UK import 1999 TJ 4.0L.
It's got a Rancho 9000XL lift kit, with BFG 32" (Load C) tyres. Otherwise, it's relatively stock except for a speaker upgrade I installed a couple of weeks ago.

I have a few niggles that have come up, and I'm addressing them one-by-one. I've just got some LED front lights and indicators. I'm trying to find some cheap front flare delete options....

... but the ride is still a bit of an issue.

I'm driving on relatively standard UK country roads - nothing off-road. But even now, the suspension is pretty bumpy. I found the adjustment knob on the Ranchos and adjusted it all the way down to the softest setting, but it's still way more bumpy than I'd expect. I've also tried slightly under-inflating the tyres without much luck. Otherwise I'm hoping you guys might know something that could help?
 
Mr Valmonty said:
Load C. Running 27psi currently
Click to expand...

That's perfect then pretty much.

I would say at this point your ride is about as good as you're going to get it, especially since the Rancho RS9000XL is a great shock.

Have you ever owned a vehicle with solid axles before? They will obviously never ride as good as independent suspension, and if you haven't owned one before this can be an eye opening experience for some.
 
My current Rancho RS90000XL shocks are also at their least stiff #1 setting and I consider them a little too stiff too. Switching them to the RS5000X shock would really significantly improve the ride, that's what I ran previously.
 
Hey @Mr Valmonty ,

Since you're new, I thought I'd be sure you knew that you've already received replies from the two very experienced and trustworthy members, so what's above might be all you need. I'm also thinking about buying some RS5000X shocks, so I found Jerry's reply interesting.

@Chris , could you say a little more about how our TJs' solid axles provide a bumpier ride than "independent suspension"? I have a lot to learn, and am curious about this. I can also Google it if I just need to educate myself.
 
SSTJ said:
Hey @Mr Valmonty ,

Since you're new, I thought I'd be sure you knew that you've already received replies from the two very experienced and trustworthy members, so what's above might be all you need. I'm also thinking about buying some RS5000X shocks, so I found Jerry's reply interesting.

@Chris , could you say a little more about how our TJs' solid axles provide a bumpier ride than "independent suspension"? I have a lot to learn, and am curious about this. I can also Google it if I just need to educate myself.
Click to expand...
With solid axles, the wheels can’t move independently of one another. When you got a bump in the road on say the right side, the axle as a whole is going to move.

Independent suspension on the other hand allows the wheels / suspension to move independently of one another, thus allowing for one side of the vehicle to absorb a bump independently.

This is a good read:

https://www.theengineblock.com/off-...ependent-suspension-vs-solid-axle-suspension/
 
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I think you're right guys, I've not had a solid axle before. Good to know there are some solid people around for high quality advice. It's not unbearable - and probably not bad enough to warrant a change in shocks. But at least I have a backup in mind :)
 
Hi, just to chime in from another UK perspective; we have no importers of the Rancho shocks so to get some would be over £300 ($400) when shipping and import fees are taken into account, so they aren't necessarily the bargain that you would expect.

I recently ordered some Ironman foam cell shocks for my TJ. They are more of a mid-range shock but were only marginally more expensive than Ranchos. Hopefully I can get them installed soon and report back on the ride quality
 
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Lot’s of good information on this thread. Adding another bit, solid axles are inherently heavier than efficiently designed independent suspension assemblies, so the unsprung weight is considerably higher. Lower unsprung weight allows for more refined transfer of energy from bumps. TJ’s are mathematically limited by a sprung to unsprung weight ratio in how smooth a ride they can possibly offer. Same goes for my MGB-GT.

https://www.machinedesign.com/mecha...ifferences-between-sprung-and-unsprung-weight
 
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