Front suspension stiff

[Airplanedoc]

I have a 1985 Nissan 720 2WD that's a project truck, I bought a few years ago with a blown motor, I have since replacement the motor and all the front suspension bushings, ball joints, shocks and all the steering components with the exception of the steering box. I've had the front end alignment done but the suspension is real stiff and feels like I'm riding a tank, I never drove it prior to doing the work so I'm not sure how it rode before.  I didn't index the torsion bars prior to removing them but  followed the maintenance manual when I did the reinstallation, hoping you gentlemen might have some ideas. I did a search on the forum but didn't find any similar topics.   

[datzenmike]

I think a ride in another 720 will show you that this is normal for an '80s small truck. Did you replace rubber suspension parts with poly? this might add a small amount of harshness as they don't have as much compliance and vibration isolation as the much superior rubber parts.  

[Airplanedoc]

I didn't use poly, my 1991 Nissan D21 rides a lot better.   

[datzenmike]

Newer technology better seats?

 

What tires are on it? Sidewall rating??? If 4 or 6 ply side walls it will carry heavy loads but will give very little on bumps.   

 

D21 is likely heavier. Heavier rides softer.

[Airplanedoc]

It's got 205/75R14 with 2 ply sidewalls, I'll have to put some miles on it to see if it gets better.  Would adjusting the ride height affect the ride?  

[IZRL]

I was just thinking this yesterday. I just got my 720 running and it's the first time I drive it since I bought it as well. It has got to be the roughest ride I've ever experienced. Suspension is stiff as hell and you feel even the slightest crack on the road. I thought it could be the fact that the torsion bars are cranked all the way up. But from what you're saying it doesn't matter either way. I have regular road truck tires Michelin LTX MS2 108t tires at the moment. And the truck came with some god awful electric seats. They are ugly as hell but are almost as cushioned as a lazy boy recliner. They look like they came out of a 90s van or RV. I imagine the ride is worse with the oem seats. 

[datzenmike]

4 hours ago, Airplanedoc said:

It's got 205/75R14 with 2 ply sidewalls, I'll have to put some miles on it to see if it gets better.  Would adjusting the ride height affect the ride?  

 

Two ply is fine. The original 520/521 and 620 trucks were 6 ply, made for WORK.

 

The spring rate remains the same no matter the ride height.

 

Ride comfort or lack of is very subjective. These trucks are 40 years old and can't be compared to today's vehicles running on McPherson struts and gas shocks. It simply is what it is.

[Airplanedoc]

Thanks datzenmike I appreciate the information and will consider it normal and move on to next item that needs attention. 

[Thomas Perkins]

I use poly since 2009.Rides awesome.Unlike rubber, polyurethane offers higher load-bearing capacity, better compression set, and superior tolerance to greases, oils, oxygen, and ozone. Because rubber is biodegradable, it tends to rot and degrade over time with time.Rubber gives a smoother ride.The rubber in mine wore out and messed up the metal,it had to be fixed by welding.Made my tires turn in causing the tires to wear on the inside.They put poly in it.Cost over 300 to fix.That was back in 2009.I.need to grease them.I will check in the morning.They will squeak if you don't keep them greased.

 

 

 

 

Edited December 31, 2023 by Thomas Perkins