Rough/Bouncy Ride

[john68c10]

68 C10 2WD Shortbed Fleetside 327/manual...

Lowered 1" front 3" rear (new LMC springs)

Monroe OE Spectrum shocks (also new)

255/60/17 new tires

Okay, truck drives smoothly until I hit any sort of bump/small pothole. It goes through them rough/bouncy...(especially at the rear)

Speed bumps need to be taken at a near crawl to avoid the rear jumping around and a hard jarring...

What can I do to settle this all down some...??

[A1971Blazer]

hard to tell without looking but I bought a 68 about a year ago that had been lowered in the front and rear with springs.
It was a project for my grandson so I didn't drive it much before I started working on it.
The first step was doing a disc brake swap up front.
The first thing I noticed as I tore into it was that the lower control arms were already sitting on the bump stops and it had absolutely no suspension travel in the front.
So with that said, have you checked to see how much travel you have before the lower A-arm bump stops make contact?
Your springs may be allowing it to bottom out.
If so, that will result in a really rough/bumpy ride.
My solution was stock height springs and 2½" drop spindles

[john68c10]

Originally Posted by A1971Blazer

So with that said, have you checked to see how much travel you have before the lower A-arm bump stops make contact?

2 1/2" travel in lower A-Arm before contact.

[67C10Step]

Check your rear bump stops as well. A 3" drop in the rear is not excessive but I did a 4" drop on mine and installed shorter bump stops to give just a bit more travel before bottoming.
I know there are a ton of trucks out there with lowered rears without out it, but a shock relocation kit might be of some help as well.

[john68c10]

I don't feel that I'm bottoming out on anything...it's just rougher than I'd like. Can the new springs need time to season some ? Will time soften the ride out ?

[A1971Blazer]

Originally Posted by john68c10

I don't feel that I'm bottoming out on anything...it's just rougher than I'd like. Can the new springs need time to season some ? Will time soften the ride out ?

new springs will soften some over time, are the shocks gas charged?

[john68c10]

Originally Posted by A1971Blazer

new springs will soften some over time, are the shocks gas charged?

Yes

[A1971Blazer]

Originally Posted by john68c10

Yes

those will add some stiffness but shouldn't affect drastically the way you describe.
Did you remove or replace the control arm bushings by chance?

[john68c10]

Originally Posted by A1971Blazer

those will add some stiffness but shouldn't affect drastically the way you describe.
Did you remove or replace the control arm bushings by chance?

The control arm bushings have not yet been replaced

[A1971Blazer]

Originally Posted by john68c10

The control arm bushings have not yet been replaced

OK just another thought...? just making sure the control arms move freely up and down.
I have had an issue with new bushings that were too tight and resulted in the control arm movement being stiff.
At this point, I would say, just drive it some more and see if it gets any softer?
I can't think of any other obvious cause(s)....sorry

[CC69Rat]

A coil spring is nothing more than a straight bar, coiled up to achieve torsional rigidity. The thicker the coil, and the tighter the spacing = spring rate. This same concept applies another way. ..

Think of a diving board. The board is 12ft long. 250lb man jumps on the end of it, bounces, and in the water he goes.

Now, cut 2ft off the board. Same man, bounces.. in the water he goes.

Do you feel like the 12ft board flexed more or less than the 10ft board? The shorter the board gets, the more stiff it becomes. The shorter the total length of your coil, the diameter of the coil itself and coil spacing between each coil matters too..

Same idea on your coil springs really Side by side, the dropped spring (new) is marketed and sold as measured against the (new) stock height springs. So, your 1" drop springs probably didn't actually lower your truck 1" lower than it was when you started. .. correct?

This situation kinda sounds (to me) like the coils you have from LMC are too soft. The diameter of the coil, coil spacing (spring rate) and overall length of the coil (before its coiled up) all make a difference in the ride.

Think of the fella on the end of the diving board. 8ft board = super stiff. The longer the board, the more bounce and soft feeling it will be.

As for the back ones.

Same deal really but it sounds like you're going to need a rear shock relocation kit. I'd say, if you stand at the rear of your truck. Get down kinda low so you can see the rear axle and the position of the shocks in relation to the ground. Are the rear shocks standing what you'd consider vertical? Or are they kinda laying more horizontal?

When you drop one of these 67-72s, especially SWB any more than 3-4" the rear shocks will be laying almost horizontal. The relocation kit helps move them to more of a vertical position and increases the effectiveness of the shock. .. eliminating your soft bouncy feeling.

I have a 67 SWB now. QA1 rear, and I moved mine completely outside the frame rails to get them almost vertical. The shock relocation kits help a lot and that's where I'd start with your truck. Hope this helps

[john68c10]

This thread has caused me to take a closer look. Now, here's my updated take on things...

At least 80% of the issue is on the rear...in fact if the rear was as good as the front...I would never have posted.

One thing that I didn't think to mention is that my truck is equipped with the helper leaf spring in the back and, since lowering, it is just contacting at ride height. So, definitely with this additional spring...any action will see the combined stiffness of both the rear spring and the helper spring.

Question(s) Should I remove the helper spring ? Is the helper spring adjustable ?

Second, the rear shocks are at approximately a 45° angle, therefore I'm getting at best only a percentage of full shock effect...so a shock relocation kit is called for.

[MySons68C20]

Originally Posted by john68c10

This thread has caused me to take a closer look. Now, here's my updated take on things...

At least 80% of the issue is on the rear...in fact if the rear was as good as the front...I would never have posted.

One thing that I didn't think to mention is that my truck is equipped with the helper leaf spring in the back and, since lowering, it is just contacting at ride height. So, definitely with this additional spring...any action will see the combined stiffness of both the rear spring and the helper spring.

Question(s) Should I remove the helper spring ? Is the helper spring adjustable ?

Second, the rear shocks are at approximately a 45° angle, therefore I'm getting at best only a percentage of full shock effect...so a shock relocation kit is called for.

Shock relocate for sure and pull the helpers as you are not gonna haul much I'm assuming.

[john68c10]

Originally Posted by MySons68C20

Shock relocate for sure and pull the helpers as you are not gonna haul much I'm assuming.

Right, I'm even removing the trailer hitch as the truck is strictly a cruiser now.

[bnorth]

Most of the ride quality comes from the back so I'd say you found your harshness issue if those helper springs are engaged. Orienting the shocks more vertical should help rebound and clean up some of the bounce. In general lowering springs generally have a higher spring rate than oem it will ride a bit rougher.

[Already Gone]

Just redid Suspension and other thngs to my 92,000 mile 1972 Long Box truck over last Winter and have put about 1000 miles on it since back together. Decided to go with a 2 1/2 inch dropped spindle and retained the original coil Springs. Out back I first used a 4 inch dropped spring but the back was down too much for me, pic of truck on hoist, so got 3 inch ones and it gave me that low lean look I wanted. I too had the factory overload spring on the truck but had already had em moved earlier whe rear fuel tank was installed. I used shock relocators with the OE Spectrums that had been on the truck for a few years already. Put 255/60 17 tires on 17 x 8 rims on all 4 corners. The truck rides and handles super and you can take corners quite spiritidly.