Lowered shocks

[LordDevlin]

I'm trying to figure out another situation I'm having with my truck as I work through all the issues of a new old vehicle, especially one that has had some mods.

that being said, when I get up to about 50 miles an hour or so and hit a bump, the back end of the truck seems to really bounce hard and I almost hit my head on the roof. The axle has been flipped and there are two leaves back there, with all new spring perches and everything.. the p.o. had a shop to all the work and it looks good. Not sure if the springs are posies, and I recently read someone else having the same issue of bouncing hard with the posies in the rear. I do not have a notch, and I know some of you will tell me I must have one, but it seems as though there hasn't been an issue of bottoming out at all with the way they have it set up. Could this crazy bounce be from the rubber bump stop hitting the axle and then somehow creating this rear end bounce? The truck is down for a day or so while I iron out a loose front end but when its back on the road I will mark the bump stops to see if they mark the axle.

This got me into to looking at lowered shocks. I was surprised to see that the nitro slammers that everyone refers to for lowered applications are the same travel as the regular ones for these trucks, about 12.5 to 20.5 inches. I was expecting that they would be same travel but from some a much shorter compressed length.

Can someone explain to me what makes a lowered shock a lowered shock? Do they somehow take into account that your default starting point is less than half of the travel or something?

Thanks for your time.

[mr48chev]

First thing I'd do is pop one of the shocks off and measure the compressed and extended lengths and measure the distance between your shock mounts and see if your shock mounts at static ride height are pretty well close to the center of the shock's travel.
Too long a shock body will bottom out and too short of a shock won't let the suspension go through it's full range of motion when going over uneven ground. Not that we would ever think of going over uneven ground with a lowered truck.

On the shocks that are on it, do they control the oscillations of the rear axle after the bump or does the truck kind of have the rocking motion for a bit after the bump?

If the ride is way too stiff they may have put shocks that are too heavy duty for the application on it. Back when I was installing shocks daily in Texas in the 70's we had to tailor the shock choice to the customer as quite often the heavy duty socks (Monroe 500) that we sold then were too stiff for a lot of customers butts. They made some cars running on H 15 tires ride like a lot of cars rolling on 20's do now.

That brings up another question, what size rims and tires are on it? If the rims are 17 or larger with a low profile tire it's going to ride like crap over bumps no matter what you do with the shocks. My Cad DTS is a prime example of that with the factory 17 inch rims on it. It rides a lot rougher than my wife's Monte Carlo with 16 inch rims and a slightly taller tire does. Strange as it sees the smoothest riding rig on the place is my 1 ton flatbed dualie.

[LordDevlin]

Ill check the shocks out tonight.

So does the lowered shock really only have a not as stiff quality to them that makes them lowered shocks?

It has 15s with good sized tires, probably about a 225 75 or so.

I feel like the bump may oscillate the truck a few times more than it should after the initial one, which would point to the shocks for sure.

[_Ogre]

The axle has been flipped and there are two leaves back there...
I do not have a notch

without a c-notch and only 2 spring leaves your probably on the bump stops most of the time
speed accentuates hitting the bump stops causing the roof in head syndrome

my 58 has the axle flipped on top of stock springs, minus the 2 short overload springs
also a 3'' c-notch and the bump stops have been moved to the frame and shortened
i still use both upper and lower 58 shock mounts, if yours are different no idea of correct numbers

i initially ran monroe-matic 33086 (very common shock for 70-90 trucks and vans)
even then i hit the bump stops at speed mostly going thru a dip at speed
i went to monroe air chocks, i don't have a number but look at the shock number and find a replacement air shock

your going to need to do some work on the rear suspension

shock mount setup using stock 58 mount. 4 leaves





c-notch and bump stop (bad pic)

[LordDevlin]

Did some investigating this past weekend and figured I should update as to what I found. Previous owner went back to his mechanic guy and asked some questions that I had been asking... said that it was probably the best rear end suspension set up of that style that I would see, and that the shocks were definitely suited for the changes he made.... checked the shocks and found out that I only had about half and inch of compression before they were bottoming out. Got some new springs and they are running pretty good.. could maybe be stiffer though. Now I am definitely using some "lowered shocks" as they are shorter.

The set up in the rear was all redone... and seems to be well done (aside from the shock selection). The two leaf system is not just two leaves, they are tapered and I assume lowering springs... and there's all new aftermarket style perches installed as well.

Problem solved for now.. I don't feel any jamming up anymore, which would have been the spring bottoming out before, and now would be axle to bump stop. I am still going to mark the bump stop or axle and see if they are hitting.