The Stovebolt Site Forums The Shop Area Driveline Replacement Rear shocks seem to be too short.

I ordered replacement shocks from RockAuto. I tried installing them and they seem like there too short. I have my bed removed so I thought maybe if the truck was resting on it’s wheels and I jacked up the rear axle compressing the spring it would help. It did a bit but not enough to install the rubber bushings, washers and the nut. I know I I installed the bed the additional weight might be enough to close the gap but I’m concerned the shorter shock might not be enough travel in the down direction.

Thinking RockAuto had their inventory screwed up, I checked several other vendors and they all seem to sell the same length shock (21-1/4” fully extended). The shock that came out is 26” fully extended which seems a bit long as the suspension fully down only requires a shock that is about 23” extended.

Any ‘Bolter run into this issue?

What rear shocks did you buy?

I installed Monroe Gas-Matic 5826 on my truck and they went right on. I haven't detected any problems with handling or travel.

I wonder if all your new parts and bushings and cushions may have just pushed things slightly out of reach. A ratchet strap might pull things together enough to install them.

The weight of the bed may compress everything to the right location jacking it upwind no bed on might not be enough weight.i think my shocks came from rock auto .blue in color.

Is this on your 52 or your 59?

Phak1 has a 52 with a 59 235 engine .

Lol. I have been reading his signature wrong for a very long time...

Yes Kevin is correct and it’s a 3100 with stock suspension and original torque tube. The ones I received from RockAuto are Monroe TS 33949. It’s possible they are the right ones but I just want to be sure.

Otto, I looked up Monroe Gas-Matic 5826 and it doesn’t look like the right shocks for the rear as both sides are threaded. The bottom should have an eye with rubber bushings. Here is a picture of the one you recommended.

Sorry Phil,

I mixed up my front and rear part numbers.

Monroe OE Spectrum 33049 were on the rear

Monroe Gas-Matic 5826 are on the front

It looks like your shocks are one number off from mine. 33049 vs 33949

No, I am suffering from fat finger. They are 33049! My mistake, but the good news is since they are working for you, I have my assurance that they are the correct ones for the truck, so there going on.

Thanks all for your input!

Phil,

I bought the same shocks, also from Rockauto, and also thought they were too short. Like you I was working with a bare chassis. But was assured by the guys here that they were correct. I compressed the suspension a bit and installed them. I'm waiting on getting the bed and cab installed till after the snow melts.

If your shocks don't fit with the truck frame on jack stands and the rear hanging free, I wouldn't use them. You shouldn't have to jack/pull the rear and frame together to make them fit, putting shocks on that are to short could cause them to pull apart if you go over a bump and the truck catches air. Shocks are not meant to be axle travel stops.

Monroe has a calculator on their web page that lists shocks by the compression and extension measurements. The compression measurement is measured with the truck sitting on it's tires minus the distance from the top of the rear axle to the frame bump stop. Then jack the truck up and let the axle hang free, that's the extension measurement. I would find a shock that is a little shorter and a little longer to have a slush factor built in for safety.

https://www.monroeheavyduty.com/dow...-mounting-length-chart-hd-commercial.pdf

Mike B

Monroe's own website lists the 33049 as the correct application for a 1951 3100.
Link

The chart that Mike linked to doesn't even include the 33049.

I don't know about these trucks specifically, but Chevrolet did use the shocks as suspension travel limiters on some of their vehicles.

Found the specification chart that includes the 33049.

Great chart to have! Thanks.

To close this thread, I temporarily installed the bed, jacked up the axle and it was just enough to get the top nut started. So the shocks are installed.

Yaaaayyy!

But doesn't that say that the shocks are fully extended when stopped on level ground? If you hit a bump while moving the shock will compress, but on the "rebound" it will be length limited and the tire could leave the ground? And if you hit a pothole wouldn't the fully extended shock prevent the tire from falling into the hole without taking the rest of the truck with it? Sounds to me like you need longer shocks.

That said, I'm no suspension expert.

Bill you are correct
When the vehicle flies up off a bump the suspension basically hammers the shock and it will fail
The shock cannot be the limiting travel stop for the unsprung mass traveling away from the vehicle
My friend did this exact situation on his off road go cart and it failed on the first drive through the bush
Now a vehicle not being as violent a ride
It might just take a bit longer to fail
-s

I've put over 5000 miles on these shocks in the last 2 years and have had absolutely no problems. The truck handles like it's on rails at highway speed over smooth and rough roads.

Atlanta's roads are as bad as any in the rust belt metropolises and I've hit plenty of sink hole craters while driving. I've never experienced anything that felt like the suspension had bottomed out on the shock absorber stops.

Even if the shocks are slightly shorter than factory spec, who is going to be driving a 70 year old truck in such a manner that the suspension is fully extended on a regular basis? Or ever, for that matter?

I compared the shocks I removed with the new ones before installation. They were clearly a different design/brand but I don't know what they were. Fully extended they were the same length as the new ones.

I was hoping I had some pictures of the new and old rear shocks extended next to each other. Unfortunately I don't. These are the front shocks and I couldn't swear that the old shock is fully extended in the first pic. Probably irrelevant to our conversation on rear shocks but I post in defense of the Monroe shocks sold for these trucks. They seem to be the right ones and they work well..

Bill and 2ManyTrucks; that was my concern, it will clearly take the shock to it’s fully extended state before the suspension is fully down, so the shock is limiting it’s travel.

All of the Vendors I looked at, list the same length fully extended shock for a ‘52 3100 and the fact that they were not expensive, leads me to the decision that I’ll give them a try.

Is there any documentation available on the specifications for the original shocks?

Just looked at my shocks this am as they were lying on the floor waiting for me to complete my rear axle .The shocks are the same 33049 Monroe .

Here's the thread on the same question I asked a couple of years ago. Jerry said "don't worry".

Monroe's website lists the 33049 as correct for the rear of a 3100.

Also, I don't plan on making my truck "catch air" so I don't think I'll worry about it. I questioned the position of the lower shock mounts and everything I saw (including the FAM Section 4 sheet 1.00) was that they pointed downward below the springs (that's the way they came to me.) One could reverse them and gain a couple inches on the shock length.

Here is a photo of the old (maybe original) shocks held up to the new. The bottom eyes are aligned and both shocks fully extended.

Like Kevin, I’m not going to worry about it. The worst that could happen is the shocks get destroyed.

Here some more imfo but maybe part numbers are to old ,I found the old shocks off of mine ,they were from close to when I bought the truck in 1988 and most likely from a Canadian tire store .