Rear End Custom Shock Mounting

[Adam Moskowitz]

Ok so due to mounting a 40 gallon suburban tank into my 74 1 ton crew cab, I have to cut the passenger shock mount off the frame since it's mounted inboard. My question is, since the shock mounting will now be completely custom, how is the best way to mount new shocks on the 14 bolt rear? It is a stock leaf springs with a shackle flip and small block and some beefy aftermarket shocks. I know the shocks should be mounted as far outboard as possible on the axle though it will still be in between the frame rails. If they are both on the forward side of the axle tube is that okay? Better to mount them straight up or at an angle? Any help appreciated, thanks!

 

[75gmck25]

The stock upper shock mounting for my K25 3/4 ton is just a lightly reinforced area on the frame, and quite a few folks have had trouble with the shock moving and elongating the hole.

I've seen a couple versions of upper shock mounts that folks have fabricated for their trucks, and there are commercial products.
This is one of the examples.
http://offroaddesign.com/catalog/RearShockBrace.htm

If you scroll down in this article, they have several more examples.
http://forum.73-87chevytrucks.com/smforum/index.php?topic=31725.0

Bruce

 

[Adam Moskowitz]

I wouldn't be mounting the shocks to the frame like that. Since I have to relocate the passenger side mount entirely I am going to build my own crossmember just forward of the fuel tank and make that the upper mounting point for the shocks. Just trying to see what the best shock angles are and best theory on mounting them to a solid rear axle since both shocks have to be right above or in front of the rear axle now

 

[Craig 85]

I would think you could mount the right shock on the forward side of the axle tube, similar position to the driver's side. Older Ford's do this. I know once I put the 3" lift on my K30, the R/R shock housing was interfering with the axle tube. I had to flip the shock over. If you didn't damage the mount taking it out, you could mount it on the forward side of the right frame rail. You could also remove the axle mount and weld it to the front side.

The main reason the shocks are mounted on either side of the axle was to help with axle wrap under load.

Here's my stock K30 for reference.

You must be registered for see images attach

 

[Adam Moskowitz]

With both mounted in front of the axle would I get bad axle wrap issues?

 

[shiftpro]

With both mounted in front of the axle would I get bad axle wrap issues?

Not really, it would be hard to notice the difference.
The more vertical the shock is mounted, the better it dampens the energy from rebounding springs. But ya not much room for that, if you're using the stock box. Buggies and hardcore trail truck, rock crawlers and such extend their long shocks up over the frame rails.

 

[Adam Moskowitz]

Not really, it would be hard to notice the difference.
The more vertical the shock is mounted, the better it dampens the energy from rebounding springs. But ya not much room for that, if you're using the stock box. Buggies and hardcore trail truck, rock crawlers and such extend their long shocks up over the frame rails.

Ok good to know. I am running a 1" body lift so I can go just a little above the rails. Would the ideal positioning be straight up and down off the axle then? Or lean them slightly back or in for when the springs compress?

 

[bucket]

I would think you could mount the right shock on the forward side of the axle tube, similar position to the driver's side. Older Ford's do this. I know once I put the 3" lift on my K30, the R/R shock housing was interfering with the axle tube. I had to flip the shock over. If you didn't damage the mount taking it out, you could mount it on the forward side of the right frame rail. You could also remove the axle mount and weld it to the front side.

The main reason the shocks are mounted on either side of the axle was to help with axle wrap under load.

Here's my stock K30 for reference.

You must be registered for see images attach

I did exactly that with my Burb. I used the axle, springs, hangers and shock mounts from a K30. Of course, the 40 gallon tank was in the way of where the right shock was supposed to go, so I just mounted the shock forward of the axle. I even cut the tabs off the axle housing and simply welded them to the forward side of the axle tube.

And my actual K30 was done the opposite. The left shock was moved to behind the axle due to a clearance issue with the gooseneck plate.

Niether truck has ever experienced any type of axle hop. And I've done some rough stuff with the both of them.

 

[Adam Moskowitz]

Awesome to hear! So essentially just mirroring the drivers side is fine? Is there any benefit to mounting them at a different angle or more vertical?

And do you have any pictures of the 40 gallon tank in your burb? Would love to see just to reference some points while I mount the 40 in my crew cab

 

[bucket]

Yep, just mirror the other side and it will be fine.

Mounting the shocks at an angle is often good for packaging, but more upright is better for axle control. I mounted mine at a good bit of an angle, this way I knew my standard lift shocks would have enough travel for the rear suspension. It works excellent for my application. Iirc, it's a similar angle compared to my K30.

Unfortunately, I don't think I have pictures of it and I'm out of town for a while.

 

[shiftpro]

Ok good to know. I am running a 1" body lift so I can go just a little above the rails. Would the ideal positioning be straight up and down off the axle then? Or lean them slightly back or in for when the springs compress?

Yes if the shock is on the rear side of the diff axle. When the springs compress the axle/diff moves back a bit, so a little clearance is a good safety factor.

 

[Adam Moskowitz]

Awesome I appreciate it

Yes if the shock is on the rear side of the diff axle. When the springs compress the axle/diff moves back a bit, so a little clearance is a good safety factor.

Both shocks will be mounted on the front side of the axle however I can mount them out a little and angle them back

 

[shiftpro]

Here's my stock K30 for reference.

You must be registered for see images attach

[/QUOTE]

Nothing like a grimy rusty oil coated frame and diff... thanks for the eye candy Craig, it's 'healing' to see this. Good job buddy, you can sleep well at night.

 

[75gmck25]

It looks like GM had a different rear shock mounting on the K30 than on the 3/4 ton trucks.

My 8200 GVW K25, has the lower shock bracket on the 14 bolt FF right next to the U-bolts, and the shock goes straight up from there and lines up with the outside of the frame. It is then just bolted to the side of the frame. This means that it would not be in the way of anything mounted inside the frame rails.

Bruce

 

[rpcraft]

Keep in mind if you mount the shocks straight up and down you will need to get new shocks and that are not stock length. as to which the only way you can determine is to have the suspension under full droop and compression. Not sure what your spring pack looks like but the easiest way I have seen is to unload everything but the main spring and then drop and and squash it and measure each way.