Dropmember

[no moa]

At the risk of sounding like a moron, I have to ask, as i haven't found a reason "why" in the projects and build section.

Dropmember? whats the point of this? Give you a lower center of gravity? Suspension geometry?

Just curious.

[jimmydean]

The short answer is it allows you to lay frame without z-ing the frame. It does a whole bunch of other cool stuff, but check out:
http://porterbuiltstreetrods.com/sit...3-2-dropmember

<edit> It's also a piece of art that you can use your truck to showcase, but that is just pimp factor.

[N2TRUX]

The first serious obstacle to overcome when trying to lower a 60-87 GM truck is the crossmember being the lowest point of your frame. This eliminates that problem and many more issues.
Posted via Mobile Device

[no moa]

Originally Posted by jimmydean

The short answer is it allows you to lay frame without z-ing the frame. It does a whole bunch of other cool stuff, but check out:
http://porterbuiltstreetrods.com/sit...3-2-dropmember

<edit> It's also a piece of art that you can use your truck to showcase, but that is just pimp factor.

Well that answers that!

I was looking at Porterbuilts site, and reading every 67-72 build i can and thought, whats the point of that? Now i know.

Hopefully someday when i bag my truck, i'll use that baby!
Thanks guys.

[lolife99]

Here's a good read from this thread,... about the Dropmember.
(You can find it here: http://67-72chevytrucks.com/vboard/s...=442400&page=3)

Quote:
I figured I would go ahead and include some more technical information in regards to the suspension/steering geometry of the Porterbuilt Dropmember and some background as to "why".

When I first designed the Dropmember back in 2004-2005 I spent a lot of time tweaking the geometry in order to make it accomplish exactly what I wanted. This system was never designed to be an "ultimate performance" suspension system... but I wanted to develop a system that was an improvement from the factory design, could be driven at an extremely low height, and plant the rails on the ground with a big wheel... without the need to "Z" the frame.

First on the list was the necessary ground clearance. The Dropmember moves the suspension up in the chassis so that the lowest part of the front suspension is actually 1.25" off the ground when the frame is resting flat (the lowest point is the lower control arm outer bushing sleeve). This allows the truck to be driven extremely low without hangin up on all the imperfections on the road.

Second was to narrow up the trac-width. The Dropmember narrows the track width right at 1.5" per side (from stock) allowing more tire clearance while riding and turning when extremely low.

Third, we wanted to move the wheel center-line forward to center the wheels in the wheel wells... mission accomplished. You can run a 22" wheel and not even worry about cutting into the firewall for tire clearance.

And while striving to accomplish these key points we also wanted to make some "improvements" to the C10 geometry.... as in it's factory design there is a lot to be desired. As many have been learning, thanks to Rob from No Limit and his "make it handle" thread, one of the key points to making these trucks handle better is to add caster. The Dropmember has 6.97 degrees of caster in its design.

Another key point we implememted was to design the camber curve to where it didn't gain a lot of camber through compression. We didn't want the truck to have extreme camber when aired out and have that "broken" look. Some might argue that camber gain is essential to a performance suspension... and it is... but that was not the overall goal of the Dropmember. The Dropmember only gains 1 degree of negative camber through 6 inches of compression. Doesn't make it stick in the corners like a porsche, but looks good at the show.

We also wanted to adapt a rack and pinion steering gear to the design, not just because we had to in order to get the trac-width narrowed, but it also decreased the sprung weight considerably. We mounted the rack high on the crossmember in order to accomplish all we wanted (with it being a factory replacement rack we didn't have the liberty to put it anywhere else). The downfall to this was the necessity to notch the frame for the rack's tie-rod clearance. Not too big of a deal for most guys looking for this type of product, as they would expect a little cutting and welding. The big upside is the angle for the steering linkage. On most motors and header combos its a straight shot. It was important to keep the bumpsteer in check as well, and we were able to hold to the standard of .1 degree of bumpsteer per inch of wheel travel.

If anybody has any more technical questions they can feel free to ask, as I will be more than happy to answer any questions.

On a side note... keep your eyes peeled for our performance version of the Dropmember as it is just around the corner