Shortening 55-59 Frame and Porterbuilt

[58-GMC]

I am looking for some feedback on shortening the frame of my 58 GMC when installing the rear Porterbuilt Dropmember.

Here's my idea...Because the 55-59 frames are "straight" it looks like I should be able to shorten the frame within the notch, thus eliminating the need to make additional cuts on the frame.

I made an illustration showing my intent. Does this look like it would work?

[Pro Performance]

When shortening down a frame, you will want to take a certain section out of the frame, so everything else lines up as it should for a short bed.... Meaning bed bolts, fasteners & other misc. items. I am not sure where the ideal cut marks are on the frame, but might be something to check out.

[58-GMC]

Thanks Travis for the input. I should have my parts by the end of the week. I will take a better look at it then.

Anyone else have any suggestions? I tried finding a long bed diagram but didn't find anything. Does one exist online like the one I found above for a short bed?

[kwmech]

Does Porterbuilt have a recommendation?

[58-GMC]

I did send them an email with my questions – they replied with their install instructions. No word on if this would work though.

I know they are busy guys so I didn't want to keep drilling them with questions. Do you think that would be the better way to go?

[58-GMC]

I was steered towards the Poncho build. Looks like this may have answered my question.

http://67-72chevytrucks.com/vboard/s...=544316&page=2

[greystoke]

have you completed this frame shortening yet?

[58-GMC]

Not quite. I have the truck over at a shop who is doing the work for me. Will try to get some pics up soon!

[greystoke]

I have a 59 gmc, will be interested in the details/measurements. Did you get instructions from Porterbuilt? if not I can send you what they gave me.

[58-GMC]

I did not get any directions from porterbuilt on how to shorten. Would love to see them if you wouldn't mind sending them over.

Once my shop shortens it I will try to remember to get some measurements for you. If I forget just remind me.

[greystoke]

give me an email and I'll forward them

[58-GMC]

PM sent - thanks!

[ChuckDriver]

Any updates?

[greystoke]

Hey Chuckdriver,

The rear four bar mount uses the existing holes that were used by the leaf spring mount perch. Since the long wheelbase is 9.25" longer ( 123.25 ) than the short wheelbase (114 ) sliding this four bar mount forward 9.25" will get the axle where it needs to be. I'm looking for more info I have on this so stay tuned.

[greystoke]

ok, I found this picture provided by 58-GMC, he had the long wheelbase also, if you take the dimension from the picture ( 14.75" ) and scribe a line and then measure forward from the rear rivet mounting hole 9.25" you should hit the line you scribed from the first measurement. Any other information you need feel free to ask. Between 58-GMC and myself we should be able to help.

[58-GMC]

Thanks for posting that greystoke.

Below are a few more that I have. Mattyparty was kind enough to do some measuring on his short wheelbase so I could compare. He took these pics.

This is showing the distance from the front of the rear cab mount to the back of the Porterbuilt 4-link mount.

[58-GMC]

Greystoke, how is your build coming? Have you been able to shorten yours?

Unless something comes up, I should be going out to the shop to see my truck on January 25th. I will try to get some pics then. It should be shortened and have all Porterbuilt suspension installed.

[ChuckDriver]

I'm putting the coil over version on my 57. If you need other measurements just let me know!

[58-GMC]

Thanks ChuckDriver! I'm interested to see how the coil over version looks...I'll definitely be following your build thread.

[greystoke]

I injured my back, nothing horrible just needing healing time. I love the way Chuckdriver laid out all the parts..pretty cool.