Author Topic: unknown drop - which shocks to use  (Read 2097 times)

Offline Ranzag

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unknown drop - which shocks to use
« on: April 20, 2020, 03:14:11 PM »
First off, I am not a mechanic, and i have limited mechanical experience - but i'm trying to learn.

I bought a 79 GMC stepside from a guy, who bought it from a guy, who bought it from a guy,....
The truck was lowered by one of the many previous owners, but i'm not 100% sure how.
The rear axle was flipped, and i'm assuming that was all that was done to the rear.
The front... no idea - my assumption is that the springs were either cut or heated until it dropped.
I'm pretty sure the shocks are totally shot, so i want to swap them out.

It's not a yearly driver, just a summer toy - It'll be lucky to get 1000 km on it this year
I plan on eventually getting proper drop spindles/drop springs, but that isn't in my budget this year.
What do i need to do to figure out which shocks i should purchase that would get me through the summer, and maybe next summer.

Offline JohnnyPopper

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Re: unknown drop - which shocks to use
« Reply #1 on: April 20, 2020, 08:44:05 PM »
Congrats on getting a cool truck!

There's no easy way to say what you need-

The only thing to do is pull the existing shocks, look for ID of some type, google numbers on the shocks, and see if you can match them.

I don't know if you have a NAPA nearby, but those guys usually have catalogs that are rich with factoids.

I would say 'good luck' but 'luck is for Rabbits'  ;)
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline VileZambonie

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Re: unknown drop - which shocks to use
« Reply #2 on: April 21, 2020, 06:51:57 AM »
Do you own a tape measure and a floor jack? Measure eye to eye at normal ride height, measure the distance from the frame to the bump stops, jack it up so that the frame is supported on jack stands and repeat the measurement  eye to eye for both sides.
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline Ranzag

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Re: unknown drop - which shocks to use
« Reply #3 on: April 21, 2020, 10:21:46 AM »
when i jack it up and put the frame on stands, i want the tires just a hair off the ground, correct?

I also cannot get any info off the existing shocks. they are so rust covered that any markings are long gone.

Offline JohnnyPopper

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Re: unknown drop - which shocks to use
« Reply #4 on: April 21, 2020, 10:45:33 AM »
Numbers are usually stamped near the base/bottom. Use some vinegar.
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline chevn-up

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Re: unknown drop - which shocks to use
« Reply #5 on: April 21, 2020, 06:06:28 PM »
Ranzag... The rear "flip" is a 5-6 inch drop. The rear shocks need to be those for a flip drop. Also shock extensions will be required on the rear axle. If the front is lowered more than 2 inches, as described, then drop shocks also required there. DJM suspension is a great brand to get the parts without breaking the bank. Hope this helps.

Offline Ranzag

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Re: unknown drop - which shocks to use
« Reply #6 on: April 22, 2020, 08:19:16 AM »
Thanks all. I've ordered shock extenders for the rear and a relocation kit for the front. After installing i'll take the measurements and get the correct length of shock (hopefully). I've read and watched quite a few youtube videos about it and the extenders should help smooth out the ride from my understanding.