How to determine proper shock size

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

MisterB

Full Access Member
Joined
Sep 9, 2019
Posts
676
Reaction score
845
Location
Northwest
First Name
AJ
Truck Year
1980
Truck Model
GMC K2500 4X4
Engine Size
350
It's time for new shocks. I have Rancho RS500's, and I just want to buy the same ones again. Problem is, my truck has a 6" lift, and 35" tires on it, so I can't just select the shock size based off year, make and model.

I'm aware of how I can remove the bottom bolt from one front and one rear shock, pull shock all the way out and measure middle of eye to middle of eye (then push all the way in and measure), and then repeat for the rear, but is there an easier way to get the proper size?

I figured there would be a number on them and I could order based off that number, but I looked up the number in the pic below and I can't seem to pull up anything.
You must be registered for see images attach


Sent from my SM-N975U1 using Tapatalk
 

QBuff02

I like Big Blocks and I cannot lie
Supporting Member
Joined
Feb 28, 2017
Posts
867
Reaction score
1,591
Location
Central IL
First Name
Quincy
Truck Year
1982
Truck Model
K30
Engine Size
454
I just went through alllllll of this last month, and lemme tell ya it sucks. that's a Rancho RS5000 series shock in the picture. my shocks that I replaced did not match the lift that's on my truck, P.O. obviously just ordered shocks and threw them on without much care. So I measured eye to eye on the shock mounting tabs themselves on the truck. the shocks I removed were too short on the rear and too long on the front. If you google Rancho RS5001 (which is what you have) it'll give you the part you need for an exact replacement. Here's a direct link to the specs on it.

https://www.gorancho.com/products/s...rber/rancho-rs5000-shock-absorber-rs5001.html

However if you feel what you have isn't right then measure the mounting eyes on the truck frame to the axle eyes for your center to center, it's what I did and then I went to Summit racing and once you get in the shock tab, the drop downs allow you to select different shock lengths for your application. If I remember correctly, those shocks above were in stock at summit, but the correct rear length I needed was made from unobtanium so I had to select a length that was within a half inch or so of my measurements to be proper because the right ones I needed were back ordered and the expected shipping date kept changing from 2 weeks out to almost 5 weeks out, Summit let me cancel those shocks and order a different set- I was in a bind because I had removed and thrown the old junk shocks into the scrap pile and they were long gone so I had NO shocks and needed something. But I went with a skyjacker shock for the rear just to get shocks on the truck and they are not gas charged like the fronts and it does ride a little different, but it does ride better as a whole because the shocks actually work all the way around.

So, my advice is measure your eye to eye on the truck, verify the part numbers of your current shocks and go to summit racing and select your make/model and then in the sub menus for the shocks select the right free and collapsed lengths and get the shocks you need. There is also different drop downs for selecting shocks based off the amount of lift the vehicle has. If you just want direct replacements, the number on the shock is the number you currently have and most all of their part numbers never change.
 

MisterB

Full Access Member
Joined
Sep 9, 2019
Posts
676
Reaction score
845
Location
Northwest
First Name
AJ
Truck Year
1980
Truck Model
GMC K2500 4X4
Engine Size
350
I just went through alllllll of this last month, and lemme tell ya it sucks. that's a Rancho RS5000 series shock in the picture. my shocks that I replaced did not match the lift that's on my truck, P.O. obviously just ordered shocks and threw them on without much care. So I measured eye to eye on the shock mounting tabs themselves on the truck. the shocks I removed were too short on the rear and too long on the front. If you google Rancho RS5001 (which is what you have) it'll give you the part you need for an exact replacement. Here's a direct link to the specs on it.

https://www.gorancho.com/products/s...rber/rancho-rs5000-shock-absorber-rs5001.html

However if you feel what you have isn't right then measure the mounting eyes on the truck frame to the axle eyes for your center to center, it's what I did and then I went to Summit racing and once you get in the shock tab, the drop downs allow you to select different shock lengths for your application. If I remember correctly, those shocks above were in stock at summit, but the correct rear length I needed was made from unobtanium so I had to select a length that was within a half inch or so of my measurements to be proper because the right ones I needed were back ordered and the expected shipping date kept changing from 2 weeks out to almost 5 weeks out, Summit let me cancel those shocks and order a different set- I was in a bind because I had removed and thrown the old junk shocks into the scrap pile and they were long gone so I had NO shocks and needed something. But I went with a skyjacker shock for the rear just to get shocks on the truck and they are not gas charged like the fronts and it does ride a little different, but it does ride better as a whole because the shocks actually work all the way around.

So, my advice is measure your eye to eye on the truck, verify the part numbers of your current shocks and go to summit racing and select your make/model and then in the sub menus for the shocks select the right free and collapsed lengths and get the shocks you need. There is also different drop downs for selecting shocks based off the amount of lift the vehicle has. If you just want direct replacements, the number on the shock is the number you currently have and most all of their part numbers never change.
That's awesome info. Thank you. If I measure eye to eye, can I just do that with the current shocks installed, and the truck on level ground? Is the part number C274G1 in the picture?

Sent from my SM-N975U1 using Tapatalk
 

QBuff02

I like Big Blocks and I cannot lie
Supporting Member
Joined
Feb 28, 2017
Posts
867
Reaction score
1,591
Location
Central IL
First Name
Quincy
Truck Year
1982
Truck Model
K30
Engine Size
454
That's awesome info. Thank you. If I measure eye to eye, can I just do that with the current shocks installed, and the truck on level ground? Is the part number C274G1 in the picture?

Sent from my SM-N975U1 using Tapatalk
Yes, measure at ride height to get your shock lengths.


Sent from my iPhone using Tapatalk
 

QBuff02

I like Big Blocks and I cannot lie
Supporting Member
Joined
Feb 28, 2017
Posts
867
Reaction score
1,591
Location
Central IL
First Name
Quincy
Truck Year
1982
Truck Model
K30
Engine Size
454
Yes, measure at ride height to get your shock lengths.


Sent from my iPhone using Tapatalk
And the part number of your current shock is the "RS5001" that is stamped into the shock tube if that's what I think you were asking?


Sent from my iPhone using Tapatalk
 

MisterB

Full Access Member
Joined
Sep 9, 2019
Posts
676
Reaction score
845
Location
Northwest
First Name
AJ
Truck Year
1980
Truck Model
GMC K2500 4X4
Engine Size
350
And the part number of your current shock is the "RS5001" that is stamped into the shock tube if that's what I think you were asking?


Sent from my iPhone using Tapatalk
If I ordered with that part number, would it give me the same length?

Sent from my SM-N975U1 using Tapatalk
 

MisterB

Full Access Member
Joined
Sep 9, 2019
Posts
676
Reaction score
845
Location
Northwest
First Name
AJ
Truck Year
1980
Truck Model
GMC K2500 4X4
Engine Size
350
And the part number of your current shock is the "RS5001" that is stamped into the shock tube if that's what I think you were asking?


Sent from my iPhone using Tapatalk
By the way, I just noticed something. When I enter that RS5001 part number in the search box on Amazon, it brings up those shocks, and guess what? I have a stock 1980 K25 already entered, and it comes up in green and says they will fit my truck, even though I'm sitting on a 6" lift with 35" tires.

This tells me the PO just put stock sized shocks on it, or kept the prior shocks on after doing the lift, no?

Sent from my SM-N975U1 using Tapatalk
 
Last edited:

QBuff02

I like Big Blocks and I cannot lie
Supporting Member
Joined
Feb 28, 2017
Posts
867
Reaction score
1,591
Location
Central IL
First Name
Quincy
Truck Year
1982
Truck Model
K30
Engine Size
454
Most aftermarket shocks like that from rancho or any supplier for that matter will cover a couple of different sizes of lifts due to their range of travel. One part number might be good for stock up to say a 3-4" lift with one part number or a 3-6" lift with another part number and still work with no issues. If you haven't had any issues with the ones currently on it then I'd order replacements of what you have, bolt em on a go.


Sent from my iPhone using Tapatalk
 

MisterB

Full Access Member
Joined
Sep 9, 2019
Posts
676
Reaction score
845
Location
Northwest
First Name
AJ
Truck Year
1980
Truck Model
GMC K2500 4X4
Engine Size
350
Most aftermarket shocks like that from rancho or any supplier for that matter will cover a couple of different sizes of lifts due to their range of travel. One part number might be good for stock up to say a 3-4" lift with one part number or a 3-6" lift with another part number and still work with no issues. If you haven't had any issues with the ones currently on it then I'd order replacements of what you have, bolt em on a go.


Sent from my iPhone using Tapatalk
OK, good to know. It's pretty jarring going over a speed bump, for example, but I don't know how much of that is normal and how much of that might be because these shocks look old and shot.

Sent from my SM-N975U1 using Tapatalk
 

Craig 85

Full Access Member
Joined
Jan 25, 2017
Posts
3,892
Reaction score
4,036
Location
Nashville, TN
First Name
Craig
Truck Year
1985
Truck Model
K30 SRW
Engine Size
454/TH-400/NP205

MisterB

Full Access Member
Joined
Sep 9, 2019
Posts
676
Reaction score
845
Location
Northwest
First Name
AJ
Truck Year
1980
Truck Model
GMC K2500 4X4
Engine Size
350
Thanks again for the help.

Rock auto and Summit both have painful websites. Once I semi figured out Rock auto, some of it was in stock, and some of it was a month out. Rancho's web site is no better, and they don't want to answer their tech line for help.

I ended up going with the same size Rancho shocks that are on the truck, by using the part number. I did decide to upgrade to their newer X line. Appears to use the same part number, other than an additional duplicate number at the start. I verified the size for the X model is the same as the regular RS model, and they match up.

Plugged the part numbers on Amazon, and they had everything in stock and free two day shipping. Done deal.

Thanks guys!

Sent from my SM-N975U1 using Tapatalk
 

80BrownK10

Full Access Member
Joined
Oct 22, 2019
Posts
1,878
Reaction score
1,240
Location
Greenwood, SC
First Name
Nate
Truck Year
1980
Truck Model
K10
Engine Size
350
It's time for new shocks. I have Rancho RS500's, and I just want to buy the same ones again. Problem is, my truck has a 6" lift, and 35" tires on it, so I can't just select the shock size based off year, make and model.

I'm aware of how I can remove the bottom bolt from one front and one rear shock, pull shock all the way out and measure middle of eye to middle of eye (then push all the way in and measure), and then repeat for the rear, but is there an easier way to get the proper size?

I figured there would be a number on them and I could order based off that number, but I looked up the number in the pic below and I can't seem to pull up anything.
You must be registered for see images attach


Sent from my SM-N975U1 using Tapatalk
Someone has given you an answer I'm sure but you can buy them based upon make and model and lift. It will say like stock height, two inches of lift, 2-3" lift 4-6" lift etc.
 

80BrownK10

Full Access Member
Joined
Oct 22, 2019
Posts
1,878
Reaction score
1,240
Location
Greenwood, SC
First Name
Nate
Truck Year
1980
Truck Model
K10
Engine Size
350
Thanks again for the help.

Rock auto and Summit both have painful websites. Once I semi figured out Rock auto, some of it was in stock, and some of it was a month out. Rancho's web site is no better, and they don't want to answer their tech line for help.

I ended up going with the same size Rancho shocks that are on the truck, by using the part number. I did decide to upgrade to their newer X line. Appears to use the same part number, other than an additional duplicate number at the start. I verified the size for the X model is the same as the regular RS model, and they match up.

Plugged the part numbers on Amazon, and they had everything in stock and free two day shipping. Done deal.

Thanks guys!

Sent from my SM-N975U1 using Tapatalk
Is Amazon still shipping in two days to your house? Most stuff these days I get prime is still taking almost three weeks to deliver
 

MisterB

Full Access Member
Joined
Sep 9, 2019
Posts
676
Reaction score
845
Location
Northwest
First Name
AJ
Truck Year
1980
Truck Model
GMC K2500 4X4
Engine Size
350
Is Amazon still shipping in two days to your house? Most stuff these days I get prime is still taking almost three weeks to deliver
I'm in Washington state, so technically Amazon is a brick and mortar store for me. I get to pay state sales tax, and everything lol. But yeah, they're pretty quick on most the things I order. I did notice that they are showing the shocks will be delivered on Monday. That's not two days, but also not 3 weeks

Sent from my SM-N975U1 using Tapatalk
 

80BrownK10

Full Access Member
Joined
Oct 22, 2019
Posts
1,878
Reaction score
1,240
Location
Greenwood, SC
First Name
Nate
Truck Year
1980
Truck Model
K10
Engine Size
350
I'm in Washington state, so technically Amazon is a brick and mortar store for me. I get to pay state sales tax, and everything lol. But yeah, they're pretty quick on most the things I order. I did notice that they are showing the shocks will be delivered on Monday. That's not two days, but also not 3 weeks

Sent from my SM-N975U1 using Tapatalk
We pay sales tax too. They changed our law here so that we pay the sales tax, plus we have a gazillion warehouses in this state so I am pretty sure that counts as an in store business anyway. We didn't pay tax for years though.

Amazon has gotten sorry over the years and coronavirus has made them even worse. They are late on prime deliveries in the past when they come out a a warehouse n my own state. The specific shipment I am talking about was less than a two hour drive from me.
 

Latest posts

Forum statistics

Threads
42,065
Posts
908,290
Members
33,542
Latest member
willyg
Top