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Old 03-06-2011, 03:15 PM   #1
lakeroadster
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Join Date: Sep 2009
Location: High Plains of Colorado
Posts: 2,485
Upper Shock Relocation 1963 through 1972

I posted this data in my build thread and thought it might be worthy of its own post. My truck is a 1965 SWB C10. I am pretty sure this modification will also work on 67-72's.
Because the rear of the truck has been lowered 5” the rear shocks are inclined about 40 degrees. Therefore they need to be repositioned so the shocks are more vertical.

Upper Shock Brackets:
I designed some new upper shock brackets to accomplish this. The new brackets replace the stock upper mounts and bolt to the frame using the rivet holes from the original stock upper mount. (Per Monroe, shocks cannot be angled more than 30 degrees. If they are more than 30 degrees they may tend to have lapses in dampening.)
Rear Shock Brackets:
The stock lower shock mounts on the 63-66 coil spring trucks are far superior to aftermarket mounts. The stock mounts are a heavy steel stamped part that captures the shock on both sides. Supporting on both sides makes a huge difference in the brackets strength and ability to properly load the shock. There is simply no need to replace the stock mounts. The replacement mounts that are being sold capture the shock on one side only. If you are replacing the lower mount with one of these aftermarket brackets you are replacing a strong part with a weaker one. Based on the numbers I have crunched the stock lower shock mount is 5 times stronger than some of the aftermarket brackets being sold for dropped trucks.
The stock shocks were bottoming out when I bought the truck. I did some research on Monroe Shock Absorbers website http://www.monroe.com/catalog/miscApplications.asp . They have a pdf entitled “Mounting and Length Sheets” that lists all their shocks and includes mounting configurations and lengths. Using this data and the dimensions of my new set-up I selected Monroe shocks 32207. These have an Extended length of 17-7/8”, and a collapsed length of 11-1/4”. These shocks were originally used on ½ ton Ford trucks and therefore the valving will be correct. With my rear spring and custom snubber set-up the shock length = 11-3/4” with the rear axle against the snubbers. Therefore the shocks won’t bottom out before the snubbers engage. Ride height shock length = 14-1/4”.


Stock Upper Mount


To remove the stock rivets I drilled a 3/8” hole in the center of each rivet.



Then used a chisel to shear the head off the rivet


Crossmember with bracket removed.


Here is the new bracket I designed and fabricated above the stock bracket


New bracket moves the top of the shock back about 4 inches


And up a little over an inch
New bracket bolted into crossmember with (2) 7/16” bolts, nuts and lockwashers. (Used a step-bit to open up the original rivet holes in the crossmember about 1/16”.) Note: I used (2) 1/2" flat washers inside the tube to center the shock and eliminate any side to side shock movement.



As viewed from above


And plenty of clearance between shock tube and axle tube


Shocks are now 18.5 degrees off vertical at ride height. (90 - 71.5 = 18.5)


Here is a drawing I made of the upper bracket. It is made from 2” square tubing, 3/16” wall thickness


Bullet Proof Stock Lower Shock Brackets


The following is some supporting data and dimensions that may prove helpfull.
On the rear suspension I installed 5" lowering springs and replaced the stock bump stop with custom bump stops the stock 31000 Monroe shocks will bottom out before the rear axle tube contacts the bump stop. That is not good.

Same kind of story for the front shocks, stock Monroe 33033's will bottom out.

Monroe pdf with shock dim's can be found here: http://www.monroe.com/catalog/docume...engthSheet.pdf
Monroe-Matic (Rear) P/N 31000 Collapsed Length = 12.000"
Monroe-Matic (Front) P/N 33033 Collapsed Length = 10.125"

Here are shock measurements (shock mounts are all stock and have not been altered. Stock snubbers have been removed and replaced with custom snubbers) :

Dimensions shown in red below are shock dim's. with the modified upper mounts.

Rear: I have 5” CPP lowering springs on the rear. All shock dim’s are from eye to eye:
Rear Axle Hanging Free, Tires off the ground: Shock Length = 17-1/2” ---- 16-1/2"
Ride Height, Shock Length = 15-1/2” --- 14-1/4"
Rear axle Bottomed Out on Custom Snubber: Shock Length = 12” --- 11-3/4"
Rear axle Tube Bottomed Out against Frame: Shock Length = 11-1/4” --- 10-1/2"
2-1/2” Suspension Travel Before Contacting Custom Snubber
3-3/4” Suspension Travel Before Axle Tube Contacts Frame (No Snubber)

Shocks: Monro-Matic Plus P/N 32207: 17.875" Extended, 11.250" Collapsed
http://www.streetsideauto.com/p/monr...ic-plus-32207/
Front: Previous Owner heated the stock coil springs. All dim’s are from eye to eye:
Front Suspension Hanging Free, Tires off the ground: Shock Length = 14”
Ride Height, Shock Length = 11-1/4”
Lower Control Arm Bottomed Out on Custom Snubber: Shock Length = 9”
Lower Control Arm Bottomed Out, No Snubber = 7”
2” Suspension Travel Before Contacting Snubber
4” Suspension Travel with no Snubber

Shocks: Monroe Gas Magnum RV P/N 555002: 12.750" Extended, 8.625" Collapsed
Here is a reply I received from a Monroe Web Inquiry in regards to my choices above:

John,

The shock you selected for the rear, 32207, would appear to be close as far as the dampening goes. It is used on old 1/2 ton trucks from Ford and Dodge, so it seems the dampening would be similar. The RV shock you have discovered is a retrofit shock for trailers. The dampening characteristics are similar to the original shock. These will probably work out okay, but I can't really give a solid guarantee on these based on all the modifications.

Thank you for your interest in our products.

Monroe Team Member,

Andy

Also: here is another reply from a Monroe Web Inquiry in regards to Monro-Matic shock installation angles, in the stock positions, mine were 40 degrees off vertical:
Thank you for contacting Tenneco Automotive.

The shocks would not function properly if they were mounted more than 30 degrees off from 90. With them being 40 degrees off, they may tend to have lapses in dampening.

Thank you for your interest in our products.

Monroe Team Member,

Andy

Last edited by augie; 04-04-2011 at 11:08 PM.
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