Dropping a C30 flatbed

[Mike Bradbury]

My latest project is going to be a dropped '71 C30. I am having trouble locating the lowering spindles and springs. Anybody know a supplier? I want to keep it a super stout C30, not trying to lay frame just want a static 5/6 drop to give it a drivable ride.

[Smitty]

Why don't you check this place in Santee. Tell them what you want and what your end goal is. But don't know what to tell you about spindles.

National Spring on Magnolia Ave in Santee, CA - 619-258-2724

Had them reverse the eyes and make some leaf springs for a '59 1/2 ton years ago and they did a great job. They may even be able to direct you toward someone who knows about spindles.

[LockDoc]

-
You might see if there is anything available in spindles for the '73 up 1 tons. I'm not sure if there is but they should interchange.

LockDoc

[Mike Bradbury]

I am building my own upper and lower A arms as well as a custom drop member so even if is off I can make the arms to work with it. I was able to get 2.5" drop spindles for my '69 C20, I am not sure if there is a difference between a C20 and a C30 spindle. They are both eight lug so I may be able to get C20 spindles to work.
I purchased them through Early Classics so I guess I will have to find another place.

[LockDoc]

Originally Posted by Mike Bradbury

I am building my own upper and lower A arms as well as a custom drop member so even if is off I can make the arms to work with it. I was able to get 2.5" drop spindles for my '69 C20, I am not sure if there is a difference between a C20 and a C30 spindle. They are both eight lug so I may be able to get C20 spindles to work.
I purchased them through Early Classics so I guess I will have to find another place.

I just put complete '73 C30 spindle assemblies on a '72 GMC C20 frame and everything bolted right in.

LockDoc

[D-n-Tyke]

Did you pick that up off of CL? My son just showed that to me this afternoon and wanted to go look at it and then I saw you post this. Looks like the same truck. Nice grab!

[Mike Bradbury]

You it was a C list find. The body is in great shape but everything else is pretty rough. Not too much of a problem for my build though, since I plan on changing most everything on the truck.

[SCOTI]

As mentioned.... 73-up spindles can be used. They're not a direct swap but can be used w/the right supporting parts.

[67 cst swb]

Found this pretty quickly on a google search.

https://switchsuspension.com/chevrol...p-spindle-set/

https://westernchassis.com/1971-91-C...SABEgLF9PD_BwE

[cangim]

Excited to see this take shape. Nice grab!

[CG]

Do you still have the Callahan Auto Parts truck?

In my 20 years here that truck is in my top five from all areas of the board.

[Mike Bradbury]

Originally Posted by CG

Do you still have the Callahan Auto Parts truck?

In my 20 years here that truck is in my top five from all areas of the board.

Yup still got it, still drive it all of the time. Thanks for the props. It was a fun build and I am looking forward to the C30 build.

[Mike Bradbury]

Originally Posted by 67 cst swb

Found this pretty quickly on a google search.

https://switchsuspension.com/chevrol...p-spindle-set/

https://westernchassis.com/1971-91-C...SABEgLF9PD_BwE

Yeah I found those western chassis spindles too. I am amassing a parts list before I order so that I am sure everything fits. I am building my own custom front cross member so I guess any year would work. I do like the option of those '75 3" drop spindles you found.

[SCOTI]

Originally Posted by Mike Bradbury

Yeah I found those western chassis spindles too. I am amassing a parts list before I order so that I am sure everything fits. I am building my own custom front cross member so I guess any year would work. I do like the option of those '75 3" drop spindles you found.

As far as I've ever seen, the C20/30 drop spindles only come in the 3" variety.

[Mike Bradbury]

Scoti that is interesting because until that link was posted I had only seen up to 2.5". Western Chassis and POL are all in the same building with the same sales reps just answering different phones. I like the 3" but the control arms Western Chassis makes are designed to couple with the 2.5" and correct any geometry issues caused by marrying drop spindles with stock A arms. Since I am building my own cross member I can make what ever adjustments I need to to get the ride height I want.
Here is the Western 2.5" drop spindle:
https://westernchassis.com/1971-91-C...t-on-Calipers/

[SCOTI]

Interesting. Only had 3" when I was looking circa 2010. I don't believe my C30 uses D52 calipers though so maybe there's a difference.

Wouldn't be the first time internet ad descripts were inaccurate.

[Mike Bradbury]

Originally Posted by SCOTI

Interesting. Only had 3" when I was looking circa 2010. I don't believe my C30 uses D52 calipers though so maybe there's a difference.

Wouldn't be the first time internet ad descripts were inaccurate.

How much did you drop your 2010? Spindles 3" but did you use bags or coils? It look pretty low to be coils.
If Bags, is it still rated at a one ton?
Flip kit for the rear?

[SCOTI]

Originally Posted by Mike Bradbury

How much did you drop your 2010? Spindles 3" but did you use bags or coils? It look pretty low to be coils.
If Bags, is it still rated at a one ton?
Flip kit for the rear?

Nothing newer than a '99 in my fleet (?).

My 89 dually is dropped about 7/9 for driving & can plant the frame rails + front raised x-member when it's air'd out. It has 3" spindles, 1.5" x-member notch, & C30 rated/spec'd bags on Porterbuilt 1" forward front lower control arms. It uses a tweaked/home-built/used Ridetech four bar set-up w/C30 rated/spec'd rolling-sleeve bags in the back.

My '99 OBS 3/4 ton CC uses 3" drop spindles + 1-coil trimmed from the original HD springs & a Bell Tech flip-kit w/1.5" lift shackles in the rear. The lift shackles only raised the rear back up about .750" so the total drop is about 5/7.

[Mike Bradbury]

Yeah I have really thought about ditching the leaf springs altogether and going with the rolling sleeve bags in the rear.
Are the front bags sleeves or convoluted?
Do you have a build thread for your '89?
I have always leaned toward static but I am trying to think outside my usual process on this build and the more beta I can get the better the end result.

[SCOTI]

Originally Posted by Mike Bradbury

Yeah I have really thought about ditching the leaf springs altogether and going with the rolling sleeve bags in the rear.
Are the front bags sleeves or convoluted?
Do you have a build thread for your '89?
I have always leaned toward static but I am trying to think outside my usual process on this build and the more beta I can get the better the end result.

Ridetech spec'd Firestone Dbl convoluted bags in front:

https://67-72chevytrucks.com/vboard/...d.php?t=640843

[Mike Bradbury]

I just read through your build thread, The rear bags are just what I was looking for. I may do a triangulated four link to eliminate the pan hard bar but the bag design you made is perfect for my application.
I did have a question about welding to the axle tubes, When I built my C10 truck arms and welded the brackets to the Lincoln 9" I had the axle straightened before I powder coated it just in case it the welding warped it at all. How much welding did you have to do for the Bag brackets on your axle?

[SCOTI]

Originally Posted by Mike Bradbury

I just read through your build thread, The rear bags are just what I was looking for. I may do a triangulated four link to eliminate the pan hard bar but the bag design you made is perfect for my application.
I did have a question about welding to the axle tubes, When I built my C10 truck arms and welded the brackets to the Lincoln 9" I had the axle straightened before I powder coated it just in case it the welding warped it at all. How much welding did you have to do for the Bag brackets on your axle?

The 4-bar brackets are basically like flip kit brackets, They cinch up to the original leaf pads on the HD 70 housing tubes (it's a re-worked Ridetech bolt-on kit). I just welded them @ the ends so nothing to the tubes there. They use 9/16" bolts as well to secure the top/bottom 4-bar brackets.

For my Panhard bar, I bought some DOM 4"ID tube. I cut a rectangular piece out of the tube that was used as the base for the bracket itself. I built & welded the bracket to that first w/rosette & corner-joint welds. Once cooled & cleaned up, I positioned it on the pass side axle tube & tacked it in place. I then wrapped towels soaked in cold water @ each end of the bracket to help w/keeping the heat zone minimized. Welded small lengths & re-soaked the towels as I progressed.

I did not have it professionally checked for straightness after nor have I experienced any issues. Axle tube thickness is @ least .250" & the bracket base DOM material was similar @ .250".

If you go through the trouble of modding/changing the rear suspension, I would do parallel 4-bar. The triangulated stuff was a compromised set-up from OE's. I'd opt for a true 4-bar & Panhard bar for simplicity or get fancy w/a Watts link set-up. Mine has spherical joints @ one end & poly bushings @ the other for all four bars. Panhard is heim joints.

[Mike Bradbury]

Same with mine. My truck arms on the C10 use the spherical joints as well as the pan hard bar. I do not like the Watts link at it clutters up the simplicity.

[SCOTI]

Originally Posted by Mike Bradbury

Same with mine. My truck arms on the C10 use the spherical joints as well as the pan hard bar. I do not like the Watts link at it clutters up the simplicity.

Yeppers.... I like your C10's set-up & followed the build.

[Mike Bradbury]

Do the brackets that bolt to the axle for the 4 bars have the perch for the bags? Still trying figure out how you mounted the bags behind the axle with out welding brackets to the tubes.

I am going to do a complete cab back custom frame so if I need to tweak anything I can in the design phase. The bags look close to the wheels in your pics, Do you find any clearance issues when the axle is twisting left and right over uneven road surfaces?