1972 Chevy 4wd Longhorn Project: Never Ending Changes

[Dieselwrencher]

Today the correct DIY4X rear shackle brackets arrived. Too bad there are no shackle bars.

[mknittle]

Man those are healthy looking!

[JAA]

Dieselwrencher, I am loving your build and plan to do the same thing to my 71 C20. My question to you is did your truck have factory rear coils, and if so, could you provide more info on that conversion? I apprciate all the pics and info you posted on the front end. It made a big difference in the confidence I had in myself to do the swap to the 2wd frame. Thanks!

[SS Tim]

Originally Posted by JAA

Dieselwrencher, I am loving your build and plan to do the same thing to my 71 C20. My question to you is did your truck have factory rear coils, and if so, could you provide more info on that conversion? I apprciate all the pics and info you posted on the front end. It made a big difference in the confidence I had in myself to do the swap to the 2wd frame. Thanks!

If I may, Ryan started with a Longhorn. These were leaf sprung trucks (either 20 or 30 rated) built on a slightly longer 1 ton frame. These frames are heavier than the C20 or the K20 frames. if you have a coil truck now the best bet might be to find a K20 frame to roll under your truck or if you must a C20 leaf spring frame (Chevy option GMC std.) and convert the front end over.

[JAA]

Originally Posted by SS Tim

If I may, Ryan started with a Longhorn. These were leaf sprung trucks (either 20 or 30 rated) built on a slightly longer 1 ton frame. These frames are heavier than the C20 or the K20 frames. if you have a coil truck now the best bet might be to find a K20 frame to roll under your truck or if you must a C20 leaf spring frame (Chevy option GMC std.) and convert the front end over.

Thanks. Yeah, I couldn't remember if the longhorns were all leaf spring trucks or not. But I still have not found out the complete differences between the rear sections of the two frames. (leaf spring/coil spring) The frames are the same width I believe. My dad has a '72 swb K10 and I have been measuring the two frames.

And sorry Ryan. I dont mean to hijack your thread.

[SS Tim]

Here wade through this and I will try to update it with frame section height this weekend.
http://67-72chevytrucks.com/vboard/s...d.php?t=521844

[Dieselwrencher]

Originally Posted by JAA

Thanks. Yeah, I couldn't remember if the longhorns were all leaf spring trucks or not. But I still have not found out the complete differences between the rear sections of the two frames. (leaf spring/coil spring) The frames are the same width I believe. My dad has a '72 swb K10 and I have been measuring the two frames.

And sorry Ryan. I dont mean to hijack your thread.

No big deal. I have heard that guys have put leaf spring hangers on coil rear suspension frames. If I remember correctly, the frame is different in that the frame junped out a little next to the coil area to give room for the suspension travel. But I think as long as you aren't trying to go low with it, you should be able to mount leaf springs on it. But, like Tim said, finding a donor frame might be the way to go. I know it would be faster any way.

[JAA]

Originally Posted by Dieselwrencher

No big deal. I have heard that guys have put leaf spring hangers on coil rear suspension frames. If I remember correctly, the frame is different in that the frame junped out a little next to the coil area to give room for the suspension travel. But I think as long as you aren't trying to go low with it, you should be able to mount leaf springs on it. But, like Tim said, finding a donor frame might be the way to go. I know it would be faster any way.

Ok, thanks for the info. I'll check out the link Tim provided and take some more measurements.

[ryanroo]

Originally Posted by Dieselwrencher

Today the correct DIY4X rear shackle brackets arrived. Too bad there are no shackle bars.

i think... were i in charge of making those things i would do it a little differently.
they do look beefy for sure though. also i might recommend that you tie the two side plates of the shackle together somehow. since i doubt you are building a rock crawling/tow machine the added stability will be a benefit to you.

looking forward to some pics with them installed.

Ryan

[84 400]

The Diy4x is plenty beef. I run it on my 77 K10 and wheel it all the time and tow .. with it. The brackets are way beefier then the stock stuff. It does stink you have to buy the shackels seperate or build your own. The Diy shackles are stout too. I run there cross tied ones.

BTW this is a impressive build. Nice to see someone stick with a project .

[Dieselwrencher]

Seeing how now I will be building shackle bars, I will tie them together. It's weird they didn't send any at all. You guys have a great Sunday!

[mknittle]

Originally Posted by Dieselwrencher

Seeing how now I will be building shackle bars, I will tie them together. It's weird they didn't send any at all. You guys have a great Sunday!

tieing them together made a huge diffrence on my old jeep.

[mknittle]

hey, Ryan when I change over from the auto trans to a5speed on my 90 12 valve what years flywheel will fit?

[Dieselwrencher]

Originally Posted by mknittle

hey, Ryan when I change over from the auto trans to a5speed on my 90 12 valve what years flywheel will fit?

As far as I know 89-02 will work. When you get to that point, let me know.

[woodwright]

Originally Posted by JAA

Dieselwrencher, I am loving your build and plan to do the same thing to my 71 C20. My question to you is did your truck have factory rear coils, and if so, could you provide more info on that conversion? I apprciate all the pics and info you posted on the front end. It made a big difference in the confidence I had in myself to do the swap to the 2wd frame. Thanks!

JAA, The frames are different. The leaf spring frames are straight in the rear, and the coil spring frames bow out a little over the axle. I converted my rear coil C10 the rear leaf K10. Click on the link in my sig.

[mknittle]

Originally Posted by Dieselwrencher

As far as I know 89-02 will work. When you get to that point, let me know.

Thanks ryan,

[6lcummins]

Originally Posted by mknittle

hey, Ryan when I change over from the auto trans to a5speed on my 90 12 valve what years flywheel will fit?

Trick question...

This depends on the transmission you go with.

Getrag G360 takes the 89-93 12 1/4" flywheel.

NV4500 will accept a 94-03 12 1/4" flywheel or with a starter spacer a NV5600 99-05 13" flywheel. I would recommend sticking with a 12 1/4" clutch as they have 22% more friction material than a 13" clutch.

[mknittle]

Originally Posted by 6lcummins

Trick question...

This depends on the transmission you go with.

Getrag G360 takes the 89-93 12 1/4" flywheel.

NV4500 will accept a 94-03 12 1/4" flywheel or with a starter spacer a NV5600 99-05 13" flywheel. I would recommend sticking with a 12 1/4" clutch as they have 22% more friction material than a 13" clutch.

this is where the plot thickens,
My dad is is swapping out the getrag and transfer case for a 2wd nv 4500 for his peterbilt pickup. So it looks like he will need to swap flywheels. and I can
use his old one for the getrag?
my dad is trading me the parts he isnt going to use. Dana 60/70 np getrag/np 205} All L have to do is the sheet metal work on a 1940s peterpilt pickup he is building.



i am confused about how the 12.25clutch has more friction materal.And what are the diffrences in the two 12.25 flywheels?
I am not douting what you say but trying to learn more about these great little engines.


Thanks to both you and Ryan for the info Mark

[Monty]

Originally Posted by Dieselwrencher

Today the correct DIY4X rear shackle brackets arrived. Too bad there are no shackle bars.

i used those same parts to convert my 72 Sub to leaf springs when i did the 4x4 conversion. i used 64" springs IIRC and had to fab the front hangars for the rear springs because i couldn't find anything else that would work.

i 'think' that i also used ORD cross tied shackles with those DIY hangars and everything fit like a glove. i'm in the process of prepping the drive train now (427 truck motor, 465, 205)

you can also D&T the tube of the DIY hanger in the middle for a grease zerk instead of using drilled bolts, should you want greasable stuff...

[ryanroo]

Originally Posted by mknittle

i am confused about how the 12.25clutch has more friction materal. Mark

taking a SWAG here but i assume the 12.25 clutch disk has more material because the difference between the outside diameter of the material and the inside diameter of the material is greater than that of a 13 inch

ryan

[mknittle]

Originally Posted by ryanroo

taking a SWAG here but i assume the 12.25 clutch disk has more material because the difference between the outside diameter of the material and the inside diameter of the material is greater than that of a 13 inch

ryan

that makes sence.

[6lcummins]

12 1/4 clutch disc setup
http://valairinc.com/performance/images/nmu70119-04.jpg

13 clutch disc setup
http://valairinc.com/performance/images/nmu70279-04.jpg

The physical size of the button/clutch material is where the difference is found. The 12 1/4 is physically larger.

And I'm wrong the getrag will swap with the NV4500 according to ValAir:

"We no longer offer replacement Getrag clutches.

The 12 1/4" NV4500 clutch will fit your stock Getrag flywheel or you can upgrade to the 13" conversion kit found here. 5 speed 13" upgrade."

Nick

[ryanroo]

i am thinking a little here again (always sketchy business... me thinking) but if the apply pressure from the pressure plate is the same, the lesser friction material may have a better chance at holding torque while also causing more chatter. the idea is that less area with equal force would end up being a higher apply pressure. then of course the friction material and surface condition of the metal surfaces would play into the equation as well. and also the increased leverage that the bigger diameter clutch plate has on the input shaft would also increase its effectiveness as it would have more mechanical advantage on the shaft. that would probably only help in the engagement not necessarily the maximum torque holding capacity once engaged.

is there a notable performance issue with the 13" vs the 12.25"?

ryan

[6lcummins]

Originally Posted by ryanroo

i am thinking a little here again (always sketchy business... me thinking) but if the apply pressure from the pressure plate is the same, the lesser friction material may have a better chance at holding torque while also causing more chatter. the idea is that less area with equal force would end up being a higher apply pressure. then of course the friction material and surface condition of the metal surfaces would play into the equation as well. and also the increased leverage that the bigger diameter clutch plate has on the input shaft would also increase its effectiveness as it would have more mechanical advantage on the shaft. that would probably only help in the engagement not necessarily the maximum torque holding capacity once engaged.

is there a notable performance issue with the 13" vs the 12.25"?

ryan

More contact area, more grab, and better for more power. The dual discs utilize the 12 1/4 buttons. As far as a noticable difference most wont but there is a good difference in cost.

[Dieselwrencher]

My shackle bars arrived from DIY4X. No other real progress on this except trying to find where I hid parts for it.