is c-notch necessary?

[danieljpeter]

Hi there,

I want to static drop my truck as much as I can without cutting into the bed. I had done this on a newer chevy truck years back, and a mini-c notch was required to get the diff pumpkin right up tight to the inside of the bed floor. This is as low as you can go using the stock rear end without cutting the bed.

I assumed this would be the same case with my 66 GMC. But once I had the bed off and started measuring things it looks like with no c notch, I can get the diff pumpkin within 1/4" of the bottom of the bed. I have the stock dana 44 rear end that came in these GMCs.

This may have to do with the fact it is a GMC and has leaf springs and a dana 44 instead of trailing arms and coils with a 10 bolt rear.

But I see no reason to c notch it unless I want to be pounding the bottom of my bed wood with my differential or plan to cut out a hole in the bed. If I was going to cut a hole in the bed I would do a full-on large c notch.

Can the others who have done under the bed mini-c notches verify whether or not they had the same experience?

Thanks,

Dan

[SCOTI]

My 68 had a wood floor w/the bolt-in style c-notch from CPP & the rear frames are the same as the 63-66's. The 12-bolts pumpkin hit the bed floor if the air was too low in the rear or there was too much weight (cargo). I don't/didn't play w/my pressure settings so basically my system was 'static' or fixed @ a constant ride height which equalled about 7-8" of drop in the rear. I only adjusted the air pressure when using the truck as a truck (cargo, towing a trailer, etc...).

Not using the c-notch would almost garantee no damage to the bed floor.

[mnky30]

[danieljpeter]

Thanks, good info. As soon as it warms up this morning I'm going to bolt everything up.

I cut everything off my axle and smoothed it yesterday. I flipped it to the top of the leafs. Today I'm going to set the pinion angle, weld the perches, and bolt everything up and see where I stand. I'll take some more measurements and decide if I want to do the notch or not.

I will be close to the axle/frame hitting after the flip because my leaf springs are sagging so much. I might decide to put overload bags in just because it is cheaper than new leafs, and the adjustability means I don't have to engineer the ride heights as carefully.

PS: I'll go take some pics right now.

[danieljpeter]

Here are the pictures. On my second measurement, it looks like my axle will hit my frame when the top of the diff is 3/4" or so from the bottom of the bed wood. Maybe I could benefit from a 3/4" or so notch? It's just a lot of work to get that extra 3/4" before my pumpkin hits the bed.

Tough call for me to make.

Thanks,

Dan

[mnky30]

you could always put some bump stops on the frame so the diff wont hit the bed. looks good

[protrash64]

Here is my 'burb without a notch...pumpkin doesnt hit.

[protrash64]

Sorry. heres pic.

[danieljpeter]

protrash64,

do you have any pictures of how low your burb sits?

Thanks,

Dan

[shortbed70]

My 65 chevy sits on the bumpstops now that are trimed in half and I have about 3\4" between axle and frame and that is about what I have from the top of the diff to the bottom of my wood floor so I plan on bagging and using a 1/2" shorter bumpstop so when its laid out at a show or something its not hittimg the bottom of the floor or if I have a bag faliure or something I could limp some where to fix. I'm not going to run a notch because I won't gain anything unless I move my floor up.

[shortbed70]

Heres the only pic I can find right now but this is sitting on a trimmed stock bumpstop about 3/4 from frame above axle.

[mnky30]

dan
did you get ever thing welded up on your truck?

[lolife99]

Really clean truck you are working on. Keep us posted on your progress!

[Twisted Minis]

Those bags and plates look familiar.

Looks good Dan. Just make sure you can get the U-bolts back off when you make the bag brackets on the axle.

Here is the U-Joint article I was talking about earlier.
http://www.airridetalk.com/articles/...nt-enigma.html

[danieljpeter]

Hahhaha. Yeah, I think if I mount the bag plates 1" or so from the axle housing I will be okay. If I remove all the hardware and the u bolt plate from the bottom I should be able to rotate the u bolt 90 degress and slide it out. I will double check this works before welding anything.

I have made some classic mistakes in my day, so I appreciate you looking out.

Thanks!

Originally Posted by Twisted Minis

Those bags and plates look familiar.

Looks good Dan. Just make sure you can get the U-bolts back off when you make the bag brackets on the axle.

Here is the U-Joint article I was talking about earlier.
http://www.airridetalk.com/articles/...nt-enigma.html

[mnky30]

dan
i'm pretty close to you and i have a angle finder 2 types one you dial in and and with a needle. if you need to borrow i can bring out one day. that way your not spending money on some thing you are not probly goning to use again for a long time.
vinnie

[danieljpeter]

I know how you guys like pictures and all. I've been working a lot lately, haven't had a lot of time to work on the truck. But I will probably slap it back together and drive it around this weekend.

This is just supposed to be a low budget, functional, lowered truck. Wanted it to be as low as possible without cutting into the bed. The bags are just to get the ride height correct and to be able to haul, not for hitting switches or hopping or anything.



Here are the bag brackets. I bought the bottom plates, and made axle tabs for them. I made the top plates from 1/4" steel.

I like using the all-thread to hold the plates where they need to be. You set them to where the bag would be collapsed (3" for slams) and everything works out good.












I couldn't make the triangle gussets as big as I wanted, because they would hit the bag. I didn't like having just plain old 1/4" cantilevered out so far with the bag mounted to it. It probably would have been okay, but I wanted to stiffen it up a bit. I got some 1/2" square solid stock and put a piece of either side of the top of the bracket. This will also keep the bed wood from pressing down on the air fitting once installed.






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[danieljpeter]

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Flat black paint.














The driveline was hitting the top of the hole in the crossmemeber it passed through. I cut out all of the metal except for the top most piece of metal. Then I made a 3/8" steel plate and bent it and welded it on top to restore some integrity:







So I just need to find some shorter shocks and set up the shock mounts so they act as a droop limiter. So when I jack the thing up by the frame it doesn't try and tear the bags apart.

Then I'll probably drive it until january and start my tranny swap then. I miss driving it too much to do all the work at once. I have a rebuilt sm465 with cast iron bellhousing all painted up and ready to swap in.

Thanks for your help.

[Twisted Minis]

Damn Dan, nice work. That's a clean bag mount.

[danieljpeter]

Nothing too fancy. I don't stress over making **** all perfect like you.

It should be strong enough, eh? I'm trying to break the habit of building **** too heavy and making boat anchors out of everything I do.

[protrash64]

Nice to see an update.....nice work too. Thats a good tip on using the all-thread for adjusting stuff. I think it would be handy in a bunch of different places.

[danieljpeter]

Went out last night in the refrigerator I call a shop and mounted and plumbed the bags.








I drilled a hole in that big funky bumper that I'm rockin and welded an 1/8" steel fitting through it. One side is the compression fitting with the air line, the other side is the schraeder valve. I burned all the paint off the license plate side, so I touched it up with white. Now I have this bright white spot. I should have just left the paint burned off!







I love those metal/rubber wiring clamps for airline. They hold stuff good without wearing through it.





Ran airline inside frame rail where I could.









I still need shocks. I think I will just use the "other hole" closer to the axle next to the stock upper mount. This will correct some of the messed up shock angle you get from lowering the back end. I think I will just use the stock shock tabs on the axle. The shock won't be as straight up and down as I'd like, but it should work OK. So with the axle to the frame there is 10" from the center lower hole to the upper shock hole. With it aired all the way up and the crap arched out of the leaf springs it is 14.5 from center center hole. The only shocks I could find that meet this criteria are these:

http://catalog.monroe.com/monroe/pro...catalog=MONROE

They are monroe RV shocks. I think people use them on car trailers and stuff. They are 9.625 compressed and 14.75 extended. Pretty much perfect dimension wise. I think they are around $20 a piece, too. I don't want to mess with standard lowered chevy shocks, they are probably not the right length for me and more money than I want to pay. I'm pretty sure the rv shocks will ride good enough for my tastes.











If you look close, you can tell the bottom air brackets are just tacked in place. This was a suggestion from seth @ twisted minis. Then after I do my tranny swap if I end up needing to shim the pinion angle I can reweld the bottom bag brackets if necessary. Also, the truck isn't heavy enough without the bed to compress the bags all the way! Those slams take a lot of weight to compress. When I jump on the bumper I can get the axle to smack the frame, though. I think with the bed on it will be bottomed out. Then I'll just shoot some air to it to get a nice ride height.

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[danieljpeter]

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[lolife99]

Any plans to notch the frame?

[SIR]

great work... but one question,with the bags deflated the edge of the rear bracket clears the lip of the rim nicely,but it looks like when there full you don't have much room between the bracket and the tire.my question is if you go to a wider wheel/tire combois it going to hit?.it looks like if you have a wider rim that extends past the backing plate it's going to rub...then again I could all wrong..been there before.