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Old 11-24-2003, 11:37 AM
scott ticknor's Avatar
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c-notching a frame

I will be lowering our truck next spring and want to get all the info that I can. The least I want to lower it is 3" front and 4" rear.I would like to go lower but I am unsure about doing the c-notch. Now the truck is not what I would call a classic, It`s a `82 Custom -deluxe (which means it is neither) But with some modification,we can have some fun. What I would like is some feedback from people that have notched their frames so we can make the decision: to notch or not to notch...

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Old 11-24-2003, 11:57 AM
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Only going a 3/4 drop I don't think it will necessitate "C" notchng the frame. You should be able to get by with dropped spindles or shorter springs up front and reverse the shackles in the rear with little or no sacrifice to ride characteristics. If you want to get radical and slam it to the ground then it would justify "C" notching. If you do decide to notch it, look in some of the custom truck magazines for a kit to do it. I'm not sure whether it's Sir Michaels, or Godfathers, but one of the ads shw the different drops and what you can get to do it. I also ran across this site Right Here that pertains to mini trucks but can be adapted to full size. Instead of notching they backhalved the frame. Look at page three on the site for some pics. Hope some of this helps you out.


Last edited by Kevin45; 11-24-2003 at 12:14 PM.
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Old 11-24-2003, 04:55 PM
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"C-ing" a frame for clearance of the rear axle housing has been done for many years. It is the easiest and the most unsafe way to get the clearance. The rear portion of the frame becomes very weakened when this is done due to the 'C' section being removed.

If you need additional clearance the safe way is to "Z" the frame. This is done by cutting the rear portion of the frame diagonally and raising it up so that the bottom of the rear section sits on the top of the forward section. It is then welded all the way around with gussets added as well. A greater drop can be achieved the same way by raising the rear portion even higher and filling the space with heavy wall rectangular tubing. The floor pan or in the case of a pickup, the floor of the pickup bed will have to be raised to accommodate the raising of the frame section.
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Old 11-24-2003, 06:05 PM
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I say go drastic and make it lay frame! Nothing looks better on trucks than the front bumper touching the floor. I've seen a few c'd frames, but never one that ended up defective. I wouldn't recommend towing with it afterwards though. There's tons of kits out there that would get you low, just pick up a truckin mag and you'd find at least 3 different ones. Some may even have a bolt on kit.
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Old 11-24-2003, 10:49 PM
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Yes ,c-notching can be done ,but if you do, I would suggest fully boxing the frame at least a foot around the notch . And as stated, you probably won't want to pull a trailer with it . Also ,if you are going to "flip" the rear axle to drop it , I would suggest checking the axle to box floor clearance to make sure that it don't hit when the suspension bottoms out ! Rick
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Old 11-26-2003, 11:03 AM
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I agree with GT, lay frame!!!! It can be done with Airbags.. I have had 2 cars with bags, one a 1993 GMC Truck and my 1997 Tahoe, they both lay frame on 20's...

If you C-notch the frame make sure you reinforce the remaining frame by boxing it in.... This will help keep the frame strong in the rear of the truck...

When I did a Flip on my Trucks, I had to notch the rest of the crossbar as well, and cut out an opening on the driveshaft tunnel. But it sounds like you are not doing this much...

Good luck
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Old 11-27-2003, 06:49 AM
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When I worked on race cars we used to notch the frames. We did it for clearance and also to weaken the rear frame rails. We then added roll bars that added some strength back in. The idea was to allow the frame to give some on impact, to help save the rest of the car. We regularly replaced the rear frame rails after accidents( they occured too often), but they were relatively easy to replace because of the frame design being several pieces welded together. With a truck, the rear bumper is usually the part that takes any impact on the rear. Since it attaches directly to the frame, an impact can cause severe damage to the frame. Another consideration has to be the location and type of springs and mounts. Leaf springs will have the rear mounts behind the notch(weakened area). A stiffened ride, coupled with bad roads, could damage the frame while simply driving the thing.

Before notching the frame of anything driven on the road, I would definately consider other options.
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Old 11-30-2003, 03:37 PM
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when you lower the truck to where you want it (for fitment), you want to check out the distance from the axle to the frame. you want 3" minimum here, otherwise bottoming out will be a problem at some point. if less than 3", i would recommend "c-section", meaning not a notch, but a full section of frame above the axle. this will be much stronger and not prone to possible frame bending that can happen with c-notches. (can- not will)

good luck!
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