boxed rails and 4 link suspension - The 1947 - Present Chevrolet & GMC Truck Message Board Network

smart68 · 01-29-2009, 08:32 PM

I am working on a 77 GMC SB Step Side. It is currently a frame with 4 tires. I have an engine that will put out lots of HP. I have been told I should box the rails to keep the frame from twisting from the torque of the engine. Others tell me not to box the rails but to install a 4 link rear suspension. I would appreciate comments from anyone who has experience with either or both.

James McClure · 01-29-2009, 10:18 PM

Smart, This is my opinion and it's worth what it costs. You live in the "salt" belt like I do. Don't box. It would be a rust out nightmare real quick. Look at the frame of an 18 wheeler. Wide open 3 sided beams and still only 1/4" thick. Our trucks are 3/16". True the truck frames are wider or taller, but not that much when you consider the raw HP and torque these frames have to endure. A 4 Link will help and it's easier to deal with than boxing in what you got now. Remember that whatever you do the frame HAS to flex or it WILL break. jim

Wild83C10 · 01-29-2009, 10:26 PM

Check the performance section of the forum. Some guys there are running pretty quick. I bet they either have a mostly stock frame or a complete custom tube frame. What kind of tq are you talking? I don't think boxing the frame, except mayb in key sections, will be necassary.

fast75 · 01-30-2009, 03:57 AM

both of these guy's have some good points. things to consider: 3/16th metal doesnt look very thick, but when you start adding it to your frame the weight adds up quick. are you going to drop the truck any? if so, the added weight will affect your alignment considerably. boxing the frame is good if you plan to pound the piss out of it ie: drag racing. not good for a daily driver. just my 2 cents..............

smart68 · 01-31-2009, 05:17 PM

Thanks for the replies - seems like the consensus is to leave the frame alone. I'm good with that - less work. I just need to find some good info on the 4 link which I am sold on. I plan to leave the truck pretty close to factory hiegth. I will post some pictures soon.

JS

PhilaTruck · 01-31-2009, 05:34 PM

These light trucks have pretty strong frames- that's why they're heavier than passenger cars.

And yes defintely go to the "haulin" forum. Years and years of experience there.

So what kinda numbers are we talking here?

smart68 · 01-31-2009, 05:42 PM

The engine is a 454. It has a blower on it. I purchased it from my neighbor who has all the paperwork on it. He says it has never been put on a formal horse power or torque machine (maybe someday I will have it done) but it appears it should be pushing 500 - 550 HP. I know its a lot for a two wheel drive short box but I just couldn't help myself. I want a truck I can take to the races or just tool down the interstate. JS

PhilaTruck · 01-31-2009, 07:55 PM

Sounds pretty cool.

Check out some of the combos in this thread: Engine & drag analyzer thread

Oh, BTW- welcome to the forum. You'll find a great community here.

-Todd

Wild83C10 · 01-31-2009, 08:13 PM

Pretty decent power. I bet the torque is much higher then the HP. Torque is what puts you in your seat. A BBC and a roots? blower will provide more then enough torque to put a big smile on your face and keep your butt in the seat.
Good luck, the 4 link will definitely help put the torque to the ground. Don't forget to work on the front suspension too.

smart68 · 02-01-2009, 12:02 AM

OK you can see a picture of where my truck is right now - a little cold to work on it today. I will have to get all the particulars on my engine and have it checked out. I know this is going to take me a while but just looking at the engine makes my blood boil - I am so anxious to get it done.

I am going to remove the rear springs and brackets and build the 4 link suspension for it. I spoke to a guy who said he will help me set up an adjustable 4 link. I am checking into having the frame powder coated before I start putting it together - I will remove the front end and install heavier springs for the added 454 weight. I will keep changing my Avatar as I add and build. JS

BigBlocksRule · 02-01-2009, 10:54 AM

Get some CalTrac bars and you'll be good to go. As these guys said, these frames are thick and strong. I'm building a '56 that will set on a '63 GMC chassis. The trailing arm suspension launches a lot like ladder bars but is a lot more street friendly. Good luck, a rat with a huffer is always cool.

01-29-2009, 08:32 PM	#1
smart68 Registered User Join Date: Sep 2008 Location: Kimberly, ID Posts: 7	boxed rails and 4 link suspension I am working on a 77 GMC SB Step Side. It is currently a frame with 4 tires. I have an engine that will put out lots of HP. I have been told I should box the rails to keep the frame from twisting from the torque of the engine. Others tell me not to box the rails but to install a 4 link rear suspension. I would appreciate comments from anyone who has experience with either or both.

01-29-2009, 10:18 PM	#2
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	Re: boxed rails and 4 link suspension Smart, This is my opinion and it's worth what it costs. You live in the "salt" belt like I do. Don't box. It would be a rust out nightmare real quick. Look at the frame of an 18 wheeler. Wide open 3 sided beams and still only 1/4" thick. Our trucks are 3/16". True the truck frames are wider or taller, but not that much when you consider the raw HP and torque these frames have to endure. A 4 Link will help and it's easier to deal with than boxing in what you got now. Remember that whatever you do the frame HAS to flex or it WILL break. jim __________________ 1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shotJim or Paladin whichever you choose.

01-29-2009, 10:26 PM	#3
Wild83C10 Registered User Join Date: May 2002 Location: NJ Posts: 910	Re: boxed rails and 4 link suspension Check the performance section of the forum. Some guys there are running pretty quick. I bet they either have a mostly stock frame or a complete custom tube frame. What kind of tq are you talking? I don't think boxing the frame, except mayb in key sections, will be necassary. __________________ 83 C10 Stepside (SOLD, it was a blast!) 383 MASS-FLO EFI/TKO II 600/3.90 Posi 10 bolt S475 and C4 DM running, fine tuning turbo= Douchebag Racing: Runs Fine all the Time

01-30-2009, 03:57 AM	#4
fast75 Go Hard or Go Home! Join Date: Dec 2008 Location: quitman, tx Posts: 261	Re: boxed rails and 4 link suspension both of these guy's have some good points. things to consider: 3/16th metal doesnt look very thick, but when you start adding it to your frame the weight adds up quick. are you going to drop the truck any? if so, the added weight will affect your alignment considerably. boxing the frame is good if you plan to pound the piss out of it ie: drag racing. not good for a daily driver. just my 2 cents.............. __________________ 75 short wide 350, some mods, scare the piss outta ya quick. 2008 Dodge crew cab. YEAH, it's got a hemi, your ass is going to jail quick. Some day's, it's just not worth chewing through the restraints................................

01-31-2009, 05:17 PM	#5
smart68 Registered User Join Date: Sep 2008 Location: Kimberly, ID Posts: 7	Re: boxed rails and 4 link suspension Thanks for the replies - seems like the consensus is to leave the frame alone. I'm good with that - less work. I just need to find some good info on the 4 link which I am sold on. I plan to leave the truck pretty close to factory hiegth. I will post some pictures soon. JS

01-31-2009, 05:34 PM	#6
PhilaTruck Right on the line, baby! Join Date: Oct 2003 Location: Phila, PA 19130 Posts: 1,486	Re: boxed rails and 4 link suspension These light trucks have pretty strong frames- that's why they're heavier than passenger cars. And yes defintely go to the "haulin" forum. Years and years of experience there. So what kinda numbers are we talking here? __________________ 83 GMC 406 th400/3.73 Eaton Truetrac posi, headers, x pipe, & racePros. Tubular control arms, lowering rear springs, caltracs. Still ugly, but getting built right, although slowly Click and scroll down for site vendors! Subscribe here!

01-31-2009, 05:42 PM	#7
smart68 Registered User Join Date: Sep 2008 Location: Kimberly, ID Posts: 7	Re: boxed rails and 4 link suspension The engine is a 454. It has a blower on it. I purchased it from my neighbor who has all the paperwork on it. He says it has never been put on a formal horse power or torque machine (maybe someday I will have it done) but it appears it should be pushing 500 - 550 HP. I know its a lot for a two wheel drive short box but I just couldn't help myself. I want a truck I can take to the races or just tool down the interstate. JS

01-31-2009, 07:55 PM	#8
PhilaTruck Right on the line, baby! Join Date: Oct 2003 Location: Phila, PA 19130 Posts: 1,486	Re: boxed rails and 4 link suspension Sounds pretty cool. Check out some of the combos in this thread: Engine & drag analyzer thread Oh, BTW- welcome to the forum. You'll find a great community here. -Todd __________________ 83 GMC 406 th400/3.73 Eaton Truetrac posi, headers, x pipe, & racePros. Tubular control arms, lowering rear springs, caltracs. Still ugly, but getting built right, although slowly Click and scroll down for site vendors! Subscribe here!

01-31-2009, 08:13 PM	#9
Wild83C10 Registered User Join Date: May 2002 Location: NJ Posts: 910	Re: boxed rails and 4 link suspension Pretty decent power. I bet the torque is much higher then the HP. Torque is what puts you in your seat. A BBC and a roots? blower will provide more then enough torque to put a big smile on your face and keep your butt in the seat. Good luck, the 4 link will definitely help put the torque to the ground. Don't forget to work on the front suspension too. __________________ 83 C10 Stepside (SOLD, it was a blast!) 383 MASS-FLO EFI/TKO II 600/3.90 Posi 10 bolt S475 and C4 DM running, fine tuning turbo= Douchebag Racing: Runs Fine all the Time

02-01-2009, 12:02 AM	#10
smart68 Registered User Join Date: Sep 2008 Location: Kimberly, ID Posts: 7	Re: boxed rails and 4 link suspension OK you can see a picture of where my truck is right now - a little cold to work on it today. I will have to get all the particulars on my engine and have it checked out. I know this is going to take me a while but just looking at the engine makes my blood boil - I am so anxious to get it done. I am going to remove the rear springs and brackets and build the 4 link suspension for it. I spoke to a guy who said he will help me set up an adjustable 4 link. I am checking into having the frame powder coated before I start putting it together - I will remove the front end and install heavier springs for the added 454 weight. I will keep changing my Avatar as I add and build. JS

02-01-2009, 10:54 AM	#11
BigBlocksRule Registered User Join Date: Jun 2008 Location: Lubbock, TX Posts: 2,047	Re: boxed rails and 4 link suspension Get some CalTrac bars and you'll be good to go. As these guys said, these frames are thick and strong. I'm building a '56 that will set on a '63 GMC chassis. The trailing arm suspension launches a lot like ladder bars but is a lot more street friendly. Good luck, a rat with a huffer is always cool.



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