traditional hotrod

[Iforgotmypassword]

I am a bodyman, and have access to all the equipment I need to complete this project. What I need is advise from you suspension guys that have alot of knowledge in the lowering aspect of this project.
First off, I have a 67 GMC . What I want is to build a hotrod (doesn't need to haul anything) that might have been built by an old time rodder in the 60's, that thought this "new style" truck would make a great rod. I would like to use a minimum of off the shelf parts, instead, using old fashioned hotrod ingenuity.I would also like to retain the 6 bolt drum brakes. What I want is no more then 8" from the bottom of the rockers to the ground, preferably 6".
What would be the simplest way to do this, if this were 1967?
Briefly, this is what I am doing besides lowering.
I have the top chop(3 3/4") about 80% complete. I will then cut 24" from the box with the wheelwell centred in the box ,and of course alter the frame. Then I will paint the truck in a traditional color, probably dark marroon, and keep the original wheels and use" baby moons" for the centres.
Any advise or comments on this project would be appreciated. Thanks.

[protrash64]

I think you are probably looking at raising the x-member up on the frame to get approx 1.5''. Sectioning your control a-arms you can get another 2''. I dont know if you want to cut coils, but you could probably use a new 2'' drop spring for a total of 5.5'' in the front.

The rear will be a spring drop (assuming coils)....you could use some Jeep springs (TJ???) for about 4'' and some blocks. I dont know the details on the exact Jeep coils, but a lot of the 60-66 crowd does it.

Hope this helps; I think its about as traditional as you get for lowering.

[N2TRUX]

Advise- I am not a fan of Z'ing the frame at all, but that would be a "traditional" way of lowering the truck with out bags.


Comments- It sounds more like a "custom Rod" than a "Hot Rod" that your wanting to build. While I applaud your tribute to retro styling with the traditional colors and chopped top, I don't think cutting the bed 24" is going to look good at all unless it's a long wheel base.

[dammitmitchell]

i erpsonally only support cutting a bed short when you are doing 4x4's....
period...
it's better to just get a short bed.. or leave it alone..
u can always "smooth the box" and put the typical custom rear lights etc... caddy lights and vette lights have been done a lot..
also the solid tailgate weld lookd good too (when a read body guys does it)
good luck

[Iforgotmypassword]

Thanks for the advice, guys. I think I may compromise on this one and switch over to 5 bolt discs , and use a drop spindle and maybe lowering springs.
I really don't likethe idea of z-ing the frame for structural reasons. I have a complete 78 Chev beater that I can use for parts sitting in my yard.
As for my plans for the box, has anyone else shortened their box to 6' rather then the stock short box length which I believe is 6' 6"?
I have several reasons for cutting the box rather then buying a box or using parts to build one. New Chinese box sides are expensive, and you pay the freight.A used short box in decent shape is impossible to find around here, so shortening mine makes the most sense, and I figure if I'm going to that much work I may as well be different and go 6' with the centre of the wheelwell in the centre of the box.I don't think a few more inches on either side of the wheel will look odd, just different.

[Iforgotmypassword]

I guess I also have a complete 80 Z-28 here . Any suggestions on using the complete sub-frame? Anyone know how much that would lower it , and any problems?
I am kind of getting away from the "what would have been available in '67" theme but if I can get what I want and save alot of work, I'll bend the rules.

[N2TRUX]

Brian- Lets start from the bottom and work up. Your 78 beater is a perfect candidate for your suspension upgrade. You can acquire everything you need for the front suspension. You can go the "package" route and swap the entire front crossmember with all of the suspension attached, or do it by pieces.

The later A-arms will bolt up to your truck with minimal issues. The 67 frame does not have a "flare" at the top to clear the power steering box, but you know how to solve that. So for the front suspension you can acquire, 5 lug discs, power brakes, booster, power steering, etc for your 67. No need to use the Camaro clip at all.

As far as the rear axle goes, the 78 is not a "bolt in" but it can be used. I "think" all 67-72 GMC's had rear leaf so it is a close fit. It is probably wider than your 67, but it can be accomplished. Another alternative is to have your rear axle shafts redrilled, or better yet by 5 lug replacement axles.

Now, on to your short bed dilemma. I understand that SWB sides might not be abundant in your area. It's funny how common they are in the Southern states, but not so much the farther North you go.

Regardless, you have the skills to cut a frame and bedsides down, so that's not an issue. There is a great article in our FAQ forum showing what I feel is the "proper" way to shorten a LWB frame to SWB.

If your going to take an additional 6" off of the bed, let me suggest you spend some time photoshopping a side view of your truck to see where it might be best to take it out of. You know how critical proportions can be to the aesthetics of your project.

[ruffrida2005]

I would use the whole frame of your 78. Depending if it's a 1/2 ton. The frame is the same as your 67. It would be a lot less work then swaping out the front end. Your GMC uses leaf springs in the rear and the chevy will should have trailing arms. As far as the front if you use the 78 you can use 2 1/2 drop spindles or 3". You can use 2" drop springs as well. As far as the back. You can either swap the springs to Jeep TJ springs, but with that you dont have the hauling rate anymore. Look at a lot of the vendors and you can find how small of a spring you can get. If you want the rocker to be 6" from the ground your going to have to c-notch the frame. You can buy that from a lot of vendors. Using this frame you will have your 5 lugs. The rear end on the 78 is just a little wider then the 67 so you will have to make sure you get the correct BS for the rims. i would use the 67 rear just for the narrower axle, then swap out the axles. Again a lot of the vendors sell the axle swap.

[N2TRUX]

Originally Posted by ruffrida2005

.... As far as the back. You can either swap the springs to Jeep TJ springs, but with that you dont have the hauling rate anymore.... .

Help me out here. I thought the TJ springs were a replacement for 67-70 coil spring trucks ? Yes or no?

[Spray-Bomb]

Originally Posted by ruffrida2005

I would use the whole frame of your 78. Depending if it's a 1/2 ton. The frame is the same as your 67. It would be a lot less work then swaping out the front end. Your GMC uses leaf springs in the rear and the chevy will should have trailing arms. As far as the front if you use the 78 you can use 2 1/2 drop spindles or 3". You can use 2" drop springs as well. As far as the back. You can either swap the springs to Jeep TJ springs, but with that you dont have the hauling rate anymore. Look at a lot of the vendors and you can find how small of a spring you can get. If you want the rocker to be 6" from the ground your going to have to c-notch the frame. You can buy that from a lot of vendors. Using this frame you will have your 5 lugs. The rear end on the 78 is just a little wider then the 67 so you will have to make sure you get the correct BS for the rims. i would use the 67 rear just for the narrower axle, then swap out the axles. Again a lot of the vendors sell the axle swap.

The frames are NOT the same & in 78 they did not have trailing arm rear suspension

Also you cant put 5 lug axles in a 67/68 rear end, as they are different widths (unless they are after market axles, made for the narrow 67/68 rear)

For the rear, being a GMC you should have leaf springs (unless it has the optionary trailing arm suspension) You can flip the axle on top of the springs as mentioned above which will give you roughly 6" of drop, you can also cut your spring perches off & move them up some to gain more drop & since you dont care about hauling anything, you can take a few leafs out to gain a lil more drop & a smoother ride

As for the front, I would swap in the whole front clip from the 78, its not that hard, as its only a few bolts
Get some 2.5" drop spindles (3" drop spindles have a hard time clearing 15" wheels... if they even clear)
You can cut about one "round" off your coils in the front to gain roughly 2.5-3" depending on your particular springs
As for modding the front cross member, I am not a fan of sectioning them as it changes the geometry, but channeling them is cool in my book (cutting a channel in it for the frame to drop into more / lets it set up higher on the frame) IMO you need to brace the UCA mount when you do that, it does mess with your steering some too & you can run into pan clearance

Imo, for the front the best thing to do if you want to be lower than just drop spindles & cut or lowering springs, is to Z it
That takes care of having to worrying about front end geometry

[blime81]

78 frame is not the same as the 67s.

Swap the entire front crossmember from your 78. Disk brakes and pwr steering all at once. Install it raised up and cut out a coil to drop it down (you wanted old school).

As for the back, I have been looking at a bunch ways to drop the backend of my leaf sprung 72 as well.
Some options that you might wanna consider:
-A flip kit (though I am having trouble locating one, not sure if 73-87 kit will work, see my other thread)
-Dearching the springs (this is in keeping with your old school theme)
-Buying a new set of dropped leaf springs and or dropped shackles depending on how low you need to go.

Good luck (and one more vote to not chop the bed)

[N2TRUX]

So as not to confuse the OP, let me recap here. You can not swap the 78 frame to your 67 because there is a difference in body mounts as well as the back half of the frame is completely different. The front suspension can be swapped as a unit, or in pieces as I mentioned above.

[smbrouss70]

Originally Posted by Iforgotmypassword

I guess I also have a complete 80 Z-28 here . Any suggestions on using the complete sub-frame? Anyone know how much that would lower it , and any problems?
I am kind of getting away from the "what would have been available in '67" theme but if I can get what I want and save alot of work, I'll bend the rules.

I'll probably catch a lot of flak for this, but a "traditional hot rodder" would use what he had available, since there was not much aftermarket parts available, especially for suspension, in the late 60's. The 78 front susp. swap would give you basically the same thing that you have already, but with rubber bushings instead of steel & 5-lug disc brakes. You would still need to buy (read: aftermarket) drop spindles, shocks, and springs (or cut the springs). The 80 Z28 front clip wouldn't have been available back then, but it would have been something that would have been done back then to get a truck low and still ride good. Just look at it as an improved version of the 67-69 camaro clips that were available back then. As far as how much it will lower it, the consensus of the friends that I know that have done it, approx. 7 inches lower than stock. That is with stock springs and spindles on the Z28 front end. That would also give you the rubber bushings and 5-lug disc brakes (although only 11" discs), as well as narrowing the track with of the front suspension and giving you better geometry than a truck (that was designed for work).

For the back, to keep it simple (and match bolt patterns front/rear) use the 80 Z28 rear end which is narrower than the truck rear, if you want some deep dish wheels on the back. I would try and use the leaf springs off of the Z28 also for a smoother ride, since you are not worried about hauling anything. That would probably require fabricating you own leaf spring hangers & notch, but still something that a late 60's hot rodder would do. You could also keep the truck leaves and do what Spray-Bomb listed or you could swap in a coil set-up from a 67-72 chevy truck and still use the Z28 rear.

Here are a couple of links that show a completed truck with a Camaro front subframe and one that shows what it takes to get the subframe grafted into the trucks frame.

http://louisianaclassictruckclub.fre...ruck-t337.html

http://louisianaclassictruckclub.fre...uild-t335.html

[joe231]

Originally Posted by N2TRUX

Help me out here. I thought the TJ springs were a replacement for 67-70 coil spring trucks ? Yes or no?

actually they work on the '60-'70 trailing arm/coil sprung trucks.

[N2TRUX]

Originally Posted by joe231

actually they work on the '60-'70 trailing arm/coil sprung trucks.

OK, that's what I thought.

smbrouss70 & Spray-Bomb- No flack, just a request for consideration of the use of practical logic here. When I suggested to the OP that he Z the frame he didn't want to do that because "I really don't like the idea of z-ing the frame for structural reasons." which I adamantly agree with.

Knowing that, why would you recommend using a Camaro sub frame? Yes, Camaro, Nova, Chevelle, Pacer, Volare, etc sub frames were used "back in the day" only because there wasn't any more practical choices.

With the option of having a parts truck right there with everything he needs to "bolt on" 5 lug power disc brakes, I see no logic at all in considering lopping off the front of your frame to acquire the same thing.

[smbrouss70]

Originally Posted by N2TRUX

smbrouss70 & Spray-Bomb- No flack, just a request for consideration of the use of practical logic here. When I suggested to the OP that he Z the frame he didn't want to do that because "I really don't like the idea of z-ing the frame for structural reasons." which I adamantly agree with.

Knowing that, why would you recommend using a Camaro sub frame?

In his very next post after the one you quoted was when he asked about using the camaro subframe. The camaro subframe slides into the original frame rails and is braced and welded, unlike a z which is basically butt-welded then plated. The subframe is far stronger in my opinion. I'm not saying that he HAS to do it my way, but giving more information that no-one else had given at that point. I myself am going the camaro subframe route having seen other trucks that already had it. Once again, this is only my $0.02

[ruffrida2005]

I've been told that the TJ springs will swap to our trucks with trailing arms, but it's a softer spring rate from what I've been told! I've never used them.

[ruffrida2005]

when did they stop putting the trailing arms in the trucks? I know the frames body mounts are diffrent, but isn't that it between those 2 frames?

[Shane]

1973 was first year for leaf springs on 1/2 tons trucks STANDARD.

[joe231]

ok, so I stand corrected, TJ springs will work on '60-'72 coil sprung trucks.....


ruffrida, they are a softer spring that rides nice, just can't really haul anything with them.

[michael bustamante]

heres another thing, the p steer gear box on a 78 is metric I believe, so the threads wont match traditional (sae) hoses butI f you have the p steer pump and hoses, you shouldnt have any problems there

[joe231]

I believe 1980 is the year they changed the p/s to metric....
you can swap the fitting in the back of the pump to match which ever gear box you have, if needed

[N2TRUX]

Originally Posted by ruffrida2005

I've been told that the TJ springs will swap to our trucks with trailing arms, but it's a softer spring rate from what I've been told! I've never used them.

You are correct, but the OP was asking about a 67 GMC. Am I mistaken in thinking that all 67-72 "GMC's" were leaf spring trucks?

As far as the power steering concerns, it wouldn't matter what year they became metric. He will need the complete system from the 78 regardless of metric or SAE.

[XXL]

Originally Posted by N2TRUX

Am I mistaken in thinking that all 67-72 "GMC's" were leaf spring trucks?

Leafs were standard, but coils could be bought optionally... just the opposite of Chevy. Not sure why other than market differentiation (??)

[N2TRUX]

Thanks XXL, I am more informed on 73-87's but I "thought" that was the case with 67-72 GMC.