Project: Custom 71 4x4 hotrod

[brossow]

Is the spare tire crossmember sturdy enough to handle the stress of having shocks attached? When I removed mine, I remember it being rather flimsy -- enough to hold a spare but not much more. Yours may be completely different and in better shape than mine.

[silver7]

I found a gentlemen in VA to do an even swap for my tires. His tires are 35" Super Swampers and mine are 33" BF Goodrich MT and since we both have 15" rims so we'll just trade tires. I hope to do the swap within the next couple of weeks - here are some pics.

[silver7]

Originally Posted by brossow

Is the spare tire crossmember sturdy enough to handle the stress of having shocks attached? When I removed mine, I remember it being rather flimsy -- enough to hold a spare but not much more. Yours may be completely different and in better shape than mine.

Good question. I call it the spare tire cross member but I may have been for something else. My truck is not an original 4x4 so who knows what have been added and subtracted along the way. But it is very sturdy. In fact, the steel is as thick as my frame.

Here are a couple of photos of it.

[yellow70GMC]

Originally Posted by brossow

I must be missing something. I'll trust you on this for your setup. The more I think about it, essentially what you've done is created a sort of combined trailing arm and leaf spring suspension in one. Sorta.

As for my Caltracs, I'm not preventing fore-aft movement. That's not what a good traction control system does. My goal is the same as what you called it but not what you described: preventing spring (axle) wrap, which isn't fore-aft movement at all but rotation of the axle in place, causing the leaf springs to "wrap" into an S shape. During normal driving the axle still needs to be able to move forward and backward as I described previously and hence the need for the front pivot. Under hard acceleration, however, if the axle tries to rotate forward, the Caltracs prevent this rotation.

But like I said, I'm not an engineer and maybe I'm missing something. I'll leave it at that and hope it perfectly works for you. Sometimes I overthink things.

Cheers,
Brent

He's right, and i'm afraid you're going to break your front mounting points on those bars if you beat on the truck too hard. I hope you don't, though. But yeah "axle-wrap" refers to the axle twisting, not moving forwards and backwards. It needs to move forwards and backwards, that's what the shackle is there for. Brent already described it perfectly. Not tryin to knock your build at all, just my .02 cents. Whether or not my opinion is really worth that much or not is debatable trucks looking great though, can't wait to see more.

[silver7]

I know what the shackle is for but that described movement is exactly what I am trying to reduce. My set-up is similar if not identical to a lot of other 'homemade' traction bars out there so I like my chances. In fact, I found a lot more truck guys using my kind of traction bars versus the Caltracs. This guy '6600duramax' is on our forum board making and selling a traction bar which mounts the same way as mine.

http://67-72chevytrucks.com/vboard/s...d.php?t=364788

But, if the ride happens to be a little stiffer than desired, I can always add a small shackle to my front mount to allow my springs to elongate 'a little' when compressed. Maybe that will give me the best of both worlds. Either way, I appreciate the dialogue on the subject.

[Conroe trucker]

I like what you are doing, and the fact that you are hammering through it.
I wish I'd the balls to make those kinds of changes on mine, but alas, I'm kind of an old fuddy traditionalist.
If my head does not hit the roof when going over a railroad crossing, I think something is wrong........

What will happen is as the leaf spring compresses and unloads, they will force the axle to twist on the springs, since the ladder is not compressible between the axle and frame.

So as it goes up, (compresses), the nose of the axle will be forced down, cause the leaf is now longer.
As it unloads, goes down, the nose will be forced up, because the leaf is not shorter.

You will be able to test this easily with the truck jacked up and a set of tires on it, by raising and lowering the axle.

You have two different ladders in your design, one is fixed, the other, (spring), will elongate or shorten depending on load.

That is the problem.

Most link design have two equal length tubes on each side, not one that changes length. Look at a 32 high boy. The way around this is a hairpin type where both tubes connect at one point on the frame. That lets the axle pivot the nose to allow the drive train to stay inline.

If they both have roughly the same length you may not have that much of an issue, but because it looks cool does not mean it will work real well.
That pic that you posted of the long ladders under that truck looks cool but also like a lot of stuff for nothing.
My thought is that a traditional simple bolt on ladder that hits the leafspring would be much better than that, like is what is used on Camaro's, and would be protected by the tires.
Also, why not mount the ladder on top of the axle to get it out of harms way?

I went back and looked to see how my lowered truck's shocks were mounted.
We moved used the same brace you have, and made a bracket tht moved the shock back a few inches.
Works ok so far.
You could also bolt that spare tire carrier back after reinforcing it.

There is a elegance in simplicity.........
The guys that designed these trucks 40 years ago where a lot smarter than we all realize.
The only real improvement in their designs have been with the computers; engine control, auto transmissions, etc.
Not easy to fix the basics.

It's yours!
Built what you want, then tell us how it works.
We might all be changing to your design if works.

[Wildstreak]

wow nice swb frame! what size are those rear wheels? they look huge!

[silver7]

Conroe - thanks for information. If my design doesn't work I'll man up and post it for the group.

I like the idea of trying to get a spare back on the cross member.

Nice pic of your frame. Looks great! I hope to moving that way soon.

[6600DURAMAX]

I am also not an expert on the traction bar issue but I do have some great first hand knowledge of the system. This traction bar issues is alwasys a huge debate from both sides. Yes the type of traction bars I build will provide a stiffer ride (than without the bars) but it will definatly keep your axle planted on the ground. If you mount a ladder bar system (bars on top and bottom of the axle that connect to the frame at a single point) this ride will be even harsher and allow almost zero movement in any direction. The bars I built keep the axle planted MOST OF THE TIME. I am running a 468 with 35's and a line lock. If I lock the front and mat it I get some wheel hop, if I let off and feather the throttle (keep it under 6000rpm) the hop goes away. I have found out the longer the bar the better. A true four link system is best way to ensure no wheelhop.
We have multiple trucks running the single bar system and have overall good luck all around.

If I was going to critique your bars at all I think they are a little short, other than that you will have to watch the heims you are using. They will were out pretty quick and start to rattle. If you dont drive it a bunch it could take a long time though.

Great build, keep it up!!

[brossow]

Originally Posted by 6600DURAMAX

I am also not an expert on the traction bar issue but I do have some great first hand knowledge of the system. This traction bar issues is alwasys a huge debate from both sides. Yes the type of traction bars I build will provide a stiffer ride (than without the bars) but it will definatly keep your axle planted on the ground.

I believe it keeps the wheels planted, but it also obliterates the point of having a rear suspension, preventing the springs from functioning as intended. To each his own, but I can't believe there are people who think that stopping the virtually essential fore-aft movement of the axle is A Good Thing™. I won't say more on the subject, especially in this poor guy's build thread.

Brent

[yellow70GMC]

Originally Posted by brossow

I believe it keeps the wheels planted, but it also obliterates the point of having a rear suspension, preventing the springs from functioning as intended. To each his own, but I can't believe there are people who think that stopping the virtually essential fore-aft movement of the axle is A Good Thing™. I won't say more on the subject, especially in this poor guy's build thread.

Brent

x2. On with the build! Any updates?

[silver7]

You have your opinion and I have mine so I guess you'll have to accept it and respect it or stop posting in my build thread.

Yes I do have an update - thanks for asking yellow70GMC. Last night I was able to get my cross member lengthened 3.5" and welded together. I think I broke my vise trying to bend the added piece of steel to the same shape as my cross member. All I need to do is finish grinding the welds flat and drilling some holes to mount it to the frame. I also picked up some grade 8 hardware at the local automotive faster shop today for the cross memberand for the new shock mounts I made. The upper shock tabs I ordered from Barnes 4WD were supposed to be here today but I guess they'll be here tomorrow. I was ready to get this finished up tonight but I guess it will have to wait until I return from business travel on Friday.

I decided I wanted to put on front axle on as well to be sure my front dual shock mounts attched without any issue but noticed my new U-bolts were lining up as well as I hoped. If you remember I have a 71 chevy C10 converted to 4x4 so I don't know if the U bolt brackets or the Dana 44 is original or not. Anyways, I needed a tool to expand and compress my U bolts about a 1/4" to get them to line up with the bracket holes. I stopped by Home Depot on the way home and was going to make a widget of some sort when I came across this sweet Irwin tool which works for compressing and expanding.

I'm really hoping to have my frame and suspension completely together this weekend before Sunday. If this works out I can then take it apart next week and get it sent out for sandblasting. I still haven't decided yet if I am going to powder coat it, paint it or coat it with aSEM liner like my buddy Nick used to coat the frame of the 67 Mustang he restored. My front and rear ends are powder coated Speedway Black (tons of metallic flake) so I'll probably do the same on my frame.

I did all of this pre-work with the hope I don't need to do any more welding or major surgery afterwards so I could powder coat - but you know how that goes. Nick loves the liner concept, powder coat is so durable and paint just seems easier. What do you guys think?

[msgross]

your u bolts must be 2.75" and the top plate is 3" from a slightly newer axle...

[yellow70GMC]

I would say powdercoat, depending on the cost of that liner. powdercoated stuff is sooo nice if you ever take your truck offroad, mud and stuff comes right off with just a hose most of the time.

[silver7]

I agree. Powder coat is very nice. Especially when it has a clear coat too.

Mike - you see any issues making the U bolts fit? Those long bolts flex a lot. I guess I could swap the bolts, Summit has always been great about that. And do you think Freeney is going to be able to play Sunday? I bet he plays all 3rd and longs.

[6600DURAMAX]

All of mine is powder coated then toipped with clear. It was one of the best decisions I made on the build. I agree on your one thought thou....... you need to have everything mocked up EVERYTHING. I had ALMOST everyhting. I never put my driveshafts in because I thought they would be fine. Well I have a 1350 cv in the front shaft and it is a lot bigger than the stock 1310 stlye. Bottom line is I had to grind the top side of the crosssmemeber jsut to get it to fit. Plus I wish I could add a set of front traction bars (let the flaming start on why anyone would ever want to do this...ahhahah) but I have no place on the frame to attach them to now!!

Bottom line- just make sure you like everything before it goes to the powdercoaters!!

Good luck and keep the pics coming

[silver7]

Front traction bars would rock!

Glad to hear the powder coat decision was a winner. Yellow70GMC makes a good point about cleanability too.

6600Duramax, do you know the supplier of your powder coat? The speedway black w/clear coat I have on my axles is a ' prismatic powders.' And how did you touch up the spot your spot on the cross member after you had to grind it? This speedway black has a ton of metal flake in it so I was concerned about using a 2 stage to fix areas needing extra work and the powder to be removed. I actually called NIC Industries and they said they would mix me some 2 stage urethane liquid at $64.95/qt.

How did you strip your frame? Sand blast or chemically? Did you also powder coat your leaf springs and traction bars?


Sorry for all the questions but I appreciate any feedback. Thanks.

[silver7]

My upper shock tabs were here when I returned from my trip Thursday.

Yesterday I sanded my shock cross member welds flat as well as drilling 1/2" bolt mounting holes for it and my frame . I still struggle with underestimating the time it takes to cut, grind, weld and drill steel.

Today I noticed my lower shock brackets did not provide enough space in between my shocks when mounted so I had to start over. I hate it when that happens. After some corrective surgery and adding some flat washers I was finally able to get one lower shock bracket tack welded to my axle housing. Unfortunately, I have to travel again this week but I'll get back at it later this week.

One important point I failed to mention was when determining the location of my shock cross member I had to take into consideration the max and min stroke length of my shocks. I needed to make sure the shocks I used were near fully extended without weight on them so when I put the engine and body on it, and go to carry a load down the road it could compress under the additional weight. My SLF-85140 Superlift rear shocks had a max extension of 26" and a min extension of 16" (checked them myself to be sure). My shocks will extend to 22" mounted under no weight except for the frame so I have room in both directions..

[msgross]

more progress than I had... I was in little rock all week.. good news was that the chief of staff of PA informed me that i'm now promotable and moving into a Bn S3 job...

GO COLTS!!!

[silver7]

Congrats brother. I was the 504 PIR BDE S-3 Air for about 2 years so I know a little bit about that stuff. Long hours, and no sleep during the MDMP working hand-in-hand with the RAVN (Regimental Aviation officer) seting up air corridors and air assaults was the norm for me. I pissed of a few BN S-3s in my day but I managed to keep my rank some how. GOOD MEMORIES.

Go Colts!

[msgross]

Freeney is "da man"...

[silver7]

That was an awesome sack. He pushed that boy back like he was nothing. If the rest of the defense plays with the same passion and heart as Freeney the Saints don't stand a chance - even if they got an onside kick. . .

[msgross]

worst throw I've seen Peyton make all year... so be it.

[silver7]

I hate to see Peyton lose like that. Ouch. . .

[Damien]

Looks like you have come a long way. The powder coating on the axles looks great. A word of advice, Do not use a cinder block on its side to support a load. The side is the weakest part of the block.

Originally Posted by msgross

I just replaced the driver side O2 sensor @ 50K miles since it was fouling all four driver side plugs and not the pass side. had to pull the front driveshaft in order to reach the cannon plug, what a PITA..

O2 sensors are emission equipment, as are your spark plugs. I would have taken it to a dealership and have them change it along with the plugs. Emissions equipment is covered under warranty to at least 100k or 10 years by federal law.