Technical UPDATE x2> Calling all suspension setup experts! real time axle wrap

I am experiencing some engine mount shearing wheel hop, literally. I have a hopped up inline 250 in a C10 pickup. It is turbocharged and backed by a 700r4. To get a better understanding how the rear end housing moves when torque is applied to it, I put a video recorder and torque braked it up!

I was shocked to see how much the rear end rotates. I understand that the suspension setup is not idea for maximum traction drag launches, but I am not trying to achieve that anyways. Just a fun weekend warrior that is not afraid to light em up. I have removed many of the leaf springs to lower it and have sacrificed suspension function, but damn it looks good! give and take....

What can I do to minimize the axle rotation? and maximize traction?

Here is the video..



And the truck:

 

Your springs are shot. Replace them.

Have a spring shop make you a set that are as low as you want, but with all of the necessary leaves.

 

slapper bars and a second set of shocks mounted so you have shocks front and rear of the axle! Those year chevy trucks along with the later truck arm type were terrible for wheel hop.

 

Yeah you really don't have anything significant to combat axle wrap at all. The leaves removed to lower don't help at all. Is that a sort of helper leaf inside of your factory leaf location ? Has an upward bend of sorts....I dunno. Try some slapper bars, Cal-tracs, or old school Lakewood traction masters. Also a wider heavier spring will be more rigid, but then you would have to go with wider perch mounts. All kinds of fun solutions. Cool looking truck. And turbo ???? Whoah nelly.

 

Thats not a suspension. You have no frame clearance at all.
Rebuild the springs correctly.
Mount the axle above the springs.
Add a well built C notch to the rails above the axle.
Theres no easy, cheap, CORRECT way to do that much lowering.
You gotta bite the bullet or unfortunately live with the consequences...which will be bad ride, axle wrap and eventually cracked/damaged frame rails from contact with the housing.
You could get a spring shop to make a stiffer set of almost flat springs, but I think they will still lift her up a bit.

BTW...truck looks AWESOME...so I certainly don't blame you for wanting to leave it at that height!

 

Why not do a full notch, with a four link and coil overs? Not exactly traditional but will provide a much stronger, safer ride. Or air suspension with a notch and four link?

Instead of the shitty box section notches or pipe c notches you yanks do.. get some laser cut plates like this and do it properly..

And +1, truck looks awesome!

 

The original trailing arm and coil spring suspension would allow no axle wrap, put it back in and problem gone.

 

cheap way is to put a clamp over the leaves in the front clamping them together.

 

Instead of taking the leaves out to lower it, turn them over and put them on top to keep the stiffness or put the spring under the axle with all of the leaves.

 

you said it is a C10, then you talk about leaf springs, then I scroll down and see the pic, it's a GMC. No wonder. How about getting a Chevy frame and run the trailing arm suspension? they work nice.

or...come to the realization that slamming a truck with stock leaf spring suspension will not work for drag racing, and do what some of the others suggested.

I built some imitation CalTracs bars for my Chevy II, which has the original monoleaf springs. launches nice, runs around 10.0 at 134 mph, no wheel hop at all.

 

Turn the U-bolts upside down and run 'em through the frame, you got no travel anyway. Truck looks great at that level.

Those years GMCs had leaf springs and the Chevys had the trailing arms? Weird.

 

Is that sitting on the rubber bump stops?

If so, the springs probably have no [or minimal] load on them.
A spring will flex/compress/wrap up easier from a relaxed position.[ to more it loads, the more effort is required to wrap it]

Get the spring set properly, so there is no bind or bottoming out at all.
Then Add another 1/2 leaf to the front of the spring.

 

Do like the super stock Mopars did, clamp the front of the springs tight together starting at the mounting bolt and clamp them all the way to the axle, then use the rear of the spring for suspension. Add back some half springs to help stiffen the front and keep them from twisting, it probably rides rough already, so it shouldn't effect anything but axle twist.

 

A Cal Trac lookin set up would be ideal but still pointless without travel. Put the leaves back, install notch and flip kit with cal Trac or cheap slappers and a good shock. Without the travel you might as well weld the frame to the axle so it's officially solid like a rail.

 

That's just all kinds of wrong
& Where you want to start it's the main problem either.
If the lowered stance and ride height need to be maintained you need to start cutting the frame out of the way so it's not riding on the axle. Btw the lowered stance is the cause of the problem, all you did was throw most of the spring out, no wonder there's no spring to control the axle.

Caltracks don't work without suspensions travel, they work because of suspension travel.

 

Ummmm....yeah, I guess ?? Any device stiffening the front leaf pack will reduce his axle rolling back on itself. Having said that....I just noticed my comment regarding the inner structure is the damned frame sitting on the snubber. That goes into the realm of my Suburban mods'. Totally off topic vehicle....but I notched and plated the frame on that...so yeah.

Cal-Tracs and their derivitives are good for axle wrap. Hell, even cutting a leaf just a little past half will help as a cheap traction device. Either way the leaf pack needs to be solidly bolted together, rather then sliding around haphazardly. He may as well have a mono leaf....pretty much what it's doing anyway.

I dunno' why I reply to your reply. It's hard to give any answer whatsoever when you dunno' budgets/experience/willingness to correct/vehicle usage on an original post. My answer was just a list of shit flung to a wall....shotgun answer...to a shotgun post. No offense to the original poster whatsoever...or to you of course.

 

No worries we are all just providing a vague answer to a vague question. Regardless the frame has got to get off the axle and the front half stay flat which any one of our answers provides depending on the OPs budget and skill set.

 

As always with the HAMB, all sorts of responses, all great ideas for me to choose from. Thank you. My main objective was to actually see what was going on with my rear end and solve any issues.

After watching the video a few more time and reading all of the responses, I have decided to flip the rear axle. That will mean adding the leaf's back, which will provide the leaf support that it needs. I will also add a set of custom ladder/traction type bars if need be.

Attached is a picture of the original rear suspension setup.

 

You'll still have the frame riding on the axle ?

 

I should have addressed this. The video looks a little deceiving. At ride height, the rubber bump stop is 1/2" from the frame and the axle is around 3 1/2" from the frame. I have yet to bottom out, but after the flip, if I need to notch it, I will.

 

1/2" is not enough.

 

A nice start on a tight new spring pack would be a great start. Western Chassis used to be a great place to buy from....new ownership currently.......& when I ordered my notch kit....the guy sounded a bit overwhelmed. In any event, I started like you.

I removed a few leafs(not as many as you), relocated my leaf spring hangers/removed frame rivets. I trimed the top of the hanger for clearance, & moved up an inch and a quarter on the frame with a template. (Suburban means build your own crap) Drilled new holes/grade 8 bolts/welded up old holes. I believe I also had an 1 1/4 " rear shackle revision too.....maybe inch and a half?? 6" drop in entirety. After driving it for a year, the Cnotch appeared& the third leaf disappeared for an ultimate 8" drop. Bump stop nowhere close.

I slid into mine gradually, in steps....while driving it. Didn't want to hang myself with something I didn't like, or wouldn't work. Only aftermarket shit is the frame plate and the KYB shocks. I think you can grab a decent leaf spring pack used....up to 1973 ???......a half dozen leaf pack bolt kits....and just play with it.

I took my packs apart at least 4-5 times....& re-assembled. For me, having a selection of leafs helped greatly. 52" was the length....4WD & 2WD had same widths, and different rates. A regular jambalaya of sorts, and it works well. No flip kit. I don't like 'em. Yours is obviously a little older.....but do your homework, & check around. I have $160 in mine(plate kit), shocks not included.

Of course you will have to correct your pinion angles. Did that 4-5 times too. Daily driver fun & lunacy/idiocy.....but screw it....it was worth it......my 2 year old can literally fall into the Chili Wagon now. That's greatness.

 

Good news. After deliberation and input from you all, I decided to make some "traction sticks". I got all the pieces from Summit Racing, 5/8" rod ends, threaded swag tubing, and coil-over shock mounts. Here is a picture of the new setup:



And more importantly, the results. I took it out today to test it. It feels totally different it terms of torque transfer. When I torque brake it, the rear end feels like it is lifting up when torque is applied, where as before, the axle would rotate and stay soft. Now its just smooth single tire annihilation, no wheel hop. Ha!

Here is a crappy video:

 

If both ends of that traction arm are fixed (they appear to be), and the front mount is not the same length as the as the front mount of the spring mount you will bind the traction arm mounts, and they will fail.
This is why drag cars with leaf springs and ladder bars put the axle spring mounts on sliders.
Cal Tracs pivot at the front mount so they do not bind.
You don't have much axle travel (but you should) and may want to rethink your design.

 

So it looks like you've bound the overload helper to the other leaves with clamps.

The bar you added has a different arc of movement than the springed axle does. Basically a triangle has been formed now and you're expecting one of the legs to change its length as the suspension moves. The legs are frame spring mount to axle centerline, frame bar mount to axle, and frame spring mount to frame bar mount. Incidentally, with a caltracs bar the last leg of the same triangle is on a pivot to allow movement and locks against the spring.

When you want to keep something from moving a common way is to diagonally brace it forming a triangle. You've formed this triangle in something you want and need to move freely.

 

I was going to mention the same thing here. That C-10 should have a truck arm ( trailing arm) suspension. They don't hop. That parallel leaf setup doesn't look like the correct setup for that truck.

That aside, when your suspension bottoms out that is what is causing any hop you are experiencing, it is now using the tires to absorb what your springs should be absorbing. A quick fix would be a pair of air shocks and add a little air pressure when you want to go to the burnout contest.

 

it's really a GMC.

 

So I have a genuine question.

I wanted to run traction bars and posed this Very same dilema and was told by multiple people that the leaf spring doesn't move in a true arc, and that a set up like this will work fine.

How do actual traction master bars work then without binding the rear suspension?