Rear Suspension Lesson Learned

[houston54]

I admit that sometimes I try to do things on the cheap and sometimes that works well and other times not so good.  One that falls into the not so good category is my decision to use 3 inch lowering blocks on my rear suspension.  Thankfully I identified the problem before anything catastrophic occurred.

This issue came about while I was trying to solve the "buggy ride" qualities the 54 was exhibiting during its shakedown period.  I have not "C" notched the frame and still had the bump stops in place.  The rear suspension travel was being limited by the stops to about 1/2 inch thus creating the poor ride.  Once I removed the bump stops the increased travel created an interference between the left spring and a trail pipe.  To solve this I removed the 3 inch blocks (aluminum) to gain some height.  Examining the blocks revealed where some material had broken off and other fractures in the body of the block.  I can imagine that at some point they would have failed miserably with further damage happening as a result.

Currently the suspension consists of stock rear springs with two lower leafs removed and reversed installation to center the wheel better (long end at the front now), fabricated bottom/shock mount plates, and stock rear shackles.

I will be replacing the rear shackles initially to see how far that will lower the rear.  If this does not work out to my satisfaction I will either try a pair of spring sliders or swap out the springs for some F-body leafs I have.  That will require new front spring perches and revised rear mounting.  Another option would be to fabricate some 2 inch lowering blocks from some steel.

Probably the best but most $$$ option would be to purchase a leaf spring kit from one of the suppliers.  I would only need selected components though or have to redo some of the frame work already done.

(Side bar) Can someone clarify if the scrub line is determined by the wheel rim or the brake drum?

Any suggestions or cautions from those who have been here before?  Changing from leafs to another suspension type is not an option on this truck at this time though.

Just glad I got those lowering blocks out in time and into the recycle bin.

[unklian]

I think the Scrub Line is based on the wheels,not the brake drum'rotor.

I guess flat tires are more likely that wheels falling off.

[sirstude]

From the NSRA point of view, scrub is determined from one wheel to the tires on the other sides.  They assume you will only have one tire go flat at a time.  I guess they figure we are all law abiding citizens and won't run into some nice policeman throwing a spike strip.

Doug

[GPster]

I sub-framed one of these trucks for a guy one time and off of the old frame I saved the spring hangers (forgings/castings?). They were riveted to the frame and I just drilled out the rivets. On the frame I was working on the rear spring hangers (the front of the read spring) were fairly tall. The ones that had been on the front spring looked to be the same style but they weren't as tall. I drilled out the rivets on the rear hangers and substituted the front hangers. The springs were made with 1 3/4" leafs on both end so I gained some drop that way. Might have changed the shackles too. Of course you'll still have to "C" notch the frame. One thing to check is when you use lowering blocks is you are only changing the relation of the axel to the spring. The shock is still operating in its same range. When you use flatter springs or change their mounting you may be getting to the point where the shock will be totally compressed against it's stop. I have heard of these new types of aluminum lowering block breaking. Also their sale is aimed at kids that will use them on some mini truck with 20" rims and 45 series tires. Which is ok but you're dealing with spring leafs that are 1 3/4" wide not 2 1/2". It took a lot of time but I managed to make a set of 3 1/2" blocks for1 3/4" wide springs. I used two pieces of railroad track and just used my bandsaw to remove any metal that didn't look like what I wanted. Also an easy way to get something that looks like a piece of box tubing that is 3" x 1 3/4" is to take some pieces of 3" channel and cut off one side to make it look like an "L". Take 2 "L"s and weld them together to make a box. If you think they will warp sideways box the ends. Of course I not only have a problem about talking too much I also have a problem buying something I think I can make. GPster

[houston54]

I did swap the front spring hangers to the rear on this set up.  It helped get the height down but I am currently using the stock rear shackles.  I have picked up a set of 2.25 inch long (eye to eye) shackle straps from the local trailer shop which I plan to install tonight.

If that does not get the back down then I will try a set of spring sliders.  Has anyone used those?
The ones I see are for 2.5 inch springs so I will have to use bushings on my stock springs to prevent side to side slop.

GPster - thanks for the insight.  I am hoping to not have to C notch the frame at this point as I have my wiring running inside the boxed frame and it was a lot of fun getting it in there and inside conduit.  Problem was compounded by having the bed already in place.  I had considered the shocks will need to be redone and you confirmed it.  It also seems I suffer from the same afflications you do (yapping/fabbing)

[Jbird]

After having an alooneyum lowering block disentegrate a few years ago. If I have to use them I make my own out of thick wall square tubing. You can manipulate the rear axle position a tiny bit by fiddling with the locator pins/holes. I finish them up by welding end caps into them and waa laaa a hollow cube of STEEL. That was worth a couple of cents...?   Jbird

[UGLY OLDS]

I'm a thrifty, naw..Make that CHEAP "home builder"...I take two 5" long pieces of 2" X 6" .250 wall tubing  & tack weld them together "lengthwise" on the 2" side...Measure in 2 1/2" in from the end along the center of the tubing..drill a 3" hole in the middle cutting 1 1/2" from each piece ...Drill a hole in the side 2 1/2" in from each end centered on the 2" side of the tubing for the spring center bolt using the same center line you used for the 3" hole...Break the tack welds...VOLIA  :!:  2 ready made spring perch's ready to weld to the axle tube with a "built in" lowering block..   Need less drop  :?:  Use 2X4 tubing.. Need more drop  :?: Use 2 X8 or 2X10 tubing .. ( Look under "structural steel"..)  Trim the ends on an angle..Add 2" wide flat plate to fill the holes..weld it up..PRESTO  :!:  Indestructible lowering blocks with a spring perch built in  :!:   Works GREAT for me....


WOW   :!:  I shudda saved this for "Tech Tip Month"  :!:  :!:

Bob........