Customs 3 inch drop and slams hard...need tech help

Oops...sent to early. I put 3 inch blocks in the back and my drive shaft slams on every bump in the road. I put a Ford 9 inch rear end in the back and removed my shocks. Will installing new shocks stop my driveshaft from
Slamming? Any help is greatly appreciated!! Thanks!!


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Ummm, yeah, ya kinda need shocks.

how big in diameter is your drive shaft ?

how are the rear leafs and how is the diff mounted?

sure it’s the driveshaft hitting the ground n not the diff hitting the floor or frame ?

 

Driveshafts can't hit the ground!! [unless they drop out]

The driveshaft yoke could be bottoming out in the transmission

 

Good shocks will help but you need bump stops to limit your suspension travel.

 

Massed produced family sedans were not designed decades ago anticipating Hooligans decades in the future would try to make them into really cool Cruisers with simple mods. You could benefit from reading some books on suspension design and principles. Basically, it requires what's commonly called 'suspension travel'. The car was built with an adequate amount for the original design. When you added lowering blocks, you reduce that travel margin by the thickness of the block...plus it may already be suffering some spring 'sag', which reduces it even further, even before you hit a bump.

There are numerous ways to remedy this problem....some are simple....don't carry rear seat passengers, especially if they are 'big' people, install stiffer springs, modify the frame rails (aka "C" notch) which increases room for the axle travel, but is a relative expensive modification.

Meanwhile, get some decent shocks. They weren't on the care just for grins. They perform a needed function by damping suspension movement.

Welcome to the HAMB..........lots of good stuff here.

Ray

 

Stick some "air shocks" in the back! You can adjust the stiffness and ride height by adding or letting out air. (Not talking about "air bags"!)

 

Drive shaft issue talk of 9” rear and we get a great picture of the front bumper at night.
brilliant ,,,, headlight

Un lower it by un blocking it and it will probably go away. That answer fits your post perfectly

Did you use those smart lowering blocks ?

 

My high school auto shop put 3 inch lowering blocks on about 12 years ago and then it sat, unfortunately. I like the stance and am scared to cut into the the body. I’ve been thinking of air shocks but I need to weld mounts first. I’m just getting started and don’t have a lot of experience...yet. Here’s a pic of my axel and where I’m thinking of mounting.


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Dude.... mount the shocks off the u-bolt plate...

 

Get the popcorn.

 

With no shocks that thing should be bouncing all the time even after you stop. Not safe and should not be driven. Mount them on brackets under the springs and at least to the body like the cheap Chevrolet’s. I cannot believe that car would not still have the upper mounts.

 

Weld a stud and reinforce the lower spring mount and then measure distance to top shock bolt, at ride height.
Then jack up car and see extended length, then load it up to see compressed length.
Shocks will help ride ALOT.

 

is this a joke?

Shocks-yes, mounted to the top of the axle- no
Even if it were a good location, your shock would be like 4 inches long.

 

Those shock mounts (if that's what they are) go on the bottom of the rear end not the top.

Pat

 

stop - do not drive until repaired - stance is important for the "Cool" look - damaging your ride in the process is not - where did the shocks mount on old rearend? - usually the bolt plate under springs has a bolt stud or eyelet for attaching bottom of shocks - there are aftermarket brackets that can be welded to bottom of axle housing for shocks - but, need to know how to weld good - not all cars can run 3" blocks without notching the frame, etc - shocks are not to be mounted straight up and down

 

I think some photos would be a lot more helpful for a newbie than instruction in 25 words or less.
(I have pix of a similar set up with blocks but I can't find them at the moment.)
Do the shocks first. That will probably solve the problems. Check the total suspension travel and buy shocks that are within that size range. Add rubber snubbers later if you need them...... which is common with any 'drop'.

 

Stock shock mounts are on cross member right above hand in picture. Previous post of attaching shock mount to bottom u-bolt plate would be about right.

 

Lowered and bumping
You have 2 choices
Raise back up or re-engineer the stuff it’s hitting
Never be afraid to do a well thought out cut on a car to achieve the desired results.

 

Lots of ways to mount shocks.

 

Damn guys obviously the guy is new to this. Help him out and quit being dicks. Ya gotta start somewhere better an old car than a tuner or monster truck Shit.

 

https://www.jalopyjournal.com/forum/threads/question-about-mounting-rear-shocks.1024223/

https://www.jalopyjournal.com/forum/threads/rear-shock-location.833038/

 

Post of pic of what the drive shaft is hitting
Also make sure it’s not the driveshaft hitting the trans. The driveshaft can move forward when you lower a ride and damage a trans.

 

shocks are going to go this way
The upper mounting stud is circled

 

get us a pic of the drive shaft going into the trans as it sits in those pictures.
then
Block the front wheels & Get the stands under the rear axle. High enough to crawl under and let the car down on the stands so the weight is of the car is on the springs. Have a look , you’re going to want at least 4” clearance (fist is pretty close) anyplace your fist doesn’t fit will need to be moved, removed, redesigned, reengineered, re think smaller lowering blocks.
Then get is some good pics of the tight areas , look for shiny spots because that will be where it’s hitting and some pics of the drive shaft going into the trans with weight on the springs.

 

BTTT
to help the man out

 

^^^^ is good advice.

Then if he changes the lowering blocks [or removes them] the shocks are not altered in length.

If he wants the shocks leaning inward , use Tri-5 Chevy spring plates [for eyes at the bottom] with 2" wide springs. With 2-1/2" wide springs use 67-69 Camaro spring plates.

These plates can be swapped side to side if he wants the shocks inboard or outboard of the frame rails

It is easier to buy suitable parts than make them

 

Do you know that it is the driveshaft that is hitting, or pinion flange, or are the axle housings hitting the the chassis? Does it occur mostly under acceleration, which would indicate spring wind-up. You should be easily able to determine the impact location by looking for evidence of contact on the various components, e.g., circumferential scratches around the driveshaft, shiny spots or scratches on top of the axle housings and/or bottom of the frame rails. If it's the driveshaft, you can gain a little by tapering the blocks, to rotate the pinion downwards. This has some limit, as you don't want the U-joint angle to become excessive. Ford rears have an inch or so pinion offset, is there room between the drive shaft and passenger side tunnel to accommodate that, and allow for 2 or 3" of "bump"?

And, of course, you need shocks. Your proposed location of the axle attachment point is not great; for optimum effectiveness, this should be as close to the wheel as practical. They can be vertical, or leaning in at the top, up to 30 degrees +/-. In theory, the more they lean, the stiffer they should be.

 

@Desmodromic .....good post above....but for the last sentence. That seems opposite of what I would expect and believe is the case. Shocks mounted at any angle loose effectiveness compared to shocks mounted nearer to vertical. My understanding, for a given shock valving, the steeper the angle, the less shock stroke and the less the damping effect.

I may be mistaken, wouldn’t be the first time, nor the last. But until I hear/see an explanation to the contrary, I got to stick with that notion.

Ray