lowering rear of car w/o blocks (long)

Discussion in 'Classic Mustang Specific Tech' started by latamud, May 11, 2005.


  1. latamud

    latamud Founding Member

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    Everytime I use lowering blocks I manage to crack one. They have always been a temporary fix to see where the car will sit though. I learned this from my friend John 4 years ago and this is my second time doing this. The benefit is getting the car lowered, stiffening up the rear, and not having to worry about cheap cast aluminum lowering blocks breaking. The list below is as detailed as possible, it is cheap and quite simple.

    What you will need:
    2 pairs of leaf springs
    (1)5/16"x60" allthread
    (5) 5/16 nuts that fit the allthread
    (2) 2.5" 5/16 allen head bolts
    (2) 5/16 lock nuts for the allen bolts above
    (3) 5/16 flat washers
    (4) 2.5" or 3" squared U bolts with
    -these should fit on top of the leafs without binding
    -threads should go up enough to clamp tight onto the leafs
    (4) flat plate steel strips with 2 holes on each end for the U-bolts
    (8) washers the same size as your squared U bolts
    (8) lock nuts the same size as your squared U bolts

    Prop the car up on jackstands at the frame rails. remove the leaf springs and keep a jack under the rear end. You will have to loosen the U-bolts and the rear shock lower mount. It is possible to do this in the car but easier to remove the leaf springs. I pulled them apart down to the individual leafs. I number each leaf from shortest to longest, 1,2,3,4 on a 4 leaf set. Now, the leaf set I pulled from the Mustang, lets call set1. The extra set I had came from a 68 Cougar, set2. I used a hammer to knock the clamps sliding them close to the eyes on leaf 4. I removed the through bolt that centers each leaf and holds them together. Keeping set1 in order I placed, from set2, leafs 3 and 2 on top on a negative arch. A mental picture, the space between set1 and leafs 3/2 from set2 is a football shape. That's an American football for anyone outside the US. Set the leafs in its side. Now, take the length of allthread and lock up two nuts in the center on the rod. Run it through one of the 5/16 washers and then through the hole to center the leafs starting on the set1 leaf 1 all the way through the set2 leaf2. On the set2 leaf2 end place the washer and hand tighten one nut. On the opposite end on the allthread, lock up 2 nuts. For safety reasons I put the Squares U-bolts together loosly and place it inward on the leafset as possible to prevent the negative arched leafs from slipping off the set on either side. I used a workbench but this could easily be done one the ground. On the set2 leaf2 side I put a 1/2 box end wrench. On the other end I used an impact gun with a 1/2 socket. Keeping the 1/2 wrench braced I torqued the other end with the inpact gun intermitantly until the set was tight enough to fit in a vise, which isn't necessary but helps take tension off the allthread. As it tightens keep moving the squared U-bolts more inward for safety. In the vise I clampted down close to the center of the leafs then tightened with the impact gun some more, and kept doing that until there was no light between the leafs. It is just the same if you use the impact gun and wrench all the way down. Once tight, either clamp the vise tight as close to the allthread as possible. Or, w/o a vise use C clamps on both sides of alltherad. Once clamped down, using the same method to tighten in reverse, loosen the allthread and remove it. Replace it with 1 5/16 allen bolt and flat washer on the set2leaf2 side. You might need a hammer to carefully help it through the leafs. On the other end use 1 5/16 locknut. Try getting the squared U-bolts as close to where the original clamps were. I tightened them down to just where the top 2 leafs(set2leaf3,2) compress a little, and the U-bolt wont slide back and forth. The original clamps we left by the eyelets, I thry to get them over as many leafs as possilbe and hammer them towards the center. Repeat with the other side of set1. This is probably lower tham most like it. Results vary depending on arch, and wear on the leafs you use. If too low, try removing one of the set2 leafs. Removing the set2leaf2 will lift the car a little. Removing the set2leaf3 will lift it more. Unfortunately and regretfully I didn't take any before and after pics. To give an idea, with stock leafs and no blocks I had a 2" gap from the top of the tire tread to the rear fender lip on a 25" tall tire. After this mod using set2leafs3,2 I lowered aprox 3" with the tire tucked hiding the tread line on the sidewall inside the fenderwell. I think I have an old pic of what the car looked like before. I'll post later.
  2. latamud

    latamud Founding Member

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    These are old pics but a good idea of how the suspension changes with the Opentracker rear leaf mod. Next time I remember to take the camera to the shop I'll take a shot of the leaf springs from under the car.
    Before
    [​IMG] [​IMG]
    After
    [​IMG]
  3. 12sec67

    12sec67 Active Member

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    good post....

    but,
    you know they make cast steel lowering blocks as well that don't crack...

    your stang sits very nice :nice:
  4. ozstang65

    ozstang65 Founding Member

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    Lowering blocks of any kind increase the amount of torque (Force x Distance)that the axle exerts on the springs, ususally increasing wheel hop - both in acceleration and braking. They are BAD!!!

    I once did something similar to this on my Escort, but I just inverted the top leaf. Pretty much sent it on the bump-stops :D (Only for motorkhana use, I wouldn't use it on the street that way)

    How long have you been using this reverse leaf setup? The only problem that I could forsee would be the leaves eventually breaking due to being stressed in the opposite direction. Springworks can usually de-arch springs a given distance - but obviously at a cost.
  5. latamud

    latamud Founding Member

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    I agree that any lowering blocks are bad. I think of them as pedastools. The taller they are the more dangerous. Imagine a rockingchair. Now the same rockers but a 10 foot chair. Which one is going to be more stable? I first did the reverse arched leaf setup about 4 years ago, but it was my friend John that taught it to me. He has been doing things like this for years before I tried it. The first car I did it to is still holding up. The leafs stressing and breaking is a possibility, I won't deny. My opinion, I doubt it, and if it does? I'll go find another set of leafs and rebuild. Doing this mod to me was almost free. Nuts and bolts. I had less than $20 in hardware and took about 2 hours beginning to end. I don't know how much it costs to de-arch leaf springs. And even if you have them de-arched, how do you know how much it will lower the car? If you install them and its too low or not low enough will they redo them? I was surprised I got the ride height where I wanted it on the first try. I was willing to pull it apart after I was done it it was too low.

    I'm still waiting for some criticizm on this. I'm interested in what feedback we can get on the mod.
  6. HistoricMustang

    HistoricMustang Active Member

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    It is a swap off.

    The advantage of getting the car lower offsets any potential wheel hop. Plus wheel hop can usually be controlled with 4 1/2 or 5 leaf springs or if necessary some type of traction bars. I never had to use the bars but sure do love my "poly" lowering blocks.

    HistoricMustang
    www.historicmustang.com
  7. Hack

    Hack Active Member

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    Great write up, latamud. Very complete and your explanation will really help me.

    I plan on doing this mod to my car. I like the idea of this so much, because I should be able to tune the height to exactly what I want. And it's very inexpensive. Also, getting some of the arch out of the rear leafs will help reduce roll oversteer from the rear end.

    I don't like the idea of lowering blocks, either. Lowering blocks accentuate many of the bad characteristics of a rear leaf suspension. They are easy to install and their effect is very predictable, though.
  8. Opentracker

    Opentracker Member

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    Nice work Bart. Here is a photo of the leafs on our '66 coup. Notice the leaf on top in a negative arch and the leaf pack is flat. We can add leafs or change the leaf pack arrangement to change the ride height and spring rate to most anything desired. I did the leafs 4 times on this car till I got it right. I have been doing this for years and have had no problems.

    If you look at racing springs, they have two long leafs in the pack that go from end to end. The way I get that is to cut the eyelets off of the #1 leaf in a used set of springs, and put that long leaf in the #2 spot of the pack I'm working with, and go from there.

    I have never seen or herd of anyone doing this before. It is a trick that my brother and I came up with. The only testing done so far has been on our cars and our friends cars.
    [​IMG]

    The black thing is the Watts Link I made for the car.


    John
  9. HistoricMustang

    HistoricMustang Active Member

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    John, you are correct.

    As I have tried to explain before the early models springs retain an "arch" and hence the reason for cracking of most lowering blocks. This is why I installed a "poly-carbonate" set and eliminated this problem while keeping the classic look and not creating problems elsewhere by playing with the springs.

    I do not suggest using "poly-carbonate" lowering blocks unless that area is inspected on a very regular basis. Mine have a lot of laps with no problems, but they are inspected quite often.

    HistoricMustang
    www.historicmustang.com
  10. Opentracker

    Opentracker Member

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    If I had to use lowering blocks (and I hope I don't) I wouldn't use alum. or steel. That poly. spacer sounds like a good idea. Less weight and it will flex a bit with the spring. It also won't put as much stress on the spring perch.

    If anyone does try the leaf spring rebuilding idea please use caution and be safe. Springs under tension hold a lot of force. I use a new or good used all thread each time I do a spring pack. They can become damaged as the spring slides by.

    John
  11. latamud

    latamud Founding Member

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    Thanks for the help John. I forgot to mention the the #4 leaf if you cut the eyelets off because the set I got off the cougar was so rusted from the rubber sandwich bushing that after I pulled it off and stood on it, it bent. I didn't get to use it. :(
  12. xoxbxfx

    xoxbxfx Founding Member

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    Old thread but I wanna say thank you...Im gonna do it today if I can find another set of springs!!!
  13. 65mistress

    65mistress Member

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    I'm still not being able to visualize this. Do you have any pictures of the process?
  14. xoxbxfx

    xoxbxfx Founding Member

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    Dont make fun of my MSpaint skills...but heres the idea.

    [​IMG]

    Blue is set 2, black is set 1. You pinch the whole setup down with the threaded rod so you can clamp it with the ubolt and metal plate setup.... Then you run a real bolt down the middle to hold it all together.
  15. 65mistress

    65mistress Member

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    Awesome, thanks xox... that helps a bunch.
  16. latamud

    latamud Founding Member

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    Oohh, good pic! It might take a few trys to get it to sit and perform where you want it. If its too low, remove the blue number 2 and see how that works. I wanted to revisit this thread after seeing it mentioned on another thread. I link this post everywhere. Thanks again John!
    [​IMG]
  17. xoxbxfx

    xoxbxfx Founding Member

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    Heres how the 66 sits with used 2&3 leafs and brand new stock leafs

    [​IMG]
    [​IMG]
  18. Opentracker

    Opentracker Member

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    That looks nice! Good job on the spring rebuild. How much time did it take to do both sides? Did you hit that stance on the first try?

    John
  19. xoxbxfx

    xoxbxfx Founding Member

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    From takin apart the origional spring to having the new one ready didnt take more than an hour. Dunno how long the overall time would have been...but it took somethin like 5 hours to take out the origional front leaf bolts:( I think I could do it again in less than 30 minutes. First try was a charm for me.
  20. BIG-MAC

    BIG-MAC New Member

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    I used blocks to mock-up how much drop I wanted and then had the springs dearched the same amount at a spring shop.
    [​IMG]

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