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  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang Specific Tech

Lowering blocks/U bolts

  • Thread starter Thread starter SadbutTrue
  • Start date Start date May 10, 2007

SadbutTrue

Founding Member
May 1, 2002
2,390
4
49
Granada Hills, California
May 10, 2007
#1
  • May 10, 2007
  • #1
Anyone have opinions regarding lowering blocks? I am going to drop my car about an inch sooner or later, but I have fairly new (and stiffer than stock) leaf springs on the car and it'd be a shame to get rid of them already. Lowering blocks seem to be an option, but they also sorta... well... they do seem like a half-assed solution, to be sure. While I realize its not optimal, as long as there aren't any major risks and it won't completely mess up any aspects of the car's performance, they'd be a cheap solution until I have more money for rear leafs...

On a similar note, does anyone know where to buy longer/wider u-bolts? The ones I have around my 9inch now barely fit, and only do because we bent the hell out of them. I couldn't for the life of me find any new u-bolts that'd fit my car when I put the rear in, so i had to reuse the ones from the old 8 inch rear. If I got lowering blocks, longer/sturdier/wider u-bolts would be a necessity, so yeah, if you know where to get some let me know.
 

HistoricMustang

Active Member
Apr 11, 2003
2,359
0
46
Confederate States of America
May 10, 2007
#2
  • May 10, 2007
  • #2
SadbutTrue said:
Anyone have opinions regarding lowering blocks? I am going to drop my car about an inch sooner or later, but I have fairly new (and stiffer than stock) leaf springs on the car and it'd be a shame to get rid of them already. Lowering blocks seem to be an option, but they also sorta... well... they do seem like a half-assed solution, to be sure. While I realize its not optimal, as long as there aren't any major risks and it won't completely mess up any aspects of the car's performance, they'd be a cheap solution until I have more money for rear leafs...

On a similar note, does anyone know where to buy longer/wider u-bolts? The ones I have around my 9inch now barely fit, and only do because we bent the hell out of them. I couldn't for the life of me find any new u-bolts that'd fit my car when I put the rear in, so i had to reuse the ones from the old 8 inch rear. If I got lowering blocks, longer/sturdier/wider u-bolts would be a necessity, so yeah, if you know where to get some let me know.
Click to expand...

Lowering blocks can sometimes be a challenge because of slight curve of the spring in the application area. Aluminum tends to crack and steel also has issues. Mine are actually home made from polycarbonate and are holding up very well and allow for the flex needed.

If anyone interested I will try to get up a photograph. This is one of the items that we will be offering in 2008 providing a 1" drop.

I believe my longer bolts came from Speedway Racing Products. It has been awhile and am sure they could be ordered from perhaps NAPA and Currie Enterprises.

HistoricMustang
 

ga289stocker

Member
May 23, 2006
238
0
16
Sugar Hill, Ga
May 10, 2007
#3
  • May 10, 2007
  • #3
Here is pic of the aluminum 1" jobs i got from Mustang's Unlimited for about $50. They have been on for around 3 years and lots of hard launches at the track and i haven't had any issues w/ them thus far....

 

65fastbackresto

Active Member
Apr 13, 2007
1,229
7
39
AR
May 10, 2007
#4
  • May 10, 2007
  • #4
Mustang Unlimited

Sent me the wrong parts. I ordered shock braces and u bolts and they wont fit my car for some reason. Was putting one of the new rear leafs on yesterday and had to use the old hardware to put it back together. The u bolts they sent me wouldn`t even fit the shock braces that came in the same box....
 

xoxbxfx

Founding Member
May 9, 2001
3,959
0
0
Southlake, TX
May 10, 2007
#5
  • May 10, 2007
  • #5
Napa should be able to get you the Ubolts.

Lowering blocks seem to get a bad name but honestly lots of cars run them. Just make sure you tightem them down well and put a lock washer on it. Id drive the car for a week and make sure they stay tight.
 

mdjay

Premium Sponsor
Dec 9, 2003
896
0
16
Las Vegas, NV
May 10, 2007
#6
  • May 10, 2007
  • #6
65fastbackresto said:
Sent me the wrong parts. I ordered shock braces and u bolts and they wont fit my car for some reason. Was putting one of the new rear leafs on yesterday and had to use the old hardware to put it back together. The u bolts they sent me wouldn`t even fit the shock braces that came in the same box....
Click to expand...

A stock 65-66 needs a 2 5/8" spread. This is standard. So it's likely that someone changed the rear end along the way. As far as Ubolts are concerned, see if there's a "Spring Service" shop in your area. They can made in about any dimension needed. When I was running leafs, I had them bend 1/2" bolts instead of the 7/16 ones.
 

66Restomod

New Member
Jan 4, 2007
11
0
1
May 10, 2007
#7
  • May 10, 2007
  • #7
I guess I am knew to this whole lowering thing, but what are lowering blocks. How exactly do they work?

Is it safe for him to do that and drive on them without worrying?
 

rbohm

Founding Member
Apr 12, 2002
6,698
550
204
tucson,az
May 10, 2007
#8
  • May 10, 2007
  • #8
66Restomod said:
I guess I am knew to this whole lowering thing, but what are lowering blocks. How exactly do they work?

Is it safe for him to do that and drive on them without worrying?
Click to expand...

lowering blocks go between the axle and the leaf, thus raising the axle the height of the block, and lowering the car. as long as you dont use a block more than 2" thick, there are no problems with lowering blocks in daily driving, or any other use.
 

SadbutTrue

Founding Member
May 1, 2002
2,390
4
49
Granada Hills, California
May 10, 2007
#9
  • May 10, 2007
  • #9
Does a 1" block directly mean a 1" drop? I would think slightly less. Thanks guys.
 

88gt

Founding Member
Aug 2, 1999
794
0
0
Drillers cabin
May 10, 2007
#10
  • May 10, 2007
  • #10
SadbutTrue said:
Does a 1" block directly mean a 1" drop? I would think slightly less. Thanks guys.
Click to expand...

It means 1", just as much as a dropped coil means 1" - 1 1/4" drop...it's as close to that as it can be.


Jim
 

HistoricMustang

Active Member
Apr 11, 2003
2,359
0
46
Confederate States of America
May 10, 2007
#11
  • May 10, 2007
  • #11
SadbutTrue said:
Does a 1" block directly mean a 1" drop? I would think slightly less. Thanks guys.
Click to expand...

Yep, this makes sense with friction, spring compression, etc...............somewhat less than 1 inch.

Now, THIS is tech.

Kind of like if you cut a coil spring does it increase or decrease the rate. There have been fist fights over this one!

HistoricMustang
www.historicmustang.com
 
O

Opentracker

20+ Year Stangneter
Feb 4, 2004
516
0
16
May 10, 2007
#12
  • May 10, 2007
  • #12
Some good reading about leaf springs and lowering.

http://forums.stangnet.com/showthread.php?t=544275
 

ozstang65

Founding Member
Jul 13, 2002
313
0
0
Queensland, Australia
May 14, 2007
#13
  • May 14, 2007
  • #13
Torque = force x distance.

If you increase the distance betweeen the axle centreline and the spring (ie, with lowering blocks), you get an increase in the amount of torque being applied to the spring - simple math that cannot be disputed.

More torque applied to the spring = more wind up and potentially more axle snapping, diff destroying, gearbox exploding axle hop if your shocks aren't up to keeping everything together.

If you're casually driving, lowering blocks won't be a problem. Personally I wouldn't use them on a racecar. The cost of getting a set of springs exactly as you want them is a helluva lot less than replacing the aforementioned drivetrain items.
 

HistoricMustang

Active Member
Apr 11, 2003
2,359
0
46
Confederate States of America
May 14, 2007
#14
  • May 14, 2007
  • #14
ozstang65 said:
Torque = force x distance.

If you increase the distance betweeen the axle centreline and the spring (ie, with lowering blocks), you get an increase in the amount of torque being applied to the spring - simple math that cannot be disputed.

More torque applied to the spring = more wind up and potentially more axle snapping, diff destroying, gearbox exploding axle hop if your shocks aren't up to keeping everything together.

If you're casually driving, lowering blocks won't be a problem. Personally I wouldn't use them on a racecar. The cost of getting a set of springs exactly as you want them is a helluva lot less than replacing the aforementioned drivetrain items.
Click to expand...

Great observation! That is why some flex is necessary in the early models. My ride was called the "Flexible Flyer".

My lowering blocks even have flex built in by using a "polycarbonate"!

Happy Motoring!

HistoricMustang
wwww.historicmustang.com
 

ozstang65

Founding Member
Jul 13, 2002
313
0
0
Queensland, Australia
May 15, 2007
#15
  • May 15, 2007
  • #15
HistoricMustang said:
Great observation! That is why some flex is necessary in the early models. My ride was called the "Flexible Flyer".

My lowering blocks even have flex built in by using a "polycarbonate"!

Happy Motoring!

HistoricMustang
wwww.historicmustang.com
Click to expand...

Why do you find the need for blocks? Is it to keep some arch in the springs with a low ride height or just for 'fine tuning'?

Some Oz Historic Racing action for those who are interested.
 
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