Back too high...

[donkost]

Geoff,

The staggered shocks actually first appeared on the 68 1/2 428 4sp Mustangs. That configuration continued on through 1970 on the 4sp equipped cars. A change on the Competition Suspension for the 71-73's included staggered shocks on the 3514bl and 429 CJ regardless of transmission. I knew the M/T  cars had some terrible wheel hop. I had a 67 Mustang 289 4bl with a 4sp that had wheel hop so bad, I actually started breaking rear suspension pieces and drive line parts. A 9" differential swap and some Ansen Ground Grabber traction bars fixed that. I became aware of wheel hop with an automatic equipped car when a friend that owned a GTO wheel hopped so badly it twisted the axle tubes and broke the  welds loose from the center housing. We found the 9" for my 67 while going to pick up a replacement differential for his GTO which had gone past the point of being repaired any further.

What year GTO would that have been?  I'm thinking one of the earlier years.  I had a '68 GTO back when it was only a 12 year old car, and it amazed my friends how well-planted the rear was.  Even on violent dump the clutch smokey burnouts that thing would just sit back, smoke the tires, and launch without any drama.  Stock BOP 3.55 Posi rear, never had it apart.  I did add a rear sway bar from a '70 GTO in the final year I owned the car, but that wasn't to address wheel hop, and there was none to begin with.  Walked right into the neighborhood Pontiac parts department in '82 and bought that rear sway bar right off the shelf.  heh  I do recall earlier model year Mustangs having a wheel hop problem.  I think you can even see this in the Bullitt chase scene.

 

[secluff]

donkost, The GTO was a 70 with a 400 Ram Air engine. I remember what looked like a grey foam block on top of the air cleaner with holes in the middle for the air cleaner and smaller ones on the side for the two "Nostrils" on the hood. Didn't have the  more engineered look the Ford ram air systems had, But it worked cause that car ran like stink! He had replaced just about everything that would unbolt on the rear suspension. When he purchased the replacement differential assembly he also made a deal with the salvage yard to get the entire rear suspension from the donor car. That and switching from the Goodyear Polyglas to Firestone Wide ovals helped some but didn't eliminate the problem enough for him to keep the car. He finally sold it and bought a 396 Nova that was about as quick!

 

[Jean-Pierre]

Hi Guys, I'm back  

So, I changed my shock absorbers by KYB. The news ones were 3cm shorter so I was happy thinking that the back of the car was going to go down but not realy... 

However, I had a hard time depositing the old ones. I also had to dismount the fixing of the springs to take them out.

I see the shackle too but that's the stock dimension (90mm spacing)

So, there I don't know what to do anymore...

Change the shackles by shorter ones or put a rear end lowering kit...

I would check the measurements on the shackles. I know they make extended ones. Your shackles look to to be only lightly rusted.

Just a thought......

On the frame, we still see the brand of leaf springs. I think they were fixed with shorter shackles before...

 

[Hemikiller]

I can see the mark on the rail. Given how much the shackles move, I wouldn't run anything shorter.

If you want it lower, change the springs.

 

[Jean-Pierre]

Hi guy's,

Finally, I put a rear end lowering kit and the résult has not bad at all...

 

[Stanglover]

Hi guy's,

Finally, I put a rear end lowering kit  and the résult has not bad at all...

 That looks better!!