Suspension How much should I lower an 86 with 96-2004 SN95 spindles and P245/60R/17 tires?

[Compuguy2142]

I'm attempting to design the suspension on my 86. I plan on buying 96-2004 SN95 spindles for the 5 lug and disc brakes. I already own 17x8 bullit wheels. It is my understanding that the spindles are already 1.2 inches lower. For the coilovers should I go 10, 12 or 14 inch? What is the maximum to lower and have no wheel well clearance problems and a good turning radius? I read that the maximum tire size without having to make modifications is P245/60R/17.

 

[Mustang5L5]

The spindles don't lower the car at all. If you are sticking with a stock k member you should use 94/95 spindles as the 96+ spindles can cause bumpsteer issues when you lower a car with a stock k member. If you are running a MM k member then you can use 96+

Coilover spring lenght depends on the rating of the spring.

Max tire size also depends on wheel specs (bS and offset). 245s fit fine, but 275s can be made to fit with some mods and properly fit wheels

 

[Compuguy2142]

The spindles don't lower the car at all. If you are sticking with a stock k member you should use 94/95 spindles as the 96+ spindles can cause bumpsteer issues when you lower a car with a stock k member. If you are running a MM k member then you can use 96+

Coilover spring lenght depends on the rating of the spring.

Max tire size also depends on wheel specs (bS and offset). 245s fit fine, but 275s can be made to fit with some mods and properly fit wheels

Mustang5L5,

I am planing on a QA1 MUK11 K-member. This K-Member allows 2 choices for Rack placement. The 96-04 spindles drop the Tie-rod location about an inch from the 94-95 spindles so the QA1 K-member addresses this with the change in rack mount location.

I also decided on Mickey Thompson Street Comp 245/245/R17 tires. The tire height is off from stock by 0.1 inch. One tire revolution a mile. So the Odometer and Speedometer, while slightly off, is miniscule.

QA1 is advertising their kits with 10, 12 or 14 inch spring length.. I took that to mean Shock/strut length. So this is not correct. It is spring length.

I see that now:

AXLE TYPE SPRING LENGTH 900-1099 1100-1249 1250-1449 1450-1599 1600-1899 1900+
Solid Axle 8” 200 225 300 350 400 450
9” or 10” 175 200 225 250 275 350
12” 105 130 170 225 250 300
14” 95 125 150 175 225 275

79-Present Mustangs
1450-1600 1601-1750 1751-1900 1901-2100 2101-2300
150 175 200 225 250

So let's say you want a 225# spring rate. You can get that in any length from 8" to 14". So how do you choose?