Guidance Needed on Addressing Ride Height on '78 928
#1
Rennlist Member
Thread Starter
Guidance Needed on Addressing Ride Height on '78 928
Per my post earlier this week, I have installed Bilstein shocks on my '78 but retaining the original springs. The ride height before installation was pretty much perfect but now the front is sitting really high (see pics). The rear is sitting a bit higher but is not as bad.
After installation I drove the car approx. 30 miles so I assume everything should have settled and the current height is what it will be without further intervention.
I have additional items that need to be installed (passenger side tie rod and lower ball joint) this coming weekend so I have an opportunity to make some changes before I align the car.
I am thinking about cutting the springs and see where things settle and then possibly doing Eibachs later on if I am not happy with the results.
So my question is if I do move forward with cutting how many coils should be removed? Should I do something else?
Pic #1 - Shows previous ride height
Pics #2 & #3 - Show current ride height front and rear
TIA
After installation I drove the car approx. 30 miles so I assume everything should have settled and the current height is what it will be without further intervention.
I have additional items that need to be installed (passenger side tie rod and lower ball joint) this coming weekend so I have an opportunity to make some changes before I align the car.
I am thinking about cutting the springs and see where things settle and then possibly doing Eibachs later on if I am not happy with the results.
So my question is if I do move forward with cutting how many coils should be removed? Should I do something else?
Pic #1 - Shows previous ride height
Pics #2 & #3 - Show current ride height front and rear
TIA
#2
Rennlist Member
Harvey,
I believe the shop manual states that the car will be at least 10mm higher when using gas shocks compared to the oil shocks. Not sure if the spring was different for cars equipped with the gas shocks but you might want to adjust the front height with the spanner tool. When you installed the Bilstein shocks, did you install the adjustable spring perches? If so, it is an easy fix to lower it. It also takes much more than 30 miles (75-100) to settle the suspension.
Cheers!
Carl
I believe the shop manual states that the car will be at least 10mm higher when using gas shocks compared to the oil shocks. Not sure if the spring was different for cars equipped with the gas shocks but you might want to adjust the front height with the spanner tool. When you installed the Bilstein shocks, did you install the adjustable spring perches? If so, it is an easy fix to lower it. It also takes much more than 30 miles (75-100) to settle the suspension.
Cheers!
Carl
#3
Chronic Tool Dropper
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Harvey-
Mine (later S4) takes 75-100 miles to settle completely. 30 Mins of driving here is much fewer miles than 30 mins there, though. Regardless, the procedure for setting height starts off with the car fully settled, measured, then adjusted, repeat as needed. Your brand new high-pressure new gas shocks will take longer to settle than the low-pressure Boges, so patience and some driving would be my initial recommendation.
So how did you decide on the initial adjustment position for the sleeves? In a perfect situation, you would have measured the installed height of the spring on the old shock at full extension. Pretty easy to do with the shock and spring laying on the floor. Pre-assemble with the the new lower collar and spring perch but without the spring, adjust as needed to get similar spacing. Then assemble again, this time with the spring.
I wouldn't start cutting the old spring too soon. It's not out of the question, but cutting out coils does increase the spring rate as well as move the height adjustment range. Decide if that's what you want. Most folks find that, while the car feels like it handles better with lowered ride height, it actually corners faster at closer to factory height unless there are other compensations made. Toe change and a little bump-steer are the 'downsides' of lower front height.
Remember also that there are different front spring lengths for the adjustable vs non-adjustable shocks IIRC.
What are the actual ride-height numbers now, and what are your target numbers?
Mine (later S4) takes 75-100 miles to settle completely. 30 Mins of driving here is much fewer miles than 30 mins there, though. Regardless, the procedure for setting height starts off with the car fully settled, measured, then adjusted, repeat as needed. Your brand new high-pressure new gas shocks will take longer to settle than the low-pressure Boges, so patience and some driving would be my initial recommendation.
So how did you decide on the initial adjustment position for the sleeves? In a perfect situation, you would have measured the installed height of the spring on the old shock at full extension. Pretty easy to do with the shock and spring laying on the floor. Pre-assemble with the the new lower collar and spring perch but without the spring, adjust as needed to get similar spacing. Then assemble again, this time with the spring.
I wouldn't start cutting the old spring too soon. It's not out of the question, but cutting out coils does increase the spring rate as well as move the height adjustment range. Decide if that's what you want. Most folks find that, while the car feels like it handles better with lowered ride height, it actually corners faster at closer to factory height unless there are other compensations made. Toe change and a little bump-steer are the 'downsides' of lower front height.
Remember also that there are different front spring lengths for the adjustable vs non-adjustable shocks IIRC.
What are the actual ride-height numbers now, and what are your target numbers?
#4
Rennlist Member
Thread Starter
Hi Carl,
We did install the adjustable perches and they are maxed out unfortunately. Thanks for the insight on the additional miles needed to settle the suspension. I will make it a point to drive it this evening and tomorrow to get some additional miles on it.
BTW - We spent some time at Fernandina Beach a few weeks ago. Great area.
We did install the adjustable perches and they are maxed out unfortunately. Thanks for the insight on the additional miles needed to settle the suspension. I will make it a point to drive it this evening and tomorrow to get some additional miles on it.
BTW - We spent some time at Fernandina Beach a few weeks ago. Great area.
#5
Rennlist Member
Thread Starter
Great advice Dr Bob. I probably need to let it settle a bit more before I make any measurements. I am just comparing where it was previously to where it is now visually.Plus the car has been in the garage since I got home the night of installation.
#6
Addict
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Quick and easy reference measurement is from the floor to the middle lip of the fender - only to determine if it is still settling.
#7
Burning Brakes
Went through the same thing years ago when I had to replace the front Bilsteins on my '82. The springs on the early shocks with the non-height adjustable spring perches are taller than the later springs that come with shocks with adjustable perches.
You need a pair of S4 front springs - problem solved.
James
You need a pair of S4 front springs - problem solved.
James
Trending Topics
#8
Team Owner
What James said^^^
#9
Rennlist Member
Maybe used S4 springs from 928 Intl?
I ended up cutting 1 1/2 coil off each spring (I think) when I did mine.
And cutting greatly increases the rate.
Maybe S4 springs are the way?
I ended up cutting 1 1/2 coil off each spring (I think) when I did mine.
And cutting greatly increases the rate.
Maybe S4 springs are the way?
#10
Rennlist Member
I tried a set of single green stripers from an 86, then a set of the brown striped S4 springs (from 86.5) and that didn't work either.
Cut a coil off the brown stripers, but didn't like the way they seemed to assemble, so aborted. ( Might still have them if needed).
Might have worked though.
Finally went to a set of eibach fronts that fixed it.
Same situation, all caused by a swap to new bilsteins --- which held the car very, very high.
And this is for an 84 euro that had factory bilsteins originally.
Eibach / Bilstein combo really feels good now.
Cut a coil off the brown stripers, but didn't like the way they seemed to assemble, so aborted. ( Might still have them if needed).
Might have worked though.
Finally went to a set of eibach fronts that fixed it.
Same situation, all caused by a swap to new bilsteins --- which held the car very, very high.
And this is for an 84 euro that had factory bilsteins originally.
Eibach / Bilstein combo really feels good now.
#12
Rennlist Member
Hi Carl,
We did install the adjustable perches and they are maxed out unfortunately. Thanks for the insight on the additional miles needed to settle the suspension. I will make it a point to drive it this evening and tomorrow to get some additional miles on it.
BTW - We spent some time at Fernandina Beach a few weeks ago. Great area.
We did install the adjustable perches and they are maxed out unfortunately. Thanks for the insight on the additional miles needed to settle the suspension. I will make it a point to drive it this evening and tomorrow to get some additional miles on it.
BTW - We spent some time at Fernandina Beach a few weeks ago. Great area.
Did you tighten the lower A-arm bolts (rear ones) while the suspension was unloaded (car off the wheels)? If so, the bushing in the lower A-arm can bind and prevent proper settling. Shop manual mentions to not tighten them to correct torque until the car is on the ground. That way the suspension has a chance at settling further.
Glad you liked the area, it is a relaxed small town but growing fast. Let me know next time you pass this area, I'd be more than happy to show you around if I'm home.
Cheers!
Carl
#13
Burning Brakes