Stiff springs + tall sidewall = tire bounce?

[xelderx]

OK...I have a problem. I'm running 245/45-16 Kook RS2 tires. Koni single adjustables in AWR housings...450# front springs...38psi in the tires. I can't keep the front end settled at all. Terrible bouncing after I hit a bump. It really screws me up in a corner. Smooth corners and she just rails no problem. One little bump and I'm fighting it. It can't completely be the tires fault can it? I'm starting to think I have a dampening problem with the front Konis. The rears have 600# springs and they are fine. No bouncing at all. The front is seriously scary. I had the struts off yesterday and they aren't leaking at all. No visual problems.

I don't remember having any sort of issue like this on my 225/45-16 tires. They had a much shorter sidewall though. I'm really liking the grip I can get out of these 245 tires if I could just keep them planted.

I have an autoX on Sunday and I'll be using my old 225/45-15 Hoosiers. They have a really short stiff sidewall unlike the Kooks. We'll see if that helps.

 

[gavin_leslie]

1..your tires and pressures are goofy, but that just a distraction more than anything
2..you said that you took the struts apart, did you try to compress/extend the shafts fully to see if there was any resistance/choppiness/inconsistency? (mungled piston)
3..talk to Lee. He looks to have you covered.

If its not the control arms hitching on something, or you banging off the bumpstops/inner fenders, theres probably only one other thing it could be..the strut(internals).

FYI..Ive messed up the foot valves in a set of SAs by being too aggressive with an impact wrench on the upper strut nuts. The vibrations of the impact was enough to tighten the adjusters on the front so hard that I snapped the upper adjuster key. On the rears the bottom nut on the piston shaft had loosened so much that I was stuck with full soft no matter what I did with the knob. Hard/expensive lesson to learn. Point is...internal damage can happen and have all sorts of consequences.

Good luck

Gavin

 

[xelderx]

I checked the shafts breifly as I was swapping springs. Nothing major. What do you think on my tire pressures?

 

[gavin_leslie]

Its a pretty wide tire and a relatively light car...38psi seems pretty high. Id be closer to the factory recomendations. That said, I dont think thats the cause of your bouncing though, from your description of whats happening to the car something else is off.

Gavin

 

[Jeff@Tri-Point]

What are your rebound adjustments in the front? Have you checked to see how much travel you have in the front? You might be hitting bumpstops...

 

[xelderx]

I actually got most of it figured out. I'm not sure why, but I lowered the car about an inch and it got much better. I think the bounce had something to do with the struts being set too high. It meant that even small bumps put the shocks at their maximum length on rebound. I can still tell a little bit of bounce in the tires, but it's not anywhere near as bad. plus I don't get that horrible banging noise as the struts reach their maximum stroke. Now if I can just get the tires to stop the slight rubbing on the fender. It isn't bad.

 

[Jeff@Tri-Point]

I actually got most of it figured out. I'm not sure why, but I lowered the car about an inch and it got much better. I think the bounce had something to do with the struts being set too high. It meant that even small bumps put the shocks at their maximum length on rebound. I can still tell a little bit of bounce in the tires, but it's not anywhere near as bad. plus I don't get that horrible banging noise as the struts reach their maximum stroke. Now if I can just get the tires to stop the slight rubbing on the fender. It isn't bad.

Wow, your car is that high? (omg)

What is your ride height? From Ground to Side Rails?

 

[xelderx]

It's tough to measure on the side rails since they aren't square. From the ground to the center of the fenderwell is 24 1/4 inches.

 

[xelderx]

http://www.mazdas247.com/forum/attachment.php?attachmentid=102133&d=1172939325

That's her about a month ago. She's about an inch lower now.

 

[gavin_leslie]

Topping out the struts is a strange one but very much could be a possibility given size of the tires. Do you know the fully extended length of the AWR konis?

Say you had tires that were wide enough that you had to raise the ride height to clear the fenders and then AWR shortens the strut shafts(or body) comparative to the stock protege strut lengths. Its very possible that you would have topped out the struts. This would make a bit more sense as the symptoms got worse when you raised the spring rates. You have a stronger spring thats able to force the weight of the car upwards more(banging into the strut tops more)

How much more room do you have to adjust the springs downward out of curiosity? And what is the ride height of the car in that picture comparative to a stock Protege(sill height?)

Gavin

 

[xelderx]

The fronts and rears both rub slightly under hard compression. I need to get at the fenders with a grinder or at least a bigger hammer to make a little more room. I could maybe go a half inch lower once I get the fenders out of the way a little better.

 

[gavin_leslie]

Just a suggestion

Gavin

 

[xelderx]

Ha...right now I'm still working with my BFH. Next will be the Rotary grinder to actually grind off the inner lip I just pummeled into laying flat. If that doesn't solve the problem I'll be hunting a saw.

 

[gavin_leslie]

In the "why didnt I think of that" category you can do what Ron Bauer did with his CSP NC miata..get some replacement front fenders to hack up. The rear fenders..well, you are on your own there.

Did you get to check the fully extended height of the AWR inserts(compared to the length of the protege struts)? Just curious as to which Insert they used.

Gavin

 

[Jeff@Tri-Point]

In the "why didnt I think of that" category you can do what Ron Bauer did with his CSP NC miata..get some replacement front fenders to hack up. The rear fenders..well, you are on your own there.

Did you get to check the fully extended height of the AWR inserts(compared to the length of the protege struts)? Just curious as to which Insert they used.

Gavin

I currently use the 8611-1257 race's and they are the exact same lenght as the 8610-1436 race.

Extended Length on the Insert itself is 540mm ~21.26"

THere are only two inserts available in the 8610's, so not a lot of options.

 

[xelderx]

In the "why didnt I think of that" category you can do what Ron Bauer did with his CSP NC miata..get some replacement front fenders to hack up. The rear fenders..well, you are on your own there.

Did you get to check the fully extended height of the AWR inserts(compared to the length of the protege struts)? Just curious as to which Insert they used.

Gavin

I'm currently on the lookout for a set of front fenders in decent shape. I haven't had a chance to check the exended length on the shocks, but Jeff probably has it right.

The car feels really good right now. Since I lowered it the struts aren't topping out anymore and it has made a huge difference.

 

[aMaff]

Would fenders from a 1999 Pro fit? I can't remember the production dates...

If so, I may be heading to the pull a part on the south side of atlanta next weekend to get some stuff for the Miata, so I can grab the front fenders from that 99 (if they're still there) while I'm down there

 

[xelderx]

Would fenders from a 1999 Pro fit? I can't remember the production dates...

If so, I may be heading to the pull a part on the south side of atlanta next weekend to get some stuff for the Miata, so I can grab the front fenders from that 99 (if they're still there) while I'm down there

Headlights are different. I need 2001+ fenders.

 

[wolfpackMSP]

could I interrupt for a min.

 

[xelderx]

could I interrupt for a min.

By all means....