Suspension Tuning Advice - Updated

[67TXStang]

I replaced my front suspension earlier this year. The car drives well on smooth roads. If the road is not smooth, it feels like an old truck. It is very rough and sounds like I bouncing down the road. I could use some advice improving the suspension. I want a good compromise between comfort and cornering ability.

Let's start with what I have installed: OpenTracker stock style UCA and LCA, roller spring perches, 1 1/8 sway bar (from Dallas Mustang), heim joint adjustable strut rods, existing Monroe gas shocks, new springs, and all new Moog steering components. The spring isolator is made of Midolene (NPD) and the sway bar end links are Energy Suspension poly pieces.

The springs are not common so I'll need to explain what I did. I purchase the HD style springs for a '68 Mustang from NPD. These are made by Eaton and rated at 428 lbs. I cut off a little less than 3/4 coil to get the ride height to be a little less than stock. Based on the explaination on the Eaton website, I believe this results in a spring rate around 450. I chose to do this so it would be better than stock but a little less stiff than a 620 spring.

I've checked everything to make sure nothing is loose as it sounds like it. However, everything is torqued per the Shop Manual. I'm wondering what could be the problem. Maybe I should have replaced the shocks rather than reuse the Monroe shocks I had. If I push down on the fender and release the car with go up and then stop which I was always told was a good way to see if a shock was bad (might be way off here).

Any suggestions are greatly appreciated. I have plenty of work left to do on my car so if different parts are in order assume a fairly small budget.

 

[67TXStang]

Re: Suspension Tuning Advice - New Shocks?

Forgot to mention I recently had an alignment performed on the Mustang. I provided the specs based on posts I had read. The exact settings are:
Left: -.1 camber, -2.3 caster, and .00 toe
Right: 0.1 camber, -2.8 caster, and -.06 toe

I did not ask that they set the caster higher on the right side. They said it is normal because roads normally angle off to the right. The additional negative caster helps to offset this angle.

 

[Shaun]

Re: Suspension Tuning Advice - New Shocks?

I've never used Monroe shocks but if they are anything like KYB's then they will make your car crash and bang along like a dump truck.

I've been using/dealing custom valved Bilstein's for a while now and I and my customers can't say enough good things about them. They eliminate the 'crashing' KYB method of absorbing bumps.

I would go with the street valved option with your current setup - http://www.streetortrack.com/Bilstein-shock-package-for-67-70-Mustang-Street-valving-pr-24058.html (quoting the 67-70 set as I'm guessing from your username/sig pic this is for a 67).

 

[Midlife]

Re: Suspension Tuning Advice - New Shocks?

A couple of observations.

Are you sure you have negative caster? I believe you want 2-3* of positive caster.

A 1 1/8" anti-sway bar, along with relatively stiff springs, is going to give you a fairly harsh ride when the road is bumpy. All the shocks are going to do is change the rate at which rebound from a jolt is going to give you. Even weak shocks probably won't help a whole lot.

My advice (given for what it is worth) is to go with the same anti-sway bar, weaker coil springs, and stiff shocks. That will give you a more pleasant ride down bumpy roads, yet give you cornering ability. An alternative is to go with a 7/8" or 15/16" anti-sway bar with your current set-up to give you a bit more comfortable road ride.

 

[Anonymous]

Re: Suspension Tuning Advice - New Shocks?

What size tires are you running? A low profile 40-50 will have a harsher ride than a 60 or 70 series tire. Better shocks like the Bilstein's or Koni's and yes, dbl check that your caster is +.

 

[Starfury]

Re: Suspension Tuning Advice - New Shocks?

I'm going to recommend ditching the Monroe shocks, regardless of whatever else you do. I don't think they're causing your problem, but I don't think they work well at all on any classic car. Monroes tend to be mushy and unresponsive compared to something like KYB GR-2's.

 

[67TXStang]

Re: Suspension Tuning Advice - New Shocks?

My tires are 225 70 14's on stock style steel wheels.

I was concerned about the 1 1/8" sway bar when I originally installed it. I received it essentially for free so I decided I would give it a shot. If anyone is in Texas with a smaller one diameter sway bar and would like to trade, please let me know.

The Bilsteins are no doubt a great shock. The price of $360 for a set is quite an investment for me right now. Two people mentioned KYB shocks, one somewhat positive and the other somewhat negative. Are the GR2's bad shocks?

 

[Anonymous]

Re: Suspension Tuning Advice - New Shocks?

Well, $360 for a set is a lot cheaper than Koni's :amaz

I have no experience with KYB's, but from what I've read, there are more bad things written than good.

 

[Shaun]

Re: Suspension Tuning Advice - New Shocks?

My tires are 225 70 14's on stock style steel wheels.

I was concerned about the 1 1/8" sway bar when I originally installed it. I received it essentially for free so I decided I would give it a shot. If anyone is in Texas with a smaller one diameter sway bar and would like to trade, please let me know.

The Bilsteins are no doubt a great shock. The price of $360 for a set is quite an investment for me right now. Two people mentioned KYB shocks, one somewhat positive and the other somewhat negative. Are the GR2's bad shocks?

The sway bar isn't making the ride harsh. Sway bars control roll, shocks are making the ride harsh.

I'm running a lot stiffer front spring than you with Sport valved Bilstein's and it rides alot smoother than cars with stock springs and KYB shocks...

 

[Fast68back]

Re: Suspension Tuning Advice - New Shocks?

My tires are 225 70 14's on stock style steel wheels.

I was concerned about the 1 1/8" sway bar when I originally installed it. I received it essentially for free so I decided I would give it a shot. If anyone is in Texas with a smaller one diameter sway bar and would like to trade, please let me know.

The Bilsteins are no doubt a great shock. The price of $360 for a set is quite an investment for me right now. Two people mentioned KYB shocks, one somewhat positive and the other somewhat negative. Are the GR2's bad shocks?

I've got a set of KYBs sitting in the box on a shelf in the garage, to be honest, I cant recall if they are front or back shocks.... Shoot me a PM, I'll make you a helluva deal..... I bought a suspension kit from Dallas Mustang quite a while back and got the sway bar, springs and shocks, I used everything but theses shocks, I think I had already bought some GR2's, which have since been replaced with Bilstein's from Shaun.

 

[pprince]

Re: Suspension Tuning Advice - New Shocks?

I switched from KYB's last summer to Koni's and I was amazed by how much the ride improved.

I have 480# springs and a one inch sway bar with polyurethane bushings.

I just purchased adj strut rods and roller perches from Shaun so I am excited to see the next improvement.

 

[Starfury]

Re: Suspension Tuning Advice - New Shocks?

When talking about KYB's, you need to compare apples to apples. There are two different types of KYB shocks, the GR-2's and the Gas-A-Justs. GR-2's are designed more for ride comfort than performance, but will tend to feel less mushy than a set of Monroes. Gas-A-Justs are a great bang for the buck for a performance shock but are very stiff and offer poor ride quality.

Neither of these will compare to an Edelbrock IAS or Bilstein, but they're more economical and therefore fairly popular.

 

[67TXStang]

I mounted up a set of GR2 shocks on all four corners of the Mustang last weekend. The Monroe shocks I took off were in bad shape. They were easy to compress by hand and did not rebound at a consistent rate. One made a little hiss noise which made me think it leaked.

I hoped my problems would be solved by new shocks but they are not. When driving over a slightly bumpy road, everything is fine. If there is a small/medium pothole, it sounds like a suspension component is lose. On compression, there is a metallic bang noise. I've checked all the bolts/nuts again and everything is tightened properly. I'm not sure of the cause but it sure is annoying.

 

[garner67]

Good shocks are well worth the investment; performance shocks make a huge different in ride quality. After replacing all of your suspension, why skimp out on cheap shocks?

 

[Jonk67]

I mounted up a set of GR2 shocks on all four corners of the Mustang last weekend. The Monroe shocks I took off were in bad shape. They were easy to compress by hand and did not rebound at a consistent rate. One made a little hiss noise which made me think it leaked.

I hoped my problems would be solved by new shocks but they are not. When driving over a slightly bumpy road, everything is fine. If there is a small/medium pothole, it sounds like a suspension component is lose. On compression, there is a metallic bang noise. I've checked all the bolts/nuts again and everything is tightened properly. I'm not sure of the cause but it sure is annoying.

Have you checked other bolts/nuts for looseness? I had a clunk when I first got my car w/worn out original suspension and had a clunk when I hit the brakes, figured the UCA's were shot, after checking over the car I found all of the motor mount bolts were hand tight as well as many other bolts put on during install of a motor. The PO stated the motor was rebuilt ~5yrs. ago so they must not have torqued them. Just a thought to look elsewhere besides the suspension.
Keep us updated on solution,
Jon

 

[67TXStang]

Garner67 - My car needs new floorpans, quarters, has rust in a door, and in one of the front fenders. Comparing your car to mine, it seems we are at different points. If I were in your shoes, I might be able to justify it as it does not seem your Mustang needs as much as mine. Do you believe the KYB GR2's cannot be used without the sounds I mentioned.

JonK67 - Good point. I've only focused on the suspension bolts but it would be something else entirely. I'll check out other bolts and see what I can find.