5SPD07GT

i read about a guy with the mid mufflers who had it hitting like you described, he used felt pads that go on furniture to keep it from scratching the floor

Sam Strano

Do not "trim" your bumpstops. You have a damping problem. Your shocks suck, and it's only made worse by the stiffer, lower springs. See above when other folks told you that the ride gotbetter with a shock change. I don't care how few miles are on them, they might not be "worn out" but they are not capable of damping the car correctly.

How do I know this? Easy, I get to drive two Mustangs with the same springs but different shocks everyday. One has stock GT shocks, the other has Koni's. And this is with stock springs, not lowering springs that demand even more from the dampers like you have.

Cutting the bumpstops won't help because you will still get to the stops, and when you do you'll just hit them harder and they won't be as forgiving. You get a faster harder spike in wheel rate, and in the end it's not their fault anyway. Witness the fact a lot of your complaint stems from small sharp impacts, that don't even really get you down on the stops anyway. In fact I'm sure that the more rolling the dip or bump is the less bad the car is..... That's a damping issue.

You need to upgrade your shocks and struts. They are spring dampers, you changed the spring rate, and the amount of travel the shocks have to work in. And they weren't meant for the rate or height to begin with, and didn't work all that well (that admittedly could have been worse) stock.

I think there are only two choices. D-specs or Koni's. A quick search will give you all kinds of opinions both ways. I think either would help you immensely. I prefer Koni's, and a I'd recommend them here if only because I already had a customer compare D-spec to Koni with the very same springs you have (and older man who does not race and lives in Michigan). In fact you can find his thought in an old thread if you look around. But, none the less either would be an immense help to you.

I want to note two things. I am a vendor here, and I sell both D-spec and Koni. I'd be happy to discuss the differences as I see them, but sell you whichever you prefer. BTW, I'm one of the few that sells both brands. I don't recommend one over the other because I can't get one of 'em. I recommend what I feel it best for the job that needs done.

F1Fan

Hi 07torchredgt,

Don't trim your bump stops, all that will do is cost you an extra $20 to replace them later. You need to check for exhaust cleareance over the axle, check the drivers side as it is usually the side that is lower fo some reason, adjustit to get the most clearance possible by rotating and moving tubes in and out. Youshould not have any metal on metal sounds or it'is an exhaust or installation problem. Get some more support for the over-axle pipes to gain clearance over the axle, the exhaust shop will have some sort of rubber strap or bushing hanger to increase support which should raise the pipes maybe an inch or more depending on how it's done.

As Sam posted most likely you alsoneed dampers to allow youtoregain control over the body and axle. This is the same thingI've posted about onemillionthree hundredseventy two thousandfour hundred and nine times before. Change the springs and you neeed an adjustable damper so you can find the right damping levels for the new spring set, wheels and car weight. Every car is different and adjustability is the key to a happy suspension and good ride.

I doubt the tires wheels and tires are a major problemas I recall FK series tires are luxury performance tires so unless you are running 40+PSI the rideshould be pretty smooth. If the roads at that bad you may have to revert back to stock springs and install a set of adjustable D-Spec dampers which are capable of being adjusted for a smoother ride than the Koni Sport dampers can be and go from there.

HTH!

timothyrw

that was likely me. but it wasn't the over the axle part. it was farther towards the rear, where a support bar for the axle back muffler (that goes into the hanger) was hitting the body underneath.

Sam Strano

I don't like doing this, but in the interest of fairness I have to. I have dyno curves for both the Tokico's and the D-specs. I don't agree that the D-specs can be adjusted for a smoother ride. While it's true they can get a touch softer at times in compression, the lack of adequatedamping is what's contributing to the impact harshness.

We don't need to get all sidetracked on this. Suffice to say that I have run both, and dynoed both through the range. I prefer Koni, but don't think D-specs are a horrible answer.

None the less, you have a shock issue. Not a bumpstop issue, and likely not even a spring issue. They aren't that low or that stiff, but they are lower and stiffer than stock and that will firm the ride up, but more than anything it requires much better damping control over what was barely adequate for stock stuff.

Vapour Trails

How much are the Konis?

07torchredgt

F1 Fan... SAM STRANO... YOU GUYS REALLY ARE AWESOME! I just wanted you guys to know, i really appreciate the time you put into answering our questions and problems.


Having said that, It definately is a METAL on METAL clunk, so im guessing its the exhaust. Driving it more today, i realize its not just sudden bumps, but also rolling dips that can cause it to clunk... It is also more pronounced when under load and weight transfer compresses the rear. I will have to determine where exactly the exhaust is hitting... Any suggestions with people who are familiar with this problem would be AWESOME...

As for the dampers, I will be buying some from you Sam, but truth be told the konis , and even the Tokicos are out of budget. I will have to save some money in the mean time, and it will most likely be the D-Specs. Hopefully things go well and I can affoard the Koni's , but we will have to see, I would love to hear more about the difference between them, and why you would reccomend the Konis first...


One thing I have to ask is I havent gone for an alignment yet, and I dont want negative camber to tear up my tires. If I wait a month or so (2000km) would It negatively impact my tires? I dont want to pay for 2 alignments after switiching the shocks too...

Sam Strano

$710 shipped. D-specs are $539 plus shipping (say $559-569 shipped depending on location). Koni's do cost more, never in doubt. But it's not hundreds more and I feel it a much better put together part over the long term.

Again, I have uses D-specs and found them to be much better than I had assumed before running them. That was a pleasant surprise, but I think Koni's are a better long term damper. YMMV, as there are a million opinions in the world, and those that have run one but not the other are never shy about giving an opinion. All fine and dandy, but I take everything with a grain of salt if I can't do a direct comparison like I have here.

I also can't say that if you have D-specs you should change unless you have a specific reason. Between myself and two customers I know 3 folks who have change to Koni's. All 3 are happy with the change. Take it fwiw.

attridgerm

I had the same problem whan I first installed my Ultra-Lites and kept the stock shocks/struts. But then I installed Steeda's Pro-Action shocks/struts (designed to work w/both the Ultra-Lites and Sport springs) and never had the problem again. Great responsive ride without the jarring associated w/the FRPP handling package.

redxls

explain to me why shorter bump stops are not needed when you lower your car. If you lower say 1inch then you are 1 inch closer to the bump stop and have 1 less inch of travel than the factory intended. I started a post about this question but it seems to fit in here as well. I have vogtland springs and koni's and my rear end hits hard. I can help it some what by loosening the shock but that does not help my handling balance. I have looked at my bumpstops and I am hitting them on occassion so I am looking for a shorter set in the rear if anyone can point me in the right direction