Cowl Shake!

[fink46]

Have had this cowl shake ever since I got the convertible cobra and I would really like to fix it. Its really bad at like 55-60 mph and its still there at higher speeds but not as bad.

So far I have had all four tires balanced, new mm steering rack bushings installed and mm flsfc installed. I'm trying to think what else to do to eliminate this? I read that someone reccomended the mm k member brace but I thought convertibles had one from the factory already installed? Thought about a strut tower brace but I don't like the appearence of them under the hood and drilling holes to mount it. Was wondering if anybody has had any experience with the cowl shake and what you did to get rid of it? Also, if anybody recommends the strut tower brace as a cure?

 

[whitedevil95]

Have had this cowl shake ever since I got the convertible cobra and I would really like to fix it. Its really bad at like 55-60 mph and its still there at higher speeds but not as bad.

So far I have had all four tires balanced, new mm steering rack bushings installed and mm flsfc installed. I'm trying to think what else to do to eliminate this? I read that someone reccomended the mm k member brace but I thought convertibles had one from the factory already installed? Thought about a strut tower brace but I don't like the appearence of them under the hood and drilling holes to mount it. Was wondering if anybody has had any experience with the cowl shake and what you did to get rid of it? Also, if anybody recommends the strut tower brace as a cure?

I have the exact same issue. Havent resolved it yet. :bash:

 

[03snkvert]

I have the Same Issue, and hoping the FTBR bushing kit may help resolve it!

I think it may be some kind of Vibration in the Drive line.

 

[Anabolic]

not muc h you can do, there's no structure to the top of the cars, i would suggest a 8pt roll cage and weld in subframe connectors.

 

[jpk]

I have a strut tower brace and still get this. Every little bit of stiffening helps a bit, but really I haven't got it corrected.

Been thinking about getting the full Kenny Brown jacking rails/matrix brace to tie into the full length subframe connectors I already have. I had that on an older Cobra SN95 coupe and that chassis was solid. But it's heavy and expensive and I don't even know if it will fix the issue on the convertible.

 

[SlowSVT]

In a vert with a heavy high output engine getting rid of cowl shake is going to be an uphill battle which will only get worse as the chassis fatigues. The fender aprons on this car are pretty flimsey and have lots of voids and gaps. The only way to address this is to reinforce the entire chassis structure from axle-to-axle but that is a huge undertaking.

Avoid shocking the driveline with clutch dumps which will accelerate chassis fatigue/shaking and turn up the radio

 

[fink46]

Thanks for all the advice so far! I'm going to go ahead and try the strut tower brace and see if it helps to eliminate this. Do you think 2 or 3 point strut brace? Have heard from some that the 2 point is pointless and others say it helped their cowl shake:shrug:

Its just that the other day I got the car out for a cruise and it was rattling so bad I thought one of the tires were going to fall off! Seems to be somewhat temperamental to certain roads, it will be worse on ones that aren't smooth. But its the worse at about 55mph. Lower speeds... can hardly tell its there.

 

[Anabolic]

people drag race with convert cars lol.. Would get a 3 point strutbrace wich actually attaches to the cowl.
Seriously think of a cage, that's your best bet besides MORE weight factor it ties in and reinforces the body quite a bit.

 

[Anabolic]

I know it's a big deal and not many people want a cage, but with swingouts swing style, once you sit down if you're not 6'10" you wont notice it

 

[whitedevil95]

Thanks for all the advice so far! I'm going to go ahead and try the strut tower brace and see if it helps to eliminate this. Do you think 2 or 3 point strut brace? Have heard from some that the 2 point is pointless and others say it helped their cowl shake:shrug:

Its just that the other day I got the car out for a cruise and it was rattling so bad I thought one of the tires were going to fall off! Seems to be somewhat temperamental to certain roads, it will be worse on ones that aren't smooth. But its the worse at about 55mph. Lower speeds... can hardly tell its there.

We arent talking about while under heavy acceleration. Just normal driving from 55-65 my whole car has a slight shake to it. This summer im going to balance the drive shaft and get it re-aligned. I hope this might fix it. Maybe a way to ajust the pinion angle. I also came from a 95 coupe with subframes and that car felt solid.

 

[jpk]

We arent talking about while under heavy acceleration. Just normal driving from 55-65 my whole car has a slight shake to it. This summer im going to balance the drive shaft and get it re-aligned. I hope this might fix it. Maybe a way to ajust the pinion angle. I also came from a 95 coupe with subframes and that car felt solid.

Get the 3 point brace if you are going to get one. My chassis was pretty decent with just that and subframe connectors until I had the IRS bushings and lowering springs put in. Now it vibrates more at speed, like you describe.

I am thinking in addition to the jacking rails and cross brace maybe bump steer kit and IRS rear steer kit will help. I've been thinking about how it drives and how the issue is reaaly been since lowering the car, so getting really correct alignment as the suspension moves over uneven roads is probably important in addition to stiffening the chassis.

 

[03snkvert]

Get the 3 point brace if you are going to get one. My chassis was pretty decent with just that and subframe connectors until I had the IRS bushings and lowering springs put in. Now it vibrates more at speed, like you describe.

I am thinking in addition to the jacking rails and cross brace maybe bump steer kit and IRS rear steer kit will help. I've been thinking about how it drives and how the issue is reaaly been since lowering the car, so getting really correct alignment as the suspension moves over uneven roads is probably important in addition to stiffening the chassis.

What bushings did you use?

 

[jpk]

What bushings did you use?

I have the Steeda bushings for rear diff, subframe, and IRS.

 

[03snkvert]

I have the Steeda bushings for rear diff, subframe, and IRS.

Were you able to get a better angle on the Drive Shaft? Only reason I am asking is because I have heard getting the correct drive shaft angle can help with the drive train vibrations.

I am putting in the FTBR kit w/ the rear differential lowering mount, hoping to get a better drive line angle. I am hoping this will help with some of the vibration. The car vibrates around 60mph, but anything above or below, nothing.

 

[eaglesnick]

I have a vert and have gotten rid of most of the vibrations and cowl shake. Invest in the following:

MM 03-04 Cobra Strut Tower Brace for Whipple and KB cars (Black) - Strut Tower Braces - Suspension - 03-04 SVT Cobra

Recommend the one for the whipple/KB in the event you go twin screw, (however the biggest blower you can fit under it is the 2.9 non-crusher)

FTBR Order Page

Get the FT5001 kit which comes with the lowering brace to correct the pinion angle on driveshaft. While you're at it get the milled FRPP rear diff cover and upgrade the toe links and the sway bar end links.

Chassis Stiffening FIT System 1994-2004 Mustang

If you already have full length sub-frame connectors just order this

Stifflers Web Brace 79-04 Mustang

and

http://buystifflers.com/stiffeningrail94-04Mustang.aspx

and lastly these:

Lower Chassis Brace 96-04 Mustang

http://buystifflers.com/stifflersspiderbrace1999-2004mustang.aspx

If you have headers or an aftermarket k-member make sure you tell them what your setup is to make sure you get the right parts.

 

[eaglesnick]

Were you able to get a better angle on the Drive Shaft? Only reason I am asking is because I have heard getting the correct drive shaft angle can help with the drive train vibrations.

I am putting in the FTBR kit w/ the rear differential lowering mount, hoping to get a better drive line angle. I am hoping this will help with some of the vibration. The car vibrates around 60mph, but anything above or below, nothing.

THIS!! I had vibration at highway speeds and this did the most to eliminate the vibration.

 

[03snkvert]

THIS!! I had vibration at highway speeds and this did the most to eliminate the vibration.

Good to hear.... I am in the process of putting this together now, and will be waiting for the weather to warm up to check it out.