Speedtoys

Hmm...I would figure most of the noise up thru the rear wheels into the cabin...is higher freq.

Ive used this above wheel liners on my other cars to great success.

http://www.soundservice.co.uk/acoust..._wool_AMW.html

ReDesign by FEATHER

I nearly have the Rear Wheel Well Liner project ready for some GTS fitting in Texas on Tony 77's car. I got the mounting bracket for the right front designed and fabricated and have made some small brackets to move a couple of the original mounting points a little so they work with my New Liners. I also have the jig nearly built to use to drill the mating holes for clipping the outer halves to the inner halves. I'll finish that this evening and then drill a pair of freshly blown liners and see if my connecting clips work.

I had to make some minor changes in the forms last night to adjust for some forming difficulties, but now I think they are where they need to be. When they are final for sure I'll clean them up a bit for more nearly perfect forming.

I still have some laminating and final forming in this set I'm taking to Texas, but should be able to get that done before I leave Wednesday morning early.

What I don't have is the sound deadening material that I ordered the week before last. If it comes today or tomorrow I may be able to take some of that with me and maybe get it cut and fit to these liners I'm fitting in Tony's car.

If you are coming to Spring Fling early maybe you can find us and help with the fitting.

Jerry Feather

Tom in Austin

Look forward to seeing them Jerry! Catch ya down in Rockport Friday evening ...

Alan

Jerry - what have you selected for sound deadening? will it be glued to the liners?

I have some thick (3/4") nitrile closed cell foam in there now, a panel glued above and seperate pieces glued to the backs of each of the 2 part (front/rear) S4 splash shields.

Alan

Jerry Feather

Hi Alan. What I think I was able to learn is that there are three ways to deal with noise. One is to dampen it and that is usually done with some very heavy material on panels so that they are reduced in their ability to vibrate and thereby not transmit the sound. Another way is to absorb it and that is where the closed cell foam you are using will help some. However, I am told that the road noise from the rear wheels in our cars is more low frequency and therefore requires quite a bit of material to absorb it. Someone on here recently suggested that it is actually high frequency. Actually I suspect it is a pretty good mixture of both. However since low frequency takes form 10 inches to 70 inches of material to absorb it we would need quite a bit of closed cell foam. The third way to deal with the noise is to block it. Mass Loaded Vinyl is designed to block the noise.

Therefore I have found a product that is a composition of closed cell foam and MLV. It has a 1/8 inch layer of MLV and a quarter inch of closed cell foam for a total of 3/8 inch thickness. That is the total thickness that I have allowed for in certain places on these new liners although most other places can take a whole lot more thickness.

What I intend to do is try to develop my material for as much of the new liners as seems to be best and then let the final user add whatever else they might want. My original thought was to put something like this on much of the liners then suggest that the user simply stuff the void between the liner and the car with sealed bags of fiberglass insulation or something similar.

Or I will also be making the liners available without anything and leaving the insulation up to the user in its entirety.

Here is a picture of the sample of the material I have ordered.

Jerry Feather

Jerry Feather

Alan, The material that I plan to try first will be glued onto parts of the new liners for those who choose it as an option. Unless the material shows up today I wont have it available for the fitting at Spring Fling on Tony's GTS, and I haven't figured out a design to cut the material to glue it on the liners. However, I am thinking of taking some large baggies with me and perhaps a gob of fiberglass insulation and maybe we can test my idea about using that to fill the voids.

The additional consideration with my new liners is that the liners themselves I expect will block some of the sound, perhaps 15 to 20 percent, more or less.

As to the 3/4 inch closed cell foam you are using, do you have any way of telling how effective it is with the road noise?

Jerry Feather

Herman K

You can copy the cut patern from my liners also the marine industry has a foam liner with a sound barrier that is use in small engine room on yachts.

Speedtoys

That stuff works better ON the body...and it has to be a 100% COMPLETE seal between inside and outside, or the high frequencies still get thru.

IMHO, we want some cavity fill for the road noise, like the rockwool product. Not a vibration damper for the liner...thats not the noise were concerned about (vibration).

Jerry Feather

I think I made that same mistake when I first heard the suggestion, probably earlier in this thread, that MLV would be good for our noise problem. I too thought it had the purpose of reducing vibration of the panel it is stuck too. Now I am convinced that it is not used for that. It is mounted to the structure with the closed cell strata in contact with the structure, so it would be less likely to dampen anything. They told me it is to simply block the sound.

Thanks Herman, for your offer. I still have Tony's original throwaway liners, so I could use those. However, since my liners are not shaped like the originals I will need a completely different pattern for the sound material.

Jerry Feather

Jerry Feather

I made it to Spring Fling and had the opportunity to do some test fitting of the GTS version of the WW Liners in Tony's GTS. What I found was that I am still pretty far off in respect to having the liners fit the GTS cars, and I was also off quite a bit, for some reason, in fitting the mounting brackets that Herman and I patterned off of his GTS several months ago. I was pretty discouraged by all of that but then it was not so bad as it might have been since just before I left for Spring Fling I had made the deposit on the 93 GTS that I am now calling my "GTS4."

I now have my GTS4 at home and have just jacked it up to start using it for fitting the GTS version of the Liners and mounting brackets. I'll be working on that tomorrow and I suspect I can have them fitting in a fairly short time even though I found that I was pretty for off with Tony's car. Driving 1400 miles to do a test fitting is a lot more difficult than walking from the shop to where I have my GTS4 jacked up now.

I have been giving some more thought also to the manner in which I will be installing the sound blocking material that I bought a roll of a few weeks ago. I think that will go pretty quickly once I get to that point.

I didn't take any pictures of the project while I was at Spring Fling, but I think Tony did. By now however, I suspect he has lost interest in posting them here.

Jerry Feather

Herman K

You should know

Bertrand Daoust

Very nice job.

On my list for sure!

Thanks Jerry.
It's because of guys like you that the 928 can be what it is today.
Keep up the good work.

Brent

My my, them sure are prudy.

Speedtoys

Looks good.

What about 300 of us wouldn't do for an S4 version.

Jerry Feather

There will of course be a version for the S4 and GT cars as well. I could have and was in fact working up the S4 version first with the expectaqtion of then somehow extrapolating into the GTS version. However, to some extent the GTS version kind of dictates back into the S4 and earlier form for some of the fit, in order for the inner half of the liners to become universal, that is, the same for all versions, at least in the basic form, but not in all the mounting.

Anyway, I have felt compelled to finalize the GTS version first and then, to the extent necessary, work back through the model years. I suppose I will end up having to buy a few more 928s in order to be certain about the fit in the cars before S4.

So, what I have to do now is refine the outer form for the GTS version and that will involve incorporating what i learned with Tony's car. I'm going to fit those liners in my GTS4 and see if what I found with Tony's is common to mine, then make the changes in the GTS outer form and try again. I hope I don't have to do this more than about twice before I have the GTS outer half zeroed in. Then that will also be ground zero for the S4 and earlier versions, at least from the plastic rocker panel line and down. Above that line is where the GTS and others differ, I think.

Jerry Feather