Saving the "Rat" - Restoring a 69T

[kkinzli]

Day 33: Today I was able to strip the tar off of the front passenger patch piece installed on day 32, clean up to clean shiny metal and use the new spray gun to shoot epoxy over everything! I think it turned out pretty good.

[hun911]

Originally Posted by kkinzli

I think my Rat has very few issues so it makes progress go quickly. Going to be in Budapest starting May 4th so we will have to get together for a beer. I would love to come see your car in person

I would be happy to meet you!

[RWebb]

tell us about your plans for sound "deadener" etc.

[kkinzli]

Originally Posted by RWebb

tell us about your plans for sound "deadener" etc.

I am not exactly sure what I want to do for sound deadener. I have been thinking of Dynamat but that can get expensive. I have also thought about doing a roofing type rubberized mat. My dad and I put this type of material on a flat patio above his garage to prevent leaks and it has worked out great. It is not a conventional roofing tar. It is a rubberized mat that has adhesive on the back covered in paper. The paper needs to be removed and it becomes a gaint sticker. The mat is roughly 2-3mm thick and seems to be of pretty good quality.

[911 tweaks]

sounds like "Bi^ch-o-Thane" by W.R.Grace Company...awesome roofing sealant material in rolls...if this is the same stuff, after you peel back the paper, if it touches itself, you will never seperate the stuff...
This will add quite a bit of weight if that may be a concern...

Keep rockin'...you are doing great...

Bob

[kkinzli]

Originally Posted by 911 tweaks

sounds like "Bi^ch-o-Thane" by W.R.Grace Company...awesome roofing sealant material in rolls...if this is the same stuff, after you peel back the paper, if it touches itself, you will never seperate the stuff...
This will add quite a bit of weight if that may be a concern...

Keep rockin'...you are doing great...

Bob

My dad and I had to throw several sections away as they got stuck exactly as you said In terms of weight I am not too worried as the car is going to be my daily driver when I am all done! Thanks for the encouragement! Hopefulluy this weekend I can weld in the rear of the passenger floor pan.

[Deschodt]

There are cheaper alternatives to Dynamat, Fatmat, whatever... Beware of the tar paper idea, it'll work, but come summer, it'll smell eventually ;-)

[95avblm3]

Eastwood has a product similar to Dynamat that I believe is significantly less expensive. Also, I can't remember if I read it here in your thread or another, but someone pointed out that you don't have to cover every surface for sound deadening purposes... the larger flat areas should suffice like the squares in between the "ribs" in the floor pans. By using a selective application method, the material will go much further.

[kkinzli]

Originally Posted by Deschodt

There are cheaper alternatives to Dynamat, Fatmat, whatever... Beware of the tar paper idea, it'll work, but come summer, it'll smell eventually ;-)

Do you mean the Thermo-coustic from Eastwood? I am not sure if the rubberized liner I am talking about smells like tar. I will have to check.

[kkinzli]

Originally Posted by 95avblm3

Eastwood has a product similar to Dynamat that I believe is significantly less expensive. Also, I can't remember if I read it here in your thread or another, but someone pointed out that you don't have to cover every surface for sound deadening purposes... the larger flat areas should suffice like the squares in between the "ribs" in the floor pans. By using a selective application method, the material will go much further.

Thanks for the tip Do you mean the Thermo-coustic liner? It is $30 for 5 (12" by 12" ) tiles from Eastwood. I think 3 boxes would do everything I need. Do you have any experience using this product?

[RWebb]

I would put down some sound deadener - use it in strips or squares over 1/4 of the floor area to save wt. or entire area if you don't care...

on top of that, you can use a so-called Mass Loaded vinyl (MLV) product (again I encourage you to sic some students on how it all works, esp. any that are interested in the acoustics branch of physics or bioacoustics over in the Biology Dept.)

the above is what I am doing, except I only removed part of the factory deadener instead of adding more - the MLV can be lifted out to save some wt. for AutoX or track use

NEVER use a roofing material inside the passenger cabin.

to make it a concoursmobile, but not one that has modern levels of performance, use coir or horsehair (search on those terms; thread active this week)

BTW - buy Frere's book on the 911 and study carefully - it has tons of info in it.

[RWebb]

oh yeh - I like the stuff from Cascade Audio -- they are the only place I've found that seems to have even minimal technical knowledge...

[95avblm3]

Originally Posted by kkinzli

Thanks for the tip Do you mean the Thermo-coustic liner? It is $30 for 5 (12" by 12" ) tiles from Eastwood. I think 3 boxes would do everything I need. Do you have any experience using this product?

That's the stuff... It's pretty much just peel and stick. My neighbor covered his entire interior in it on his 71T (floors and sides all the way up to the shelf behind the rear seats). I think that is overkill and I believe RWebb has the right idea with strips or squares over a 1/4 of the area.

My dad used it on the inside of the door skins of his '61 Austin Healey. It really gave them a nice solid sound when closing... you know, like German cars come standard with

I had a flyer in the mail from Eastwood yesterday and I think the Thermo-coustic may be on sale right now. I'll check when I get home from work and let you know.

[RWebb]

BTW - rap on it with your knuckles bare, then add the stuff (mostly in the center) and check by rapping some more

- when the resonance declines in amplitude and the resonant freq. shifts lower you are about done, i.e. you have "done spreaded the Q out" (in Southern)

(see how all those courses come in handy)?

[95avblm3]

Well said. I took a class on Vibrations (no seriously, I know you're laughing but this was for real) in engineering school that dealt with such subjects. I recall quite a bit of differential equations were required to explain it, which quite frankly has long since slipped my mind (not that I was ever that great at it to begin with). Your suggestion is a practical way to know that you have done the job right... And if all else fails, you can always add more.

Originally Posted by RWebb

BTW - rap on it with your knuckles bare, then add the stuff (mostly in the center) and check by rapping some more

- when the resonance declines in amplitude and the resonant freq. shifts lower you are about done, i.e. you have "done spreaded the Q out" (in Southern)

(see how all those courses come in handy)?

[Flieger]

I liked my Mechanical Vibrations class. The Mechanical Controls Systems class is more of the same sort of fun. But mostly just looking at things in the frequency domain and analyzing the critical parameters that way, then using a computer to solve for time domain response.

I am forever grateful for the grad student way back when who made up the LaPlace transform/inverse transform table.

[kkinzli]

Thanks for all the advice about the sound deadening material. I think I am going to go with Eastwood stuff. I never learned much about vibrations as I am a civil engineer but we did study the natural frequency of objects such as bridges in wind loading. Check out the Tacoma Narrows bridge
Tacoma Narrows Bridge Collapse "Gallopin' Gertie" - YouTube

[95avblm3]

Originally Posted by kkinzli

Thanks for all the advice about the sound deadening material. I think I am going to go with Eastwood stuff. I never learned much about vibrations as I am a civil engineer but we did study the natural frequency of objects such as bridges in wind loading. Check out the Tacoma Narrows bridge
Tacoma Narrows Bridge Collapse "Gallopin' Gertie" - YouTube

I think we studied the Tacoma Narrows... but my favorite was a semester long project in a machine design class where we were assigned to study and develop our own redesigns of the walkway that collapsed at the Kansas City Hyatt in 1981. It wasn't a natural frequency problem but a structural deficiency that resulted from a deviation in the construction from the intended design... a deviation that if memory serves me resulted in essentially doubling the intended load on the upper part of the structure... Google Kansas City Hyatt collapse.

But I digress...

Keep us posted how the Eastwood product works out for you.

[kkinzli]

Originally Posted by 95avblm3

I think we studied the Tacoma Narrows... but my favorite was a semester long project in a machine design class where we were assigned to study and develop our own redesigns of the walkway that collapsed at the Kansas City Hyatt in 1981. It wasn't a natural frequency problem but a structural deficiency that resulted from a deviation in the construction from the intended design... a deviation that if memory serves me resulted in essentially doubling the intended load on the upper part of the structure... Google Kansas City Hyatt collapse.

But I digress...

Keep us posted how the Eastwood product works out for you.

Thanks! I know all about the Kansas City Hyatt. I had to analyze the failure in structural analysis!!

[Flieger]

If your a civil engineer and what you build moves, there is a problem. If you are a mechanical engineer and what you build doesn't move, there is a problem.