Mylar washers

[Don Payne]

Anyone see a problem using Mylar washers on certain engine parts like valve covers, timing covers, etc. to allow for more thread engagement? I looked up the specs on Mylar and it looks like it can take the heat. They are super thin at like ~.016".

I picked up some of these at the local Mashall's Industrial:
http://www.marshallshardware.com/pro...d=2-301-66-294

Mylar®
Physical-Thermal Properties

Mylar® polyester film retains good physical properties over a wide temperature range (–70 to 150°C
[–94 to 302°F]), and it is also used at temperatures from –250 to 200°C (–418 to 392°F) when the
physical requirements are not as demanding. Some physical and thermal properties of Mylar® are
summarized in Table 1. Detailed information and other physical and thermal properties are described
in the remaining pages of this bulletin.

[Michael Everson]

Not sure why you would want to do that. I would use the proper hardware before trying something different.
Mike

[Don Payne]

I am using ARP 12 pt stainless valve cover bolts that are only .75". They only grab like 2 threads before I start torquing. I really don't want to strip the threads in my nice AFR heads. The last time I took the valve covers off, I noticed some shavings.

[Michael Everson]

The lack of a washer won't gain you much. Might want together longer bolts. I think the ARP bolts are designed for the thin steel covers.
Mike

[ROADRACER83]

Don:

Washers are used under fasteners to spread the force more so there is less chance of cracking of cast parts or warping of stamped covers and flanges. A bolt by itself or with just thin flexible washers just concentrates the force in a very small area. Washers are not there just to allow the bolt to turn easily or to prevent marks on the cover flange. Get some longer bolts or better yet use studs that go all the way to the bottom of the threaded hole and use nylocks and washers on the cover. That solves several problems: You use all the availble threads, you are not repeatedly taking bolts out and wearing the threads out. I use long set screws and stainless nylocks and washers. The set screws come in various lengths and sizes and have an internal hex to allow them to be tightened to the bottom of the threaded hole. They are cheaper ( like 15-35 cents apiece) than ARP bolts, locally available at most any fastener store and work great. I just show McMaster/Carr as a reference to show what they look like. Most engines use 1/4-20 thread size for valve covers etc. Bolts always seem to be too long or too short when you are not using factory components or bolts. The factory engineers get to spec the exact bolt they want. They are not limited to 1/2 inch or 1/4 increments.

McMaster-Carr

Also ARP makes a little kit. Pricey, but mo' betta to save threads in the heads.

http://www.summitracing.com/parts/AR...7606/?rtype=10

Ron

[Jack Wojack]

I would recommend The ARP SS valve cover stud kit WITH the 12 point nuts. The the 12 point nut takes a much smaller diameter socket which works nicely with my aluminum valve covers. Yea... they are pricey.

Jack

[CraigS]

What Jack said!

[Don Payne]

Dude! Those are SO not worth that kind of money. I am a believer in doing it right the first time, but dang brother. Springing for the ARP SS 12pt bolts was already a stretch.

[ROADRACER83]

Originally Posted by Don Payne

Dude! Those are SO not work that kind of money. I am a believer in doing it right the first time, but dang brother. Springing for the ARP SS 12pt bolts was already a stretch.

You can also cut 1-1/4 inch long pieces of 1/4-20 thread stock with a hack saw and use them as studs. Round off the ends with a bench grinder so the threads have no burrs.

The set screws work great and are dirt cheap. Think outside the box and save money and the threads in your heads. Studs are almost always a better solution except where only a bolt will do.

Places you can buy long set screws and nylocks in your neighborhood.

Salt Lake City Bolts nuts | Bolts nuts in Salt Lake City, UT - YP.com

Ron

[convincor]

Call ARP. They used to do exchanges if you needed something different than what's in the kits. http://arp-bolts.com/
Or get the 1" http://m.summitracing.com/parts/arp-611-1000

[tirod]

Each and every OEM fastener in automotive use, especially on the engine, is a specifically designed part - not a generic hardware store bolt. The thread, pitch, length of thread and unthreaded shaft, type of head, and Grade of construction will tell you exactly what the engineer in charge considered when specifying it. Learn to "read" a bolt and you learn the anticipated stress level, vibration resistance, and what quality level is really needed for that job.

Bolts and studs only need about 3 1/2 threads to fully engage, same for the nuts on them, with one thread left exposed. There's your correct length on most applications, and you can proof it by simply measuring how long most of the factory engine bolts are in each instance.

Tapped threads in aluminum are not the best choice for parts that experience constant disassembly. Use studs in an appropriate length, with an appropriate locking method for the nut in it's environment. You don't need the same kind on the intake side of the head as the exhaust.

More builds would have less problems if the factory bolts and nuts were used, or at least emulated in the application. The engineering would be more appropriate to the job, and the result will be more reliable and workmanlike. That reflects better on the builder than exotic fasteners in obscure drives chosen entirely because they exhibit conspicuous consumption or slavish devotion to a race car motif on a street driven car.

For all the attention the engine gets, nobody really even thinks about the four bolts, or two u-bolts that do ALL the work - the ones holding the back u-joint on the differential yoke. Those are a critical application and work in a hostile environment, but are usually snugged up and virtually ignored their entire working life.

Kinda like most of the honest working people behind the scenes, taken for granted and ignored.

[Don Payne]

Wow, that was a good read! Thanks for sharing.

Originally Posted by tirod

Each and every OEM fastener in automotive use, especially on the engine, is a specifically designed part - not a generic hardware store bolt. The thread, pitch, length of thread and unthreaded shaft, type of head, and Grade of construction will tell you exactly what the engineer in charge considered when specifying it. Learn to "read" a bolt and you learn the anticipated stress level, vibration resistance, and what quality level is really needed for that job.

Bolts and studs only need about 3 1/2 threads to fully engage, same for the nuts on them, with one thread left exposed. There's your correct length on most applications, and you can proof it by simply measuring how long most of the factory engine bolts are in each instance.

Tapped threads in aluminum are not the best choice for parts that experience constant disassembly. Use studs in an appropriate length, with an appropriate locking method for the nut in it's environment. You don't need the same kind on the intake side of the head as the exhaust.

More builds would have less problems if the factory bolts and nuts were used, or at least emulated in the application. The engineering would be more appropriate to the job, and the result will be more reliable and workmanlike. That reflects better on the builder than exotic fasteners in obscure drives chosen entirely because they exhibit conspicuous consumption or slavish devotion to a race car motif on a street driven car.

For all the attention the engine gets, nobody really even thinks about the four bolts, or two u-bolts that do ALL the work - the ones holding the back u-joint on the differential yoke. Those are a critical application and work in a hostile environment, but are usually snugged up and virtually ignored their entire working life.

Kinda like most of the honest working people behind the scenes, taken for granted and ignored.

[CraigS]

If you go to a drag race where they are running the nitro dragsters and rebuilding the engine between runs you will get a real good indication of the importance of studs for often removed parts. BTW for anyone who hasn't done this I think it's a must see bucket list thing. When those guys leave the line the earth vibrates. Fun times!

[rich grsc]

Originally Posted by Don Payne

Dude! Those are SO not worth that kind of money. I am a believer in doing it right the first time, but dang brother. Springing for the ARP SS 12pt bolts was already a stretch.

But you want to use mylar washers????

[Cone Basher]

X2 on using the correct length of bolt for you application and screw in studs are even better when you are bolting to aluminum components. I stripped one of the header bolts when I built my Coupe and replaced it with a longer bolt. If I ever have to take the headers back off will definitely use studs.
HTH
CB

[Don Payne]

Originally Posted by rich grsc

But you want to use mylar washers????

Yeah, Yeah. Well I tried doing it right the first time! This is the second go around.

For the record, I have yet to hear any comments on the MYLAR. I may send these shorties to ARP for an exchange on some longer bolts.

[ROADRACER83]

Don:

Here is my post from above. Put the gun down and read the replies. To put it succinctly the mylar idea sucks. The purpose of a washer or flange head bolt or nut is to spread the load and help lock them onto the flange of the cover to add friction and prevent the bolt or flange nut from backing out. The mylar won't do any of that and it won't give you any more threads to keep the bolt from stripping the threads in your head.

"Don:

Washers are used under fasteners to spread the force more so there is less chance of cracking of cast parts or warping of stamped covers and flanges. A bolt by itself or with just thin flexible washers just concentrates the force in a very small area. Washers are not there just to allow the bolt to turn easily or to prevent marks on the cover flange. Get some longer bolts or better yet use studs that go all the way to the bottom of the threaded hole and use nylocks and washers on the cover. That solves several problems: You use all the availble threads, you are not repeatedly taking bolts out and wearing the threads out. I use long set screws and stainless nylocks and washers. The set screws come in various lengths and sizes and have an internal hex to allow them to be tightened to the bottom of the threaded hole. They are cheaper ( like 15-35 cents apiece) than ARP bolts, locally available at most any fastener store and work great. I just show McMaster/Carr as a reference to show what they look like. Most engines use 1/4-20 thread size for valve covers etc. Bolts always seem to be too long or too short when you are not using factory components or bolts. The factory engineers get to spec the exact bolt they want. They are not limited to 1/2 inch or 1/4 increments.

McMaster-Carr

Also ARP makes a little kit. Pricey, but mo' betta to save threads in the heads.

http://www.summitracing.com/parts/AR...7606/?rtype=10

Ron"

I'm tryin to help, not make life more expensive or more difficult. Most of my suggestions are cost effective little tips from years of racing on a budget and trying for reliabilty and ease of maintenance, but if nobody reads them I'm not sure why I frickin try. Why don't you go ahead and put bolts in and then send a thread out to ask how to install Heli-Coils when the holes in the head strip out. You got 10 people telling you to put in studs that are a better way to do it and how to do it inexpensively, and why bolts are hard to get in the correct size and, ah shit I give up. I'm tired and cranky.

Ron

[Don Payne]

Sheesh! I guess there is no 'tongue in cheek' emoticon.

So Ron, just for sh*ts and giggles...after all the good information here on the purpose of washers and such (of which I am really appreciative), why the hell do mylar washers exist if all they do is suck?

The purpose of this thread was to ask about the properties of mylar being used as a washer. I don't imagine some company out there decided to put a lot of R&D out just to create something that sucks. (Insert tongue in cheek emoticon here)

[ROADRACER83]

Don:

Sorry, I should not text when I'm tired. The stud idea is still the best for the valve cover and oil pan or timing chain cover application.

The mylar washers are really not washers in the usual sense. they really should be called shims or seals. They are mostly used for sealing around a bolt or nut to prevent oil or fluid from leaking around the head of the bolt or for shims for bearings and shafting to keep the components from rubbing on each other. A good example would be a shim on the shaft between the wheel on a lawn mower and the frame. Or on a shopping cart on each side of the wheel where the pin goes through. They are not good for spreading the load under the bolt head or nut like a stiff metal washer because they are too soft and flexible. You can also use thin stainless shims for the same purpose. I'm going to get some ice cream.

McMaster Carr calls them shims. I think that is their only reason to live.

McMaster-Carr

Ron

[Don Payne]

AH! I get it. That explains why it was not designed for this application!

Cheers brother,
Don