Chain Guard Width [Archive]

Ryan Schoffer

03-13-2004, 12:31 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by DJHache:
You don't want to fail tech because of something like a chain guard...
Go with the bigger one. <HR></BLOCKQUOTE>

at least if you do fail tech because of it, it is an easy part to fabricate there

Dominic Venieri

03-13-2004, 01:00 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Ryan Schoffer:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by DJHache:
You don't want to fail tech because of something like a chain guard...
Go with the bigger one. <HR></BLOCKQUOTE>

at least if you do fail tech because of it, it is an easy part to fabricate there <HR></BLOCKQUOTE>

Wouldn't you rather just cover your ass on the first try than waste time at the competition making a new one?

Ryan Schoffer

03-14-2004, 10:54 PM

of course - i'd say to be safe, make it 3x the width of the widest part of the chain, with a little extra (1/16" or so)

Michael Jones

03-15-2004, 10:11 AM

Agreed. You'll be surprised what they measure. We discovered last year two days in advance that we kinda forgot about the radius rule on the front bodywork.

We figured, hey, it's not like it's jagged or pointy so it's within the spirit of the rule, and besides, no one's going to measure that, right?

Turns out they have a tool for that.

Luckily, we had extra roll hoop padding and red duct tape that was a near perfect color match, so it actually looked right, at least from a distance.

But I'll tell you, as you're fashioning such a solution on the spot, you feel like a dumbass. And you are if you violate a basic rule. Easily done, happens all the time, but you really want to avoid such nonsense.

That, and tech inspection can be hectic, especially on Thursday as you're simultaneously running from design to cost to presentation. The extra few grams of steel are totally worth it if you can avoid having yet another thing to do that day.

Sam Zimmerman

03-15-2004, 10:12 AM

Last year we felt that one area of our car didn't need a chain guard according to the rules. The inspector felt otherwise stating it was a "judgment call." As soon as he raised an issue, we smiled, agreed with him, and started bolting on a chain guard we had fabricated and painted just in case. He and our team steward were quite impressed that we had come prepared just in case our interpretation of the rules didn't match his.

Moral of the story, if you are going to try to interpret the rules, interpret them as both worst case and best case and plan accordingly.

Thrainer

03-06-2008, 03:54 AM

Is it possible to use a CF chain guard after proving structural equivalence?

I'm sure there are a couple of teams with CF chain guards and would appreciate some advice.

A Richards

03-06-2008, 04:22 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Thrainer:
Is it possible to use a CF chain guard after proving structural equivalence?

I'm sure there are a couple of teams with CF chain guards and would appreciate some advice. </div></BLOCKQUOTE>

Well I haven't read the 2008 rules, but if they are the same as the 2007 rules then im pretty sure that the phrase 'no alternatives are allowed' would clearly indicate that you cannot use a CF chain guard regreadless of any numbers that you can magically invent

fade

03-06-2008, 04:34 AM

I think TU Graz had one in the Italy comp, here (http://racing.tugraz.at/fileadmin/galleries/2007/2007_09_21_ATA_Italy//DSC_7571.jpg) but
Ive seen other pics of the car with a painted steel one not sure what FS Italy requires. Also i remember tech inspectors (East & West) holding dial calipers on several occasions.

A Richards

03-06-2008, 07:14 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by fade:
I think TU Graz had one in the Italy comp, here (http://racing.tugraz.at/fileadmin/galleries/2007/2007_09_21_ATA_Italy//DSC_7571.jpg) but
</div></BLOCKQUOTE>

I wouldnt be suprised if that chain guard on graz's car is steel with a single layer of carbon laminated over it to make it look pretty. If it was carbon then it must be about 15layers or something. would be a dumb idea in my opinion. please correct me if im wrong. i dont see how a CF chain guard would get past the rules when it is writen so clearly. Anyone actually done it and pulled it off???

kuck

03-06-2008, 07:36 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by A Richards:
I wouldnt be suprised if that chain guard on graz's car is steel with a single layer of carbon laminated over it to make it look pretty. If it was carbon then it must be about 15layers or something. would be a dumb idea in my opinion. please correct me if im wrong. i dont see how a CF chain guard would get past the rules when it is writen so clearly. Anyone actually done it and pulled it off??? </div></BLOCKQUOTE>

You are correct. The TU Graz scatter shield was steel thick enough to meet the rules with carbon fiber for appearance.

Mike Sadie

03-06-2008, 09:04 AM

I have heard of tech inspectors sticking a magnet to the chain guard to check that it is indeed steel. I would imagine it is required to be steel (as opposed to something like ti) so they can perform this check, preventing people from skating around the rules with a dangerous aluminum POS.
We tried to pass equivalencies with a kevlar composite chain guard about 5 years back, but that was promptly shot down. Their response was along the lines of, 'Metal will deform and still protect, composites will fail and become useless.' (valid point)

Steve O

03-07-2008, 12:39 PM

Read your rule book... it is surprising how many answers it can give you...

Here is the chain guard section of the 2008 rules. Notice the "must be steel" portion of it in section A and the phrase (to confirm A Richards suspicions based on last years rule) "No alternatives are allowed."
I really am quite surprised that you and your team have not read that part of the rule book yet http://fsae.com/groupee_common/emoticons/icon_eek.gif

3.5.1.4 Drive Train Shields and Guards
Exposed high-speed equipment, such as torque converters, clutches, belt drives and
clutch drives, must be fitted with scatter shields in case of failure. Scatter shields
for chains or belts must not be made of perforated material.
A. Chain drive - Scatter shields for chains must be made of at least 2.66 mm
(0.105 inch) steel (no alternatives are allowed), and have a minimum width
equal to three (3) times the width of the chain.
B. Belt drive - Scatter shields for belts must be made from at least 3.0 mm
(0.120 inch) Aluminum Alloy 6061-T6, and have a minimum width that is
equal to the belt width plus 35% on each side of the belt (1.7 times the width
of the belt).
C. Attachment Fasteners - All fasteners attaching scatter shields and guards
must be a minimum 6mm grade M8.8 (1/4 inch SAE grade 5).
D. Attached shields and guards must be mounted so that they remain laterally
aligned with the chain or belt under all conditions.
E. Finger Guards – Finger guards may be made of lighter material.

As for the 3x's the width question; I would measure from the width of the pins (i.e. the widest portion of the chain).

Thrainer

03-08-2008, 04:32 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Mike Sadie:
... We tried to pass equivalencies with a kevlar composite chain guard about 5 years back, but that was promptly shot down. Their response was along the lines of, 'Metal will deform and still protect, composites will fail and become useless.' (valid point) </div></BLOCKQUOTE>

I appreciate your answer, thanks.

However, I don't agree on the technical reasoning.

What is a knight's armour made of?
What is a modern policeman's armour made of?

Just to stay on topic and catch the "read the rules, stupid!" momentum: Where does it say that the chain should be in the middle of the shield?

Drew Price

03-08-2008, 05:10 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Thrainer:

What is a modern policeman's armour made of? </div></BLOCKQUOTE>

So is your team an acredited designer and manufacturer of cutting edge ballistics products? http://fsae.com/groupee_common/emoticons/icon_wink.gif

Requiring a specific material in a very safety critical area is a very good way to ensure that all entrant cars have at least a reasonable chance of not hurting anyone, given that we are students, not professionals. I bet you will find similar regs in the SCCA and other sanctioning body's rule books on similar matters.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Thrainer:
Where does it say that the chain should be in the middle of the shield? </div></BLOCKQUOTE>

As for that, I think that would follow under the 'Spririt of the Rule' vs. 'Letter of the Rule,' and keep in mind that all the tech inspector has to do is disagree with your interpretation in order for you to have to spend time in the paddock making a new one.

Sam, props to your team for thinking exactly like that.

Best,
Drew

Steve O

03-09-2008, 04:47 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
Just to stay on topic and catch the "read the rules, stupid!" momentum: Where does it say that the chain should be in the middle of the shield? </div></BLOCKQUOTE>

I wasn't quite that derogatory;however, I do think it's silly that you would question something spelled out directly in the rule book.

As for the position of the chain, I certainly didn't say it had to be in the center. The second part of my post there was legitimately attempting to help you with your problem as that isn't an answer spelled out in the rule book. Now that you mention it though, I would say that would qualify under the good engineering practice rule. The reason they have the width rule is to provide enough lateral protection (even though the chain shouldn't ever really want to travel laterally in a break!) from chain scatter. If your chain is close to the edge of the guard it may somehow find its way out of the guarded area.

Just remember as a couple have said already, that "good engineering practices" rule is the tech inspectors free reign to fail you for anything they deem unsafe regardless of if you comply with the rest of the rules. They have failed people by saying that zip ties in the engine bay had a sharp edge on them and that someone could get hurt in an emergency situation. Tread carefully when stretching rules and make sure you have a plan B in case they say no.

Steve

Thrainer

03-09-2008, 01:47 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Drew Price:
... So is your team an acredited designer and manufacturer of cutting edge ballistics products? http://fsae.com/groupee_common/emoticons/icon_wink.gif

Requiring a specific material in a very safety critical area is a very good way to ensure that all entrant cars have at least a reasonable chance of not hurting anyone, given that we are students, not professionals. ... </div></BLOCKQUOTE>

Who says we aren't? http://fsae.com/groupee_common/emoticons/icon_wink.gif

You're right, and another reason could be to keep cost down. If one team is allowed to have a composite chain guard, then every team wants to cut weight to a third or so.

However, which of the following parts are NOT safety critical at speeds of up to 110 km/h?
1. Monocoque
2. Wheels
3. Suspension arms

All these are allowed to be made of composites. Yet it seems that the majority of teams have not tried it.

Steve, you're right. But, putting one layer of CF onto a ~3 mm steel plate arguably is just as silly as my question was. http://fsae.com/groupee_common/emoticons/icon_wink.gif

Mike Sadie

03-09-2008, 04:11 PM

Yes, those items are critical. The failure mechanisms are different between isotropic materials and composites. Carbon or kevlar reinforced composites are relatively weak during compressive and impact loading situations.

A CF monocoque is not much lighter (possibly equal) with a well designed steel chassis. A CF chassis (hopefully) would never see an impact like a flying chain link. If it did, I would expect failure. But for everything short of that case, a carbon chassis is absolutely appropriate.

The reasons so few teams make them are:
outrageous material costs if you plan on using the most effective process (tooling board buck mold, CF female mold, CF chassis)
extensive time on a huge mill or a lifetime with powertools
access to an autoclave big enough
lack of experience or mentors

Wheels - no one manufactures them. Very difficult to lay perfectly (must be perfect for use), tire mounting issues, experience

Drew Price

03-09-2008, 04:54 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Mike Sadie:
Wheels - no one manufactures them. Very difficult to lay perfectly (must be perfect for use), tire mounting issues, experience </div></BLOCKQUOTE>

Don't know if you guys have seen these yet, looks like a pretty sweet setup, if a bit less attractive than products from our friends at, say, BBS.

Best,
Drew

Drew Price

03-09-2008, 04:55 PM

Silente

11-15-2009, 10:01 AM

Hi everybody,

One more question about this old topic:

3.5.1.4 Drive Train Shields and Guards
Exposed high-speed equipment, such as torque converters, clutches, belt drives and
clutch drives, must be fitted with scatter shields in case of failure. Scatter shields
for chains or belts must not be made of perforated material.
A. Chain drive - Scatter shields for chains must be made of at least 2.66 mm
(0.105 inch) steel (no alternatives are allowed), and have a minimum width
equal to three (3) times the width of the chain.

Chain protection could have some holes on it or not? what i mean is: it is possible to create holes on the surface of this part?

D Collins Jr

11-15-2009, 10:24 AM

"Scatter shields for chains or belts must not be made of perforated material."

They cannot have holes in them.

Silente

11-15-2009, 11:07 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">not be made of perforated material </div></BLOCKQUOTE>

Sorry, my fault.

Thank you very much.

francoisboisguerin

05-27-2011, 05:02 AM

Hello,

if the scatter shields must not be perforated, how is it possible to fix it on the car? We can use fasteners attaching of 6mm grade 8 so we need holes in it. Is it also possible to cut it if a tube of the frame is in the way of the scatter shields? I mean the width will not be 3 times equal to the width of the chain as there is the tube.

Thank you

Tech Guy

05-27-2011, 06:34 AM

Francois,
A little common sense and thinking of the intent of this rule should answer your questions. "Perforated" means a material with lots of holes in, not one or two through which you put a bolt to mount the guard. Some teams were drilling lots of holes in the chain guards or using material more like a mesh to "make it lighter". Hence the "no perforated" rule. If you have to notch the chain guard to get around a frame tube or some other thick metal part, then that part will do the job of the bit you cut out of the chain guard, and is usually OK with the tech inspectors. If you want an official answer, then send a question in to the Rules Committee.

Canuck Racing

05-27-2011, 06:39 AM

The perforation rule is to prevent "lightenting holes" being drilled into it to save weight. A gaurd with holes is not very effective or safe but people in FSAE will try anything to save weight. Drilling bolt holes at each end is acceptable (assuming you put bolts through them http://fsae.com/groupee_common/emoticons/icon_wink.gif .)

As far as the tube clearance, I would recommend you go over or under the tube and notch the shield to fit with the nodes it may run into (eg it will not be 3x the width in all areas, but only a few small spots where there are tubes filing it in.)

Send pictures to the rules commitee if you're in doubt. Better to take care of it now than when you're trying to get through tech.

Adambomb

05-27-2011, 10:09 PM

+1 on sending it to the rules committee. This particular rule is subject to a lot of questions since there are a lot of creative ways the chain guard could be mounted.

Actually your fastest bet for an answer would be to search out all the posted answers for other peoples' questions about this rule on the rules committee forum, as this question may have already been asked by another team, and if you have a printout from the rules committee forum when you're going through tech that's pretty decent insurance. I know our team has sent a question to them at least once about chain guard mounting.