Big lips going out?

[swerve2007]

"Quote:
Originally Posted by swerve
the area you call the 'back lip' is in fact the weakest part of the wheel"

""What makes you say this? What makes the backside of a wheel inherently the weakest? What if the face of the wheel was mounted to the barrel in such a way that it had only a 1/2" lip, leaving the front of the wheel with a 8" lip? That .5" lip is weakest? I think your statement is over-generalizing, or more likely, incorrect""

incorrect?
you are grasping straws- i am replying directly to your statement that "all wheels have 'back lips' so there should be no problem having one in the front".
i said that in fact the 'back lip' on a normal wheel is the weakest part and by adding additional lip on the front you are adding additional stress area. the further away you move from the bolt-up face, the stronger the 'moment arm' is acting on the material meaning it is easier to damage.

"Is a Volk GT-C with a +43 offset is stronger than a Volk GT-C with a +30 offset? Or is a Volk TE37 with a +43 offset is weaker than a Volk TE37 with a +30 offset?"

in fact yes, the offsets do make a difference in strength of a wheel.
most of the cast wheels out there are 'overdone' (hence heavy) to protect from damage to the product and litigation etc. you may not actually break the wheel during normal driving but that does not mean that it is not weaker. best test-lab is the racetrack- any lips there? need i say more?


unless you are a structural engineer (which i am) i am done arguing unless you want to put some money on it and then i'll run some finite element analysis and take your cash so i can buy me some rims.

 

[02#154]

"Quote:
Originally Posted by swerve
the area you call the 'back lip' is in fact the weakest part of the wheel"

""What makes you say this? What makes the backside of a wheel inherently the weakest? What if the face of the wheel was mounted to the barrel in such a way that it had only a 1/2" lip, leaving the front of the wheel with a 8" lip? That .5" lip is weakest? I think your statement is over-generalizing, or more likely, incorrect""

incorrect?
you are grasping straws- i am replying directly to your statement that "all wheels have 'back lips' so there should be no problem having one in the front".
i said that in fact the 'back lip' on a normal wheel is the weakest part and by adding additional lip on the front you are adding additional stress area. the further away you move from the bolt-up face, the stronger the 'moment arm' is acting on the material meaning it is easier to damage.

"Is a Volk GT-C with a +43 offset is stronger than a Volk GT-C with a +30 offset? Or is a Volk TE37 with a +43 offset is weaker than a Volk TE37 with a +30 offset?"

in fact yes, the offsets do make a difference in strength of a wheel.
most of the cast wheels out there are 'overdone' (hence heavy) to protect from damage to the product and litigation etc. you may not actually break the wheel during normal driving but that does not mean that it is not weaker. best test-lab is the racetrack- any lips there? need i say more?


unless you are a structural engineer (which i am) i am done arguing unless you want to put some money on it and then i'll run some finite element analysis and take your cash so i can buy me some rims.

I don't care what your title is... it doesn't mean you can't be wrong. Don't take it so serious. I asked someone to explain it to me. I'm not a structural engineer so please, if you have the time, explain to me why the lip on the backside of a wheel is weaker than if it were in front of the wheel. If you can't, then fine. You know you're right and that should be good enough for you. Why get all riled up when someone doesn't already "get it" like you do? If you can't answer my question then just don't say anything. All I've heard so far are facts stated simply as facts. I'm looking for an explanation. I'm not a numb-skull and I'll evaluate arguments/rebuttals. But I don't just accept statements like those made earlier in this thread.

As for your proposition on a bet, I wouldn't be foolish enough to make that wager. As I said in my first post on this thread:

"I don't understand this. Even wheels with "no lip" has a lip... it's just on the other side of the face of the wheel. Do you mean that the wider the wheels is, the weaker it is? Even so, why would wide mean weak?

What am I missing? I've never heard of a big lip being bad in any way other than subjective opinions on aesthetics. I'd like to hear more regarding this."

Ever since then, I've not gotten anyone trying to explain to me, a lowly non-structural engineer. And if nobody cares to explain, then I'm cool with that too. I'll just continue to call BS until/unless someone does.

BTW, I just went through the thread with Firefox's search function and I never used the term "back lip" except in quoting you, Swerve. But I'm not a structural engineer so maybe I did it wrong.:biggrin: I'm just ribbin' ya, Swerve. I hope you can take it with a grain of salt (or whatever you structural engineers do).

J

 

[02#154]

Hey Swerve... I don't wish to create stress in your day but if you can answer my questions, which are real, legitimate "I don't understand why, so if someone can please explain" type questions, I'd sincerely appreciate the education. OTOH, no need to continue if you're other replies will just be "it is because I say so and I'm an engineer". Hope it's the former, not the latter.:smile:

"Quote:
Originally Posted by swerve
the area you call the 'back lip' is in fact the weakest part of the wheel"

""What makes you say this? What makes the backside of a wheel inherently the weakest? What if the face of the wheel was mounted to the barrel in such a way that it had only a 1/2" lip, leaving the front of the wheel with a 8" lip? That .5" lip is weakest? I think your statement is over-generalizing, or more likely, incorrect""

incorrect?
you are grasping straws- i am replying directly to your statement that "all wheels have 'back lips' so there should be no problem having one in the front".
i said that in fact the 'back lip' on a normal wheel is the weakest part and by adding additional lip on the front you are adding additional stress area. the further away you move from the bolt-up face, the stronger the 'moment arm' is acting on the material meaning it is easier to damage.

Why is that, in fact, the weakest part of a rim?

"Is a Volk GT-C with a +43 offset is stronger than a Volk GT-C with a +30 offset? Or is a Volk TE37 with a +43 offset is weaker than a Volk TE37 with a +30 offset?"

in fact yes, the offsets do make a difference in strength of a wheel.
Okay, I'll concede this if you're talking about any offset other than 0. Once you have *any* offset, the larger side will be measurably weaker. But if the offset moves to the negative side as opposed to the positive side, are you saying that it will become weaker and weaker, the bigger the front/exposed lip gets?
most of the cast wheels out there are 'overdone' (hence heavy) to protect from damage to the product and litigation etc. you may not actually break the wheel during normal driving but that does not mean that it is not weaker. best test-lab is the racetrack- any lips there? need i say more?

This isn't a question, but I'd like to note that F1 has pretty big lips. So did the purpose-built race cars I saw at the ALMS event last year. Just saying...

unless you are a structural engineer (which i am) i am done arguing unless you want to put some money on it and then i'll run some finite element analysis and take your cash so i can buy me some rims.

 

[swerve2007]

i am not aggrevated at all, the point i was making is that several people have indeed added correct information to this discussion already and i guess i am used to take people word as i would think any normal person would not spill b/s just for the sake of it. and it doesn't make a diff who you are, i know plenty of idiots with a degree.
if you are searching for justification of term 'weaker' equaling with failure, that may not be the case. i can assure you though that any wheel with added lip will be heavier and the space for the lip is created by either by moving the spoke disk by offset or by curving the spokes themselves which is worse as you now added even more weight as the spokes have to be larger and longer, and the attachment point is acted upon by a leverage-arm (moment arm) of the spoke, instead of just being 'pushed upon' by it. it is almost impossible to explain this without diagrams etc and i do not have to proove my point that badly.
summing it up- if you take a wheel of constant size and weight and you increase the front lip, you will create either a weaker wheel of the same weight or heavier wheel of the same strength.

lastly, bringing F1 wheels into it, notice the lip is 'creased' not flat which adds strength like puting ribs in the food cans 9not mentioning advanced forging methods and ultra-expensive materials). many of the wide-lipped exotic wheels that were mentioned here are multi-piece not cast and have much stronger hoops made by rolling, so yes, these may not be weaker or heavier but much more expensive.

 

[02#154]

It's quite possible that other members have posted accurate information but nobody posted a "and here's why". I wanted to understand why: as the offset grows more and more positive, the wheel becomes stronger and stronger (or the corollary, which is as the offset grows more and more negative, the wheel becomes weaker and weaker). In the peanut sitting between my ears and behind my eyes, I just couldn't understand why... I still don't. I'm hung up on the fact that, as you decrease the lip in front of the rim, you increase the "lip" in the rear. I figure that the forces that act on the front of a rim also act on the rear of the rim. Oh well... not looking for anyone to "prove" anything but if anyone wants to explain this to me, I'm all ears.

And hey, Swerve... you should know better by now than to just accept what people say on the Internet at face value!!! :tongue:

J

 

[swerve2007]

ok,
here are few diagrams showing the standard wheel and one with larger lip.
there are no stiffening ribs in the 'bling-lip' which makes it weaker than the 'back lip'. assuming same strength required at the same cost (no exotic materials) the spokes have to be thicker as well as their attachment point to the rim. only forces associated with the spokes and the bolt-up face are really considered here and it is a very simple drawing.
your assumption that if you increase the front lip, the rear one will decrease may only hold true for wide-body conversions- in normal situation the bolt-up face has to stay in the same location.

 

[SWIFTVISION]

Very interesting diagram....hmmm

 

[02#154]

My Volks are nothing like as shown in the diagram. When you order Volks, part of what is specified is the "face type". If you order Face 1, it'll look the same, no matter what offset you order. The differences lie in the "pad height" and offset only. I don't have a way to diagram what I mean that won't look like I did it with an etch-a-sketch.

J

 

[TURBO2GO]

I think the hot new thing is a deep CONCAVE not a big lip.

 

[davidf]

There should be a thread started on various brands of concave wheels.:smile:

 

[TURBO2GO]

There should be a thread started on various brands of concave wheels.:smile:

I'll start. BMW 6 with a DEEP concave rear Breyton GTS.

 

[Texas91Brent]

Awesome!!!!! What brand and specs? NSX fit? New Lambo Reventon..Concave style wheels..........cool

 

[davidf]

Those are gorgous.

 

[TURBO2GO]

Deep rear dish reventon:

 

[TURBO2GO]

Awesome!!!!! What brand and specs? NSX fit? New Lambo Reventon..Concave style wheels..........cool

As I wrote above, they are Breyton GTS. I don't know if they will fit an NSX but the gray metallic ones rock.

 

[Texas91Brent]

Now we are talking!!!! I like this look......Any others? TSW, I think makes some....thanks for the info....:biggrin:

 

[Texas91Brent]

I think the hot new thing is a deep CONCAVE not a big lip.

I agree, don't tell everyone......:wink:

 

[Texas91Brent]

Anymore ideas? Brands? mesh or 5spokes?

 

[Texas91Brent]

I'll start. BMW 6 with a DEEP concave rear Breyton GTS.

Any more photos? sideview etc....:smile:

 

[TURBO2GO]

Sorry I don't have any more. I scanned that one off a Tire Rack catalog. I have seen some Pro-Drive wheels sold by SOS that have a nice concave spoke in the rear. I suppose its a matter of playing with the offsets to create that look. But I see more and more supercars with wheels that are deeply concaved.

 

[TURBO2GO]

Another deep rear dish pic from a prime thread: