Thread: 57 Chevy Cruizer

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Nothing to debate. 1 5/8" .090 wall moly is .7and change pounds per foot lighter, it's also stronger then DOM. I won't consider using HREW tubing on anything that's mine... I've thoroughly crash tested moly over the years and never had a failure. If I use 100+ ft of tubing on the frame, crossmembers, and outriggers plus another 125'-140' for the cage, gussets, and supports, the net weight savings is right at 160 pounds---there's days I'd kill just to get another 25 pounds off certain areas of the car. Labor intensive has never been a consideration when I build cars for me...

Originally Posted by 1gary

Oh come on Dave.You know what I am talking about with CM being a harder material used on the street.How about not turning this into a debate??.

Gary,
No one is asking for a debate, but I truly don't understand (and I don't believe Dave understands either) your statement. What do you mean "...with CM (Chrome Moly) being a harder material used on the street"? Are you saying that Chrome Moly is less acceptable in street applications due to it's hardness as opposed to Carbon Steel? Can you explain your logic?

Guys here is the deal.I know I would have to justify all the cars I have built first and then voice my opinion and then debate why I feel the way I do.

I am not willing to do that I decided.

So straight up here is what I mean.If the car was mine,I would not use CM on the street.Great stuff for race cars.............in fact first class.

Oh, I see......

I don't allow anything but 4130 in my place just so I don't accidently end up with a piece of something else in a critical place----however---if I am helping somebody somewhere else----I'll use whatever they have, but it will only be after a very detailed look at rules to make sure that its ok for the use of vehicle---

All right ---I have gotten numerous e mails on this one---

And here is my position and background on this---
I am 70 years old so some of you might think crabby old man
Some of you want claim being a farm boy as part of your reasoning
Some of you have been professional engineers
Some of you have been in different forms of racing
Some of you have been military
Some of you have been in manufacturing
Some of you have been in aviation/aerospace

So lets sort out a few items-----
Military is just interested in if you (or the enemy) can shoot thru it
Manufacturing and engineers actually work on MININUM standards and economics(well supply costs and legal ramications before considering warantees)
Aerospace/aviation--besides weight considerations they have to deal with the biggest trail of regulations and specs of material without too much emphasis being put on costs
Nascar----I spent some time in Rick Hendricks shop and saw that the tubing in there was all ground down to the minimun od, and the welding wire was a missile grade wire that is very expensive---hundreds of dollars per pound and I couldn't even find a supplier in the midwest who had it

Now as far as 4130---there is a big riff between the condition N (normalized) users and those who want to use the already heat treated stuff--( which is the one that gets brittle after welding)

I use condition N tubing, and only weld a little at a time so as not to have a huge heat area ( like 4 to 6 welds to get around a tube) I use the OD/ID specs to my advantage for slipping tubes together for making stronger joints and /or stepping up or down a size either to pick up a stronger area or to reduce weight as it travels out of the sensitive area. I cut all the joints with a mill to fit the joint PERFECTLY, not just close enough that I can just fill er in----
I have bending dies of the sizes and centerline radius of the TUBE sizes(not PIPE ) that I use.

As I have said--there is and won't be any mild steel tube in my shop--I can buy what I need / want at a very good price because I look ahead and get all tube I need for brake and fuel lines, body mounts, seat frames, etc to run up the number of feet to at least the 400 ft price( 400 feet of tubing isn't a lot when you must realize that it takes 75 feet just to build a go KART !!!!

By severely restricting what materials are in my shop I can now also restrict the types of wwelding wire---once again being very careful not to mix them up.
In a factory ----you use whatever THEY get for the job, work your shiff and go home--as a racer , its a different story

NOW, what about a street car??????Well , if you are a 70 year old farm boy who has driven mules, Farmalls,been drafted and served in armored cav, worked for air lines, flown almost 20,000 hours, raced top fuel, funny car, pro stock, done stock block Indy car engines, late model dirt, and built karts for my sons----I want it strong, light, and fast----so 4130 CM it is

Yeah, well I'm not 70---but I still prefer normalized moly.... Much like Jerry, I've tried all the rest but I'll stick with the best.... When customers didn't want to go the extra $$$$ for moly, and It was something I felt good about using DOM, I'd use it. On my own car, the criteria is light and fast, so 4130 CM it is!!

Thanks Jerry, very good explanation of why some of us geezers are fussy!!!

Didn't get to be this age by cheating on what is right. I'm right behind you at 67.

Originally Posted by Evolvo

4130 Tubing Joint Tensile Strength Test - YouTube

Here's another that says NASCAR requires MILD STEEL TUBING for cages and frames. I, too, had heard the Cro-Mo was too brittle!

American Welding Society - Welding Journal

Velllly interestink!!!


a

And, as with most tests. It's a constant pressure that increases at a slow rate... Most of my 'tests' on moly joints were done in an instantaneous way, as in a crash. I don't really care that a joint will take xxxxx pounds of pressure for xxxxxx seconds. All I know from personal experience and watching other cars is that a moly car stays together much, much better then a mild steel car on impact. Ask any of your favorite sprint car, late model, top fuel, funny car, pro stock and a whole bunch of amateur class racers run...

Most of these test I've seen are probably important if your building an aircraft carrier or something. When I want to know the tests results that relate to Hot Rodding and Drag Racing, then SEMA is the testing I go by. They specify moly for many classes, good enough for me! If I were building boats or airplanes, then maybe some of that other test data would be pertinent....

So we do finally get to the topic I posed.Two high dollar CM Spitzer (sp) car's strut mounts failed due to wrong heat ranges on the joints almost killing two of my closest friends.Too hot a range=too brittle,too cold=cold weld.This is a pro builder who sells 100's of the product each yr and KNOWS what he is doing.Then add in the stresses of what takes place in the use on the street...well.I mean not a trailer in race car with limited use.

A safe bet is for as he said a"old farm boy" who occasionally builds a CM frame,is to use the extra 160 lbs in MS not having to deal with the if come possibility.

And yeah,I do remember when we where all younger willing to try anything.We all learned a bunch as we matured,still hot rodders,but smarter.Learned to apply what to which.

So now Dave your going to tell me you have built x number of cars and had no issues.That is all well and good.It does sound kind of silly to try to save 160 lbs on a street car.I mean for what??.For every 100 lbs=only 10 hp.This is my two cents worth to contribute to the forum.

Oh come on Dave.Fess up.Got really nothing to do with the wt.Your doing this just because.Be honest about it.

Well, if you don't understand why 160 lbs. is important to me on a street car, then you don't understand the cars I build.... The "once upon a time" stories on moly don't scare me in the least. So, your premise is that a MS car would not have broke at the strut mount or what??? How old were the cars, and how many times had they done big wheelies and come down hard??? Or what, it's impossible to have bad welds using a mig welder and Mild steel?? Too hot a range of what??? How long was the weld, was it welded on both sides, had the cars had any x-rays done after incidents??? By the way, who were these guys and when and where did this happen? 99.9% of the time that a weld fails it's because the guy doing the welding goofed!!!! Wrong filler material, wrong heat range, no penetration, whatever. If that's how you weld, then it doesn't matter what the material is, the weld is going to break!!!!!!! It's much easier to blame the material, I guess.

By NHRA rules and SEMA specs, moly is much stronger, which is why a moly car can be 1 5/8" .083 wall but mild steel has to be 1 5/8" .118 wall..... I guess me, Jerry, NHRA, SEMA, and all the guys who build moly cars are just stupid, huh??? Thank you, my cars do not have issues with the welds or the material used because I know what I'm doing and when in doubt I know who to ask..

I've got too many moly cars, parts, and pieces on the road and on the track to go for this once upon a time stuff. Maybe it doesn't work for you, maybe weight savings is not an issue with you. Don't know, don't care. I know what works, I know how to build it. All summer long I watch hundreds of sprint cars going at it on dirt tracks, all moly cars. All the NHRA Pro Classes and a lot of the Sportsman classes are all moly cars. Moly cars, when constructed properly, are lighter and safer---my criteria for my builds on my cars is the same, lighter and safer.... I've seen a whole lot more mild steel cars break welds and have parts failures then I have moly cars.

The only safe bet is to build every structural part of every car as though your life depends on it. If you don't know how to do that using the best (and lightest) materials then you still have a lot of learning to do......

Originally Posted by 1gary

Oh come on Dave.Fess up.Got really nothing to do with the wt.Your doing this just because.Be honest about it.

and now you pretend to understand my motives for building a car??? Ok, once and for all. I've already taken 300 lbs. of ugly fat off just the body shell... The quarter panels and door skins will be aluminum, the trunk lid will be aluminum, the engine block and heads will be aluminum, the seats will be aluminum, etc etc etc. The whole theme of the build is light and fast.... I'm doing this because a 2500 lb. street car with 500+ hp and toque at the wheels is fun... If you don't understand that, then there's a whole lot about building Hot Rods you don't understand.

OK Gary, I have fiqured out what you are talking about--And you have a legimatute case against CM as those MUrf's cars were built with the heat treated CM , not the condition N CM that should of been used--that whole deal transpired into one of the biggest scandles and cover ups since the Nixon era Watergate---

It was all related to big cover ups by SFI, Sema, NHRA,John Force, DSon Schumacker, Goodyear and Nitro Methane fuel supplier----there was enough heat from above that they removed like 4 or 5 members of the SFI chassis people--even the NHRA techno that was involved admitts that it was bullshit, but that they thought that the whole future of professional drag racing hinged on successively covering up the mess--

It was so much of a panic to cover up that they sent out heat treated tubing to the race tracks with some welders to change tubing on site--I think that maybe some of it was even transported by Kalitta--is that where your info feed stems from???

That was on a McKinney car, wasn't it Jerry??? I remember something about it, that's when the big deal came up on the heat treated moly and pretty much everybody stayed with normalized moly? Don't remember it having anything to do with a Spitzer car......?