IS IT WORTH THE MONEY TO GO WITH A CROMOLY FRAME ?
WHAT IS THE ADVANTAGE ?
THANKS FOR ANY HELP.

my understanding is that you don't gain any strength. because of the fact that the chromolly is stronger, builders will use a lighter gage (thinner wall) tubing so you wind up with a lighter chassis with the SAME strength as a mild steel chassis. and as we all know....lighter is better in the dunes.

not this crap again


Most of the high end builders are doing all chromoly frames.

I say get the upgrade, better than shoulda coulda woulda later.

This is a Chevy/Ford debate, do a search on chromo mild steel, lots of topics about it.....

and yoshi knows that debate first hand

Oh no he didn't!!!

here is my new and improved take on cromo vs dom. After watching the welder weld up .095 cars cromo or dom that stuff is paper thin and has to welded with care. I would never own a car with less than .120 wall tubing and if you are going to go thicker you might as well get it as light as you can an go with cromo. So yes I think the upgrade to cromo is worth it. My current car is 120 dom and It is very heavy because of the options really not the tubing but the lighter tubing even it was 50lbs would have been nice.

and away we go.....

Cro-mo isnt any lighter but it is approximately twice as strong. If done properly, you could use .060 wall and achieve the same strength at half the weight, as compared to mild steel. In reality, just about all the builders still use .095 or .120 w/cro-mo so there is more material at the joints; if they were properly heat treated, stress relieved, annealed, what ever the buzz word of the week is, it wouldnt matter.

.120 wall mild, DOM and cromolly all weight the same. Cromoly chassis are lighter because they use thinner wall tubing that has the same strength as a thicker mild or DOM.

does anyone take this extra (crucial, IMO) step?

cromoly is stronger but it cracks easier than mild, plus when the frames are made out of a thin material it cracks that much easier. the thinner matierial does need a more skilled welder also to not make it weeker. i believe nascar chassis are made out of DOM. just something to think about. im not saying one is better than the other. i think this is like what yoshi said, its a chevy/ford debate.

hmmmm intereting well in that case, I think the debate should clearly be a .095 vs .120 thickness debate because overall, the type of material as long as it is welded right really does not matter.

Worth every cent and more.
DON~~~

I will be for sure...I just dont know who does it around here.

building your own chassis?

While some may be tempted to use chromo and go with a thinner tube than they would for a mild steel chassis, I think that safety is such an important issue that all chassis should be built as strong as possible. Meaning that if you plan to put a turbo Subi engine, a V6 or a V8 into your rail, you now have the potential to go every bit as fast as a Class 1 race car or a trophy truck if you gear it the same.

I haven't inspected every class 1 car or trophy truck, but my understanding is that they are all built of heavy gauge chromo tubing. While you certainly wouldn't want your sandrail or dual sport rail to weigh as much as a class 1 or trophy truck, I would think you would want to put your family in a vehicle every bit as safe. Our rails may have slightly less tubing, but many of them have quite a bit of x-bracing, and it would be a waste of effort to design and build something to that level of strength and then use inferior materials when building it.

I have seen mild steel bend and crack, I've also seen chromo bend and crack. From what I've seen, mild steel will deform under much less of an impact than chromo, making chromo the better choice to protect your most valuable assets.

OTOH, I think mild steel is fine for my golf cart, considering it's top speed is only 40 mph.

I think the statement in bold is technically incorrect.

Take 2 pieces of .120 wall tubing, one chromo and one mild steel, and put a 90* bend of the proper radius in each. The chromo doesn't crack, it bends.

Now build 2 front bumpers out of .120 wall, one of each material. Ram them both into a wall at 30 mph and I'll bet you'll see some deformation of the mild steel bumper, and much less deformation of the chromo bumper, if any at all. If properly designed, it will not crack. I have seen more mild steel chassis cracked from flexing than I have chromo. I also factor in design and chassis age into the equation when seeing stuff like that. Sure a 20 yr old high jumper chassis isn't going to compare to a CAD designed 2600 lb dual sport car, but I'd much rather see you all safely tucked into something nearly indestructible.

Do a search! There are a MILLION topics about this already. 6 pager by tomorrow

i probably should have worded that different.

yes cromoly does bend... in a sand rail where ther is not enough bracing to keep the whole chassis from flexing (which that is about all the sand rails ive seen...) it will flex. cromoly does not like to flex like DOM so it will lead to cracking.

Exactly what I was thinking before I read your post

Heavier cars built in mild steel will have a tendancy to "tweek" the whole chassis in a good crash, whereas an untreated chromo chassis will break at weld joints in certain points. Yoshi's cars are much lighter and will not have these issues because of the light weight and I completely agree with his choice of materials. Is one better than another? The never ending debate......

LOL
yes; the quarter-annual parade of the same guys


damn, im glad i switched to aluminum

Yes
I am using .095 1.5" 4130 as the main frame with 1.25 .083 supports and crossbracing out the a$$!!

I use mild steel, 90 percent of my chassis is 120 wall, some of the cross bracing is 110 wall.

chromo is stronger because it's harder, and because it's harder it is more likely to crack under impact, but mainly within a half inch of the weld because pretty much nobody stress relieves their chassis after welding, why? Cause you need a hella big oven to do it.

Both materials will bend fine when new, it's age that starts to wear on chromo quicker, i've been told by quite a few people in the know that chromo has a shelf life. I've talked to racers that hit a wall in a race, and had a chromo tube explode in the middle of the tube, no where near a weld. Trophy trucks don't powdercoat their chassis because they are always checking for, and repairing cracks after races, some also replace their chassis every couple seasons, as the harder chromo will fatigue more after use due to vibration.

I think chromo is for racers to try and save weight, and to save weight, they go with a thinner material that is stronger, which effects welding as well, as the welder has to be good so he doesn't burn through or thin out the material to much making a weak joint. I DO NOT THINK IT'S SAFER, I actually believe mild steal is safer which is why I use it...

Nascar uses mild steal, chromo is against the rules, and they hit a concrete wall at 200 mph and i've never seen a cage failure, where dragsters still use chromo and i've seen them blow to a million pieces when wrecked....

The design is the most important thing, then the material. A trophy truck built outta sch40 will prob. hold up 100 times better than a lot of the rails on the market built outta chromo. chromo isn't the magical mojo everyone thinks it is. I would still have every single cross brace in my design if I used chromo, where some people will skimp on tubing to save even more weight because they think chromo is so much stonger, which it is, but along with it's advantages, it also has a weakness that I think out weight the positives of using it.....

So which is the Chevy , and which is the Ford ? Since we all know Chevys are better we should be able to get to the bottom of this issue once and for all.

I believe NASCAR uses mild steel because the cars get beat on all the time. Easy to chop, cut, and weld the mild steel. Dragsters dont eat the wall or each other very often so it's practical for them to use. If you run a NASCAR into the wall at 340mph I bet you'll see a few pieces

What made my decision easy was seeing pics of a members car on this site. The roof lacked a B pillar and was made of mild steel; it had a light rack done with cro-mo. The vehicle was involved in a slow speed roll (best I can recollect), the lightbar appeared to be fine but the chassis had bent considerably; if somebody had been in the passenger seat it may have made contact with his/her head. Cro-mo 1, mild steel 0 Would this have happened if the chassis was cro-mo? No way of knowing I guess but it was a good enough reason for me.

Oh yea, you dont HAVE to use heat to stress relieve.

I dont want to be part of this debate anymore, but please tell us why it is eaiers to "chop, cut and weld" mild steel than chromo? If you are buying a car and your only choice is E.R.W. or cromo, choose cromo. If you are building a car or have your choice of any material do yourself and any future passengers a favor and use D.O.M............................

I'd like to see pics of that rail, i'm pretty sure for the light bar to be fine, it is small which makes it more durable, and where ever the chassis bent was prob. in the middle of a tube, like where a B pillar "should" be. In that case, I have no doubts that a chromo chassis would have bent in the same place, IF it didn't break at that point...

Wise you've become .....(yoda )

Maybe they use an entire clip and replace the whole section each time something gets destoyed but my statement was based on the fact there are probably multiple cuts and welds along an individual tube. If that were the case, it would need to be stress relieved after each repair which would require more money and time.

Yoshi, the thread was from a few years back. I cant remember what the title was. I added the lack of B pillar to the comment for a reason. The light bar may not have been fine, it certainly faired better than the chassis. I dont believe the cro-mo chassis would have been damaged to this extent; no facts to back this up but that is my opinion.

This is what untreated chrom has a tendancy to do.....

That looks like a poor weld. Cromo typically breaks away from the weld because the carbon molecules are pushed away from the heat source and create a brittle area.

Here's the topic

http://www.glamisdunes.com/invision/index....p;hl=punchdrunk

And in enters the need for heat treating.......

Are you sure that is cromo? Those welds are nasty regardless.

Yuppers. It is one of the most highly touted builders on this website also but please do not ask me because I will not say who. Simply trying to show what chromo can do if not handled properly. Granted, this was a SANDCAR in a desert crash but please people, know the limitations of what you have. I take nothing away from what happened to this car, but if you want to hammer your rig in the desert, build it for that, period. All that really means is more bracing and post heat treatment to avoid the deficiancies here.

Just as another example, this is my jeep and if you look closely you can see how bent the bar above the passenger seat was(roof bar). It was bent down probably 4 inches(DOM), almost perfectly comforming to the rock I landed onand I know chromo would NOT have bent down that much. There is a much higher possibilty that the weld onto the a pillar hoop would have broken though without treatment, and that I am not comfortable with. Regardless, that tube would have needed replacement whether it was dom or chromo.

For the record, I like chromo for most situations better WHEN TREATED AND WELDED PROPERLY. Despite this, I almost exclusively use dom, because how many people have an oven big enough for a whole chassis? Even so, baking of the chassis is not a guarantee that you will not see that cracking like above. Above all, design is key!!

Your first pic still has nothing to do with the material being welded.

It does, I GUARANTEE Dom would not have done that!

EDIT: I also am pretty sure the roof(whoch you do not see in those pics) if made from DOM, would have crushed much further down, not good either.

Its an S.U. How can you tell the quality of the weld from the picture? Explain the second picture? Give us your car building and material experiance.

Well, I've never seen cromo break at the weld (assuming you had a decent welder); everything I have seen has been from about a half inch to two inches from the weld. The first pic shows a failure at the weld, period.

The weld at the gusset in the second pic looks to have excessive filler. Maybe it was too cold? It is more indicative of what usually happens near a cromo weld though.

I have no experience with car building or the material (you know this...). Does your experience show something different?

I don't know shiat about shiat......but I have watched off road racing on ESPN, and I have slept in a few Holiday Inns!!!:lol:
But here goes anyways..............Does it really fricken matter what material you use??? What kind of abuse to we REALLY apply to our cars in the SAND??? Say whatever ya want, but our cars don't take the abuse the desert racers do to their cars. I think what is important with a sandcar is the geometry of the chassis!!!(does the suspension cycle properly)
Of course the welds need to be good.........But can you really tell if it's a good weld by looking at it??? (if YOU can, NASA is lookin for you!!! )
So back to the topic......If you apply the same HP & torque to one sand car @ 2000 lbs. vs. one @ 2500 lbs., the lighter one will move through the sand easier. (this is one thing I do know what I'm talkin about.......I can prove it w/ physics ) BUT, the heavier car will handle the woops better!!!

What is better "chromo or DOM" is a really open ended question.
If you have decided on the builder and have an option of chromo or DOM, I think you need to decide what you will use the car for!!!
Then decide, do you want a lighter or heavier car

You make a good point; I've seen very nice looking welds that failed (the production race vehicle from DB.com comes to mind) and ugly ones that hold up.

Under normal driving conditions of 40 mph and under, I don't think it's gonna make much difference.

But if you wanna put your entire family into it and accidentally launch it off of a dropoff at 80 or 90 mph, that's when you're gonna hope and pray that your car holds up.

And that is precisely the WRONG time to be thinking about the welds, design and materials used in the car that now is entrusted with the safety of all that you hold dear. I'm willing to bet that all turbo Subis, V6s and V8s in Glamis are capable of at least 80 mph unless geared really low. I know my car will hit 110 with paddles, faster with 35" dirt tires. Nobody plans on having a wreck, but it's always prudent to prepare for the worst and hope for the best.

So far, no one has successfully explained to me why chromo is used exclusively in off-road racing, the closest vehicles to our sand rails. Trophy trucks and class 1 cars are not designed with weight limits in mind, they use as many tubes, as thick as necessary, to make it strong enough to withstand a tumble at max speed. It's harder to work with, more expensive, far more time consuming to TIG than MIG the chassis, yet that is what they all use. There must be a very good reason for it.

Any material that is improperly welded will not hold up. I'd like to see all sand rails constructed of TIG welded chromo, but it's a free world, buy whatever you like.


As for looking at a weld to determine it's quality... I'd agree, I honestly don't think I can look at a weld and tell you how well it penetrated. However, if you show me a beautiful TIG weld from a builder who has built plenty of cars with no known failures, then I'd say the proof is in the pudding. That guy not only knows how to make a pretty weld, he knows how to make a strong weld.

trophy trucks and class 1 cars have far more tube and cross bracing than any sand rail, this keeps them very ridgid. sand rails are far from ridgid, so when you use a ridgid material on a unridgid design it will lead to cracking and fatigue.

finally somebody (in this mind-numbing never ending discussion ) who actually knows what he is talking about

I agree fully with the geometry. The well desingned cars will hold up all over better than one that is not including frame cracking, trans lifespan, supension etc.

I've seen plenty of rigidly built sandcar chassis. All of the following chassis are chromo, and I haven't seen a crack on any of them. Allstar, Alumicraft, BSE, Racer, SCU, Gen 3 and newer Funcos (from what I understand), Desert Dynamics dual sports, just off the top of my head.

I have a Foddrill, and I finally got a very tiny crack in an engine support brace after about 6 yrs of duning. AFAIK, my chassis doesn't flex under normal driving conditions. I've bottomed it hard a number of times, so I take responsibility for any chassis damage at this point.

I'm not saying chromo is some wonder material, but I am saying that some of these sandrail builders really do know how to build a very strong, rigid chassis, and they choose to use chromo as their material of choice. When Penhall, Potter, Jimco, Porter, Foddrill, Alumicraft, Geiser Bros., etc all use the same material, and Yoshi uses mild steel, I think I'll vote for the guys who have actually been to the desert.