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View Full Version : chromoly or d.o.m. chassis experiences



Windy
08-25-2015, 03:13 AM
i would like your opinions and experiences with the two and wondering how long a d.o.m. will run without flexing out..????..with the 5 thousand and + mod chassis nowa days i would think the rocket by ruhlman would be the best buy..??..i know there are lots of good chassis out there just looking for more opinions..seems hard to pay 5 thousand plus for d.o.m. ..????.. thanks in advance..windy..~V~..

ambonci21
08-25-2015, 06:44 AM
Why are those cars so much money? I mean used ones are super expensive. Ive always wondered why they are so expensive. stupid qiiuestion but what is d.o.m stand for anyways?

Renegade Cust Susp
08-25-2015, 06:52 AM
Dom stands for drawn over mandrel. Has to do with the way the tubing is manufactured. If I remember correctly chromoly is only 10 to 20% stronger. Dom is rough 80k psi and chromoly is 90-93k psi. Biggest difference is if you ever have to make your own repairs you will have to tig or mig and the anneal (heat treat correctly) the chromoly or it can become brittle. Where as the dom is more forgiving to weld mig and go on if you are proficient.

JustAddDirt
08-25-2015, 08:36 AM
i would like your opinions and experiences with the two and wondering how long a d.o.m. will run without flexing out..????..with the 5 thousand and + mod chassis nowa days i would think the rocket by ruhlman would be the best buy..??..i know there are lots of good chassis out there just looking for more opinions..seems hard to pay 5 thousand plus for d.o.m. ..????.. thanks in advance..windy..~V~..

If you can afford one, and want to use a lift bar, they would be a good fit.
just because they are a moly car is not the reason for the high cost.

Moly is more rigid, and you can use thinner wall material for the same strength VS DOM, so in theory the chassis can be lighter. But once you bolt on all the suspension, and parts... that is were the majority of weight comes from. Small differences from MFG to MFG on weight of parts that are used for modified construction ex. birdcages, a-arms, spindles. All about the same within a pound or so.

Bcollins82
08-25-2015, 09:56 AM
Bottom line is that the chassis design and welding techniques are far more important to longevity than moly vs DOM. Both are used successfully, both have broken and cracked because of improper design or welding. I prefer 1020 DOM because it has tighter manufacturing tolerances than regular ERW mild steel, has better "springback", but it is more forgiving to weld than moly. There is also Docol R8 to consider, and it is supposed to be better in every way, but I have no firsthand experience with it and I'm not sure anyone besides Beakbuilt is using it in a modified?

As far as Ruhlman cars, they are high quality, but a business model of buying 2/3 of a Rocket straight from WV then prepping and installing his clip isn't exactly a business model for pumping out cheap chassis.

turner
08-31-2015, 05:25 PM
Not gonna comment on moly vs mild steel, but if you want to win, get an impressive and be done with it.Again, this years ump mod champ will be driving an impressive.The suspension should take up the (flex) not the chassis.

thinkstomuch
09-01-2015, 06:21 AM
Windy - I've got a Ruhlman for sale. it is a 2012 and updated in 2014. Good car in great shape (better price). Let me know if your interested I'll get you details - 937-802-9605

Confused?
09-01-2015, 06:56 AM
First off, CrMo can be MIG welded. Second, due to the thin wall tube that is used for chassis, it does not require pre or post heating. A qualifed welder will have no problem with it or welding CrMo to DOM. Moly chassis loan last longer than 60 nights if they are designed correctly. Any chassis can fail after one or two season if incorrectly designed and built, regardless of the steel. If you doubt the pre post heating statement, read up up on it in any AWS code book in the editorial section.