Topic: DOM VS ERW
I know DOM is preferred, but I have a good process bender here in town who can do ERW bends. Is ERW going to have me sidelined ?
Since the Car was 3100 lbs, I am using 1.75X.120
2018 B.F.E GP, Get Yer Phil
The 24 Hours of Lemons Forums → Lemons Newcomers → DOM VS ERW
I know DOM is preferred, but I have a good process bender here in town who can do ERW bends. Is ERW going to have me sidelined ?
Since the Car was 3100 lbs, I am using 1.75X.120
The rules state that "DOM mild steel is very strongly recommended over ERW" which raises two points:
(1) ERW won't get you sidelined, assuming of course the cage is properly designed and constructed.
(2) A number of other things in the rules that started out as "very strongly recommended" (or some such similar words) eventually ended up becoming mandatory. The rules are set for this year but who can say what the future will bring beyond that?
A cage is one of those things that if done well means that you have no problems and is invisible, but if done poorly can cause much headache, cost, and be a big PITA. For the very small added cost in going DOM when you are having someone make the cage, it really is false economy, even more so than the idea that these cars are $500 as raced, as the safety gear is serious business.
Really, paying for a cage is $1500 minimum, $4000 or so on the top end. The difference in the tubing cost of what, $100? just doesn't seem worth it.
If you ever want to sell the car or ever want to convert it to run in another sanctioning body, it will more than make up for the difference right there, many other sanctioning bodies do not allow ERW any more unless grandfathered in with a previous logbook.
What are they doing where they can bend ERW and not DOM?
What are they doing where they can bend ERW and not DOM?
My question as well!
The major difference between the two is that DOM tubing goes through an extra process that cold works the tube and the weld line inside of the tube so that it no longer shows. During this process the tube ends up with a more consistent size in OD, ID and wall thickness.
and is also a bit stronger all else being equal.
I would think that any bender that can bend ERW should be able to bend the same size DOM.
Was a cost factor, the local fab has lots of ERW on hand, but DOM is extra.
I may just go for the https://www.swracecars.com/store/Volvo- … -5530.aspx
I called my local steel supplier in Sacramento a couple weeks ago.
20 ft of 1.5in .120 ERW is $40 each
22 ft of 1.5in .120 DOM is $108 each.
DOM costs more than double, almost three times more.
That per foot price is about the same as 1.75 DOM .120 in Tucson.
Was a cost factor, the local fab has lots of ERW on hand, but DOM is extra.
I may just go for the https://www.swracecars.com/store/Volvo- … -5530.aspx
You mean this one that won't fail you out of tech.
https://www.swracecars.com/store/Lemons … 3-627.aspx
Not sure what the difference is between the one pre measured specifically made for the car, (Volvo 740 / 940) or the one where I measure. They have both of the same components save the side bars which will need adjustment.
The "around the dash" cage won't pass tech due to the reverse bends in the down tubes.
The "around the dash" cage won't pass tech due to the reverse bends in the down tubes.
Thanks. Was doing the through dash style, as well, I have no dash... I understood the reverse bends stipulation in the How not to fail, but given the price difference is 250.00 It is looking like the premade in dom is significantly cheaper. I am asking S&W if they have the measurements on a 940, but the 90's 740 and 940 are exact in dimensions from all the literature I can find on the web.
The reverse bends aren't the only issue with that cage, it's also missing the second door bar (something that isn't that difficult to add, but still, it's missing) and a main hoop diagonal.
The reverse bends aren't the only issue with that cage, it's also missing the second door bar (something that isn't that difficult to add, but still, it's missing) and a main hoop diagonal.
I noticed that, but the mock up for the Lemons has omitted the double door steel as well.
Issues with the volvo specific cage you linked, in list form.
1. It is missing the main hoop diagonal
2. It is missing the second bar on each door bar
3. Around dash version not allowed (you already addressed this)
4. May not come with spreader plates?
Call S&W, tell them you are doing Lemons with that particular volvo, talk through getting the cage kit you need. please do not skimp out on the cage. It's the thing that will safe your life in a big crash. Saving a little money to go ERW is not worth it.
Issues with the volvo specific cage you linked, in list form.
1. It is missing the main hoop diagonal
2. It is missing the second bar on each door bar
3. Around dash version not allowed (you already addressed this)
4. May not come with spreader plates?Call S&W, tell them you are doing Lemons with that particular volvo, talk through getting the cage kit you need. please do not skimp out on the cage. It's the thing that will safe your life in a big crash. Saving a little money to go ERW is not worth it.
I have decided to go DOM most certainly. The kits are what troubles me. the price difference is almost 225.00 and not sure enough to offset that cost of #2 and #1 in the above list. I have the 1/8th steel spreaders already. (wondering if the markup is Lemons related.)
Thanks guys for giving me the skinny on the DOM. Will certainly be using it.
That S&W Lemons kit is roughly as cheap as you can get a Lemons legal cage anywhere. The only way to do a lot better is have an in with a place to buy DOM and bend it yourself. I've done 3 cages now. First I paid $2100 to someone to custom build it for me. Then I paid about $600 to buy raw DOM and build my own. Latest car I paid about $900 to have a custom bent kit with more parts than required shipped to my door and welded it in myself. This is just the normal range of cage costs.
I know this is supposed to be cheap racing, but there are real costs associated with it. Safety is not the place to cheap out.
Talked to S&W. their engineer said they measured the 1991 Volvo 740 and my car is the 940. It has the same dimensions aside from length (.9 inches) but the length is in bumper and not body.
Ordered the specific cut kit and will add the additional bars. as I want to gusset and modify.
Thanks for talking me into the DOM.
2.5 weeks for delivery.
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