Whats the hardest part of Tube Chassis builds?

[BR3W CITY]

Say a guy has some welders, and some DOM tubing or box...how hard is it really to build a tube chassis (or backhalf even for discussion)?

To me it would appear a lot like doing a cage, but a lot more time intensive and waaay more sensitive to plumb/level/square. You don't see a ton on DIY tube chassis for certain obvious reasons, like not killing yourself...but I know its something a competent hotrodder and welder should be able to do .

[tinydb84]

I am going to comment halfway just to subscribe and see what input there is.

Between me and my neighbor we have everything we need to do something like this (mig/tig/compressors/benders/fab table). Might not do it on my 75 but by the time I get to my 66 I would be interested and going much more custom.

[Kyle@FTP]

The cage part is easy from my experience. Dont bother with DOM. Go straight to Chromoly so if you want to go faster in the future, you can just add on and not completely rebuild. I think NHRA puts out a book with all the critical specs, angles and tube sizes for each cert.

As far as back half that a whole nother ball game. tons of geometry to get things right. So many factors go into a rear suspension set up and its pretty easy to miss. Especially on a small tire and 1000+hp. But thats just my take.

This should be a great topic. I like this section here on the boards.

[HemiChallenger71]

I've seen back-half and chassis cars that were half ass and some that were middle of the road and some that are stellar.

You need a chassis plate or its really never going to be what it should be. By that I mean your doing the back half or chassis to improve over factory suspension. People are running stupid fast with stock suspension parts, drag or road racing. To achieve an improvement the work needs to be 100% perfect otherwise your kind of wasting your time.

All that said Ive seen a couple 70's and 80's cars that were rotted out, frames, floor boards etc. and the builders did a mild steel back half (on their garage floor) to save the car and put it into the local bracket class running 9's or 10's. Nothing wrong with that.

[Captainfab]

On a street driven truck I would use DOM over 4130 (Chrome Moly). IMO it just isn't worth the added expense and the extra time for a perfect fitup and to TIG it all.

If you're really serious about building a complete tube frame, I would highly recommend investing in Bend Tech Pro software. That way you can design the entire chassis on the computer before you cut or bend a single piece of tube.

[BR3W CITY]

Originally Posted by Captainfab

On a street driven truck I would use DOM over 4130 (Chrome Moly). IMO it just isn't worth the added expense and the extra time for a perfect fitup and to TIG it all.

If you're really serious about building a complete tube frame, I would highly recommend investing in Bend Tech Pro software. That way you can design the entire chassis on the computer before you cut or bend a single piece of tube.

The chassis would be designed by my partner and GM mechanical engineer, he's got a full CAD lab with all the fun stuff, and the computerized bender that can execute it if desired.

Its not a project thats high on my priority list, but a number of times I've regretted going "small" on projects and doing them 2-3 times. I really like the trailing arm rear that I have, so I think the benefits I see would be overall chassis stiffness and some weight loss.

I've only welded cage chromoly a few times, not a pro with the stuff ($$ too much to experiment with). DOM steel, and SS I'm comfortable with tho.

I'm guessing the answer is Dino, but anyone here done a home setup tube chassis?

[BR3W CITY]

Originally Posted by Kyle@FTP

This should be a great topic. I like this section here on the boards.

While sometimes not THE most active place on this forum, most of what comes out of here is good content. Most of the threads actually contain useful experience, and less rehashing than I expected.

[hotrod 80]

2 reasons to go chromoly future resale , weight reduction and smaller size of tubing . Ok thats 3 sorry . I have been told a current 8.50 cert is worth $1000 easy in resale .

[Marv D]

I've done a few mild steel backhalf's with kits, but have not and WOULD NOT tackle a full chassis as a backyard project. But that's just 'ME',, your ambition may vary.

The only way I can see to do it without having a complete race car fab shop with a jig set up for building CM chassis would be the kits like the Alston or Bickel 'buy it all here' packages. And then you better have the proper tube notchers and benders,, and plenty of extra material.

If it were a 'complete tube chassis' I wouldn't touch it unless I had a BIG space with a SOLID fab table specifically for chassis building. With out a jig things are going to warp and twist and end up with something that is... well ,,, Just having all the bars necessary to get a 25.x cert doesn't mean a vehicle really is 'safe'. Once you've been sub 10's in a car that doesn't want to go straight.... or one that consistently upsets the chassis in the shutdown or any 'quirk' that can be the result of a twisted chassis... you'll wish you built a pro-built chassis.

[Kyle@FTP]

Originally Posted by Marv D

I've done a few mild steel backhalf's with kits, but have not and WOULD NOT tackle a full chassis as a backyard project. But that's just 'ME',, your ambition may vary.

The only way I can see to do it without having a complete race car fab shop with a jig set up for building CM chassis would be the kits like the Alston or Bickel 'buy it all here' packages. And then you better have the proper tube notchers and benders,, and plenty of extra material.

If it were a 'complete tube chassis' I wouldn't touch it unless I had a BIG space with a SOLID fab table specifically for chassis building. With out a jig things are going to warp and twist and end up with something that is... well ,,, Just having all the bars necessary to get a 25.x cert doesn't mean a vehicle really is 'safe'. Once you've been sub 10's in a car that doesn't want to go straight.... or one that consistently upsets the chassis in the shutdown or any 'quirk' that can be the result of a twisted chassis... you'll wish you built a pro-built chassis.

I 100% agreed agree with that last statement. I have just crested into the 9s and luckily its in a car that is very well built. The car has gone deep into the 8s before and straight as a arrow. I couldnt imagine 9.90 with a ton of wheel input.

As for the garage build, dont be that scared. A table is simple to build and fairly cheap. lots of clamps and wear out a few tape measures. and it sounds like your partner has some fun toys to play with.

How fast do you see yourself going in the future?

[vin63]

I've built several full chassis cars in my garage from my Super Gas car to my current funny car. The common denominator has been a chassis jig and paying very close attention to plumb and level, as well as clearly establishing ride height. If you're planning on building a SFI spec chassis, I highly recommend buying the SFI documentation (this is what I did for a FED build and my current chassis).

[BR3W CITY]

Originally Posted by Kyle@FTP

and it sounds like your partner has some fun toys to play with.

How fast do you see yourself going in the future?

He's the one I'll be running the Fbody with, and he's got way more fun toys that I'm not allowed to play with. The only downside being they are housed in and often in use for commercial production. We can only sneak hot rods in there on occasion. Everything else can be made there, but has to be put together at home.

Within the next couple seasons I'd like to start aiming for 10 flat and realistically aiming for under 10.50

I don't have any intention of really being a sub 8.50 vehicle EVER, and even getting down there may be a life ambition with this truck. If I could buy a full fiberglass body and start over building a clone (ala evil twin) I would. I just was reading the rules for the Heavy Iron classes and thought the all steel body with a tube chassis is a cool idea.

The goal for the T/A is 8's, but the exponential costs under 9.50 will very possibly prevent that for at least a few more years. He can source way more funding than I can, I'm just wrangled in to do the fab and such.

[BR3W CITY]

BTW, an apparently you can just buy the blueprints from Alston...so making a chassis off of proven plans is far less intimidating.

[tiddlar]

hmm maybe guilty by design fab has some input, he built a tube chassis for an ad truck. mines over there right now waiting on wheels and tires, hes building me a full tube chassis. dont ask specs because we havent decided on details just yet

[ptc]

Originally Posted by BR3W CITY

BTW, an apparently you can just buy the blueprints from Alston...so making a chassis off of proven plans is far less intimidating.

Alston's done it all pretty much and also check out Sun Coast race cars, they have chassis kits or completed kits in different levels for trucks. It pretty much all about measuring, measuring and measuring again for plumb and true-ness while welding.

Saw a 60's era Truck tube frame chassis here locally. This is the guy Im selling parts for.

[BR3W CITY]

Thats pretty sweet.

[Gary V]

Whats the hardest part of Tube Chassis builds?

It's all about setting a realistic goal and going for it. A tube chassis is generally used in an all out race car. The SFI 25.3 spec is what to get if your going that 4130 route. Once you go down that road your going to need big bags of money and time, and oh yea... if your married set aside some geets for a divorce lawyer.

The fab part is not that hard if you have a table or jig and some tig experience. Your gonna want to have your own tube bender and notcher to do minor tweaks... even if you purchase a chassis kit. It's actually easier to just buy some tubing, understand the spec and design your own if you have the tools.

My advice is to do a 4 link back half if you want to have some fun with fab stuff/chassis setup... keep having fun with your truck. Keep it on the street and have some fun at the dragstrip when you can.

last... there's lots of aerodynamic race cars out there for sale.. cheap comparatively. Feeding one is why they are up for sale.

[Wasted Income]

Originally Posted by HemiChallenger71

I've seen back-half and chassis cars that were half ass

Which half? The back-half?

[Keith Seymore]

Originally Posted by vin63

The common denominator has been a chassis jig and paying very close attention to plumb and level, as well as clearly establishing ride height.

Yep. Getting everything square is what forms the baseline.

Additionally (to me, anyway) another hard part is that you are required to provide EVERYTHING: every nut, bolt, bracket, brake, etc.

It's not like re-doing an existing chassis where you can reuse some of the detail parts.

K

Friend of mine that lives down the street:

[tiddlar]

Originally Posted by BR3W CITY

Say a guy has some welders, and some DOM tubing or box...how hard is it really to build a tube chassis (or backhalf even for discussion)?

To me it would appear a lot like doing a cage, but a lot more time intensive and waaay more sensitive to plumb/level/square. You don't see a ton on DIY tube chassis for certain obvious reasons, like not killing yourself...but I know its something a competent hotrodder and welder should be able to do .

Click on my signature. I have. 53 Chevy truck full tube chassis.
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[tiddlar]

Chassis

[ptc]

Originally Posted by tiddlar

Chassis

Tiddlar - just for ****s and grins.... how many hours are in that chassis alone and what was the material bill? just chassis, nothing else.

And this is mild steel? or chromo?