Thread: Do I need a driveshaft loop?

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I've been working getting the frame ready for powdercoating on my '32 Coupe...repro rails with what I was told was a Pete and Jakes tubular crossmember...anyway, I've heard and seen talk of a driveshaft loop and am wondering if I should try to incorporate one on my chassis?
If it's necessary, does it have to be welded, or could I have one fabricated and attach with grade 8 bolts?
The reason I'd prefer to do that is that I'm literally ready to have it powder coated tomorrow, and if I choose to have one welded in, based on my powdercoater's schedule, i'm looking at a delay of at least another 6-8 weeks.
I don't mind a bolt on application from an appearance standpoint and would really like to keep moving rather than sit for another 2 months waiting.
Below are a couple pics...

Incorporating a driveshaft loop into the car is an excellent idea, whether it is welded in or bolted in. The main hoop should be 1/4" thick and 2" wide. I usually make mine slightly oval to accomodate driveshaft vertical movement, although the loading will be more severe on an oval unit from an engineering standpoint as opposed to a round one. If drag racing, a loop will be required at 13.99 e.t. with slicks or 12.99 e.t. with street tires. The loop should be installed within 6" of the front u-joint. THIS IS NOT NEGOTIABLE from a tech inspector's point of view.

I used to have fellows argue with me that there is no need to have the shaft enclosed 360 degrees and that just 180 degrees around the bottom would work fine. That might be true if the shaft always fell to the bottom, but that isn't always the case. The shaft has been known to auger up through the floorboard and cause serious injury to the right hip of a driver.

Here's the point: every rule that is in the rulebook is there because someone was injured or killed prior to that rule.

Nice chassis, that will look awesome when powder coated. A driveshaft safety loop is a sensible idea. It just gives that extra bit of peace of mind.

Wonder why they dont put on a smily with a whistle, that chassis is that good.

On a street car, there's nothing wrong with a bolt-in driveshaft loop.

Nice looking chassis. It may or may not be a P&J X-member, but it really doesn't matter.

I say its better to be on the safe side, plus you have easy access

It would take someone with a little more skill than a heart surgeon to put a loop in my '34 - thanks to Gibbon's "interesting" channeled floor. I had to enlarge the driveshaft tunnel just to get a 1350-series U-joint to turn.

It's strictly a street car, don't plan on any racing.
Is there any advantage of a tubular loop as opposed to one made of flat stock other than the tubular loop (even though it's bolted in) would "look" more like the rest of the crossmember as opposed to the bolt in flat stock types that are available from the different suppliers?
When I talk of a tubular loop that is bolted in, I'm picturing something that's fabricated from the same OD tubing as the crossmember that I'd fabricate mounting brackets that bolt to the rear uprights on the existing crossmember, kind of like I show in this crappy drawing below

Either one will contain the driveshaft. A tubular one would take up more space all around because of the size of the tubing. Personally, I'd use flat stock because it's easier to work with, and doesn't take up as much room. However, if you want it to look like the rest of the chassis, that works too.

How close would the loop be to the front of the driveshaft if you mounted it where you indicated in the drawing? If you need to move it forward, you could mount it off of the lower horizontal tubing in the X-member.

By the way, do you have residual pressure valves in your brakelines? I can't tell from the photos.

Yup, one on each side of the Master Cylinder...
On the driveshaft loop, I was planning on angling the 2 horizontal arms toward the front, to accomplish 2 things; get the loop close enough to the front U-Joint, and also make it easier to bolt and unbolt if necessary.
I can't find a good top view photo to sketch on, but maybe this shows what I wa thinking? (this is just conceptual and is not intended to be at a scale).

I don't think the angle idea is nearly as strong as one that goes straight out side to side.

Like this?

I don't see any thing wrong with going either way.One is done the way everyone does it.

The second version will be stronger.

I agree it will be stronger,but how strong do you need it? On this mod ,i think accessability to the trans out weighs a "HEAVY DUTY" loop.This is pretty much a daily driver right?Not a strictly strip car.You could even use 2 tubes angled back on bottom,and maybe 1-2 on top to acheive the "heavy duty" loop.I am just saying you don't have to go the usual route ,build what you need.

If you are going to bolt it in ,trans access is no big deal ,if welding it in you better leave plenty of room!! I think the tubular one would match the frame better and looks seem to be a big part of the objective on these cars. Some of the mods on my truck will be strictly for looks and some strictly for safety.
My opinion on things like this are ,if you have to add ,make or buy a part you might as well make looks part of the process.If you have to replace or buy a part that you do not have and its already costing 50-70 bucks ,I have no problem throwing another 50-70 bucks at it to make it look good also.

I would also make sure when you bolt something to a tubular structure you use a metal ferrul in the hole as to not collapse the tubing any at all.Round tubing looses its structural integrity when it gets collapsed or dented.If you use a 1/2 inch bolt ,drill a hole big enuff for 1/2 id piece of metal to pass thru the hole to keep the tubing from deforming from the pressure of the clamping force of the bolt.Ideally you would weld that ferrul into the tubing to make a flat flush area to tighten the nut and washer down to ,rather than a round surface under the washer and bolt,they make a specific tubing spacer/washer deal just for nuts and bolts on tubing.