Not trying to be a smart-azz here... but what is the actual need for a safety loop on a shaft 20" long?
(Maybe a strap across the tunnel under the front U-joint, but a full SFI loop? As someone who has snapped one on a "full size" car, and sheared a pinion shaft as well, I know the need with a 5 foot long driveshaft...)
I'm thinking more a scattershield in the U-joint "fling" zones... .040 aluminum between me and 5000+ rpm shrapnel isn't healthy.
I believe the idea is to prevent the free end of a broken drive shaft from "helicoptering" and taking out the transmission tunnel frame, seat, and legs.
Most of us building street machines install some version like the Metco safety loop, pictured below.
Not trying to be a smart-azz here... but what is the actual need for a safety loop on a shaft 20" long?
(Maybe a strap across the tunnel under the front U-joint, but a full SFI loop? As someone who has snapped one on a "full size" car, and sheared a pinion shaft as well, I know the need with a 5 foot long driveshaft...)
I'm thinking more a scattershield in the U-joint "fling" zones... .040 aluminum between me and 5000+ rpm shrapnel isn't healthy.
I think its pretty cheap insurance. If you look where you will be sitting, basically your hip and kidneys are about a foot from the shaft, anything coming through 0.040 AL sheet will be going into you. Anything to help control the chaos happening down there is a good thing. At build school they tell a story of one cutting right through the 3/4 tube like it was nothing. Guy walked with a limp after that. For $130 Metco loop with easy installation to me it's a no brainer.
2nd MK4 #10639 received 3-19-23. Wife's version. Street Snake - IRS, Willwoods, no roll bars, no hood scoop, no stripes, Blue Print EFI 306 with AOD trans, and under car exhaust. Ford Eruption Green with saddle leather interior.
1st build - Mk4 Roadster #9319, received 4-10-18. IL registration 8/6/19. Moser 8.8. 3 Link. Wilwood brakes. Blue Print 427, Holley 750, TKO 600, 0.64 OD. Paint Dec 2020. Ruby Red with Carbon Flash Black metallic stripes.
Gotcha guys...
My head is still somewhat into lets say "longer wheelbase" cars.
As I think about it, these things are pretty much like vintage front engine dragsters - you're sitting on top of mechanical mayhem, and your nuggets are really at risk.
Well, this thread cost me $150 or saved me from physical harm, just put in an order. I am still building, nearing the 1st go cart stage and this is a good time to install the loop.
20th Anniversary Mk IV, A50XS Coyote, TKO 600, Trunk Drop Box, Trunk Battery Box, Cubby Hole, Seat Heaters, Radiator hanger and shroud.
I've seen on this forum photos of a roadster's driveshaft failure and yes, "mechanical mayhem" is an apt description. Having seen the impressive damage, I installed Forte's loops on both u-joints, and may put some titanium sheet inside the tunnel at some point.
I've seen on this forum photos of a roadster's driveshaft failure and yes, "mechanical mayhem" is an apt description. Having seen the impressive damage, I installed Forte's loops on both u-joints, and may put some titanium sheet inside the tunnel at some point.
I like Titanium, too (especially on rub strips - great big white sparks!), but if you're looking to stop an energetic penetration, spend the same amount of money and use 4x the thickness of steel. Titanium's main benefit is at high temperatures, which doesn't help here. At the same thickness, Titanium isn't going to stop a penetration any better than plain steel.
I almost wonder if ballistic nylon would be a better choice. You know, body armor.
Mk4 #8861 Complete kit. Delivered: 27 Apr 2016, currently a roller.
Gen-2 Coyote, clutch, TKO600, midshift, and solid axle from Forte. Many pieces from Breeze and Replicarparts.
I almost wonder if ballistic nylon would be a better choice. You know, body armor.
Your question piqued my curiosity so I did a quick search to see what's available. Nothing for driveshafts specifically, but plenty for transmissions. I don't see why you couldn't fab a cylindrical enclosure out of alumimum around the driveshaft, and then wrap it in a ballistic transmission blanket like this one:
I have been considering a loop also. Then I saw the list of safety features of the Mark 4 roadster from FFR.
Listed is "Driveshaft safety bars". Not sure what that means
Since I am not an engineer I don't know for sure but I would be leary about trans blanket material in this use. To me that works for shrapnel. If you blow a drive shaft there may be some shrapnel but the real damage is done by that shaft swinging around. I would rather contain that w/ steel plate.
FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.
I would be leary about trans blanket material in this use. To me that works for shrapnel. If you blow a drive shaft there may be some shrapnel but the real damage is done by that shaft swinging around. I would rather contain that w/ steel plate.
+1.
A similar concern of mine is flywheel / pressure plate safety - Steel (not cast) flywheel for me along with a Quick Time steel bellhousing - too close to the knees for comfort...
Here's a pic of a roadster u-joint / yoke failure from a few years ago:
A similar concern of mine is flywheel / pressure plate safety - Steel (not cast) flywheel for me along with a Quick Time steel bellhousing - too close to the knees for comfort...
Here's a pic of a roadster u-joint / yoke failure from a few years ago:
Great example! Looks like it took out everything in the tunnel (e-brake cables, battery cable, electrical harness). This should answer the questions about running brake and fuel lines through the tunnel.
That is the photo I recall, which looks like a "once is enough" life experience.
That being said, are there any common denominators for these things failing on roadsters and the like? An imbalanced driveshaft? Improperly installed u-joints? I'm not surprised by that kind of failure on a truck with an ill-designed lift kit, or on a drag car that lifts the wheels. Assuming non-defective parts, what would you have to do (or not do) to have that sort of failure on a 2,300 pound car with 300-500 horsepower?
That is the photo I recall, which looks like a "once is enough" life experience.
That being said, are there any common denominators for these things failing on roadsters and the like? An imbalanced driveshaft? Improperly installed u-joints? I'm not surprised by that kind of failure on a truck with an ill-designed lift kit, or on a drag car that lifts the wheels. Assuming non-defective parts, what would you have to do (or not do) to have that sort of failure on a 2,300 pound car with 300-500 horsepower?
Jacob,
Just search pinion angle to see how many times this question enters the forum and assume that a fair number of builds are on the roads and tracks with drive line angle/phasing issues that could eventually lead to a part failure.
What about Carbon Fiber sheets that lined the tranny tunnel? Obviously as well as using the steel the driveshaft loop. A guy I race with designs and makes customer carbon fiber wings and splitters for race cars. He might have some insight as to how well it would stop mayhem from entering the cockpit and keep it under the car. I am sure not the cheapest idea but if it would work essentially the same as plates steel and save a lot in the weight department. Thoughts?
What about Carbon Fiber sheets that lined the tranny tunnel? Obviously as well as using the steel the driveshaft loop. A guy I race with designs and makes customer carbon fiber wings and splitters for race cars. He might have some insight as to how well it would stop mayhem from entering the cockpit and keep it under the car. I am sure not the cheapest idea but if it would work essentially the same as plates steel and save a lot in the weight department. Thoughts?
Commercial airliners use carbon fiber burst containment around the engines. A LOT of engineering goes into their design. Which I appreciate, when I sit above the wing, in the plane of rotation for the hot section.
Mk4 #8861 Complete kit. Delivered: 27 Apr 2016, currently a roller.
Gen-2 Coyote, clutch, TKO600, midshift, and solid axle from Forte. Many pieces from Breeze and Replicarparts.
There is a difference in smallish parts that go ballistic and a driveshaft that is still attached at only one end to something driving it around and around. For example, a bullet proof vest will stop a bullet, but is not much protection from someone repeatedly hitting you with a tire iron.
I think CF could be OK but it would need some careful design and fabbing. One concern would be how it is attached to the frame. For me, if I were really concerned running drag tires, I would buy some 3/16 steel plate and weld it into the frame on the inside of the 3/4x3/4 tubes on top and both sides and full driveshaft length plus an inch or two.
FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.
Titanium is a good choice from the standpoints of strength and low weight. However, it is really (read: REALLY!) expensive at more than 20 times the cost of similar thickness steel! Save your money and get the driveshaft loop!
Frank B
Last edited by frankb; 11-15-2018 at 09:03 AM.
FFR MK4 #8317, 393 Cleveland, Lunati VooDoo solid roller, CHI 3V heads and intake, TKO 600, Std roadster seats, 8.8 3.55 diff, 17" Halibrand replica wheels, Ford "Magnetic Metallic", silver ghost stripe. (Sold 10/16/21)
I think the question has turned more into what about the miscellaneous shrapnel vs the driveshaft. I DO think the driveshaft loop for me is a must have, but that doesn't stop the U-Joint caps or pieces of the yoke that may break off from making their way into the cockpit of the car. Cars with IRS, is there a way to install a fixed pipe that would go from the trans output seal to the pinion yoke to encapsulate the entire thing and all its moving pieces? Attachment 97520Attachment 97521
Metal seems a little thin for me but this gives you a visual of my thought.
Last edited by Texas Driver; 11-15-2018 at 09:24 AM.
Awwww, come on Frank. It's that kind of thinking that keeps the wheel from being reinvented. Well that plus the fact that the wheel is working perfectly well as is.
I installed Forte's loop to contain the drive shaft and I installed 16 gauge steel plates all along the inside of the tranny tunnel to help slow down the small projectiles that might occur during a failure. I also plated the foot boxes, Just not comfortable with that thin aluminum between me and the road, which is one of the reasons mine is a hog, weighting in at 2600 lbs. But I feel safer :-).
FFR6682 - received 7/30/08 - MK 3.1 complete kit, Forte built Ford Racing BOSS 427W(475HP/500lbs), TKO600, Power steering, Power Brakes, Hydraulic Clutch, VPM Front/Rear sway bars, Bump steer kit, SAI mod, 13"Front/11.65"Rear Mustang Cobra rotors w/calipers, NITTO NT05s - 255/40R17-Front, 315/35R17-rear,3.55 IRS.
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Awwww, come on Frank. It's that kind of thinking that keeps the wheel from being reinvented. Well that plus the fact that the wheel is working perfectly well as is.
Cheers,
jeff
Ya, what Jeff said, lets reinvent the wheel at least 6 different ways, using the most outlandish ideas and materials we can think up. You know, like 1" thick stainless steel tubing, mounting the shaft inside of it, then wrap bullet proof vest material around that.
About the only plausible reply has been to "Keep the shaft from helicoptering"... and beating the snot out of the tunnel (which the reply pic indicates).
A simple mid-shaft loop, and call it done. These cars have 247 other ways to kill/maim you - many of which don't involve mechanical failure.
I'm with Craig, this is an interesting discussion. Anytime you have a free-flow of ideas about a subject you will get a broad spectrum of thoughts. Even if you don't find them particularly good ideas some may stimulate further thought about how to tackle a problem. You may pick and choose bits and pieces of how others do things to develop your own method of dealing with an issue.
I'm glad this subject is getting attention. Having experienced two driveshaft explosions I know first hand how much damage can occur and how quickly it can happen. I used the word "explosion" as that best describes how quickly it happens and the damage reminds me of when I was in the Army using explosives to demo metal structures. So when I built my car I installed a driveshaft restraint system that exceeds what NHRA requires as I know what the risks are.
So if you're reading this thread and not quite sure if you need a safety loop I suggest you do an internet search and look for pictures of driveshaft failures and think about you and your passengers setting next to that spinning driveshaft. Then decide.
Mk4, IRS, (Forte: 427 with EFI, T-56 MAG, hydraulic clutch, mechanical linkage, reverse lockout control module) (Breeze: Front and Rear Double adjustable QA1's, Cockpit cubby, LED Lights, Fan Shroud, Fan Lower Support, Oil Cooler Coil, power steering hose kit) (Russ: Drop Trunk, Turn Signal)
A simple mid-shaft loop, and call it done. These cars have 247 other ways to kill/maim you - many of which don't involve mechanical failure.
+1.
Originally Posted by NAZ
I suggest you do an internet search and look for pictures of driveshaft failures and think about you and your passengers setting next to that spinning driveshaft. Then decide.
+1.
Another thought - driveshafts are most likely to fail at launch or on the shift to 2nd.
Flywheels, pressure plates and clutches generally fail near the rev limiter.
All that money and they didn't use a safety loop? Or do you think this was the result while even having a safety loop?
Dave
Mk 3.1 - #6882 - 5.0L 302 - FiTech EFI - 3-Link - 3.08 Ratio - 15" Wheels
Greenhorn and doing the best I can
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My Metco loop arrived today. Great people and show quality product. They follow up on your order immediately. I was surprised the loop included the hardware.
20th Anniversary Mk IV, A50XS Coyote, TKO 600, Trunk Drop Box, Trunk Battery Box, Cubby Hole, Seat Heaters, Radiator hanger and shroud.
I'm with Craig, this is an interesting discussion. Anytime you have a free-flow of ideas about a subject you will get a broad spectrum of thoughts. Even if you don't find them particularly good ideas some may stimulate further thought about how to tackle a problem. You may pick and choose bits and pieces of how others do things to develop your own method of dealing with an issue.
I'm glad this subject is getting attention. Having experienced two driveshaft explosions I know first hand how much damage can occur and how quickly it can happen. I used the word "explosion" as that best describes how quickly it happens and the damage reminds me of when I was in the Army using explosives to demo metal structures. So when I built my car I installed a driveshaft restraint system that exceeds what NHRA requires as I know what the risks are.
So if you're reading this thread and not quite sure if you need a safety loop I suggest you do an internet search and look for pictures of driveshaft failures and think about you and your passengers setting next to that spinning driveshaft. Then decide.
Agree 100%. A hundred dollars or so against a $30,000 & up hand built car with a drive shaft at your hip is a no brainer.
Kevin
MKIV #8234
Coyote '14/TKO-600/3-Link 3:55 Rear I love the smell of 100 octane in the morning.
NITTO NT01 275X40X17ZR - 315X35ZRX17
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