U-Joint Shroud?

[FLFrank35]

Looking for opinions...

My dad used to drag race back in the '60's, and he says I really should put some kind of steel-plate shroud or barrier around the u-joint (under the fiberglass tunnel) so if it comes apart the projectiles will be contained. I see his point but I am not planning to race. Is this a concern for anyone else? Has anyone else done anything to protect against a u-joint explosion? Thoughts?

Thanks,
Frank

[Jim1855]

It's a good idea, same thought process as a scattershield for the flywheel assembly.

Many will run some form of containment system. The driveshaft is short and there's potentially sufficient space to whip around causing damage. While it doesn't happen often it's real exciting when it does let loose.

I built a ring from a steel tube that is about midway on the driveshaft. IRS systems can run a tighter containment than a solid axle.

Jim

[cnutting]

Common upgrade for the roadster folk. Personally, I installed a driveshaft safety loop from Metco.

[NAZ]

This is a a serious concern and yes you should install a driveshaft loop. You can find them at places like Jegs and Summit Racing.

I've experienced two driveshaft explosions and both were on street driven vehicles. The damage is impressive. This is not just a race car thing. They're cheap and easy to install.

[FLFrank35]

Thanks for the responses! Just to be clear, the frame has a driveshaft loop welded onto it. I am talking a the the universal joint that connects the yoke to the front end of the driveshaft.
132032

I didn't even know this was a issue, but I think I'll put one in. Seems like simple/cheap insurance.

Thanks,
Frank

[NAZ]

I suggest you install one that's NHRA legal and place it no further than 6" to the rear of the center of the front u-joint. Don't know what the loop in the truck is made from but in the hot rod it was not sufficient as a safety loop.

[FLFrank35]

I suggest you install one that's NHRA legal and place it no further than 6" to the rear of the center of the front u-joint. Don't know what the loop in the truck is made from but in the hot rod it was not sufficient as a safety loop.

Good tip,
Thanks!
Frank

[RuffShod]

We had a Powerglide come apart in our IMCA Modified. While it was idling. Luckily we wernt in it or around it. The car, roof of the barn and concrete looked like swiss cheese!!!

Carry on....

[FLFrank35]

We had a Powerglide come apart in our IMCA Modified. While it was idling. Luckily we wernt in it or around it. The car, roof of the barn and concrete looked like swiss cheese!!!

Carry on....

Wow! That's an excellent endorsement for adding protection. I wonder why FFR doesn't reinforce the trans tunnel, or at least advise this in the build manual :confused: I'm a 1st-time build and not a mechanic or racer...I had no idea.

Since it's a tight fit between my u-joint and shifter bracket, I started looking into a Kevlar/Carbon Fiber fabric that can be resin/epoxied on the underside of the tunnel.

Thank you!!
Frank

[NAZ]

Frank, after experiencing a couple driveshaft explosions and looking at others after the fact, I have no confidence that any sort of ballistic blanket will protect you from a driveshaft or u-joint failure. It's more than just projectiles that you need to protect against, the rotating driveshaft will beat on anything in its path once it comes loose. If you can post a photo of the area that the shifter is located perhaps others can provide some ideas for you to consider.

[FLFrank35]

Frank, after experiencing a couple driveshaft explosions and looking at others after the fact, I have no confidence that any sort of ballistic blanket will protect you from a driveshaft or u-joint failure. It's more than just projectiles that you need to protect against, the rotating driveshaft will beat on anything in its path once it comes loose. If you can post a photo of the area that the shifter is located perhaps others can provide some ideas for you to consider.


I don't think I have a lot of options or space. Below are some pictures of the tunnel so far. I installed a Lokar electronic sport shifter and it has a cable and bracket that have to go in the tunnel too.

Thanks,
Frank
132168 132169 132170

[NAZ]

Frank, it appears you have enough room to add a safety loop. They are mounted behind the u-joint not over the u-joint.

NHRA requires them to be made from 1/4"x2" flat bar (there's also a spec for tubing but those are larger than the flat bar designs). This would be a good spec to follow. These are typically 5.5" exterior width and your tunnel is probably 5". Here's an example:https://www.summitracing.com/parts/sum-g7900 These universal loops can be easily modified to narrow them simply by carefully squeezing them in a vice and heating the loop. The circular portion will look more egg shaped but will not affect the integrity. Another option is to fabricate a rectangular one to the size you need. If you don't have the skill and equipment to do this, sketch out what size you need and find a local welding or machine shop. You will pay a minimum labor charge and a small cost for materials.

Now one thing I noticed from your photos that I should mention. The slip yoke is extended way too far out of the tail shaft. If you have the driveshaft attached to the rear axle and the axle and the trans are both in their correct positions, your driveshaft is too short.

[FLFrank35]

Frank, it appears you have enough room to add a safety loop. They are mounted behind the u-joint not over the u-joint.

NHRA requires them to be made from 1/4"x2" flat bar (there's also a spec for tubing but those are larger than the flat bar designs). This would be a good spec to follow. These are typically 5.5" exterior width and your tunnel is probably 5". Here's an example:https://www.summitracing.com/parts/sum-g7900 These universal loops can be easily modified to narrow them simply by carefully squeezing them in a vice and heating the loop. The circular portion will look more egg shaped but will not affect the integrity. Another option is to fabricate a rectangular one to the size you need. If you don't have the skill and equipment to do this, sketch out what size you need and find a local welding or machine shop. You will pay a minimum labor charge and a small cost for materials.

Now one thing I noticed from your photos that I should mention. The slip yoke is extended way too far out of the tail shaft. If you have the driveshaft attached to the rear axle and the axle and the trans are both in their correct positions, your driveshaft is too short.

NAZ, I'm still a little confused. The frame came with the square driveshaft loop welded to the frame. If I understand you correctly, you are saying the one FFR built into the frame is not sufficient and I should supplement it with one like the link you provided (thanks for that, BTW).

In addition to the driveshaft loop, I am trying to protect against flying debris from a u-joint failure. As far as that is concerned, are you saying I should try to put some steel in there in addition to the driveshaft loop? I considered the Kevlar/carbon fiber since it's supposed to be stronger than steel and bullet proof.

As far as the length of the driveshaft...Great:( Thanks for pointing that out. FFR send that to me, so I assumed they would send the right one. I have no idea what is the correct length. I guess I'll have to check with them.

I appreciate the advice.
Thanks again,
Frank

[NAZ]

Frank, in my experience the thin rectangle loop over the driveshaft that comes with the FFR chassis is not adequate. It's too thin and in the wrong location to prevent injury to the occupants. Here's an example of a driveshaft safety loop in a Mustang: 132192 Notice it's just behind the front u-joint and totally captures the driveshaft if a u-joint should fail. Yes, there can be flying debris and in my car I have an aluminum shield in addition to the safety loops front and rear. The primary safety hazard is a driveshaft that is flopping around at several thousand RPM. That mass will damage or destroy everything it contacts. If you want to add a shield in addition to the safety loop that would be a belt & suspenders approach but just be advised that any fabric that contacts the spinning driveshaft will be literally ripped to shreds. I'm not advocating for or against a ballistic shield, just cautioning you that a fabric one is not likely to be effective as it and any sheet metal it is attached to will be eaten in a nano-second by a spinning drveshaft that contacts it. Imagine if you will a loose piece of clothing getting caught in a drill press.

Before you get too excited about the driveshaft length make sure that the engine/trans is in position, the rear axle is in position and the pinion angle is set, and the vehicle is at ride height. If you still have more than 3/4" of ground and polished surface past the rear seal you need to consider that your driveshaft is too short. But contact a driveshaft builder near you or contact Inland Empire Driveline Service and get the 411 on driveshafts:https://www.iedls.com/

[FLFrank35]

Frank, in my experience the thin rectangle loop over the driveshaft that comes with the FFR chassis is not adequate. It's too thin and in the wrong location to prevent injury to the occupants. Here's an example of a driveshaft safety loop in a Mustang: 132192 Notice it's just behind the front u-joint and totally captures the driveshaft if a u-joint should fail. Yes, there can be flying debris and in my car I have an aluminum shield in addition to the safety loops front and rear. The primary safety hazard is a driveshaft that is flopping around at several thousand RPM. That mass will damage or destroy everything it contacts. If you want to add a shield in addition to the safety loop that would be a belt & suspenders approach but just be advised that any fabric that contacts the spinning driveshaft will be literally ripped to shreds. I'm not advocating for or against a ballistic shield, just cautioning you that a fabric one is not likely to be effective as it and any sheet metal it is attached to will be eaten in a nano-second by a spinning drveshaft that contacts it. Imagine if you will a loose piece of clothing getting caught in a drill press.

Before you get too excited about the driveshaft length make sure that the engine/trans is in position, the rear axle is in position and the pinion angle is set, and the vehicle is at ride height. If you still have more than 3/4" of ground and polished surface past the rear seal you need to consider that your driveshaft is too short. But contact a driveshaft builder near you or contact Inland Empire Driveline Service and get the 411 on driveshafts:https://www.iedls.com/

NAZ,

I like the "belt & suspenders" analogy, I understand that.:D Sounds good. The link to the Mustang safety loop didn't work, but I looked at the one from Summit you sent previously, will likely go with that. Also, I emailed Dan at FFR...He said the loop is fine for street use, but I like the added safety of an additional loop and the Kevlar/carbon fiber, so I'll probably go with both of those.

As far as the driveshaft length, I have the 3-link suspension. It doesn't appear I can adjust it fore-aft. And the engine/trans are in there tight. I tried to move the assembly further aft but it's at it's limit. Dan reminded me that 3 inches of the yoke are in the trans tail; said that's good. When I can drive it, I plan to take it to a former race mechanic's shop to look it over and make any adjustments, alignments, etc.

Thanks for the link to iedls. I found the Education Zone...very informative.

Frank

[Papa]

NAZ, I'm still a little confused. The frame came with the square driveshaft loop welded to the frame. If I understand you correctly, you are saying the one FFR built into the frame is not sufficient and I should supplement it with one like the link you provided (thanks for that, BTW).

In addition to the driveshaft loop, I am trying to protect against flying debris from a u-joint failure. As far as that is concerned, are you saying I should try to put some steel in there in addition to the driveshaft loop? I considered the Kevlar/carbon fiber since it's supposed to be stronger than steel and bullet proof.

As far as the length of the driveshaft...Great:( Thanks for pointing that out. FFR send that to me, so I assumed they would send the right one. I have no idea what is the correct length. I guess I'll have to check with them.

I appreciate the advice.
Thanks again,
Frank

Frank,

Here is a picture of the safety hoop I installed on my MK4:

https://thefactoryfiveforum.com/attachment.php?attachmentid=94617&d=1538592041

You can see how thick the steel is. This hoop won't protect from shrapnel, but it will keep the drive shaft from ripping into the passenger compartment like this:

https://thefactoryfiveforum.com/attachment.php?attachmentid=118046&d=1574704337

[FLFrank35]

Frank,

Here is a picture of the safety hoop I installed on my MK4:

https://thefactoryfiveforum.com/attachment.php?attachmentid=94617&d=1538592041

You can see how thick the steel is. This hoop won't protect from shrapnel, but it will keep the drive shaft from ripping into the passenger compartment like this:

https://thefactoryfiveforum.com/attachment.php?attachmentid=118046&d=1574704337

OUCH!! :eek:

[Bob Brandle]

Search on the forum "Drive Shaft Hoop". there have been some decent discussions.
But, to answer your question, YES, even for the street it's a good inexpensive piece of safety equipment.

[FLFrank35]

Search on the forum "Drive Shaft Hoop". there have been some decent discussions.
But, to answer your question, YES, even for the street it's a good inexpensive piece of safety equipment.

Bob,

Thanks for pointing to the Drive Shaft Hoop forum...Until recently, I wasn't even aware this was an issue or consideration so I didn't think to look for it. I read the thread and found it interesting. I appreciate you, and everyone else, giving perspective. I have one on it's way; probably install it this week.

One of the posters on the Drive Shaft Hoop forum installed a bell house blanket. I am applying some Kelvar/carbon fiber to the inside of my trans tunnel around the u-joint. Would you (or anyone else reading this) suggest applying a blanket under the entire transmission cover?

Thanks for the insight,
Frank