Anybody know why TB's are so lightly secured?

Posted By: jcc

Anybody know why TB's are so lightly secured? - 01/29/12 01:03 AM

First, I am talking about the lightweight internal spring clip at the rear of the TM mount. Doesn't seem very robust. And doesn't it supply additionally a small amount of retention front to rear of the LCA?

My guess was it's for safety, in a hard front end crash, TB just push rearward instead absorbing and releasing a lot of stored energy and entering interior of car?

Well?

Posted By: HotRodDave

Re: Anybody know why TB's are so lightly secured? - 01/29/12 01:16 AM

It would take a heck of a lot of energy to push a torsion bar through there with a clip still in it. Any way, most of the force in normal operation is torsional and pretty much none front to back. I have seen a couple cars riding around with the clips missing for who knows how many years and the bar does not try to move out.

Posted By: Kern Dog

Re: Anybody know why TB's are so lightly secured? - 01/29/12 05:20 AM

Quote:

I have seen a couple cars riding around with the clips missing for who knows how many years and the bar does not try to move out.

I agree here. It defies logic, but the T bars seem to stay put.

Posted By: 1_WILD_RT

Re: Anybody know why TB's are so lightly secured? - 01/29/12 05:23 AM

Doesn't defy logic at all... There is so much torsional load locking the bar in position & absolutely nothing trying to force it to move in a linear fashion.. Why would you expect it to move?

Posted By: jcc

Re: Anybody know why TB's are so lightly secured? - 01/29/12 10:13 AM

Quote:

Doesn't defy logic at all... There is so much torsional load locking the bar in position & absolutely nothing trying to force it to move in a linear fashion.. Why would you expect it to move?

Under heavy braking when traveling in reverse, the brake strut attaches to lca at what is basically a fulcrum, and the spindle pushes forward, and the lca tb mount point pushes rearward, against what, just a clip? A 180-360 spin at speed should be a decent amount of loading.
Still leaning towards it is an accident breakaway solution.

Posted By: Moparlar

Re: Anybody know why TB's are so lightly secured? - 01/29/12 03:06 PM

Quote:

Quote:

Doesn't defy logic at all... There is so much torsional load locking the bar in position & absolutely nothing trying to force it to move in a linear fashion.. Why would you expect it to move?

Under heavy braking when traveling in reverse, the brake strut attaches to lca at what is basically a fulcrum, and the spindle pushes forward, and the lca tb mount point pushes rearward, against what, just a clip? A 180-360 spin at speed should be a decent amount of loading.
Still leaning towards it is an accident breakaway solution.

I think you might be over thinking this. I have taken out many torsion bars that were not even close to the clip. So they had not pushed back and if they had there is no way they could have moved back forward. I am sure the strut rod has something to do with that also.

Larry

Posted By: Rick_Ehrenberg

Re: Anybody know why TB's are so lightly secured? - 01/30/12 12:10 AM

Later Mopars ('prox. '75-up) didn't even use a clip. (It was shown in the parts book, but most of the ones I've seen didn't have 'em.

If the bar has moved back against the clip, you've got bigger problems!

Rick

Posted By: it's Bob

Re: Anybody know why TB's are so lightly secured? - 01/30/12 10:40 AM

The front end of the bar does not seat on anything, there is a lot of extra room in the LCA Tbar socket. And you think they are secured lightly? Only when you don't need to get one out do they practically fall out, when you NEED to get one out you can't get them to budge, even if you take everything off the front end.

Posted By: feets

Re: Anybody know why TB's are so lightly secured? - 01/30/12 07:47 PM

Even with the front tires dangling in the air there is so much torsional load on the bars they will not come out. Think of the spring rate. Can you bench press the lower control arm while the t-bar is installed? All that pressure is mashing the hex ends into the sockets. You will not push them out.
I've seen some cars that were in very serious collisions that didn't push the t-bars back.

It's simply a non-issue.

Posted By: 440lebaron

Re: Anybody know why TB's are so lightly secured? - 01/30/12 10:46 PM

12 bolt clutch covers, 5/8 wheel studs, 8 bolt flex plates, billet rear end caps, 12 bolt ring gears, 1350 u-joints, grade 8 rim screws.......................... 4-1/4 fine thread bolts holding driveshaft to rear end!!

Posted By: Supercuda

Re: Anybody know why TB's are so lightly secured? - 01/31/12 01:56 AM

Quote:

4-1/4 fine thread bolts holding driveshaft to rear end!!

And that is all they do, hold the driveshaft to the rear end. They do not transmit any force.

Posted By: jcc

Re: Anybody know why TB's are so lightly secured? - 01/31/12 03:10 AM

Reg TB's being secured, I remember seeing here? years ago a pic of a nascar? early mopar TB secured by a bolted plate, for reasons unknown to me.

And reg overthinking the question, I've heard that before

Posted By: dogdays

Re: Anybody know why TB's are so lightly secured? - 01/31/12 05:11 PM

MOPAR engineers were very good, they didn't add anything that wasn't necessary. They looked at the loading and as mentioned above they saw the bar wasn't going to go anywhere. So just a clip was OK.

Crashworthiness? Get real. When the torsion bar front ends were designed the big safety features were door locks that wouldn't open in a crash. Seat belts were an option if you could get them at all. Steering columns would spear you. Crashworthiness was far from top of the list and if anyone gave it a thought it was to make the car more resistant to crumpling. Energy absorption and controlled deformation were decades in the future and really only occurred because of the government.

R.

Posted By: Fury Fan

Re: Anybody know why TB's are so lightly secured? - 01/31/12 05:36 PM

And keep in mind that in an accident you'd need a perfectly linear force to move the LCA rearward by about 3" to push the T-bar back, any sideloading simply puts more force on the hex.

Posted By: jcc

Re: Anybody know why TB's are so lightly secured? - 01/31/12 05:38 PM

Quote:

Crashworthiness? Get real. When the torsion bar front ends were designed the big safety features were door locks that wouldn't open in a crash. Seat belts were an option if you could get them at all. Steering columns would spear you. Crashworthiness was far from top of the list and if anyone gave it a thought it was to make the car more resistant to crumpling. Energy absorption and controlled deformation were decades in the future and really only occurred because of the government.

R.

You left out the 7"x12"x3/4" Foam crash dash safety pad

, and your point is well taken