Broken Avanti Traction Bar Stud Repair

[studeawakening]

I was doing some test launches trying to get an idea of what rpm to launch my R3 clone at. Suddenly all hell broke loose from under the car. It went into an extreme wheel hop on one side and then the other. I limped the car back to the shop and put it on the lift and found that the stud that holds the traction bar to the bracket had torn loose on the passenger side first, and then on the drivers side next. You will notice from the pictures that the stud had a very inadequate spot weld on the back side of the bracket, actually a very poor design structurally. Started scratching my head on how to fix the problem, till I came up with this fix it was looking like a nightmare, possibly having to jack the body up several inches to be able to cut the bracket from the frame as the body covers up the top weld of the bracket. I decided that I would cut the bracket open and would weld a bolt to the frame. In my bolt collection I found these large t bolts that are used to connect water, sewer, and gas pipe connections together. I cut a slot in the bracket, then slid the t bolt into place. By turning the t bolt up right in the slot I was able to get a good vertical weld to the frame, moving to the back side of the bracket I was able to get a fairly good weld on the back side. I then replaced the cut out in the slot and welded it in place and then ran a circle bead around the bolt to the bracket. I then reamed out the rubber bushing on the traction bar to fit the larger diameter bolt. I alternated welding and grinding between the two sides to keep the heat down. This repair has held up very well for a while now, I feel that it is quite a bit stronger as it is now tied to the frame and to the bracket together and not just attached to the bracket. I will also do this same repair to my sons 64 R2 Daytona, but after looking at it it will be a much more difficult repair due to clearance issues.

[junior]

Seems like a sound and simple solution to me...good idea. I would imagine, unless you have a really wide and/or tall tire on the car this should last forever. Love the fact that you are experimenting with different launch rpm, some would be afraid to put their foot into an old supercharged Stude. Good on ya! BTW, please oh please tell me it's a 4spd, makes it double good! Junior

[studeawakening]

Seems like a sound and simple solution to me...good idea. I would imagine, unless you have a really wide and/or tall tire on the car this should last forever. Love the fact that you are experimenting with different launch rpm, some would be afraid to put their foot into an old supercharged Stude. Good on ya! BTW, please oh please tell me it's a 4spd, makes it double good! Junior

Yes its a four speed

[DEEPNHOCK]

Since it is a clone....
I would suggest fabricating an outer support strap for that stud, especially since you had to remove a section of the stud mount.
That is a lot of stress being applied to that stud base.
A simple strap with two 45 degree bends mounted parallel (and in line) with the thrust angle, and the outer end of the stud would not be pushed.
Just food for thought.
Jeff

[sbca96]

You could check with Dan Giblin, and see if he has any of these left :



As originally posted here. I got MY set early on so I wouldnt miss out!

http://forum.studebakerdriversclub.com/showthread.php?12645

What is the grade of the bolt you used to replace the factory one? You will need
at least a grade 5 bolt, I wonder if that bolt is even graded, if not it will snap off
fairly quick. You could look at the backside of the frame in that area, and see if
you can get a LONG drill and drill straight through the frame. A long graded bolt
could be put through the frame and the bracket with a spacer/nut combo to take
the stress off the bolt. It will also be easier down the road if you break it again.

NOTE: you wouldnt be sandwiching the bolt in the frame and tightening the bolt
squeezing the frame, it will never stay tight, you would need to double nut/space
the bolt at the bracket. Only other way to do that would be a stout sleeve thru
the frame in that area and that would get tricky.

Also, if that was a graded bolt prior, the welding may have changed the temper
of the bolt, causing a fatigue area and will break. Time will tell I guess.

Tom

[junior]

okay, just for discussion purposes, does it really matter about the grade of bolt in this application? I thought the grade of bolt only specifies the tensile strength, and how much of that is required in this regard, as the bolt will probably fail in shear not tension. If the temper changed during welding, wouldn't the bolt tend to be annealed instead of hardened after welding assuming a slow cooling rate? I'm not sure, so if you could shed some light on the situation that would be great. Jeff's suggestion seems to make sense as it would put the shank of the bolt in a double-shear setup. In reality with a stock size tire why won't Art's solution be ok? In a severe power application that cal-trac design is mighty impressive, so simple, so effective....the photos on the website never fail to amaze me. Oh and Art...a 4 speed...how sweet it is! Junior.

[studeawakening]

You could check with Dan Giblin, and see if he has any of these left :



As originally posted here. I got MY set early on so I wouldnt miss out!

http://forum.studebakerdriversclub.com/showthread.php?12645

What is the grade of the bolt you used to replace the factory one? You will need
at least a grade 5 bolt, I wonder if that bolt is even graded, if not it will snap off
fairly quick. You could look at the backside of the frame in that area, and see if
you can get a LONG drill and drill straight through the frame. A long graded bolt
could be put through the frame and the bracket with a spacer/nut combo to take
the stress off the bolt. It will also be easier down the road if you break it again.

NOTE: you wouldnt be sandwiching the bolt in the frame and tightening the bolt
squeezing the frame, it will never stay tight, you would need to double nut/space
the bolt at the bracket. Only other way to do that would be a stout sleeve thru
the frame in that area and that would get tricky.

Also, if that was a graded bolt prior, the welding may have changed the temper
of the bolt, causing a fatigue area and will break. Time will tell I guess.

Tom

The traction bars that you are running will work better than the factory bars but they are not allowed at the pure stock drag races. The bolts I used are grade 5 which has a higher shear strength than a grade 8, do not confuse shear strength with tensile strength, grade 5 bolts work better in shear conditions and will usually bend rather than break off. Since this repair has been done this cat has been to the drag strip several times and has done numerous high rpm launches with both street tires and drag radials with seemingly no ill effects. I thought about drilling through the frame, and cutting the bottom plate and putting a spacer pipe around the bolt were it went through the frame to prevent being crushed upon tightening. This would have to be done from underneath the car, and it is right were the heavy X cross member attaches and it would compound the problem since it is on an angle at that point.

[sbca96]

okay, just for discussion purposes, does it really matter about the grade of bolt in this application? I thought the grade of bolt only specifies the tensile strength, and how much of that is required in this regard, as the bolt will probably fail in shear not tension. If the temper changed during welding, wouldn't the bolt tend to be annealed instead of hardened after welding assuming a slow cooling rate?

From what I have read, and from what I have seen, and from what I have learned
at work, the grade of a bolt is EVERYTHING in regards to how its used. Welding on
a graded bolt changes its temper it can cause it to be fatigued, depends how hot it
got and what type of welding equipment was used. Not saying for sure, just worth
mentioning.

The bolts I used are grade 5 which has a higher shear strength than a grade 8, do not confuse shear strength with tensile strength, grade 5 bolts work better in shear conditions and will usually bend rather than break off.

This is why I stated at least a grade 5, usually suspension bolts are grade 5
and head bolts are grade 8 for the reasons you mention. As I said about from
what I had seen .... years ago a guy I worked with built a beautiful Willys hot
rod truck. He used all grade 8 bolts to attach the bed to the frame .. because
they are "stronger". While he and some friends were sitting at an open patio
burger joint for lunch, a drunk in a big Caddy slammed into his truck parked
on the street. The impact broken ALL the grade 8 bolts like toothpicks. It was
like the bed was just sitting on the frame. The completely intact bed slammed
into the rear of the cab with such force that it crushed it into to the dashboard.
Had he been IN the truck he would have been killed.

So yes, grade 8 bolts are almost useless in shear. I wouldnt bother with any
bolts less than grade 5 in a car though, and never get fooled that Stainless is
stronger, usually stainless steel bolts are less than grade 3 unless indicated as
higher. I didnt realize you were running in a pure stock division.

Tom

[DEEPNHOCK]

Please provide your technical data to back up your statement about grade 5 vs grade 8 fasteners.
I would really like to know.
Jeff

<snip>
So yes, grade 8 bolts are almost useless in shear. I wouldnt bother with any
bolts less than grade 5 in a car though, and never get fooled that Stainless is
stronger, usually stainless steel bolts are less than grade 3 unless indicated as
higher. I didnt realize you were running in a pure stock division.

Tom

[sweetolbob]

Here is one data point on the shear vs tensile of various grade bolts.

http://www.rockcrawler.com/techrepor...ners/index.asp

It may all be moot when you consider the heat generated by the welding process. In any case, A neat repair that works.

Bob

[studeawakening]

[sbca96]

That pretty much sums up the SDC motto right there.

Tom

I think you guys are getting a little carried away

[DEEPNHOCK]

Uh huh...
when in doubt, use grade 5 bolts...

http://tinyurl.com/Grade-5-Bolts

That pretty much sums up the SDC motto right there.
Tom

[sbca96]

Uh huh...
when in doubt, use grade 5 bolts...:rolleyes