Twisted Frame Horns

[rick m]

Has anyone ever ended up with their frame horns, the area the trans bolts to, being twisted?  If so, how did you remedy it. I have never run in to it but need to hear how some of you may have dealt with it.

Rick Mortensen

[Zach Gomulka]

My dads was twisted and cracked. I straightened them back out, welded it up, and installed a rear brace to keep it in alignment.

[rick m]

Zach,

Where was it twisted (what side) and where did you find the crack? What did you do to straighten it? 

Rick M

[hotrodsurplus]

I have straightened several cars' frame horns. Usually the frame horns bend down. That's an easy solution: support the front beam with jack stands and chain the frame horns down at the nose cone. Then jack up the cradle. I like to slip a 2x4 between the jack pad and the cradle to protect it. You have to bend the horns beyond the finished point a little bit because of spring-back. Take a few whacks at it to see for yourself.

Bending the horns down is a little trickier. You have to chain the car down at the frame head and the cradle and then jack up against the front of the frame horns. Again, use a piece of wood between the pad and frame horns and bend more than necessary to counteract spring back.

Bending them laterally takes a bit of creativity. The one in the following photo was especially good: one frame horn was bent up and the other down AND they were both bent to the right (the car that donated the pan sustained a HUGE hit to the left rear). The long chain formed a sling from the left frame horn to the right side of the front beam. The hydraulic ram pushed from the crotch of that sling to the torsion housing. We still had to support the right-front of the beam with a jack stand to keep that side from dipping. We also had to chain down the left-front and left-rear to keep the car from raising on that side. As it was the ram wants to push itself into the ground.

That last part was a real butt clincher but we straightened that car in about an hour. It's not very difficult but you have to have some equipment.

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I have a car with a bent frame horn AND torsion housing. It cracked the web between the horns and housing too (swing-axle car). The torsion housing is bent back and rotated down a bit so I might just bend the horns back and replace that bent housing with a fresh one.

[rick m]

Hot Rod....when you say chain down the front of the cradle...what are you chaining it down to?

Rcik M

[hotrodsurplus]

when you say chain down the front of the cradle...what are you chaining it down to?

We chained down to anchor pots in the floor like these.
http://www.autobodytoolmart.com/champ-floor-anchor-pot-1600-p-11538.aspx

One is visible in the left-rear wheel well as part of the lateral-pull photo. You have to drill a 3 1/2-inch-diameter (varies by brand) hole in the floor to use them and once in they're permanent. In fact they tighten as you pull on them. But once they're in you'll find all sorts of jobs for them. They're handy like socks on a rooster. They lay flat so you never trip over 'em. It's about $40 a hole to drill the concrete.

You can also use concrete wedges. Most have a stud that protrudes from the floor surface but you can get drop-in anchors like these and just remove the bolts when you're done. You'd just have to make up some brackets to bolt to them. You can drill the holes yourself, too.

http://www.amazonsupply.com/pd34-power-drop-plated-drop-in-diameter/dp/B002709P6G?ref_=goo_pf_B002709P6G  

Those are the pieces that transform a garage from a room with car parts into a real working shop. They're awesome.

[rick m]

Thanks for the tip.  Now it is pretty clear how you pulled it bac in line.  Thanks for the input.

Rick M

[Russell]

Rick (really tried to ignore this topic but cant.... sorry)

for whats its worth IMHO i would scrap and get another pan if the horns are bent and then rebent back in shape you will have a weak point.... the last thing you want/need is this failing under load or inuse, never mind the money and time in the car, what about you.........

sorry to disagree with with the others but as i my job is inspecting metals and structures and looking for defects, i understand the properties of steel, if it bends one way then other it will become ductile then snap, its that simple.

Your friend

Russell 

[OC1967vw]

Thanks for the tip.  Now it is pretty clear how you pulled it bac in line.  Thanks for the input.

Rick M

RickM, pictures posted above were instructive and reflect the factory's instructions on collision repair.
Todays body shops straighten frames all the time. A high tech chassis/frame table is a start. Given the horns,they should be able to tweak it back in shape
Many use laser measuring systems to enhance the repair effort and insure frame straightness and symmetry.

Porsche did this years ago with their 917s that were involved in race collisions though the technology was not as sophisticated as that used today
good luck

[rick m]

I actually have a couple straight pans. Been thinking about it....

Rick M

[Russell]

Thanks for the tip.  Now it is pretty clear how you pulled it bac in line.  Thanks for the input.

Rick M

RickM, pictures posted above were instructive and reflect the factory's instructions on collision repair.
Todays body shops straighten frames all the time. A high tech chassis/frame table is a start. Given the horns,they should be able to tweak it back in shape
Many use laser measuring systems to enhance the repair effort and insure frame straightness and symmetry.



Oc1967vw, I agree 100% with you, all chassis get straightened after accidents, but the rear frame horns are a lot weaker than on normal other type chassis, again I'm not douting any advice given to rick just pointing out what I think.

Porsche did this years ago with their 917s that were involved in race collisions though the technology was not as sophisticated as that used today
good luck

[hotrodsurplus]

Russell, you bring up good points. Consider a few counterpoints. First, Volkswagen used pretty low-alloy materials. They're quite malleable (like maybe 1010) and don't readily work harden. We're also talking a few degrees more than the material's yield point. The deep-draw techniques used to form those shapes upset the metal far more than a little tweak here and there will. And we're not talking numerous bends back and forth. An unintentional bend and a correction or two shouldn't present any problems. They haven't in my experience.

As pointed out, Volkswagen considered this an acceptable procedure. We had books of VW-issued tech bulletins at the shop where I worked as a kid and this repair was part of them. If a car suffered bad clutch chatter it was almost a foregone conclusion that the frame horns were bent down a bit. As part of the clutch repairs we'd bump the horns back up and away they'd go.

As for failures, I can't foresee the horns breaking much less letting going away catastrophically. We beat the hell out of Baja bugs in the high desert, frequently bending frame horns, and the worst thing that ever happened was a few spot welds would separate. As for damage and repairs weakening the structure, yeah, I think there's potential for that. At the same time a garden-variety truss bar that ties the frame horns to the damper towers would increase the integrity far beyond what any virgin frame horns would've ever had. That's also a good idea for a high-horsepower car that's never been damaged.

I don't think there's a definitive right or wrong way as much as a right way for the application. If you don't trust the repair then swap pans. That's legit too. But I sincerely think that there's no harm in building a high-horsepower car on a pan with straightened frame horns, especially if it's been fortified with a truss bar.

[OC1967vw]

Consider a few counterpoints. First, Volkswagen used pretty low-alloy materials. They're quite malleable (like maybe 1010) and don't readily work harden. We're also talking a few degrees more than the material's yield point. The deep-draw techniques used to form those shapes upset the metal far more than a little tweak here and there will. And we're not talking numerous bends back and forth. An unintentional bend and a correction or two shouldn't present any problems. They haven't in my experience.

Volkswagen considered this an acceptable procedure. We had books of VW-issued tech bulletins at the shop where I worked as a kid and this repair was part of them. If a car suffered bad clutch chatter it was almost a foregone conclusion that the frame horns were bent down a bit. As part of the clutch repairs we'd bump the horns back up and away they'd go.

As for failures, I can't foresee the horns breaking much less letting going away catastrophically. We beat the hell out of Baja bugs in the high desert, frequently bending frame horns, and the worst thing that ever happened was a few spot welds would separate.

I don't think there's a definitive right or wrong way as much as a right way for the application. If you don't trust the repair then swap pans. That's legit too. But I sincerely think that there's no harm in building a high-horsepower car on a pan with straightened frame horns, especially if it's been fortified with a truss bar.

The best points made. With an option for an alternate pan considered.

[rick m]

I was also thinking of straightening the horn and installing a truss bar for now. I want to change the pan later but that project is not in the cards right now.

RM

[j-dub]

Is there a reference point of where they are supposed to be? How do you know for sure they are bent?

[hotrodsurplus]

Is there a reference point of where they are supposed to be? How do you know for sure they are bent?

I use the extremely accurate reference of the engine in the engine compartment. If it's too tight, high, low, or loose against one side of the engine-compartment seal then the frame horns are bent--at least they're not in the right position to make the engine sit right. Same goes for exhaust. If the mufflers sit crooked then chances are the frame horns are bent. Of course given the poor quality of exhaust systems there's a good chance that they're off too. So choose wisely. I'd make the most dominant thing fit first (the engine in the bay) and then adjust everything to suit.

BTW, it's common for frame horns on pristine cars to be bent. The engine in the nicest, most original, never-hit car I ever owned sat too low on one side. The engine in my Thing--which I KNOW hasn't been abused--sits slightly high on the left side. We assume that cars have decent tolerances but that's pretty far from the truth. Cars--especially old ones--are actually pretty sloppy. They're disposable after all.

Volkswagen of course does have a more scientific method. As part of its in-field tool-fabrication instructions is a frame-horn alignment jig. Being German it's way too complicated but it is possible to make. Of course a perfectly straight frame horn matters naught if the body was put together crooked. The engine will still sit funny if the body is wrong. 













 

[OC1967vw]

Hotrodsurplus,
excellent reference material-should help RickM and all enthusiasts-myself included
many thanks

[Jon]

Great thread!

[OC1967vw]

Thanks for the tip.  Now it is pretty clear how you pulled it bac in line.  Thanks for the input.

Rick M

RickM, pictures posted above were instructive and reflect the factory's instructions on collision repair.
Todays body shops straighten frames all the time. A high tech chassis/frame table is a start. Given the horns,they should be able to tweak it back in shape
Many use laser measuring systems to enhance the repair effort and insure frame straightness and symmetry.



Oc1967vw, I agree 100% with you, all chassis get straightened after accidents, but the rear frame horns are a lot weaker than on normal other type chassis, again I'm not douting any advice given to rick just pointing out what I think.

Let me get this straight: you conclude  that the frame horns which hold a very heavy engine and transmission power unit are a lot weaker than other chassis types especially in the face of counterfactual evidence of the number of type 1/type 2/type 3 VWs and Porsche 356s and 911s on the road today (Porsche estimates close to 80% of all Porsches made remain on the road world-wide) ?

Perhaps your experience is limited to previously drag raced cars bought in the usa which would explain their bent frame horns due to previous track usage and subsequent and associated chassis damage.

Hotrodsurplus' comments are excellent in addressing any enthusiasts'concerns regarding frame horns (and corrective actions) especially his comments regarding off road use here in the states.
As evidenced by his display of Factory drawings and literature, the Factory anticipated such "normal" misalignment and addressed this problem with the factory-designed 671 tool in 1951 to correct such minor road use-related misalignment for the frame horns and engine/transmission cradle function.

What the factory did not anticipate was off road use (as indicated by the factory drawing date of 1951) and the related torque shift/weight transfer associated with road racing a rear-engined Volkswagen (and as we know such was the case in Germany. Not in their wildest imagination would VW Factory engineers anticipate the onset of and subsequent long term popularity of drag racing/off roading Volkswagens in the US in the mid 60s/70s.
The drawings are excellent in addressing this problem. Great example of Volkswagen addressing the problem in 1951. Last time I looked,there is not a history of powertrain units falling out of their cradle/frame hornsover the last 80+ years (going back to 1936 with the earliest Porsche designed factory prototypes or Porsche no.1 in 1948.

[Bruce]

Let me get this straight: you conclude  that the frame horns which hold a very heavy engine and transmission power unit are a lot weaker than other chassis types especially in the face of counterfactual evidence of the number of type 1/type 2/type 3 VWs and Porsche 356s and 911s on the road today (Porsche estimates close to 80% of all Porsches made remain on the road world-wide) ?

911s don't use Beetle type frame horns.  Never had anything like that.
Porsche gave up on weak frame horns by the time the 356A came out.  They had to add a hoop under the ends to hold them up trying to deal with only 60hp.
In the Type 2, frame horns proved too weak for STOCK drivetrains so they had to add a hoop brace around and under them.  Then they HAD to install a rear engine mount.
Type 3s also gave up on weak frame horns by adding the rear engine brace.
Your own examples PROVE how weak the design is.

[OC1967vw]

Thanks for your comments. I am sure someone will appreciate your thoughts.
However, I stand by what I wrote.

You certainly are entitled to your opinion as is everyone here.

Best regards to you and your projects.

[Jon]

In the Type 2, frame horns proved too weak for STOCK drivetrains so they had to add a hoop brace around and under them.  Then they HAD to install a rear engine mount.

And THEN they got rid of the framhorns/hoop brace and suspended the drivetrain from the roof above the engine (with the stock nose mount and rear engine mount).

[Russell]

Great thread!

I agree 100%

Hotrodsurplus fantastic reply and technical information with VW backup, looks like I stand corrected however if it was me I would replace the pan as I'm not sure I have the skills to do this correctly however I might build a tool to fit a NOS pan I have just to check when building my cars that they are close to the manufactures guidelines.

I wish all replys on this thread were as friendly as yours. 

[rick m]

Great information.  I have the ability to straighten the horns and may do so for now.  I am planning a new drive train for the chop down the road but not in the cards at this time. This has been a really informative thread...Thanks hotrodsurplus! In all the years I've been around this cars...I have never seen the information you provided.  I am sure a lot of people will learn something from this threat.  Like Russell,  I will even check the pan I intend to use in the future to ensure it is spot on.

Rick Mortensen

[hotrodsurplus]

Great information.  I have the ability to straighten the horns and may do so for now.  I am planning a new drive train for the chop down the road but not in the cards at this time. This has been a really informative thread...Thanks hotrodsurplus! In all the years I've been around this cars...I have never seen the information you provided.  I am sure a lot of people will learn something from this threat.  Like Russell,  I will even check the plan I intend to use in the future to ensure it is spot on.

Rick Mortensen

You're welcome, Rick. I'm glad I could help. Let us know how it goes.