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Help with Front Bumper mount Area


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1 hour ago, dutchzcarguy said:

In both pictures you have to keep the spirit level right up not upside down!  OEFFF!!!  🙈

Depends on the level and shape of the glass, a lot can be used both ways. 

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7 minutes ago, Patcon said:

Actually small torpedo levels like this normally have straight tubes and can be used on any of the 4 edges

Agreed, the top edge even has a V-groove to align on curved items like pipes. Mine's not a precision level but when I checked it on flat and angled surfaces the reading appears the same for both long sides.

Edited by CanTechZ
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On 4/20/2021 at 10:08 AM, 240ZBUILTBYME said:

Can anybody tell me if the front bumper bolt holes are meant to be level? I imagine they are. 

As you continue on this (unwanted) parted of your Z restoration, I think you will be well served by acquiring a couple of laser levels.  These have become less expensive since they were first introduced to the D-I-Y community and can be really helpful for checking and restoring panel and fixture alignments. 

One of the big challenges for these types of alignment measurements is, 'Aligned (or level) relative to what?' For example, the fact that the RHS bumper mount holes are level (as in, inertial level c/o a torpedo level) doesn't tell you whether they're at the same elevation (as in, height above the floor) as the LHS holes.  As an another example, ask yourself, 'How do I make measurements relative to the centerline of the car?'

I suggest the you buy a 'plumb' laser and a 'crosshair' laser.  The plumb laser will let you check whether you car's main structure is straight (use the reference points and dimensions shown in the frame diagram in the 'Body' section of the FSM).  The crosshair level will let you check alignments for various surfaces and reference points (e.g. bumper bolt holes) relative to a consistent inertial reference.  It will also let you be sure that the whole car is sitting level, left-to-right (front-to-rear can be done, too, but not so conveniently).  The combination of both laser types will be useful when you do your frame rail replacements. 

Of course, you can do all of this work without the lasers.  The lasers just make it easier and reduce the amount of guesswork.

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14 minutes ago, Namerow said:

As you continue on this (unwanted) parted of your Z restoration, I think you will be well served by acquiring a couple of laser levels.  These have become less expensive since they were first introduced to the D-I-Y community and can be really helpful for checking and restoring panel and fixture alignments. 

One of the big challenges for these types of alignment measurements is, 'Aligned (or level) relative to what?' For example, the fact that the RHS bumper mount holes are level (as in, inertial level c/o a torpedo level) doesn't tell you whether they're at the same elevation (as in, height above the floor) as the LHS holes.  As an another example, ask yourself, 'How do I make measurements relative to the centerline of the car?'

I suggest the you buy a 'plumb' laser and a 'crosshair' laser.  The plumb laser will let you check whether you car's main structure is straight (use the reference points and dimensions shown in the frame diagram in the 'Body' section of the FSM).  The crosshair level will let you check alignments for various surfaces and reference points (e.g. bumper bolt holes) relative to a consistent inertial reference.  It will also let you be sure that the whole car is sitting level, left-to-right (front-to-rear can be done, too, but not so conveniently).  The combination of both laser types will be useful when you do your frame rail replacements. 

Of course, you can do all of this work without the lasers.  The lasers just make it easier and reduce the amount of guesswork.

Thanks namerow Yes 👍🏽 this is on my tools list already. I guess I didn’t give an explanation of why I wanted to know the level orientation of the bumper mount holes.

At the moment trying to assess the damage and decide on a course of action. If I decide to repair the damage, which way am I going to need to pull the panel? Just forward? Or up/ down as well? Is it easier to use donor panels and patch it? This is what’s swirling around my head computer atm!

When I started making the rotisserie mounts I noticed one side was different to the other, as both sides are damaged I wanted a frame of reference to know which side is closer to where it’s supposed to be.

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3 hours ago, dutchzcarguy said:

HUH??  WHAT?? 🙊

Unless the car in these pic are upside down ... then you can mearsure it this way but as i can see the airbubble in the spirit level IT'S NOT!  You CAN'T use a spirit level that way!  In the middle green glass is a small bow.. this has to be with his bow always UP..

Am i the only one that sees this????  

You have to measure this with the spirit levels top side your holding it upsidedown.. this never works! 🙈

Bumper Bracket Holes.jpg

In both pictures you have to keep the spirit level right up not upside down!  OEFFF!!!  🙈

Some spirit levels have a barrel shaped glass, rather than curved. That way, the level can be used on top of, underneath, or beside the object being checked.

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Direction...

If you replace it, you have to source the part - done

Cut it off realign, weld, grind and limit distortion

If you repair it, you have to pull, beat and reshape it back to where it should be but all the metal is there in the close to proper amounts.

One concern is if the car took that big of a shot then the whole side of the engine bay could be off. Then you cut and patch it but the repaired section is still not in the right place.

My car was put on a frame rack and needed some significant pulling to get back to where it needed to be

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  • 2 weeks later...

So I bought a cheap self leveling level laser. And surprisingly

a) I did a great job of making the chassis jig square

b) I leveled the jig well

c) my car is not as crooked as first thought

basically every point I threw at the laser turned out to be perfectly level. 
 

lower radiator support 

2B29FE20-42DA-41A1-9818-73DBA5A2EFE5.jpeg
 

bumper mount holes (we will come back to these later)

6FE4E5B0-8AE2-42AD-8A80-1EA6C2006428.jpeg328E270B-F37D-4413-B1CA-A912DC954C02.jpegC4881434-CD19-43C3-8AF3-955D94B95F2E.jpeg
 

top and bottom of front strut towers (couldn’t get a decent picture of the top measurements but they were level)

DC9BE44A-1C0E-4B85-9EB6-DE54929A45FA.jpeg61B03483-EC6A-48B0-B118-BF9EDFD996BA.jpeg
 

Front frame rails all sweet, line is hard to see but it’s there

41DCA84C-1F62-4E57-AB3C-1425ABCAAD90.jpeg2928FB7B-1CCE-44B9-803F-E4411A69EAB1.jpeg
 

FF52415E-6F82-425B-A00A-278DBAB61FF2.jpegD8E449A3-A72A-463E-9F3E-AE55F7DAAB51.jpeg
 

also measured outer rockers which look good

174CE28A-5C8E-4257-9913-BBD286F71848.jpeg
 

and rear strut towers 

8DAC663B-3133-4B19-ACDC-315D65F6C004.jpeg635FBCB3-144D-47EE-9EE4-965647F4B5C3.jpeg
 

this gives me great confidence that the damage it saw was cosmetic to the front nose and not structural. Before I started building the chassis jig I did drop some plum bobs from the strut towers and measured diagonally to check the chassis was square before commencing building the jig. My measurements were 1mm different so I’m confident the frame is square enough. Is this good enough or would you guys still advise buying a plum laser and checking datum points from chassis diagram. 

cheers Ryan

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Posted (edited)

Now... the bad news. The bumper mounts are way off if I go by the level measurements mike gave me. (Frame rails and bumper mount holes should be on the same level) 

basically the holes are pointing down. My theory is during the accident the nose was pushed down, when they repaired they didn’t bring it back up to where it used to be. Somehow they were able to get all the panels to line up enough to make the car look ok. 

6E19FBF1-5099-42BC-B153-84692A11948D.jpeg96D58F2C-D357-4A21-90E2-626C334B7428.jpeg5A10136D-F441-4375-AAC4-8304D173D220.jpegDE5A56E4-7C0D-458D-B94B-84FA69AD12B0.jpeg

so now I at least feel I have a frame of reference as to where everything is and where it should be. Now comes the hard part... lol

 

Edited by 240ZBUILTBYME
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So what are your plans?

This will be hard for me to explain but I will try. Ok, the holes aren't level. So either the front hole has to move up or the back hole has to move down.  The material above the holes appears fairly smooth, so where does the extra metal come from to move a hole down? Or where does the extra metal go to move the hole up?

Now one possiblity Is the wrinkling behind the radiator support if smoothed would allow the bottom of the radiator suppprt to move forward. This would allow the whole triangle of the head light bucket to pivot making the bolt holes more level. Does anyone know if the radiator support is supposed to be plumb in the chassis?

Ryan was your radiator support removed or replaced?

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15 minutes ago, Patcon said:

So what are your plans?

This will be hard for me to explain but I will try. Ok, the holes aren't level. So either the front hole has to move up or the back hole has to move down.  The material above the holes appears fairly smooth, so where does the extra metal come from to move a hole down? Or where does the extra metal go to move the hole up?

Now one possiblity Is the wrinkling behind the radiator support if smoothed would allow the bottom of the radiator suppprt to move forward. This would allow the whole triangle of the head light bucket to pivot making the bolt holes more level. Does anyone know if the radiator support is supposed to be plumb in the chassis?

Ryan was your radiator support removed or replaced?

To be honest I was going to purchase the clean front cut I have found and wait until I am up to replacing/repairing front frame rails, then I will remove the radiator support. My uncle and I will then reassess repairing or replacing or a combination.

yes my theory is the same as yours, if the damage is pulled out the front nose/wheel well area the front will lift and bring everything closer to where it needs to be. I think once everything is blasted and the radiator support removed we will Be able to see what needs to be done. At the moment there’s a lot of guess work. 

I can see areas on the radiator support where the spot welds broke due to the crash it had. I can see where they’ve tacked it back together in places. It was not replaced as the accident damage is very evident. 

my goal will be to build my rotisserie and get it blasted. Then the fun will begin. 

Ryan 

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Nice to see that the X-Y laser gave you some encouraging measurements

Re your plumb bob measurements, I think you should would be quite satisfied with a discrepancy of only 1mm in your LHS vs RHS measurements. I think that's probably within the manufacturer's original build tolerance (which, in the 1970's was probably on the order of 1.5 - 2 mm for this type of long, front-to-rear measurement).  One question, though:  Did you measure both longitudinal (front-right to rear-right / front-left to rear-left) and transverse (front-right to rear-left / front-left to rear-right)?  If you only did the longitudinal measurements, then you still don't know whether the frame is lozenged (also referred to as 'diamonded', IIRC).

The plumb laser will make these measurements more convenient and more accurate.  Trying to hang a plumb bob string from the center of a bolt hole or bolt head is not that easy to do with accuracy (especially if you're lying on the garage floor). 

At the back of the car, you should be using the 'C' points (holes in the rear subframe, just behind where the interior floor pan kicks up) as your reference.  At the front of the car, you should use two different sets of reference points: 1) the front (or rear) LHS and RHS crossmember mount holes in the frame rails, and; 2) the centres of the big holes at the top of the two front shock towers.  (1) will tell you about the alignment of the lower structure and the lower front suspension pickup points. (2) will tell you about the alignment of the front suspension's upper pickup points. 

Re the front bumper mount holes, I suggest you wait for corroboration from at least one additional owner of a damage-free Z to feel confident that they're supposed to be 'level'.  Although logic says that this should be the case, you just never know.  You have a lot of prospective time and effort a stake, so best to not begin until you're as confident as possible about what is 'correct'.   Also:  I'm leery about the float-level measurement methods that I've seen so far.  They measure relative to an inertial level, but you can't be sure whether both cars are sitting at the same pitch angle (aka 'rake angle') relative to inertial (or, for that matter, whether the floors underneath them are properly level).  Ideally, 'level' for the bumper mount holes should be judged using a vehicle frame of reference.  Your X-Y laser can do that, but the float level measurements may be suspect.

Another thing:  Note that the front and rear bolt holes are drilled pretty close to each other, which means that any errors made in sighting on the bolt hole centers (or the bottoms or tops of the bolt holes) will greatly exaggerate the measured front-to-rear angle.  If I was doing this, I'd use a compass to draw a bolt-hole-sized circle on a piece of wide masking tape and then draw on crosshairs. Then I'd stick the tape on the body panel over one of the mount holes.  Now repeat for the other three mount holes.

One last idea (which you can take or leave):  If you conclude that the bumper bolt holes really are out of whack, you might consider trying a bit of 'caveman' body alignment as a low-cost, low-impact first step.  Take some of the square tubing you have left over from your frame rig construction project and cut a pair of 8-foot lengths.  For both, drill a pair of correct-size holes at one end that are at the same spacing as the bumper-bolt holes.  Bolt the legs in place on the bumper/hinge-mount body panel, one one the outside of the panel, the other on the inside, securing them in place with two pieces of threaded rod (or a pair of really long bolts).  Now you have a hefty 8-ft lever that's solidly mounted to the bent panel.

If the front bumper-mount hole is higher than the rear one, you'll need to push down on the end of the lever. In this case, I would suggest you build a solid side-to-side wood trestle to put under the front of the front frame rails, right behind the rad bulkhead.  Also, put some counteracting weight in car's hatch area (sandbags, more left-over frame-rig tubing, a couple of willing bystanders, whatever falls readily to hand).  Now push down on the end of your lever and see if you can get that sheet metal to shift.

If the front bumper-mount hole is lower than the rear one, you have a slightly different proposition.  In this case, you'll need to lift up on the lever and that wood-trestle support-behind-the-rad-bulkhead idea isn't going to happen.  When you lift up on the end of your lever, you'll really just be trying to lift the whole front end of the car (and support frame) off the garage floor.  I'm too lazy to do the math, but I expect you won't be able to put more than 100 lb of lift onto the end of your lever arm before the vehicle and support frame start to lift off the floor.  Still, 100 lb of force on the end of an 8-ft lever might generate enough torque on the panel to shift the local sheet metal in the process.

And if none of this works, you can always move on to Plan B (hammer, dolly, torch).

Disclaimer:  I haven't tried the lever idea, so I can't guarantee that it will work.  Or be safe.  Caveat emptor.

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Keep in mind that all of the repair work in this area needs to be done on the jig, not on the rotisserie. The lever idea might work really well if the radiator support was out of the way. Put some force on the lever and then dolly the crumpled area behind the radiator support.

Does anyone know if the radiator support is plumb in the car or square (90d) to the frame rail?

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8 hours ago, Namerow said:

One question, though:  Did you measure both longitudinal (front-right to rear-right / front-left to rear-left) and transverse (front-right to rear-left / front-left to rear-right)? 

I measured diagonally, so rear left to front right and vice versa. I didn’t go longitudinal as I wanted to make sure it was square and not diamond as you say. But doing a longitudinal measurement as well would be prudent. 

I like the lever idea for its simplicity, however my front bolt hole needs to come up so may be less effective. As the car will lift before I get enough force on the panel I feel. When I was building the jig I purposely placed the longitudinal 3m lengths in line with the panel that the front fender rests on/bumper mounts onto, as I knew I may need to do some pulling. Also saw in @ConVerTT ‘s thread that he used  the longitudinal lengths on the jig to lever a scaffold pole into and clamped a chain onto the nose and did some pulling. Not sure how much force this places though. 

I had a similar idea of building a 90 degree pulling arm and brace that slips onto the 3m longitudinal length and use a come along and chain/clamp to pull that way.  more technical to build but more versatile in directions it could pull in. Place the panel under tension then hammer and dolly damage.

8 hours ago, Namerow said:

Re the front bumper mount holes, I suggest you wait for corroboration from at least one additional owner

I agree that the bubble levels aren’t the most accurate method but I have to take what I get lol A second set of measurements would be fantastic is anyone out there is able to help?

2 hours ago, Patcon said:

Keep in mind that all of the repair work in this area needs to be done on the jig, not on the rotisserie

Yep that’s the plan Patcon, all structural work will take place on the jig. Rotisserie will be used for blasting and epoxy, removal of undercoating, some stitch weld finishing and painting the underside when the time comes. 

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Does your work area have a concrete floor? If so you could bolt the jig to the floor and use a hydraulic bottle jack under the lever. Then hammer and dolly

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1 hour ago, Patcon said:

Does your work area have a concrete floor? If so you could bolt the jig to the floor and use a hydraulic bottle jack under the lever. Then hammer and dolly

Yes it does sir, that’s a great idea! Definitely a good option 

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12 hours ago, 240ZBUILTBYME said:

I like the lever idea for its simplicity, however my front bolt hole needs to come up so may be less effective. As the car will lift before I get enough force on the panel I feel. 

Further to Patcon's suggestion, you could also consider sliding a next-side-up extension tube over the end of the longitudinal floor runner of your frame rig and then using that as a reaction structure (i.e. put the bottle jack between the extension piece and the lever arm).  Depends on how long the existing frame 'stub' is.  I don't think I'd try this unless that stub is at least 18" long (which your pictures suggest to be the case).   The reaction load (which would be tension, not compression) would be taken out of the vehicle structure through the front-most support point of your frame rig.  Right now, I believe that is at either the front crossmember location -- which is a good distance back from the rad bulkhead.  I'd like to see the reaction load being taken up further forward.  Maybe you could rig up a chain, looped over the lower part of the rad bulkhead and then anchored to the top of the new extension tube by way of a couple of (sturdy) welded-on eye-bolts.  Include turnbuckles in the two chain drops so that you can pre-tension the chain.

While considering how this 'adjustment' might take, it may help to stare at the following two pictures for a few minutes while asking yourself, 'What panels deformed during the collision event?' and then, 'How can I un-do that deformation?'.  The panel's main strength in the vertical bending plane comes from that long doubler panel (which has been removed by the owner in the top picture). It works with the main stamping to form a box section (which is sometimes referred to as the upper frame horn).  However, notice how that box section is weakened near the front by the big hole punched in the main panel to form the fresh air inlet for the car's cabin ventilation system.  I suspect that that's where the deformation happens in a front-end collision.  In fact, in the lower picture it almost looks like the outer wall of the doubler plate has been kinked.    For reference, I've added a third picture showing a pair of virgin OE doubler plates.

S30 - Front Top Rails 1.jpg

S30 - Underside, stripped 4.jpg

 

S30 - Front Upper Beams 1.jpg

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Also this repair would be easier if you remove the doubler plate so you are not fighting the boxed section. You could remove the whole thing or just cut it far enough back to be past the damage. Then remove that portion. Then you can dolly both pieces inside and out. Weld back in with a butt seam and smooth them out. Also like Namerow suggested you could hold the car down closer to the front to reduce the stress on the frame rail. You could go on Ebay and order some frame clamps. I have an assortment that I use with come-alongs or chain binders for lighter damage work

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@Patcon @Namerow 

all great ideas, I wish I could get stuck into it already! 

my damage is as follows, lines indicate crumpled metal. Arrow indicates direction I need to pull which is why a pulling frame may be the way to go. 

A39D2BA9-A189-481B-9BD6-2EA2F3ADF827.jpeg

I do also have provisions to build a frame that bolts into the sway bar mounts but this frame will only be 25mm or 1 inch tubing, but would still bring the force forward. 

yes I will be removing the doubler panel as you call it, namerow you are correct in saying it is the weak point and if you look at my photos you’ll see mine was folded where that dimple sits. I will be cutting and replacing that damaged section with the clean front cut I have. 

 

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