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FastWoman

Bumpers -- shortening the projection of the rear bumper?

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OK, here's a pic of my stock '78 280:

280zblueengine08.jpg

Now, everyone likes to criticize the "cow catcher" or "park bench" bumpers on these machines. However, I'm one of the few people who thinks the front bumper is really sexy, in a late '70's sort of way. It adds length to the front of the car and is visually a leading edge that gives the car the same sort of pointy nose as found on a G-nose (also an incredibly sexy style). It's visually a bit like the pitot tube of a jet fighter or the bullets in the grill of a 50's Buick.

My complaint is about the rear bumper, which does look like a park bench and sticks out in a very non-aerodynamic sort of way.

So what I'm wondering is this: Has anyone ever shortened the projection of the rear bumper, bringing it closer to the body? Perhaps there's another solution that wouldn't look strange when paired with the current front bumper? (A 240 bumper would look too light, visually.)

Any ideas that would look right and still preserve the late 70's styling in the front?

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I think the struts holding the bumper are part of the problem. If you search for info on converting the bumpers to 240Z style, part of the process is killing or removing the struts. I think one of the challenges would be what to do with the end pieces of rubber since they would be pushed further forward. It might not improve the looks.

There, I managed to write that whole post without any sort of remark like, "Does this bumper make my rear end look big?" Okay, so I ALMOST made it through the whole post...

Edited by SteveJ
Just simple rephrasing...

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Well I think the front one sicks out a little also on the 280Z, but it makes since why.

What about a 240Z rear bumper with blacked out sides.

The other idea I had was cut the original bumper along the back so it would be in line with flared curved part above the bumper, think that would look very nice. Then mount it like the 240z bumpers are with a bracket. Now the problem I have is how to match the sides (I don't have a bumper to look at for ideas on that). Also its rubber, not easy to cut and bend into new shapes.

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Steve, I wonder whether the struts can be shortened or substituted. Or maybe you can just put them into a press and squish them! ;-)

I was contemplating the issue of the rubber. I know this sounds somewhat extreme, but how about making a mold set for shortened end pieces and then casting the rubber parts? Some Model T guys seem to like this product:

http://www.jgreer.com/make-concrete-mold.htm

Hey, imagine all the other places we could use this stuff! Woohoo!

AJM, the 240 rear bumper just looks like it's from a different era -- not matching the front bumper in style. I'm thinking a bumperless style could almost do, but I'd really like to have a bumper behind me.

Your idea of going flush with the trim piece over the bumper sounds pretty good. I'll have to look over the situation tomorrow in the daylight.

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If you get into molding rubber I have some ideas of other things to make also

I suspected you wanted the chrome bumpers, if not MSA has a kit to give it the molded bumper look.

For the sides of a modified bumper, without the struts, you could make a steel or fiberglass peices and coat them in rubber to get the look. It won't need to flex since the strut would not be moving.

I don't think compressing the strut fit your problem unless you release the pressure prevent it from decompressing. The other idea I have is to use a pipe to replace the strut then you can cut it to the size needed. Also I notice people are always looking for thouse struts so you have something to sell or keep it you wanted to revert back.

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Steve, I wonder whether the struts can be shortened or substituted. Or maybe you can just put them into a press and squish them! ;-)

That may be one of the things people have done. I'm getting too old to remember all of the posts I've read, though. I think you might be able to dig around zcar.com and find something on the subject.

I was contemplating the issue of the rubber. I know this sounds somewhat extreme, but how about making a mold set for shortened end pieces and then casting the rubber parts? Some Model T guys seem to like this product:

http://www.jgreer.com/make-concrete-mold.htm

Hey, imagine all the other places we could use this stuff! Woohoo!

That could work. Now all you need to do is find a 3-D printer, and you could make your own molds...

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I've got a pair of 240 bumpers that I'm going to use. I prefer that look. You might want to look into a 75 bumper though, or even a 260 bumper. The bumpers got larger each year. The 75's are a little smoother on the rubber and look to me to be a bit shorter. They will probably bolt right up too, although you might need some bodywork to smooth out the quarter panels.

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AJM, a couple of machined pipes might do the trick.

I thought of doing fiberglass pieces for the sides, as I've done a lot of fiberglass work on boats. The thing is, though, I'd need to make a mold anyway. Might as well pour polyurethane rubber into them. In fact that would be a lot easier.

Steve, I'm thinking I could make molds of my current bumper ends, chop and recombine the molds to shorten them, and then pour them.

Cozye, I had forgotten how rounded the '75 bumpers are. That might indeed be a better look. Is the '75 bumper actually shorter, or does it only look that way? I do remember on the '75 how big a pain the rubber bumper ends were. They're more prone to ripping than you'd think. Also do the bumper ends bolt to a flat/smooth quarterpanel, as opposed to a recessed area on the '78? Is that what I'm understanding? (If so, that might be why the '75 bumper rubber was such a headache.)

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Not sure on the 75 mounts. They just look smaller to me and I thought I'd read that the 77-78 bumpers were increased in size over the previous 280.

You don't think the 240 bumper with the rubber and extra bumps removed, holes filled in and chromed look good? That single clean chrome line of a cleaned up 240 bumper is the cats meow to my eyes!

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Cozye, I think the 240 bumpers look fantastic. However, they really have the look of a late 60's car -- shorter, more rounded -- very cute, but not my gig. The 280Z had a very unique style of its own that was defined by that front bumper. I know that we all must have grooved on the style back then (i.e. it wasn't my own quirky tastes), because the wedge formed by that bumper was carried forth to the '79 ZX (not my favorite style, but just saying...).

Not many cars had this sort of wedge-shaped nose. Only a few come to mind -- the Pantera, the TR-7, the RX-7. But what makes the Z stand out, IMO, is that cool floating, chrome bumper. Unique! :)

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I understand. I tried to convince myself it had character, embraces the late 70's, and that I wanted to keep it. I couldn't get over it though. I decided to cave ;)

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These are the 5 mph damage control bumpers, with shock absorbers inside the mounting struts. I have seen somewhere, that you can either compress the shock, drill some holes and lock it in place (creating a big surprise for a future owner) or I think that you can carefully take them apart and remove the springs before locking them in place.

There is actually a section in the FSM, BF-8, for testing the bumper shocks, bracing the car with wheel chocks and putting the factory jack between the wall and the bumper. It's illustrated, showing a jack, and a rag to protect the bumper rubber.

I don't know how much distance you'd get, but it might be enough.

Edit - I see that compressing the strut was mentioned above, but here's a little more detail anyway...

Edited by Zed Head

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These are the 5 mph damage control bumpers, with shock absorbers inside the mounting struts. I have seen somewhere, that you can either compress the shock, drill some holes and lock it in place (creating a big surprise for a future owner) or I think that you can carefully take them apart and remove the springs before locking them in place.

That's what I recalled reading, but since I was too lazy to search for the description, I didn't try to give specifics.

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I did that to my '74.

Before (black plastic pieces removed)

bump1.jpg

Shocks compressed and welded

bump4.jpg

After

bump3.jpg

Once you take the bumper off of the shocks, you will see a small screw in the middle of the mounting flange on the shocks. Remove this screw and the pressure will be released from the shock. Compress it to your desired length, and weld/drill/bolt it to secure it there.

Hope this helps. :beer:

Edited by g9m3c

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No offense, but I personally don't like the look of the big bumpers. As everyone knows, they were added due to U.S. federal regulations and they completely changed the look of the original S30 design. However, I know that you like the late '70s look and I think that the look of the early 260Z bumpers isn't a bad one, so it would be a good compromise between the 240 and the late 260/280 bumpers.

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If you move the bumper inwards could you then cut out two or three "ribs" from the bumper ends and glue them back together using bumper compound?

I have repaired the ends on mine using it and reinforcement mesh and they seem to be holding up well, you cannot even see they were damaged.

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Thanks, Texas! Yeah! That looks sharp! :cool:

The rear bumper guard has a different shape (other than having a couple of ribs removed) than the stock '77/'78. Specifically, it doesn't project out in a dorky mound. Rather, it just covers over the end of the bumper. I'm wondering whether this was some sort of custom-molded bumper guard. For reference, here is the stock look -- same as mine:

http://www.triadzclub.com/z/classifieds/Mar%2013_08/1977Datsun280Z/index.html

Having thought about this a bit more, I'm wondering whether I could compress the shock to the length I want, drill a hole through it someplace that won't compromise the mechanics of the shock, and put a small diameter bolt through the whole thing to keep the shock compressed. In the event of a collision, the bolt could shear, and the shock might still provide some shock-absorption protection. If desired, the bolt could be removed to restore the bumper position to its stock configuration (also replacing the original bumper guard).

I'm thinking I'll be able to mold my own custom bumper guards, but I'd love to find the pictured ones ready made. Do you know if they exist somewhere?

Edited by FastWoman

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On your bolt idea would it be easier to just wire it into place, then no hole drilling into the shock and the shock would be allowed to compress. In off road racing they will use a retention strap to keep the shock from fully extending and smacking the valves damaging or breaking the shock. On one end loop it around the mounting point then under the car from the hole for the shock and to that mounting point. You might need to use cable so to keep it tight refer to garage door cables to make the tension part.

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I like that idea, ajm. In fact I wonder if a turn-buckle could be incorporated to adjust the shock compression. Hmmmm....

On a previous topic, a thought about the bumper guard: Maybe the humps on the pictured rear guards were cut off, sanded smooth, and polished?

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The thing I like is you can adjust it later if you want.

On the bumper guard in the last picture it looks like they cut them on the seam and glued it back together taking a couple ribs out

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Tomo, see post #16. I've never used the stuff personally, but this sounds like a promising approach. I'd personally rather try to create a new part than to hack up an old part.

Which little round plugs?

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The stuff in #17 won't glue your cut-up bumper ends. Its used to repair scratches & fill gouges in the bumper covers on newer cars.

I'll bet 3M has something that will glue the cracked or cut bumper end parts.

The round plugs are the ones that cover the screws on the side where it attaches to the sail panel.

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