'72 K5 - Greg's @MightAsWellK5 Build

[AJs72K5]

You need to see if you can get ahold of this guy and his molds...

http://67-72chevytrucks.com/vboard/showthread.php?t=301706&highlight=prerunner

 

[Greg72]

Yeah, well that guy seems to have fallen off the face of the earth..... and I'm not sure I'd really be comfortable letting someone else build something as important (visually) as fenders for my truck.

I've been mulling over several ideas, and I'll probably build a large wooden fixture over the weekend to hold the fender in place so that I can start templating and re-working the opening. The idea that seems to have the most merit is to open the wheelwell about 4" at the bottom ONLY (2" on each side) and build the entire arch larger, but don't allow the opening to get taller on the fender. Basically, imagine whatever the centerpoint is to draw the current fenderarch radius. (It's about 19" down from the top of the arch)... That gives me a 38" opening for the tire as seen in the previous photos, but since I need a couple of extra inches on both sides, the radius needs to grow to maybe 21" to give me the larger opening.

The trick is that instead of using the same centerpoint to draw the new arc on the fender (which will make the opening taller as well as wider), I drop the centerpoint down by 2" so that the arch stays the same overall height.... This allows the fender to get wider in the areas where it needs to, but doesn't end up with a massive gap above the tire where it is unnecessary anyway.

There will need to be some "finessing" of the curved shapes as they pass across the side "style lines" on the fender, but I think that will be manageable and the overall appearance could end up VERY close to a "stock" fender and would preserve the original look better than just making it 2" larger everywhere.

I just ended up buying a Saginaw-800 steering box off eBay for my "mock up" work, and it's going to take about a week to get here (from Arizona) so I won't be able to do much steering layout this weekend... My objective will probably be to move the wheelbase back to 105" by moving the front frameside link mounts back another inch, and spend the rest of my time on the new fender fixturing and trying out a couple of different fender arch ideas.


-G

 

[NorCal69]

If you still need some extra "Lip", give me a call. I think that I have three or four fenders that I could cut it off and send to you.

 

[Greg72]

I definitely will need some extra material to work with, so if you're willing to send me some of that delicious "rust free" CA metal, I'm game.


-G

 

[miniwally]

I gotta run to a meeting but don't forget about articulation.

I think you need more "trimming" than you think.

 

[ashman]

If you still need some extra "Lip", give me a call. I think that I have three or four fenders that I could cut it off and send to you.

You givin' me lip boy!?!

 

[AJs72K5]

Certainly wasn't expecting you to outsource the work. Was thinking more along the lines of "borrowing" the molds. But as you said, he's been scarce for a while.

 

[Greg72]

The templating process is underway...

-G

 

[Greg72]

More fender progress....

I finished up the basic fixturing and was able to find the current center point for the stock wheel arch. The radius turns out to be a fraction less than 18".

Then carefully marked a 2" larger radius from the same center point to cut of what should have been a generous wheel opening.

Cut it out and re-hung the fender with a 1.5" spacer between the door and fender to see where things would end up with another axle relocation.

EDIT: It's a little hard to tell, but this photo represents "full stuff" of the axle. The axle is actually jacked 6" off the ground on both sides.

Turns out, the axle really wants to be at 104" for the wheel opening to work properly and to have clearance at both the front and rear of the fend arch. As it turned out, once I moved the axle back 2" more inches, the new wheel opening was just BARELY big enough with the extra 2" clearance all the way around. Fully stuffed, the tire barely misses the lower fender corners on hard left & hard right turns.

So obviously, the new fender opening is disturbingly huge so I started to try the idea of lowering the upper arch (while keeping the full width across the bottom) to see how that would look.

More work is needed to get that 1/4" rod shaped perfectly, but it seems to be coming out well... I'm looking forward to getting the wireframe tack welded and rehung on the truck. Being able to stand back a few feet and see if this shape is working or not.



-G

 

[rdn2blazer]

Great work as usual Greg. Love reading up on your build .

 

[dremu]

As always, ridiculously beautiful, meticulous work there Greg.

But tell me, is that wooden work surface a table you use frequently, or did you built a test jig / fixture just for the fenders?

-- A

 

[4X4HIGH]

As always, ridiculously beautiful, meticulous work there Greg.

But tell me, is that wooden work surface a table you use frequently, or did you built a test jig / fixture just for the fenders?

-- A

In a recent post not far up he said he was going to build a "fender jig".

 

[dremu]

In a recent post not far up he said he was going to build a "fender jig".

musta missed it. This truck is gonna be one of those that you won't want to get scratched, you know. The smallest dent will destroy 100 hours of painstaking work

-- A

 

[ktmoutfront]

I was going to post up about the first dent, after all that work. I was sick when laid mine against a tree for the first time. It was straight until then. But it was stock body.

I have have to give him props for spending 40+ hours per fender, and then willing to rock rash them.

 

[Greg72]

I was going to post up about the first dent, after all that work. I was sick when laid mine against a tree for the first time. It was straight until then. But it was stock body.

I have have to give him props for spending 40+ hours per fender, and then willing to rock rash them.

Yeah, that fixture is new. It started out as a 4x8 sheet of 3/4" MDF, a few 2x4 scraps, some glue and drywall screws. Based on the way that the fixture is built and locates the fender (indexes are the side marker light holes and fender badge holes) this is only going to work for the passenger side fender. I'll have to build a mirror image fixture for the drivers side.

Yes, this fender is taking quite a bit of time to figure out but there is some solace knowing that quite a bit of the effort had more to do with positioning the axle correctly than actual fender work. And once I get this first fender figured out, moving from prototype to finished fender (and then duplicating this effort on the opposite side of the truck) will go significantly faster.

Of course, having fixtures in my garage will be helpful if I ever decide to build more fenders in the future (due to damage or just helping out my 1st Gen brothers )

Keep on mind, the bodywork on this truck is being designed to be removeable for wheelin' adventures. So if I'm going on a trailride where I know that damage is likely, I will leave the fenders at the campsite. There is always a chance that unexpected damage could happen, but I'm not going to cry about it if it does. The labor to "fix" a dented fender is nothing compared to the hours I'd spent initially designing them.....

-G

 

[NorCal69]

Looking good, Greg. That should be pretty easy to form, beat and re-weld back to somewhat of a factory shape...


Crazy man, just crazy work.

I'll look tonight what I can cut up and send ya. By the looks of it, you might need a little extra scrap.

Are you going to keep the entire circle all the way down, or is the back of the fender going to angle back some towards the firewall?

 

[Greg72]

Mike,

Give me a call before you cut any fenders into pieces and I can describe what I'm after...

The factory shape is an almost perfect 18" radius (36" circle) until it gets to the beltline (that styleline about 2/3 of the way down)... then it slowly tapers outward at the rear of the fender, and actually tapers INWARD on the fang side. If you look at the photo I posted before I cut out the lip, I have a 20" radius (40" circle) outlined in green tape. It's really educational to see that perfect circular shape superimposed over the stock curve....if you study it a while it really teaches you where the subtle changes need to be to replicate a "factory look".

At this point, I literally have something like 1/4" of clearance at the very bottom corner on each side (at full stuff), so I am going to go back and trim another 1/2" all the way around that opening to give myself a bit more margin-of-error. Then I'll reshape that rod to get the curve optimized... the other trick is that the fender arch is not just circular in a single-dimension, it also curves downward toward the underside of the truck. I'm spending quite a bit of time making sure that my fixture captures the correct profile of that curve also so that it can be replicated with the new larger fenderlip when it gets attached.

Fun stuff!!!


-G

 

[CUCV2]

Yeah, that fixture is new. It started out as a 4x8 sheet of 3/4" MDF, a few 2x4 scraps, some glue and drywall screws. Based on the way that the fixture is built and locates the fender (indexes are the side marker light holes and fender badge holes) this is only going to work for the passenger side fender. I'll have to build a mirror image fixture for the drivers side.

Yes, this fender is taking quite a bit of time to figure out but there is some solace knowing that quite a bit of the effort had more to do with positioning the axle correctly than actual fender work. And once I get this first fender figured out, moving from prototype to finished fender (and then duplicating this effort on the opposite side of the truck) will go significantly faster.

Of course, having fixtures in my garage will be helpful if I ever decide to build more fenders in the future (due to damage or just helping out my 1st Gen brothers )

Keep on mind, the bodywork on this truck is being designed to be removeable for wheelin' adventures. So if I'm going one trailride where I know that damage is likely, I will leave the fenders at the campsite. There is always a chance that unexpected damage could happen, but I'm not going to cry about it if it does. The labor to "fix" a dented fender is nothing compared to the hours I'd spent initially designing them.....

-G

How is the enlarged front going to look with the stock rears? Are they going to need the bonus size openings as well. You are definitely headed into one of a kind territory now . Just reread the quote in your sig. I sometimes look at what you are doing and go wow, what?, wow, is it worth it?, wow, now I get it, WOW!.

 

[Greg72]

How is the enlarged front going to look with the stock rears? Are they going to need the bonus size openings as well. You are definitely headed into one of a kind territory now .

Funny you mention that...

One of the things I discovered over the last few days was that some of my original thinking about the wheelbase and location of the axles was fundamentally flawed. This truck came with a 104" wheelbase (stock) and I'd stretched it to 107" with my old leafspring setup... that was roughly 1" added to the front axle, and 2" added to the rear.

When I built the new 4-link rear suspension, I tried to keep the wheel perfectly centered in the wheelwell / fenderwell. Every stock Blazer I'd ever seen photos of always had the rear tire "forward" in the wheelwell (especially noticeable when the truck is lifted) so I figured that by centering the tire in the wheelwell, I'd be adding a couple of inches to the wheelbase. As it turns out, the location of my rear axle currently is not really all that far back....certainly not as far as I'd predicted.

Take a closer look at this photo again:

When I originally installed the rear axle and moved it back, I had to cut the fender... but if you look carefully, you can see that the cut is very asymetrical. Most of the clearance is on the trailing edge of the fender with almost NO trimming at the leading edge. This is a clear indication that the axle is not in a stock location anymore, and ultimately, this is what I have decided to do again on the current build.

Yes, the rear wheel opening is too small for the tire to actually stuff into it, so it will need to get larger; probably not as large as my new front fender opening but even the factory used smaller rear openings originally. The main thing is that I will build the new rear openings with a significant "offset" towards the rear of the truck so that the fender will grow in that direction. That will allow me to move the axle back a couple more inches from where it is now. (Current wheelbase as of this moment is back to a stock 104"). I think 106" will be pretty reasonable to achieve...maybe just a touch more depending on aesthetics.

The good thing about pushing the rear axle back another couple of inches is that I'll gain some much needed departure angle in the process. My front approach angles are already quite good, so there's not as much value in trying to move the front axle forward, especially considering all the trouble it causes with the fender / radiator, etc. Those rear overhangs were definitely more of an issue during actual 4-wheeling than the front overhangs ever were.

I guess ultimately for weight distribution it would be better to stretch things in the front, but I've already moved the entire drivetrain back a few inches so there's a pretty good chance that my front/rear weight distribution won't be any worse than it was originally.


-G

 

[CUCV2]

I like the idea of growing the opening towards the end where the wheelbase is stretched. That is what I thought was going to happen with the front fenders. The back of the front fender seems ok with no mods. It is just the front opening. Basically, from the fang and up another 6". Seems like there should be a way to localize most (if not all) of the work to the front of the fender. It is still hard to visualize your end result with the door/fender gap and radius enlargement. I am looking forward to it though.