The Stovebolt Site Forums The Shop Area Paint and Body Shop Using Fender Holes to Validate 116" Weelbase - 52 3100

Since I have been assembling my 1952 3100, I have been wondering if I have the wheelbase as precisely at 116" as the specs call for. I have measured it a number of ways but I decided to wait (before I ordered a new drive shaft) until I put the bed on to see how the rear wheels fit within the femder on the bed. Well, as I test fitted the bed onto the frame, I noticed that the top (highest) bolt hole for the fender seemed to be directly over the center line of the rear axle housing.

Does anyone know if that is a correct assumption... that dropping a blumb from the center of that top hole should point to the center of the axle housing? If so, I will stop obsessing and measure for the drive shaft.

Thanks

weelbase, blumb, fember... I must be getting old... either mind or eyesight going... maybe both.

LOL! I think speelcheck got you.

I think you're going to be close enough that it won't really matter. You're not going to move the axle, right? Who's going to know if it's just a smidgen off?

I could go out an look at my truck, but it's covered up and I'd have to get under the fender. I might be getting too old to do that for you.

Thanks Kevin;

I need to get over my pursuit of perfection. It is just not a productive effort. Good enough ought to be good enough.

Just FYI, I really can move the axle forward and/or backward (an inch or so) by dialing the Johnny joints at the end of the 4 link bars. There is also a panhard bar that helps the keep it centered. Other than that, the coilovers hold the axle to the frame (Hot rod stuff that probably belongs in the HIPO area). The pinion angle can also be adjusted via dialing the Johnny joints.

The background reason I was being so obsessive is because I have to cut into the sides of a new Mar-K bed ( I bought it maybe 2 years ago) to put in mini-tubs and I am trying to make sure the wheels are where they should be before I hack into the sides of the new bed.

Thanks for always looking out for me. Just being able to dialogue with you and other Stovebolters gives me the confidence to keep going.

I always thought the stock 1/2 ton AD trucks looked like the rear wheels sat a little "forward" in the opening in the fender. This would be a good time to resolve that problem, if it actually exists (says the guy with a flatbed who doesn't even have rear fenders).

Bill... I will augment this thread with a picture of how the wheels fit within the fender, when I bolt a fender on to check it out... stay tuned, and thanks for the perspective.

Pat, here's a picture of my truck pretty much straight-on to the rear wheels. You can see that the rivets for the fender support are basically directly above the wheel center. That support also bolts to the topmost fender bolt. You can also tell that the wheel is slightly forward of the fender opening (if my arm wasn't in the way.)

If Kevin would move his arm, you would see that the 3 o'clock position of the tire is much closer to the opening of the fender than the 9 o'clock position.

I printed Kevin's picture and placed a plastic drafting square across the top of the bed and dropping down through the center between the two rivets. The line ended up about 1 1/2 inches to the rear of the center of the axle.

The rear axle of AD trucks sit 2" forward of the centerline of the wheel well

Good perspectives gentlemen.
Kevin... I don't deserve having you crawl under your truck for this thread, but of course, I am grateful.
Stovebolters, it will be a few weeks before I get a picture of tire-within-fender and fender-on-bedside. My rims are 9.5 x 18 with 5" backspace and rear tires are 275/40 R18. I have a set of mini tubs but I am noodling on cutting down the height of the tubs. As they come out of the box, they are 10.5" high with an additional .75 flange on top. That flange collides with that top (highest) fender bolt. I really do not need all that vertical space. I calculate at most, I need 5" tub height and the .75" lip.

To condense the wait time on seeing where my wheels are positioned, I am going to bolt a rear fender on and "fake it" with the tire by just aligning it with the studs and having the tire rest beside the hub instead of being bolted to the hub.

Thanks to all of you for giving me insight into what to shoot for.

No worries Pat, my wife took that picture of me last July. So I didn't crawl under it just for you. I think I was installing the running board apron in that pic.

I bolted the driver side fender to the new Mar-K bed (fender not adjusted to any degree) and just placed the tire and wheel where they matched the studs to simulate the placement of the wheel within the wheel well. Based on the guidance that all of you have shared, I THINK it positions pretty well. Please let me know if you would rather see it more forward or more rearward, as I can dial the 4 links to achieve small movement fore and aft.
As I said previously, my hangup is that I have to measure fairly accurately for a new driveshaft, so once we have the wheel positioned well (within the wheel well), then I can measure for the new driveshaft.

Thanks to all for helping me make this build "more better".

What is your goal?

Since it's a custom job, there is no right or wrong where the rear axle rests.

If you want the truck to appear stock to the casual observer, then move the wheel forward of the wheel well centerline by 2 inches. That looks to be about 3 inches from where it is right now.

.

The question remains - Where exactly is the wheel well centerline?

If you measure at the bottom of the fender, it's one place, if you go by where the support rivets are, it's completely different.

If everything else is stock, then set the wheelbase at 116" measured from the front wheels and be done with it.

The 116 is what I did months (OK years) ago when I was assembling the chassis with no body parts as reference. Measured 116 in a number of different ways. So... we are calling this DONE... I always have the option of a little fore and aft movement as the assembly moves forward.

Thanks again all!

Next step is mini tubs.

What is the diameter of your tires? They look on the small side in terms of diameter. I have seen them in person. They are not lacking in width. Very meaty.
28" stock tires on a stock truck will look much different than a shorter tire.
Stock height tires will have their leading edge slightly behind the leading edge of the fender.

Carl, the diameter of all 4 tires is 26.66 inches. Please know that the picture of tire-in-fender well is with the truck on a lift, so rear end is suspended in air.

My dirveshaft (when I finally order it) will have a slip yoke which gives maybe a 1/4 inch room for error on specifying the length of the drive shaft... that is really all that I have been obsessing aboout (this time around). I would like to have the wheelbase as close to 116" as is practical, and after measuring a number of different ways back when I assembled the chassis, I think it is whithin 1/8" of 116.

If I was to stop measuring and start ordering, I would specify driveshaft length to be 54 1/8 inches.