There appears to be a lot of room in the engine bay. It's still early though, and the turbo isn't mounted, no brake master, steering linkage, etc.
And the core problem: Isuzu springs are very long, giving a wheel offset in the fender that is not optimal.
You might be able to re-drill the center pin location in the axle and the plate, to move the axle ahead, like people do to the rear on Chevrolet cars.
Thanks for the idea! Was estimating about 1-2" possible using that method. The steering linkage then needs to get real short, to make adjustments beyond the adjust-ability that's in there now...
If the steering box is ahead of the axle, bump steer issues may become magnified. Any chance of moving the box behind the axle if you need to?
Negative. Original NPR box was in front, steered well enough. Good point though, will dig out my copy of "race car vehicle dynamics" and run the bump steer calc numbers.
Next issue: tire to steering gear clearance. Currently have 16" rims, far too small for the wheel wells so was wanting to go to 22.5; Normal largest rims are 19.5 in the six bolt style which could fill the wells but tire selection is limited and more spendy. Used to have a set of unicorn Accuride 28157 that were 6 lug/22.5 but in a moment of blindness I sold them 10 years ago for a pittance. Haven't seen a used set since, and our wrecking yards have been taken over by LKQ- no more deals and large truck access has been eliminated. Argh! Did find a place that can, for a considerable amount, make me a set of aluminum rims in 6-8.75 and 22.5" so at least there are options. The original steering linkage is shown below with the link bent to clear the tire on right turns. The new box location is inside the center of the tire, so with larger rims it runs inside the widest part of the tire. There are a couple of options for additional clearance so I'm not too worried: -Less offset on the pitman arm (currently 4") -Larger rims (currently 16") -Moving the axle forward (needs to move ~2.5")
Nice Build I , I have always liked that Cab Style. There is a same Era slightly Customized Heavy Duty Diamond T Pickup that I have seen off and on around the Southern N.H. , Maine area Swap Meets ect.. It is so Cool that I always have to get a closer look ,the Dash looks like an Old Semi’s with a ton of period Guages and rare enough that it is the about only one that I know of around the N.E. (Unless it’s a Custom Build ?). Great Choice ! Nice Job , B.
It took a year, but I'm making progress again. Moved front axle forward ~2.5" using a 1/4" steel plate with holes to locate the U bolt pattern and pilot the axle location pin. Found a pair of Accuride 28157's and fitted to the front. (really wish I hadn't sold my set of six 10 years ago). Wheel fills the fender quite well with 9R22.5's. It doesn't look much different, but the nose is now mounted to the chassis, which means the cab can finally be mounted to the frame.
Had to tighten up the steering linkage, see first image for the issue. Shortened an AC Delco 45A6011 (GM 88910757) which was fully threaded. Now it all fits well within the 22.5 rims on the right turn. Sometimes I felt like this project was going in circles; Now at least it can go in the same circle left and right.
Went looking for a set of 28157's and found some earlier Accuride 25372 which are 22.5x6.00 with a Firestone branding. Nice enough, but only 6" wide and I want 6.75" wide to run modern rubber. He has two sets with various sizes of reasonably fresh rubber. If anyone needs these, let me know and I'll put you in touch with the seller.
Rear cab mounts had to move inwards 2". With the radiator cowl pinned to the front crossmember, the cab can finally be attached to the new frame.
While we're at it, also time to change the rear springs from leaf to air bag. Donor was some sort of a Kodiak based spartan motorhome. After seeing the different in weight due to loading on my bus, but not feeling it at all, I'm a fan. The last iteration used Freightliner parts, it was a bit overkill. This has a reasonable length for the pivot.
No pictures, but the cab is now mounted to the frame with rubber pads all around. Drilling rivets out is just mind numbingly boring. I didn't take pictures. There will be plenty more opportunities- 8 rivets down this morning, with 24 to go.
I have access to one, but can't get access to the rivet head with the bracket still mounted. For the frame holes, absolutely.
This is a very cool build indeed, now when you get it all done, you might want to see if Dave Giesler the owner of the Pioneer Auto Museum out in Murdo South Dakota, will sell you this very cool Diamond T utility/rescue rig, this machine is very unique. They are always selling and swapping a variety of machines at that place.
16" rear rims removed. Accuride 28157's located and purchased. 4 of the 6 brought back to the house... Next desert trip will be pushing to get the rear axle attached and the truck on it's feet again
Took long enough, but progress made. Frame cleared of leaf spring and other brackets. Each rivet had to be drilled through before the plasma torch could blow it out...
Air ride arms and brackets mocked up. More chances to drill large holes through high grade steel... Yippee.
Axle delivered. (Forklift makes it so much easier!) Leaf spring was a quarter inch narrower than the new air arm- argh. Plasma torch and grinder used to clean the leaf brackets off the axle.
Tires on, axle within 1/16" (±sharpie width) of where it needs to be. Air leaf mounts welded to axle. Still need to grab the panhard bar, and mount the air springs and upper shock eyelets to the frame.
Back for more. Lots of frame drilling, bracket drilling, hole drilling. Got the panhard bar mounted, with 1/2" steel plates welded to the axle.
The Jalopy Journal
