Hello!
My name is Eric and I recently decided to take on a new and exciting project. I bought a 79 toyota that is pretty much all original other than the tube bumpers. It has the 20r and 4 speed. Knowing very little about these trucks when I got it motivated me to do some reading and research on them. I have learned so much from the postings in this forum and am very thankful. I have posted some questions before but I just realized I haven't made a formal introduction of myself. I am a metal fabricator and millwright of about 10 years. I currently have a very small shop in Portland Oregon with many mechanical and fabrication capabilities. I hope to gain machining capabilities soon. I just love building anything mechanical or structural.
So the engine and transmission in my truck are original with about 300k on them. It pops out of reverse if I don't hold it in. The engine sounds and feels a bit loose and it seems like the oil pressure is a little low. It uses a fair amount of oil but it fires up every time and runs fine. It did pass deq here in Oregon.
The suspension is all original and seems to be in good shape. The front hubs lock in and out just fine. The body doesn't have any rust and appears to have the original cream colored paint.
As soon as I found this truck I knew it would become my next project. My goals in shopping for a truck were to find a good diesel truck that could be used for work and play while still having good fuel economy. this is why I chose the toyota. I know these trucks are strong and lightweight. My plan for this 79 is to drop in a mercedes 5 cylinder diesel engine and use an r150f transmission. This is not strictly a toy nor is it a rock crawler. I aim to make this truck a strong work truck with good offroad capabilities and good fuel economy. I want the power when needed and the capabilities of driving through mud, sand, rock, snow or any type of rough terrain while carrying loads in the bed or by trailer. I also want good economy when driving on the highway. I know I will need some very specific gearing.
The truck came with 4.37 gears and I have some 3.90 gears that will go in. I plan on running 31" all terrain tires. I will keep chains on board in case I need them. With this gearing and tire size I will be hitting about 2300 rpms at 65mph. I have thoughts of dropping the low range gears in the transfer case if I can do it fairly cheap. I originally wanted to use a w56 with dual cases to get this gearing but soon realized the w56 would not be very suitable for the engine I will mate it to. The w56 bellhousing was too small for the flywheel in the benz. Believe me, I tried. The engine an an om602 mercedes benz 2.5L diesel. It is a great engine with a mechanical fuel injection system. It is not the same as the om617 which is a 3.0L diesel. The one I have has less than 200k miles on it and runs great. I found that the bell housing for the r150f will need some modifications. The diameter of the flywheel for this transmission is almost the same as the 2.5L benz flywheel. The backspacing on this benz engine is different from the toyota 3.0 engine. The benz is a closer backspacing to center on the flywheel so I will have to cut the toyota bellhousing back to match the difference. I will not change the position of the pressure plate or flywheel in conjunction with the bellhousing or input shaft. I am planning on using a piece of aluminum plate to cut and drill to size to match the benz engine and I will center the input shaft of the transmission to the crankshaft and then tack the custom flange in place. I know this will be tricky and I am a bit intimidated by it all but I am confident I can make it work. The flywheel is in the machine shop right now and will be machined to match the benz bolt pattern and will have the benz ring gear fitted to the toyota flywheel. Both ring gears were really close to the same backspacing so I got lucky there. I will use the original benz starter which bolts to the engine block instead of the bellhousing. Right now I am in the process of repairing the transmission I have. I know it needs a new input shaft bearing and the tip where it slips into the pilot bearing will need to be repaired to fit. I have never built a 4x4 but in my younger days I built stock cars and drag cars and since then I have been building and repairing machinery.
Thanks for reading and I thank you for any help and expertise you have in regards to my project.
