Final drives

175/180/185 final drives are 13 and 76 teeth for a ratio of 5.85 to 1. These are the widest and strongest final drives you can have in that axle/final drive configuration. You could use late D-17 or 170 finals, which are a faster ratio, but you'll tear them up in a short period of time if you're making over 600 or 700 HP. I contemplated trying to create disc brakes and gave up. To get a rotor inside where the brakes currently go and attach a caliper on top somehow, leaves you with a very small diameter rotor and a larger diameter rotor is what you need. If you grind much of anything away at the top opening, I feel you're compromising the rear end structure strength somewhat. I thought about outboard discs and gave that idea up too, feeling the design restrictions with the final being outboard and the fact that when you were braking at the wheel, you're placing even more load on the final drive gears, which may be marginal anyway, wasn't a great idea. I finally settled in on new Kevlar disc material and new bands and changing the linkage where the brake pull rod connects to the brake pedals to nearly double the pressure the Driver can apply to be our best workable solution. We also flat needled the back side of the 2-pinion diff side gears for the first time (instead of bronze washers which never failed) and that helped some too. we're in the 1200 HP range and have an overdrive of our own on the front of the 180 trans, as well as one gear over direct inside the tranny. There is one option for ring and pinion I know of, that was done by one guy I knew 30 years ago. At my suggestion, he took a model 200 pinion shaft (10 teeth) and replaced the 180/190 pinion shaft (9 teeth) and used the 180/190 ring gear and wound up with about a 10% increase in speed. I never saw it, but he claims it fit inside with some machining. He only ran direct drive anyway, so all he had in the trans was direct and reverse. I know that a 200 pinion shaft would have to have the front of the spiral bevel teeth narrowed to get the tooth length down to what the ring gear is. I also know it's overall shaft length is a bit longer. So, what I'm saying is, it has been done and it did work.

Dr. Allis do you pull in a llss class also assume you are using the 180 too? You said you have a gear over direct in tranny, how much over and what did you have to do to make it fit. Will a 21tooth bottom work with a 35 tooth on top to = 23.8 / 1 final ratio in 3rd slot? Could be a tic slower if need be. Also where did you get your Kevlar brake materials and how did you change linkage for more pressure. Thanks for the info.

Edited by Acllss puller - 03 Jan 2016 at 11:54am

Kevlar brake discs for a 180/185/190 are available at your AGCO dealership and have been for many years. Direct drive in a 180 is 22.7 to 1 and you want a 23.8 to 1 in third, which is 5 to 6% slower than direct?? Not sure you can still use the OEM third gear top and bottom to achieve that. When you start changing the transmissions input shaft to a gear larger than the bearing hole, they are miserable to work on, and take a lot of grinding inside to get things to fit.