by Rick Prentice Â» Wed Jan 24, 2007 11:29 am
Hi Rufus. There's about 3 or 4 different versions out there now, with some homemade types too.
This is my try at explaining the simple one. Pictures would be hard to draw the "trick hole".
The simplest to make is the one where you remove the allen plug on the side of the hydraulic manifold tubes. It will be the one that screws into the smaller top tube. This tube carries the high pressure. Make sure you loosen the allen plug while everything is still attached to the T/C unit. This plug can be a pain to remove and it's easier if the lines aren't hanging loose. This port will have a fitting that will go to the "IN" port on your new control valve.
The easiest way to make this block is with an original gasket and a chunck of 3/4" material that's smooth and not all scratched up. Cut out your block to the same size as the outer gasket pattern. A square shaped block is also ok.
Next, mark and drill your three bolt holes used to fasten things to the T/C unit.
Next, locate the return(goes to the larger tube) fluid port from the T/C unit , you'll notice this hole for the return is not directly in-line with the outer manifold line and that's the reason for the gasket having that longated slot. You want to drill your hole to be in-line with the hole coming out of the T/C unit, this is important . Drill this hole all the way through, again making sure it's in-line with the hole in the T/C unit.
Now comes the tricky part. You want to mark the "high" pressure hole only from the T/C unit side and you'll only drill it halfway through, (drilled from the T/C side). If you accidently drill this hole all the way through, it's junk, start over . Then from the bottom of the block, you'll drill an upwards hole to meet the half hole you just drilled. Make sure not to drill into the bolt holes. This port needs to remain "high" pressure. You'll tap this hole out with a pipe tap for a fitting. The hose connected to this fitting comes from the "OUT" side of your new control valve. It will become "high pressure" when you use your T/C for something.
It's best to machine both surfaces perfectly flat(flycut or ground), but if your block is free of any marks, flat, and smooth, it will work fine.
You'll need new longer grade 5 or 8 bolts also.
This may seem confusing to some, but if you have a gasket, lines, and unit, in front of you, it should make sense
I tend to say much more than is needed,then leave things out, so hopefully Dan or others will pitch in and help me out.
Last weekend while at George's winterfest, I saw one of Earl's(WKPoor) blocks made of aluminum. What a piece of "ART". Earl does as nice a job as anyone could do. Once you make one of these various blocks, you'll see why they cost between $50 and $75. They take awhile to make and are critical in making things work right.
by Rick Prentice Â» Wed Jan 24, 2007 11:44 am
If you study the flow of fluid through this project, you'll see why the word's "DEAD END" came about.
When you start your Cub, the hydraulic pump starts pumping fluid through the smaller steel tube. Normally the fluid would travel through this smaller line and then be directed into the T/C unit to do it's thing, then travel back out through the larger return line and back to the pump.
With this new "by-pass" block, the pressurized fluid from the pump travels again through this same smaller line, but now instead of going into the T/C unit, it is directed out through the small removed allen plug port and back to your new control valve/valves. Then from your new control valve, the fluid returns into the bottom fitting in your by-pass block and back into the T/C unit, like nothing ever happened
If you simply install this new by-pass block and then "cap" off the fittings, the fluid cannot circulate and will distroy the pump and/or other internal engine parts(weakest link).