Tuesday, August 19, 2014

TH 425 governor loose yoke

Here is a couple TH 425 governors that have the yoke coming loose.
 Yoke brazed back in place. I submerge most of the shaft in water so none of the fits get hot and change dimension.
 Some of the new gears are different and need shimmed. Got caught on this last time. Got die button shims on order which should work. Need to get these done and back to Jim K.
Another quirk, this governor has an additional spring between the bottom of the spool and gear. First time seen this.

Saturday, August 9, 2014

Onan throttle position sensor test, Onan tps

Tested operation of the tps. Was concerned the added friction would effect the governor but it seems OK. Ran this test using the carb for fuel.
Note condensation on intake, both roof airs were running

Saturday, August 2, 2014

Onan gets a throttle position sensor, TPS for efi

Megasquirt needs a throttle position input. Most of the automotive sensors have a spring in them which would effect the onan's governor. I'm adapting a sensor from a Yamaha R6 the same as I got the injectors from. The plan is to drive it with a hex shaft (cut off allen wrench) and a couple setscrews fixed to the throttle shaft and tps.
           This is how it came out.
Yamaha tps had a range of 400 to 5,000 ohms which is fine
Started with  a steel yoke to fit the throttle shaft, this will have 6-32 set screw in it to fix it to the shaft.
The top of the yoke is aluminium for less weight. 5/16 set screw will provide an internal hex.
Bored both parts while they were assembled so the bores are concentric.
Trimming off some extra
Test fit
test fit with the governor rod
Set screw to fix to throttle shaft

clearance check
Pattern for mount
Short weld
two step bore to hold seal in
Hex drive
Epoxy holds a 5/16 set screw in the tps. it just fit!
Cut off a piece of allen wrench for a drive shaft
Made a press on bushing out of brass for the tps seal to run on.
 Marked mount for trimming off extra