Adjusting Toe in

[wbolan]

I am trying to find out some more details on how to adjust the toe in on my BH4. It's about .85 degrees on one side and 1.5 on the other side. I got the written instructions from bearhawk about using a rosebud to heat the knuckle. I have never used gas before but reading it sounds like I need and acetylene and oxygen tank and a rosbud tip. It seems there a alot of opinions on flows to use. I really don't want to go out and buy a setup for a one time use. I would like to know more from people that have done it, such as how long does it take to heat it up? Any tips and advice that is not in the written instructions. I may be able to find someone with a setup, but if there is another way someone else has done it I would appreciate it.

[Bcone1381]

I would want to partner with Bob on this job. In other words, call him, tell him what you need to do and listen to his advice and direction. As you proceed to set things up and have questions, call him back for clarification. What follows is my impression I have on this subject from the few things I've adjusted on Bearhawk steel parts. My experience is very limited, and the purpose is not "How To" but rather to give you some confidence and remove some barriers to proceeding. Again, call Bob....take what follows as novice opinion that cant be trusted. If you find after reading this "This sounds like a pretty simple thing to do." you heard me right.

I found that Steel telegraphs its temperature visually.....meaning it gets dull orange then red hot as it heats up. (Alumin does not....it just gets hot without any telegraphy, then melts.) So as you heat up the knuckle your not watching your watch, or a thermometer; watch the color of the steel. Practice on something to get a feel for it before you touch the gear. Heating up steel like this is very intuitive. It slowly changes color and goes from dull to bright before it starts to melt a puddle of steel.

I think Bob will have you take all weight off the gear leg, install a 3' pipe inside the axle tube, heat the knuckle up evenly (avoid hot spots). When it starts turning dull orange it is reaching its ability to become compliant. Then a friend starts to apply pressure to the pipe in order to move the axle for/aft as soon as possible with out very much force. "Hey! Its moving" is what I would think if I was doing it.

You need jig up eveything with marks on the floor so you know where the angle is, and where you want it to be. Once the torch is on the knuckle it will be aligned in short order. Like I say, call Bob.

[jaredyates]

The procedure that Mark was sending out was developed with Bob. It calls for a much longer pipe as I recall, but I have forgotten the spec for how many degrees were acceptable. There is a lot to it, making sure the gear is at the right part of the travel, etc.

[rodsmith]

Toe in is supposed to be 0.0 deg to 0.5 degree, I believe that is with a gear spread of 72". Brooks had great advice in contacting Bob to get the information directly from the designer. When I did this I used a 10' pipe for leverage and accuracy in getting the proper toe in. The joint should not be heated beyond dull red. This is definitely a two person job. I would find some one with an acetylene setup and experience using it to do the heating. I used a fairly small rose bud, as I recall it took a couple minutes to get the proper temperature. One of the challenges is keeping the fuselage from moving while doing this. I made up some 3/16" cables and anchored the tail and opposite gear leg to the side of the hangar.

[huntaero]

Where are you located maybe someone close by can help, i had to adjust mine but we built a Jig fixture as we had to rebuild my partners 4A gear.