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Engine basics => Engine set up tips => Topic started by: Larry Renger on May 01, 2016, 08:14:47 AM

Title: Another Fox .35 question
Post by: Larry Renger on May 01, 2016, 08:14:47 AM
If you want to improve the balance of a Fox crankshaft, how much weight do you need to add to the counterbalance area after grinding the upper areas? One of my L&J cranks is shot, and of course, they are no longer available, so I need to modify a stock one.  :'(
Title: Re: Another Fox .35 question
Post by: Dan McEntee on May 01, 2016, 11:50:49 AM
    Hi Larry;
   I have never heard of anyone adding weight to the Fox crankshaft, just doing the grinding on the web on the crank pin side. I suppose one could TIG weld some metal onto the counter weight, but don't know what that would do the the heat treatment (if any) the part got when it was made, or how to tell you got it to the weight you want, unless you have a test rig to check it with rod and piston installed.
   Type at you later,
    Dan McEntee
Title: Re: Another Fox .35 question
Post by: Larry Renger on May 01, 2016, 01:28:05 PM
L&J cranks have had the counterweight milled out and lead cast in the cavity. They have a very good reputation.  I don't know about the High Zoot cranks that Randy Smith used to sell. (Out of Stock   :'( )
Title: Re: Another Fox .35 question
Post by: RandySmith on May 01, 2016, 01:57:23 PM
You can get close from carefully grinding a scallop of both sides of the top of the crank weight on the pin side, then you can use a piece of 3/16, tungsten rod, sliced to the same thickness of the crank, inserted into a hole you put into the bottom part of the crank counterweight, lock it in by pressing, peening, and use red locktite. If you do not know how to do this, do NOT. just grind the part, and keep it cool while grinding


Randy
Title: Re: Another Fox .35 question
Post by: Larry Renger on May 01, 2016, 04:20:55 PM
I not only can do this I have a supply of the little Tungsten Carbide weights used to balance the Cox Conquest .15 shaft.  ;D  I was figuring to use three of them as they don't go all the way through the counterweight.
Title: Re: Another Fox .35 question
Post by: RandySmith on May 01, 2016, 05:41:31 PM
I not only can do this I have a supply of the little Tungsten Carbide weights used to balance the Cox Conquest .15 shaft.  ;D  I was figuring to use three of them as they don't go all the way through the counterweight.


Hi Larry

Use 2 if they are not full depth, how thick do you think they will be cut to?

Randy