2eighTZ4me Posted February 9, 2015 Share Posted February 9, 2015 I have a 77-79 5 speed. First gear is wasted. I have a very good 4 speed. Will any of the gear sets interchange between the two boxes? Meaning - can I nab first gear off the 4 speed and use it in the 5? Or will that require the countershaft to have to be swapped over as well? Thus, rendering the box to a 4 speed anyways... Quote Link to comment Share on other sites More sharing options...
Xnke Posted February 10, 2015 Share Posted February 10, 2015 Not likely. I do not believe the ratios are the same, and the thickness of the gears changes significantly through the lifetime of the FXX71X series transmission. If you have time to pull the cases and have a count, you can count gear teeth...If they have the same number of teeth, then it is worth a shot. Normally, though, if you've damaged one gear out of a pair, then the other gear is also damaged. Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 10, 2015 Share Posted February 10, 2015 Actually, 77 - 79 is the year range of 5 speed that has the same 1 - 4 ratios as the 75 - 77 4 speeds ( I think a 4 speed was also an option for 78 - 79). I was under the impression that the 5 speed is essentially the same as the 4 speed, with the 5th gear an engineered-in addition. So it would depend on the year of the "very good 4 speed", which wasn't mentioned. Ratios changed in 1975 (maybe late 74 with the body change), 1980, then again in 1981. Mastering the trivia... Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.