Ford FMX shifting trouble.

Joined: October 29th, 2017, 10:31 pm

October 30th, 2017, 5:02 pm #1

Hello,

I am working on a Ford FMX transmission, originally from 69 Mustang. Now i am going to list some info that i can think that could help diagnosing the problem.

-Transmission shifted correctly before rebuild.
-Reason for rebuild was slipping at reverse.
-Transgo SK 3-67 kit was installed when originally rebuilded.
-Shift kit was completely removed because shifting problems occured.
-Transmission was re rebuilded after it burned rear cluch.
-Noticed wear from sealing rings on front cluch when rebuilded. I suspect it was there in first rebuild also.
-Front cluch housing is replaced.
-Transmission, valvebody assembly and governor has been checked several times. Nothing unusual has been found.
-Testing servos and clutches shows no fault. Everything works as it should.
-When shifting manually, transmission works nicely. Shifts are nice and smooth. No slipping
-Reverse works as it should.

Shifting problem is as follows.

-D Range starts at 1st and goes straight to 3rd.
-No downshift to 2nd or 1st when stopping or slowing down.
-Stays in 3rd gear, Unless shift lever is put in P, R, N, 1 Or 2 when stopped, transmission starts again at 1st and goes straight to 3rd.
-3rd gear engages in correct speed, just 2nd gear is missing.
-Engagement is hars to 3rd, probably because high rpm when shifting 1-3.

Difference between Manual 2nd and D2 seems to be in few valves that are controlled in D range compared to Manual valve control of manual 2nd. Might something at this area cause sayed problem?

Any advice is welcomed.
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Joined: November 18th, 2004, 4:20 am

October 30th, 2017, 10:28 pm #2

What do you mean manual 2 and D2?

This should be a select shift transmission.
L is low gear only.
2 is second only.
D has three speeds.
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Joined: October 29th, 2017, 10:31 pm

October 30th, 2017, 11:02 pm #3

Hello Stuart, nice to have you chime in.

With Manual 2 i mean that selector lever is in 2. D2 is When selector lever is on D position and transmission should shift to 2nd gear.

There is no shift to 2nd gear, when in drive. Goes Straight to 3rd from 1st gear. Shift happens approximately when 3rd gear should engage.

Tested with 2 Governors, cleaned both of them several times. Both pressure tested fine also. This and correct shift timing of 3rd gear leads me to believe that something other than governor is the culprit.
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Joined: November 18th, 2004, 4:20 am

October 30th, 2017, 11:16 pm #4

You do have the governor on the outputshaft correctly?

Valves in the right order?
Sleeve with three pointy parts face outward.

Look up there /\ for a sticky.


Last edited by stuart40a on October 30th, 2017, 11:20 pm, edited 1 time in total.
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calicocat
calicocat

October 31st, 2017, 2:12 am #5

Hello,

I am working on a Ford FMX transmission, originally from 69 Mustang. Now i am going to list some info that i can think that could help diagnosing the problem.

-Transmission shifted correctly before rebuild.
-Reason for rebuild was slipping at reverse.
-Transgo SK 3-67 kit was installed when originally rebuilded.
-Shift kit was completely removed because shifting problems occured.
-Transmission was re rebuilded after it burned rear cluch.
-Noticed wear from sealing rings on front cluch when rebuilded. I suspect it was there in first rebuild also.
-Front cluch housing is replaced.
-Transmission, valvebody assembly and governor has been checked several times. Nothing unusual has been found.
-Testing servos and clutches shows no fault. Everything works as it should.
-When shifting manually, transmission works nicely. Shifts are nice and smooth. No slipping
-Reverse works as it should.

Shifting problem is as follows.

-D Range starts at 1st and goes straight to 3rd.
-No downshift to 2nd or 1st when stopping or slowing down.
-Stays in 3rd gear, Unless shift lever is put in P, R, N, 1 Or 2 when stopped, transmission starts again at 1st and goes straight to 3rd.
-3rd gear engages in correct speed, just 2nd gear is missing.
-Engagement is hars to 3rd, probably because high rpm when shifting 1-3.

Difference between Manual 2nd and D2 seems to be in few valves that are controlled in D range compared to Manual valve control of manual 2nd. Might something at this area cause sayed problem?

Any advice is welcomed.
Did you do any air tests before finishing assembly? I think you will find a problem with the seals that is causing the 2nd (intermediate) failure. If the air tests seem to go ok then a careful reassembly of the valve body is in order.
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Joined: October 29th, 2017, 10:31 pm

October 31st, 2017, 8:23 am #6

You do have the governor on the outputshaft correctly?

Valves in the right order?
Sleeve with three pointy parts face outward.

Look up there /\ for a sticky.

Yes, Holes in the governor lines up with the holes on the output shaft.

Governor is assembled correctly. Checked it several times. I have several manuals with the layout. Air pressure testing clicks and farts as it should.
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Joined: October 29th, 2017, 10:31 pm

October 31st, 2017, 8:40 am #7

Did you do any air tests before finishing assembly? I think you will find a problem with the seals that is causing the 2nd (intermediate) failure. If the air tests seem to go ok then a careful reassembly of the valve body is in order.
Hello Calicocat, thanks for responding.

Assembly was air tested (clutch packs) when it was on the table and after assembled on the case when also servos was tested.

Intermediate band was ok, both times that it was rebuilded. Only rear(direct) clutch pack was burned.

Intermediate band hold without slip when it is in manual 2 gear. In drive range, there is no shift to 2nd gear.

I do suspect something is wrong in the valvebody, but it has now been opened and reassembled several times with the valve layout on hand and i could not find nothing that is assembled wrong.
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Joined: November 18th, 2004, 4:20 am

October 31st, 2017, 10:44 am #8

Yes, Holes in the governor lines up with the holes on the output shaft.

Governor is assembled correctly. Checked it several times. I have several manuals with the layout. Air pressure testing clicks and farts as it should.
Something amiss with the valve body then.
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Joined: October 29th, 2017, 10:31 pm

October 31st, 2017, 11:36 am #9

Yes, that is what i suspect also.

Any pointers for where to start? I suspect that there is something wrong with the manual valve bore or something related to that. Nothing concrete to say about it, but position 2 does not use two valves that position D does use, that provide automatic function for shifting. Any thoughts on this?

I do have vacuum tester for valvebody testing, but i don`t know what should i test there, as there is no vacuum test scematics or specifications for old transmission like this. Or atleast ones that i can find.
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calicocat
calicocat

November 5th, 2017, 4:06 am #10

Hello Calicocat, thanks for responding.

Assembly was air tested (clutch packs) when it was on the table and after assembled on the case when also servos was tested.

Intermediate band was ok, both times that it was rebuilded. Only rear(direct) clutch pack was burned.

Intermediate band hold without slip when it is in manual 2 gear. In drive range, there is no shift to 2nd gear.

I do suspect something is wrong in the valvebody, but it has now been opened and reassembled several times with the valve layout on hand and i could not find nothing that is assembled wrong.
It could be something as simple as an incorrect adjustment of the shift lever. On the Mustangs/Cougars I check 1, D, N, when setting the shift lever.

I still suspect an issue with the valve body. Can you freely move the valves in the bores when you assemble? I use a small needle probe to move each valve after removal and cleaning.

If after all these re-checks still don't reveal something post back up here and let's discuss what to do next.
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