FMX Shifting Issue after Shift Kit

[copb8 97]

Recently I pulled my FMX transmission to replace all the seals due to numerous leaks from the shift lever, rear and fronts seals and speedo. While it was out my friend, who is very knowledgeable about rebuilding Mustangs, insisted I should put a mild shift kit in it. He made it sound so easy and a no-brainer that I just went with it. I used the Trans-go 37-1 kit. Now I regretting it a bit.

It was a lot more involved than I expected it to be but we were very careful and everything went back together perfectly with all the parts lining up with the instructions. Yesterday was the big day of refilling all the fluids and going through the break-in steps.

The tranny shifts into and out of gears perfectly. It shifts from 1st to 2nd at a slightly higher RPM and with a firm but very acceptable shift. The problem I'm having is with shifting into 3rd. It only shifts to 3rd at a MUCH higher RPM and only while accelerating pretty hard. If I just drive it normally like you would in neighborhoods it will stay in 2nd and not shift up. This is also the case with manually shifting. I can drop it into first and it'll shift to 2nd the moment I move the shifter to 2nd but when I shift into Drive it'll continue to hold 2nd until the RPM's are elevated.

I've checked the fluid level and it's perfect and obviously it's brand new Type F fluid.

Any thoughts?

They good news is that it's dry as a bone now so hopefully I get the shift issue resolved and have a perfect gearbox.

 

[RPM 1,190]

Will it shift correctly when shifting manually from 1-2-3?

[69ShelbyGT350H 61]

Have you tried adjusting the downshift rod from the carb to the trans? Sounds like its too far back making the trans think the car is hard accelerating. 

[copb8 97]

43 minutes ago, RPM said:

Will it shift correctly when shifting manually from 1-2-3?

No. 1-2 is ok, 2-3 is still delayed and high RPM only

[copb8 97]

5 minutes ago, 69ShelbyGT350H said:

Have you tried adjusting the downshift rod from the carb to the trans? Sounds like its too far back making the trans think the car is hard accelerating. 

I haven't tried this. So the further back it is the trans will think you're "on it" and hold the gear longer for better acceleration? I'll say that when I was reconnecting that rod it clicked right onto the throttle pin with no effort. In other words, it didn't seem like anything had changed from when I dismantled it. 

What's the proper way to adjust it to ideal?

[Ridge Runner 1,112]

I had a new rebuilt FMX do the same thing ,the shop fixed it ,they said the valve body was hanging inside. Got it back and never had another problem ,i loved that transmission.

[69ShelbyGT350H 61]

10 minutes ago, copb8 said:

I haven't tried this. So the further back it is the trans will think you're "on it" and hold the gear longer for better acceleration? I'll say that when I was reconnecting that rod it clicked right onto the throttle pin with no effort. In other words, it didn't seem like anything had changed from when I dismantled it. 

What's the proper way to adjust it to ideal?

I do not know how much will change the shift but that is what that rod does for 3rd gear. I'd have to go back to my FMX rebuild video by Ken "Bad Shoe" Collins to see what it attaches to inside the trans. Its been a couple of years and I do not remember.

[barnett468 418]

43 minutes ago, copb8 said:

I haven't tried this. So the further back it is the trans will think you're "on it" and hold the gear longer for better acceleration? I'll say that when I was reconnecting that rod it clicked right onto the throttle pin with no effort. In other words, it didn't seem like anything had changed from when I dismantled it. 

What's the proper way to adjust it to ideal?

it may need to be adjusted differently with the shift kit. the vacuum modulators are also adjustable to a small degree. if you change this setting, write down how much you changed it and in what direction . i wouldn't change it more than 2 full turns in either direction.

also, make sure the vacuum hose going to it didn't fall off and isn't cracked.

if these adjustments don't make a significant improvement, i would contact the company. 

 

[copb8 97]

2 hours ago, barnett468 said:

it may need to be adjusted differently with the shift kit. the vacuum modulators are also adjustable to a small degree. if you change this setting, write down how much you changed it and in what direction . i wouldn't change it more than 2 full turns in either direction.

also, make sure the vacuum hose going to it didn't fall off and isn't cracked.

if these adjustments don't make a significant improvement, i would contact the company. 

 

I'll give this a try and definitely keep track of my starting position.

What is a pain is that the adjustment screw is right up against the transmission support bracket. I don't see how it can be adjusted without moving the bracket.

 

[barnett468 418]

39 minutes ago, copb8 said:

What is a pain is that the adjustment screw is right up against the transmission support bracket. I don't see how it can be adjusted without moving the bracket.

 

that doesn't sound right, can you post a photo?

[copb8 97]

2 hours ago, barnett468 said:

that doesn't sound right, can you post a photo?

I'll try and get a shot tonight.

[copb8 97]

I adjusted the vacuum modulator one turn clock-wise and verified the quality of connections and hoses. Went for a drive and the car is still horrible.

Doesn't shift down to 1st unless with shifter

Slow to shift to 2nd from 1st but not harsh

Will only go into third at 60+mph if I pop and release the accelerator. Shifting manually has no effect

Will drop from 3rd to 2nd at 50mph if with an almost constant throttle put barely inching down the speed.

I ran out of time and daylight so haven't tried adjusting the modulator the opposite direction yet.

[copb8 97]

This is a story of you can't see the forest for the trees.

When the transmission acted so terribly I was SURE i'd messed something up internally when installing the shift kit even though I thought I was being very careful during the process. But there were a lot of little parts and springs to keep up with and you never know.

Well, after trying to adjust the vacuum modulator multiple directions but with no good results I decided to call Trans-go and get their input. The gentleman was very helpful but pretty technical about what I should do/check so I was a bit overwhelmed and also lacked some of the tools he said I'd need. I told him I'd get the tools and give it a shot. Then as we're saying our goodbye's he throw's "oh, you might want to check that your kickdown linkage isn't binding or putting pressure on the kickdown lever."

Well I figure that's a small thing I can certainly do immediately so I put the car on the lift and sure a day it definitely 'seemed' to be exerting pressure. I disconnected it and went for a drive. I had a brand new gearbox! I can't tell you how relieved I was.

So it turns out that one of the many, many things I did while I had access to the friend's shop was remove the 1/2" carb spacer that the previous owner had installed. Hated how it made my shaker hood scoop stick out. In doing so I basically dropped the kickdown lever 1/2" and that was enough to bind the kickdown lever. 

Thank goodness it was a small thing and thanks to all of you for your suggestions.

 

[RPM 1,190]

On 3/5/2018 at 7:37 AM, 69ShelbyGT350H said:

Have you tried adjusting the downshift rod from the carb to the trans? Sounds like its too far back making the trans think the car is hard accelerating. 

Hmm...  :)

[barnett468 418]

On 3/5/2018 at 10:38 AM, copb8 said:

What is a pain is that the adjustment screw is right up against the transmission support bracket. I don't see how it can be adjusted without moving the bracket.

 

 

[copb8 97]

13 minutes ago, RPM said:

Hmm...  :)

I know. I know. You called it for sure

[copb8 97]

3 hours ago, barnett468 said:

 

Definitely was a pain to access but doable with right tools and patience.

 

Both of which I'm a bit short of. 

[RPM 1,190]

35 minutes ago, copb8 said:

Definitely was a pain to access but doable with right tools and patience.

Both of which I'm a but short of. 

Welcome to my world. Glad she's working well.

[bigmal 225]

Hey don't sweat it. I spent a lot of time trying to work ut why my new fuel sender wasn't reading full. After lots of trouble shooting it turned out it needed more fuel. Doe!

[barnett468 418]

5 hours ago, copb8 said:

Definitely was a pain to access but doable with right tools and patience. Both of which I'm a bit short of. 

lol, we all know that feeling. Glad it was something simple in the end.