I'm hoping someone can help me with this one. So I got my 38 ford back with the rebuilt engine, but now she tends to slip in overdrive. I've been reading a lot about AODs that had a bad part at the carburetor body and the tv cable would fall off and cause this issue, but mine has a lokar kick down kit installed so that bushing isn't there. I've looked at the lokar installation manual and I'm thinking my gear selector trans arm may be out of place. Would this cause that problem without causing any other issues? She shifts through 1-3 without any real problem, but if you put any real force on the gas pedal in overdrive you can hear the transmission slip. The rpms will go up and she will basically go into neutral. Forgive the lousy quality of the photo, but below you can see that the shift arm is pointing forward instead of up like in the lokar installation instructions. Am I missing something? Lokar seemed to indicate that these would either point up or down, but not forward or backward? Any help would be appreciated.
I don't know if it matter but I added a stronger return spring to what you posted a picture of. I seem to remember reading somewhere that the lokar one was too weak but it has been over 4 years since I put mine on.
I would first install pressure gauge and set the cable to the specified PSI then drive it and see how the transmission shifts
Hello Oldsman, Thank you for responding. I'm told, but admit I didn't double check it myself, that the transmission read 35 psi with the spacer. Which is what Lokar recommends as the set point in the install instructions. Shifts fine, but slips in overdrive. I've heard that can be because it isn't keeping pressure, which had been caused by the bushing failing in some older cars. In mine it just appears that the shift lever is completely out of place. This transmission was supposedly rebuilt last year. So it is either that there is something wrong with this setting or the overdrive band has given out in 600 miles of driving. I'm obviously hoping it is that there is an adjustment out of place as opposed to having this torn down again.
Which way the lever points doesn't really matter as long as the trans is in park and the indicator on the column is showing Park. I don't see how it works pointing forward but if you are using a cable, then that is why it works. Overdrive on an AOD is a completely different shaft than the other gears so when it goes into overdrive, its a straight drive through the trans. I would think the od shaft is broke.
Oldsman has lined me out a couple of times on AOD's. Having a pressure gauge hooked up will tell you a lot. Then you can actually see the difference your adjustments are making. That is if the stronger spring deal doesn't work.
3rd gear in an AOD is direct drive, in overdrive the band applies. If it slips in overdrive its because the band is slipping. If you think your shifter isn't lined up properly you could always disconnect it, put the shifter in OD, put trans in OD and see if shifter hooks back up easily. If it does your shifter isn't causing the problem. Then you have to look at increasing throttle pressure to see if that stops the slippage.
I am going to say that there is possibly amiss alignment on the shifter. When you give it some fuel in OD the lever gets pulled into neutral. Does the shift lever stay in the OD position or does it move to neutral???
When I think of mine, if you are using a column shift with a rod, then pointing forward would be correct. If using a floor shift with a rod, then pointing up would be correct. A pressure gauge is cheap and easy to hook up, so I would check the pressure and be sure it is correct before driving it anymore.
Thanks everyone. I haven't driven it since I noticed the slipping in overdrive. Mechanic said I should be find so long as I don't let it go into OD. He set the pressure only a couple of weeks ago to 35 psi with the spacer. I had heard that the shifter lever could sometimes come loose, but if forward is the normal position for a column shifter then it looks like my OD band has worn out. I just had the transmission rebuilt about 600 miles. I'm not happy with the prospect of pulling the transmission off and having this thing rebuilt again. I'll look for a better warranty on the next rebuild! I'll pick up a pressure gauge next time I'm at the parts store and see what I can find as well. When in OD the shifter does not move to neutral and if you let the rpms drop it will re-catch. She starts to slip over 2200 rpm or so. I had heard someone saying that low pressure in OD can cause the band not to be held in place properly. Don't know if that is true, never took one of these apart to really look at how that band is actuated in overdrive. I may try 1930 A's suggestion of trying to put the transmission in OD, the shifter in OD with the shifter lever disconnected and see if it will go back on.
Well, finally found an old post on the HAMB with the following picture. This was from a 2013 post. I could find it cached in google, but not directly in the HAMB. Either way it definitely shows the shift lever in the forward position. Guess I'm rebuilding this transmission again.
I had an issue with mine being weak when standing on it. Junk yard trans and a stroker motor arent a good match. I finally killed it off due to a plugged trans cooler. We rebuilt it using 470RW planetary gears and overdrive band. Much happier with it all now, the overdrive band itself is about twice as wide and shift pattern is much better. If youre doing a rebuild it might be worth looking into
I don't know if Lokars pressure spec is right. I don't have the information handy, but google it and see what it is supposed to be. It is supposed to be set in neutral with the spacer between the cable end and the linkage
Well it took some time, but turns out the original installation used the C6 cable attachment. That meant the AOD TV cable wasn't getting a 1:1 ration of pressure to throttle and never reached 85 psi at wide open throttle. Added an adapted to the TV cable attachment and now everything appears to shifting exactly like it should. I attached photos so if anyone else is going through this and having difficulties setting their AOD maybe it will help. I've also seen an adapter that goes to the back cable bracket, but we used one at the front point here. The silver E bracket at the front. Funny thing is the transmission set to 35 psi with the lokar spacer and it shifted at all the points that you would expect, but burned out the clutches after about 600 miles. An expensive mistake.
Ensure that the detents in the shifter correspond with the transmission detents. You might need someone to move the shifter through the pattern to see if they line up correctly with the actual transmission, the intermediate rod may just require a minor adjustment?
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