lost third gear

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diymirage

diymirage

HP@idle > hondaHP@redline
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(71 duster, with a MRL 408 in it, 727 out of a 75 motorhome, promatic II shifter and lokar kick down linkage)

so recently ive noticed a slight slipping issue on the 2-3 shift
very little, and not enough to concern me
I double checked the adjustment on the kickdown cable and noticed the throttle bracket had loosened up, and this put extra slack on the kickdown
when I tightened everything back up all seemed well


until this morning, under hard acceleration, I shifted from 2nd into 3rd and the engine bounced of the rev limiter

the rest of my trip I had to get up to speed in 2nd to be able to maintain that speed in 3rd
I was not able to gain any speed in 3rd

when that also failed I put her in second and just drove her home like that (not too bad, with the 3.23 gears)


I checked the transmission fluid and it is dark red, not brown, but certainly not "fresh from the bottle bright" red

it also had a burned smell to it
(this is my first automatic transmission and I wasn't sure if I would recognize the burned smell everyone always enquires about, but it was pretty obvious)



so, what happened and what should I do next?
 
a stock 727 behind a 408? Yeah, sounds like directs are toast. What does it do in reverse?
 
seems to do just fine in reverse
it will squeal the tires if I get on it, but if I hold the brake and get on it, the engine will go up to 12-1400 RPM and hold there
 
diymirage said:
seems to do just fine in reverse
it will squeal the tires if I get on it, but if I hold the brake and get on it, the engine will go up to 12-1400 RPM and hold there
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That's odd. Generally if you lose 3rd gear you lose reverse also. The burned fluid is a sure sign something is toast and I'm with Fred on it betting on it being the high clutch
 
Yep. I'll agree with Fred & Tracy. Rev/High Clutch is toast. Probably the reason for reverse still working is the much higher apply pressure thru the reverse boost circuit. It's only a matter of time till you lose reverse if nothing is done.
Time to tear it down.
 
i guess ill call impeccable timing on this then
( i had the car put away for winter, but the weather was so nice i brought her back out...i would have been upset if this happened during the first ride of 2016)


ive looked into a few options of having it rebuild (i know, everyone says its easy, but I'm just not sure if i want to do it myself)

I'm not even sure what all i should include
the motor made 420 HP and 470 lb-ft on the dyno
do i need a bolt in sprag? shift kit?
i kinda like the idea of keeping the transmission automatic, so no need for a full manual valve body

and while it is apart again, I'm sure i should get a decent converter this time around...any suggestions on who i should have build it?
 
Great timing. Pick up a bolt-in sprag, a TF-2 reprogramming Kit & a decent overhaul kit with Alto Red clutches & bands. Billet low/reverse servo piston Kit & you're good to go. If your trans is out of an RV then you should have the 5 clutch high/reverse drum. That's a big bonus. :burnout:
 
KickDown said:
Great timing. Pick up a bolt-in sprag, a TF-2 reprogramming Kit & a decent overhaul kit with Alto Red clutches & bands. Billet low/reverse servo piston Kit & you're good to go.
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Agreed. Even though at your power level stock clutch/band material is sufficient I always upgrade to the better materials so it'll last a long long time. The cost isn't much different so why not.
 
Might even get the top hat cut so you can add an extra clutch.
 
Before running it again after the rebuild, you might consider checking the KD ratio. It's possible, even with the slack taken out, that the arm on the VB is not in the full-travel position.
 
AJ/FormS said:
Before running it again after the rebuild, you might consider checking the KD ratio. It's possible, even with the slack taken out, that the arm on the VB is not in the full-travel position.
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good advice. I've seen problems with this with modified vehicles (aftermarket carbs and intakes)
 
thanks for the advice guys
I'm not sure yet if I want to tackle this myself or have a local shop do it

I want to say I had the kickdown linkage adjusted properly, but at one point the throttle bracket came undone and loosened up, lowering the kickdown linkage pressure, so who knows, that might have been the issue


while were on the topic, any suggestion on who to contact for a torque converter?
 
The choice is yours. The guys at PTC, Dynamic, or Edge, all know their stuff & will advise you well. Just supply them with every last detail on your set up & how you intend to use the car & you wont be disappointed.
 
fishy68 said:
Agreed. Even though at your power level stock clutch/band material is sufficient I always upgrade to the better materials so it'll last a long long time. The cost isn't much different so why not.
Click to expand...

Done this with Chevy rats, in heavy cars. Had to overhaul a TH400,because of a misapplication of converter (VERY LOOSE TCI "bought it cheap, my fault ,not the old school TCI stuff.." ) The overbuild of Alto Red clutches & better bands,won't hurt.( pay attention to the clutch pack clearances) I would order an ATRA transmission book, on this .Such a good thing, read it before you tear the Beastie apart.. ( preparation, x 10, go get it,dude..)
 
probably a dumb question...but the weather is nice
what are the chances 1st and 2nd are gonna get shot if I keep driving her?
 
it won't do them any real good, but they aren't dependent upon each other, you can drive it, just go easy..
 
crap gets into everything, so the longer you drive it, the more chance you get contamination elsewhere, and that can damage the valve body, pump too. COuld also cause damage to the input shaft hub splines where the direct clutches slide on.
 
KickDown said:
Great timing. Pick up a bolt-in sprag, a TF-2 reprogramming Kit & a decent overhaul kit with Alto Red clutches & bands. Billet low/reverse servo piston Kit & you're good to go. If your trans is out of an RV then you should have the 5 clutch high/reverse drum. That's a big bonus. :burnout:
Click to expand...

I did this last summer. Read some books, watched a guy on youtube, he had a 13 part series on the 727 transmission.

Alto clutches, 4.2 kick down lever, bolt-in sprag, TF-2 reprogramming kit, and a 5,600 rpm governor kit from A&A Transmissions.

I took me about 3 weeks but the end result was awesome. Real satisfying to know that you did it yourself. I would recommend a higher rpm governor kit though as the 1-2 shift is around 5,500 rpm. Get the 6,000 rpm governor and adjust the linkage to set your 1-2 shift rpm.
 
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