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ok so i'm driving up the freeway the other day and look in my mirror to see massive white smoke... oh oh.... pull over and it's coming from the bellhousing... h9ikes... tow it home and ck it and sure enough tranns fluid... this is in a 66 mustang c4.... oh boy... well there's only two seals up there so I replaced the pump gasket and the front seal and it still leaks... now this is a running leak not drip drip… so any thoughts... somewhere I heard there might be a drain plug on the torque conv... but … so out comes the trans again.... help... thanks Doug in Oregon
 

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Auto trans fluid leaks sometimes require careful inspection to determine exactly where the leak is coming from.

BTW early C4's also have an O-Ring around the pump body.
66 should have an O-Ring unless the trans has been switched out to a later model C4.

That said, if you are sure the leak is from inside the bell housing and the front seal and pump bushing are good,
then that just leaves the converter drain plug and/or possible cracked or pin holed weld on the converter.

Might need to pressure test the converter.
 

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Auto trans fluid leaks sometimes require careful inspection to determine exactly where the leak is coming from.

BTW early C4's also have an O-Ring around the pump body.
66 should have an O-Ring unless the trans has been switched out to a later model C4.

That said, if you are sure the leak is from inside the bell housing and the front seal and pump bushing are good,
then that just leaves the converter drain plug and/or possible cracked or pin holed weld on the converter.

Might need to pressure test the converter.
Auto trans fluid leaks sometimes require careful inspection to determine exactly where the leak is coming from.

BTW early C4's also have an O-Ring around the pump body.
66 should have an O-Ring unless the trans has been switched out to a later model C4.

That said, if you are sure the leak is from inside the bell housing and the front seal and pump bushing are good,
then that just leaves the converter drain plug and/or possible cracked or pin holed weld on the converter.

Might need to pressure test the converter.
hey thanks for the quick response... this is a later model trans w/o the oring… it was installed by a shop in SD thirty years ago. I think it's about a 71... but the pump gasket is the same and the front seal is also. I thought about the welds but this happened right away, one minute it was fine the next if was leaking bad w/ LOTs of white smoke blowing out the back. shut it down right away and towed it home. it would seem that a blown gasket or seal but not a worn down part such as a bushing which would normally start to leak a little then more and more... this happened immediately.... like the torque converter drain maybe fell out or something like that... thanks again... Doug
 

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I know the C4 and C6 are similar, but I've not had a C4 apart. Particularly removing the bell housing. The C6 is case and bell all one piece. The reason I'm pointing that out is...... The C6 has a plug that holds the servo apply lever shaft in place and it is exposed to the front of the bell housing it is easily seen looking into the bell and sits close to the front pump. I don't know if the C4 lever shaft comes out through the front of the trans or it there is a plug through or under the front pump that may cause a leak, even if the pump is sealed and the convertor is not leaking. Since I am not up on the C4, this is just a shot in the dark for me. Good luck!
 

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Thanks for the information Greg. I always like learning. My hope was that the OP might get out of the box. He said it poured out, so I can't visualize that, if it happened all at once. I wonder if a bad bushing going bad all of a sudden let loose and tore up the seal. I'm just throwing stuff out there. Thanks for sharing your knowledge Greg.
 

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I guess the easiest thing first, would be to get the car up, pull the inspection plate and check the convertor for cracks, drain plug, etc.
 

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Thanks for the information Greg. I always like learning. My hope was that the OP might get out of the box. He said it poured out, so I can't visualize that, if it happened all at once. I wonder if a bad bushing going bad all of a sudden let loose and tore up the seal. I'm just throwing stuff out there. Thanks for sharing your knowledge Greg.
No lever in a C4 like that , different setup to a C6
I just realized you had a 19 year anniversary 4 days ago here.(y)
 

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hey thanks for the quick response... this is a later model trans w/o the oring… it was installed by a shop in SD thirty years ago. I think it's about a 71... but the pump gasket is the same and the front seal is also. I thought about the welds but this happened right away, one minute it was fine the next if was leaking bad w/ LOTs of white smoke blowing out the back. shut it down right away and towed it home. it would seem that a blown gasket or seal but not a worn down part such as a bushing which would normally start to leak a little then more and more... this happened immediately.... like the torque converter drain maybe fell out or something like that... thanks again... Doug
FWIW...
Front seal leaks "can" happen instantly when the bushing is bad,
even tho it might have taken some time for the bushing to wear,
once it's worn the run-out on the T/C hub will rip a seal fast.

Also the bushing can wear out fast as well, esp with hard use, ie; high RPM blast, racing etc,
OR if some foreign material got between the hub and bushing, that can ruin a bushing fast too.
Then the seal goes bad right away.

Another thing is that with hard use the bushing can "walk" forward and touch the seal and that causes an instant (huge) leak as well.

Bushing walk is not often a problem on these trannys but is common enough, I have seen it happen.
 

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I don't know a whole lot about these C4/C6 but that is just common sense. You are so right galaxiex. I read a deal yesterday, guys were talking about GM maybe 350, that some bushings should have a swipe of thread locker on them to keep them from walking in the case. I don't know, but that's what they were saying. No I don't read about a lot of GM stuff, but I was researching some GM bearings ,,,,,,, like in rollerizing a C6. :D
 

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Congrats......I've been here a couple of years, but never posted much and then I ran across DesertXL's rollerize thread. It's a good one. I'd spent most of my time @ the 2 other 460 sites. I got reamed @ 429-460 BBF. I don't mind it with 1 or 2 members, but it was a pile on. I wiped the ATF from my eyes and now it's just 15W50 under the bridge. FWIW, In my defense I got several nice PM's, but no one would say so in the thread. :cool:
 

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That's funny , has been a few years lol

I always add a little Loctite on converter bushes
Speaking of Loctite, I bought a RED tube at Wally's World, and got home and it was blue. I did a little research and found out I should have checked the number on the package. It was a good mistake cause it made me check Loctite's data sheet. I found out that almost all their lockers are good to 300*, including some red. They have a red that is good for 450*... #272. Now I'd like my C6 to never see 300*,:eek: but it might be prudent, if you're going to use it on the bushings, to have that little extra insurance. Be my thought anyway. I bought a temp gauge for this build and I'm going to buy a cooler. Hope it doesn't see 200*. Greg what do you think? I've read to try to stay under 190*. Is that doable drag racing?
 

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With a good cooler temps will stay ok. I try to use the plate type coolers approx. 11" x 10" x 3/4" temps will stay easy under 190, on average 160-180F

That is a good thread on the roller C6 , plenty good info. I always try to help out if I can ..
 

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With a good cooler temps will stay ok. I try to use the plate type coolers approx. 11" x 10" x 3/4" temps will stay easy under 190, on average 160-180F

That is a good thread on the roller C6 , plenty good info. I always try to help out if I can ..
You have been a big help for me. Frank is great, has a lot of C6 experience and knowledge, but sometimes I have to re-read his posts a couple of times to get a full understanding of his comments. This is my first Hi-Po roller C6. I'd be lost without these forums and help from people like you and Frank. DesertXL did a great job and his pictures are top notch. I'm unfamiliar with a plate cooler. What is that?
 

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My intention was to build a D2AP out of a 72 Lincoln. I found a Core D7AP I was going to use the tailshaft and tailshaft housing to get rid of the Lincoln angled trans mount. I got the D7 home and it looks like a solid trans. Supposed to be out of a Ford pick up. If you had your choice, would you build one over the other? The Lincoln has a rear 4 gear planetary and a 5 disc clutch pack back there. I have not opened up the D7.
 

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73 and later have the push-in modulator.
I prefer those units as they have the later factory changes.
Better selection of modulators compared to the screw-in style.
Aside from that C6’s are all pretty beefy and mostly the same but of course if you are making lots of power, 4 pinion planets and more clutches in the packs are good to have.
I did work on a very early 1966 C6 out of a thunderbird that had only 2 clutches in the direct clutch pack! Crazy!
Most internal parts interchange but you do need to be careful when it comes to forward drums and front planet ring gear hub.
Also output shaft snap ring thickness and park gear thickness.
Be sure to use matching parts!
The later units have thicker snap rings on the output shaft and a corresponding thinner park gear.
the early thin snap rings tend to break.
 

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galaxiex, thanks that is good information. I've kinda decided to go ahead and build the 72 (D2AP) and just use the tailshaft and housing off of the 77 (D7AP). Unless something changes when I get inside the D7. Taking the 72 apart looked pretty good, I mean there was no excessively worn or broken parts. The band was limp but still had lining and so did the clutches. It has a 'D' apply lever and I have a Superior 'E' lever and the Superior 'R' servo I'm going to use in this build along with some Alto clutches and the Red Eagle wider band. If it wasn't for the Lincoln Tail Housing mount, I probably would not have bought the core, although it was cheap at $75. I bought a C6 used tail housing on eBay and what the guy sent me was for a C4. He did give me my money back, but it cost me $12 to ship it back. I've probably got $12,000 in engine and transmission parts so far. I'm just not going to let $12 eat on me. Actually the core at $75 was cheaper than the wrong C4 housing was at $85. lol. I'll be aware on the snap rings, although I thought there were some selective snap rings, maybe that was in the drums though. I thought DesertXL made mention of some of the later drums take clutches with more teeth. I'd have to go back and check that on his C6 Rollerize thread to be sure. Memory is not what it used to be. o_O Thanks again for your response.
 

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You're welcome.

Be careful with that "E" lever and R code servo.
Band apply can get extremely firm/harsh. Also some risk of cracking or breaking the case!
The "D" lever is probably fine anyway.
I'm using the D lever and R servo in mine, tho I have not driven it yet,
I previously had the D lever and D servo and it was plenty firm with the shift kit. Almost too firm.
There are guys that use the "A" lever (smallest ratio) and R servo and 2nd gear band apply is plenty firm, esp with a shift kit.

The selective snap rings are for the clutch pack clearances in the drums.

The output shaft snap rings...
One retains the governor housing to the shaft and the other retains the rear planet hub to the output shaft,
and also prevents the output shaft from falling out of the case.

Early units (I forget what year they changed) had thin snap rings that would break and the output shaft would slide rearward and cause issues.
The later units got thicker snap rings to prevent that problem.

The grooves on the shaft for the snap rings are wider for the late thick snap ring, and of course the early shaft has thinner grooves for the thin snap ring (duh).
The shafts interchange with the correct snap rings and park gear.
Obviously, don't mix these parts, ie don't use thin snap rings on a late shaft with wide grooves, and make sure to use the correct park gear.
Everything has to match!

72 "might" have thin snap rings, but the 77 for sure will have the thick ones.

Actually I think 1976 is when the snap rings changed, so 72 "probably" has the thin ones.

So if you are going to use the output shaft from the 77 into the 72 trans, you MUST use the 77 snap rings and park gear.
These parts WILL interchange into the 72 trans.

Have fun!
 

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Sounds like you have a good selection of parts to build a nice trans .
I like the E lever + R servo combo. I've used lots like that with Franks valvebodies .
From my experience it's only when using the even higher ratio levers with the big servo that causes case issues.
Use a nice aluminium pan helps cure the case issue and supprts that side of the case at the band adjuster .

A plate cooler is a slightly more efficient cooler than a tube/fin type . Have a google around and check some pics you'll se the difference . In saying that I have used either type but lately use mostly the plate types
 
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