Author Topic: 727 trans slippin and grabbin in reverse  (Read 7261 times)

Offline F N Cuda

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727 trans slippin and grabbin in reverse
« on: February 12, 2006 - 01:38:16 PM »
My "full race prepped" 727 trans works fine in reverse when cold. I hear it's typical for it to need time to pump up when cold and this is the case with mine. I have to wait after selecting reverse before car starts moving, again I hear this is normal. Is this true? Also, I check fluid level after a short putt for temp to reach normal with shifter in neutral, right?
When I get to running temps, all forward gears work fine but reverse jumps and jerks so badly that at one point with the motor jumpin around it sheared off the copper tubing at the oil pressure fitting on the back of the motor. NEAR DISASTER! My friend lost a beautiful 'Cuda in a similar type of mishap. More on that later in this thread. Better watch your mechanical type oil pressure gauges. His broke, cut or just came out under the dash and oil sprayed all over, total loss flame job!
Mine sprayed all over the motor, headers, hood and windsheild on the driver side as I was looking over my shoulder to back up to a gas pump.
I heard people yelling and horns honking as the front of my 'Cuda turned to a major smoke bomb but no flames fortunately! I lost four quarts of oil in about three seconds or so. I heard a hot tip is to use a rubber brake line for the connection at the engine fitting for a flexible link. Anyone know about this, can it take the heat? I want to do this or go to an electric sender and gauge.
Anyway, back on topic. Is my tranny problem a filter and fluid change issue or is it bigger like a bogus torque converter or valving or clutches or... I'm told it is a 3500 stall but I'm not sure of this cuz if I hold the brakes, not just the line lock, it seems to pull really hard at about 1800 to 2000 rpm. Any input on this too?
Pix and story on my buddy's 74 'Cuda burn job to come here or elsewhere maybe more appropriate. Maybe I'll let the powers that be move it from here if wanted.
Thanks for listening and hopefully helping. ALL TIPS GREATLY APPRECIATED!
'F 'N 'CUDA!
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Offline MEK-Dangerfield

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Re: 727 trans slippin and grabbin in reverse
« Reply #1 on: February 12, 2006 - 01:53:48 PM »
I am of NO help  :banghead:, but being in Southern Cal. "cold" shouldn't be an issue with you. Something isn't right. You don't need to warm up. Do you know the history of this car? Maybe all that dragging has caused the tranny to wear down???  :dunno:

  Mike

Mike

1970 Challenger - SOLD
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Offline F N Cuda

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Re: 727 trans slippin and grabbin in reverse
« Reply #2 on: February 12, 2006 - 02:51:31 PM »
Trans is supposedly rebuilt but the only info I was given was, full race, 3500 stall, manual shift valving.
It is perfectly clean which doesn't mean anything I know as is the engine and rearend.
All claimed to be rebuilt. Good compression tells me motor part is at least very good . So I want to believe the rest is also good. Fluids all very fresh when I got it. I can only hope for the best.
I plan on doing the full trans flush, cooler, converter filter and good fluid. Is the B&M Trickshift the way to go or is there something more trick and street/strip friendly? Any tricks and or tips would be fully applied! Probably today if I get hooked up with the goods.
Here's some pix of the 74 of my buddy. Broken oil line at the gauge, no fire extinguisher (everyone get one!!) cuz it got pulled for the new carpet, instant inferno.
Long story short? He sold it to pursue the restoration of his next 'Cuda, a purple 73 dragrace only, turning street/strip. More on that later too. Perhaps he'll join us from Alabama where he moved to in order to get more for his money than in So. Cal. So far so good too! Big house etc...
OK, had 14 grand in it, 8g to get it, 6g to finish it as in the pix, very nice. Oops, forgot to insure it for the extra 6 grand over the initial 8 grand!
Readers, insure it for what it's worth.
He had it sold for 18 grand (very fair price as it was super nice), check cleared, title exchanged, was to be picked up within the week.
He decided to get a scratch fixed even tho the new owner said it wasn't necessary. My buddy's just a nice guy and the shop is a mile away.
On the way home, line broke, flames burst out, car toasted.
Insurance realizes he didn't up the value and agrees to honor the receipts and offers him 15 grand for the loss.
He tells them that he just got 18 for it so that is what it should be worth, no? No. Blue book said 8g to 16g tops.
Independant appraiser and my buddy looked up the numbers and showed BS2 'Cuda as a special body option, vinyl top, loaded, etc... NEW BALLGAME!
Blue book now showed 10grand to 30grand +++! Pictures show an 8 or 9 out of 10 point car.
Insurance says OK how about $28,500? Over $10,000 more than he sold it for.
He's thinkin about it!
Not sure what to do with the fried hulk. Not even sure where the insurance co. has it! 
Cool plates too, huh? He just got em.
« Last Edit: February 12, 2006 - 03:04:17 PM by F N Cuda »
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Offline F N Cuda

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Re: 727 trans slippin and grabbin in reverse
« Reply #3 on: February 12, 2006 - 03:02:24 PM »
Here's more from the burn victim story.
Of course photos are before and after.
The purple 'Cuda is the new toy gettin done up for the street/strip.
« Last Edit: February 12, 2006 - 03:05:12 PM by F N Cuda »
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Offline EVIL72

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Re: 727 trans slippin and grabbin in reverse
« Reply #4 on: February 17, 2006 - 01:34:52 AM »
 The trick used to be to use Ford type F tranny fluid for a firmer shift. Not sure if there's something better now.
 As for your tranny problem I'm no tranny expert, but I'd take it to a good tranny shop and have them make sure all your bands are adjusted correctly. Who knows who built this transmission. I'm sure whatever it is they will know real quick.
 As for your converter it sounds more like a stock converter if it doesn't stall close to 3500 RPM. So you can't stall it past 2000 RPM's at all? I had an old 340 converter that stalled a little higher than yours with a 383 motor.
 Good Luck with it.
ROB
1972 Dodge Challenger 340ci
1970 Pro Street Duster (Under Construction)

Offline Andrew

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Re: 727 trans slippin and grabbin in reverse
« Reply #5 on: February 17, 2006 - 02:56:28 AM »
From what Iv read on this site, their a bit odd with their numbers.
Like a 3500 stall converter might start to pull at around 2800... if that makes sence...

Offline F N Cuda

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Re: 727 trans slippin and grabbin in reverse
« Reply #6 on: February 17, 2006 - 09:14:49 AM »

thanks guys,
the part that is confusing is that it was all good for quite a while. When it started to slip n grab I quickly assumed it was a fluid level thing, it was a little low, I took care of that and the next time I drove it, it was cold again and everything was fine.
When it was warm and I was backin up it was still jerkin. Good cold, funky when warm. I just need to do the filter and fluid change and hope it's all good. Of course, when time allows!
'F 'N
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Offline F N Cuda

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Re: 727 trans slippin and grabbin in reverse
« Reply #7 on: February 21, 2006 - 10:34:14 AM »
Just did the converter, cooler and pan drain thing and changed the filter.
Went with the B&M Trickshift fluid. Unfortunately it made no difference.
Now I'm bummed. It kills me that all 3 forward gears work perfectly, and reverse only works correctly when it's stone cold.
I'm convinced it must be an adjustment. Someone else suggested it might be the torque converter.
IF ANYONE HAS ANY CLUES, PLEASE DROP THEM IN FOR ME!
Thanks again,
'F 'N CUDA
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Offline F N Cuda

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Re: 727 trans slippin and grabbin in reverse
« Reply #8 on: February 21, 2006 - 02:49:31 PM »
Talked to a trans tech dude. He's got me goin into the pan again and as per the Mopar trans book (duh), I'm gonna set the reverse band adjustment bolt, it's the only one inside the trans, the other is outside.
I'm to tighten it to 72 INCH pounds (clockwise) and then back it off EXACTLY 2 full turns.
As this is done, I'm to count how many turns it takes to get to 72 INCH pounds.
If I need to go more than 4 or 5 turns in (initial setting was 2 out,remember) then the band is too far gone and needs to be replaced.
If the adjustment is within range and the problem still remains, there is leakage/blow-by in the reverse valve body allowing a low pressure situation.
Hope I can get by with an adjustment!
These pix are what I saw on ebay when I bought this car 2 years ago.
« Last Edit: February 21, 2006 - 02:52:58 PM by F N Cuda »
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Offline EVIL72

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Re: 727 trans slippin and grabbin in reverse
« Reply #9 on: February 21, 2006 - 07:38:48 PM »
 Good Luck with it F N Cuda, Hopefully this will fix it for ya.
 
ROB
1972 Dodge Challenger 340ci
1970 Pro Street Duster (Under Construction)

Offline F N Cuda

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Re: 727 trans slippin and grabbin in reverse
« Reply #10 on: February 21, 2006 - 08:44:30 PM »
I'm told full race trannys need to be reset every ten to twenty runs or so. Mine's supposed to be full race so who knows. Hope it works. Drag to have to drop the pan to get there. Lots of fluid, mess, gaskets and silicone.
I heard that silicone only is the best, nice even coat, DON'T fill the bolt holes cuz hydro lock occurs and bolt holes strip, don't overtighten, and let it set up completely before using and I'll never see a leak, ever.
I'll be the judge of that cuz I'm gonna do it next time I go in. I'll let you guys know.
F N
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Offline JCWCuda

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Re: 727 trans slippin and grabbin in reverse
« Reply #11 on: March 04, 2006 - 08:40:38 PM »
I installed a drain plug in my trans pan ,and really helps cut down on the mess  :clapping: don't ask where i got the kit or who made it cause that was 15 years ago  :roflsmiley: Good Luck i hope it is just a band Adjustment

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Offline F N Cuda

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Re: 727 trans slippin and grabbin in reverse
« Reply #12 on: March 04, 2006 - 10:05:20 PM »
Well Dudes, I did the band adjustment and nothing changed. Bummer. Oh well.
It's really strange that it works perfectly when cold and sounds and acts like broken teeth slippin and grabbin when it gets the slightest bit warm.
Word is it must be a valve losing pressure when the fluid heats up and thins out.
I guess it's up to the pros to figure it out for me.
I'll keep in touch. And I have a drain plug too!
Oh yeh, no gasket,  red hi temp silicone, finger tight til it squishes a LITTLE, 1 hour later added 1 full turn to each bolt and absolutely no leaks from around the pan. This as per a Mopar tech, a young guy, at the Dodge dealer. He promised it would work when I asked his advice on tranny gaskets. :working: :undercar: :useless: :
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Offline Follicly Challenged

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Re: 727 trans slippin and grabbin in reverse
« Reply #13 on: March 05, 2006 - 09:05:11 AM »
Geez, I ain't no trans guy anymore either, this may require my using brain cells that ain't seen no blood in about 20 years !
Some questions;
Is this a transbrake body ?
Full manual "reverse" pattern shift ?
There are some issues with these in the valve body, but, if not, then lets continue;

"Reverse" involves the application of fluid to the Rear band servo actuator, and the front/high gear clutch Pak if memory serves me correctly. The pressure to both, is "bumped" from normal "line" pressure when reverse is selected, through the valve body, so as, to compensate for running the helical cut gears backwards(more parasitic resistence).

Anyways, If it is shifting crisp/fine, when hot, on the 2-3 upshift, we can assume High/forward clutch integrity for now.
However, the rear/low band servo is probably not "patent" when "Hot" causing the "hot" condition you mentioned. The reason it works fine when cold is the thicker fluid viscosity at the lower temp.

To try and diagnose the above, test for SLOW,  "manual" low/1st gear application as well when "HOT".
In other words, try shifting directly from "neutral to first" when hot, and see if "it's slow" there too, or, if it feels like a "dual engagement", IN, and then IN again, as opposed to going from neutral to 3rd/drive.

If it does, start looking at the rear servo, adjusting the band won't last because the problem is in the sealing mech on the rear servo Piston.

Dunno if I remember all this correctly, ain't been in a 727 for years, got "too easy" once I found a good tranny guy, and didn't have to do my own anymore !

FC out.

Offline F N Cuda

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Re: 727 trans slippin and grabbin in reverse
« Reply #14 on: March 05, 2006 - 10:16:13 AM »
FC, Thanks for the reply.
Here's some answers to your questions. I appreciate your input. Please gimme more!
Trans is claimed to be full race, to what extent I don't know.
Full manual, reverse valve body, no trans brake.
When downshifting, no motor brake, like hittin neutral. I think this is called "low band apply" which I guess I don't have.
Trans goes right into 1st hot or cold, no delay or dual engagement.
When cold, reverse takes several seconds to engage but when it does, it is good, no problems slippin at all.
How would a reverse servo piston be delt with? Pro only?
Any recommendations in the So Cal area.
THANK YOU, THANK YOU...
'F 'N' 'CUDA!
P.S. Is this good for my tranny? (pic) :useless:
Geez, I ain't no trans guy anymore either, this may require my using brain cells that ain't seen no blood in about 20 years !
Some questions;
Is this a transbrake body ?
Full manual "reverse" pattern shift ?
There are some issues with these in the valve body, but, if not, then lets continue;

"Reverse" involves the application of fluid to the Rear band servo actuator, and the front/high gear clutch Pak if memory serves me correctly. The pressure to both, is "bumped" from normal "line" pressure when reverse is selected, through the valve body, so as, to compensate for running the helical cut gears backwards(more parasitic resistence).

Anyways, If it is shifting crisp/fine, when hot, on the 2-3 upshift, we can assume High/forward clutch integrity for now.
However, the rear/low band servo is probably not "patent" when "Hot" causing the "hot" condition you mentioned. The reason it works fine when cold is the thicker fluid viscosity at the lower temp.

To try and diagnose the above, test for SLOW,  "manual" low/1st gear application as well when "HOT".
In other words, try shifting directly from "neutral to first" when hot, and see if "it's slow" there too, or, if it feels like a "dual engagement", IN, and then IN again, as opposed to going from neutral to 3rd/drive.

If it does, start looking at the rear servo, adjusting the band won't last because the problem is in the sealing mech on the rear servo Piston.

Dunno if I remember all this correctly, ain't been in a 727 for years, got "too easy" once I found a good tranny guy, and didn't have to do my own anymore !

FC out
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