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Foolishly put Lucas "Transmission Fix" in a 727

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Foolishly put Lucas "Transmission Fix" in a 727

kasman kasman
New User | Posts: 2 | Joined: 09/13
Posted: 09/23/13
01:37 PM

Hi Mopar peeps.  Noob here.   So i recently bought a '77  b200 Travco conversion (camper) van with a 360 and 727 to take the kids camping. Van has only 74K miles and generally in pretty good shape.  The previous owner had not used it much in the past decade, and I figured a lot of the rubber stuff would need replacing, so I wasn't surprised when the rear seal at the back of the extension housing began leaking.  I replaced the seal, checked the fluid level (Neutral, warm) and saw that it was a quart low.  Checked my factory manual and it specified Dextron II.  went to the local Oriellys and checked the shelf.   No dextron II, only Dextron III and IV.   Not knowing the differences (I've only owned manuals my entire life)  and not wanting to put in the wrong stuff, i was stumped.  The guy that worked there suggested I put in Lucas Transmission Fix instead as "Preventive Maintenance".   I put it in and went on with life. It's been about 300 miles, but I notice that the van seems to pull harder at idle against the brakes when I'm sitting at a light, and transmission pulls down the engine revs to the point to where it stalls at times when cold, as if the thicker stuff is making it harder for the torque converter? to slip at low RPM. likewise it seem like I have to push harder on the brakes to stop when driving around town, So I end up shifting into neutral at lights.

I think I want to get rid of this stuff,  Am I doing any damage by having it in there?  What's the best way to get it out?   The stuff is thick and I'm sure coating everything in the transmission.   Should I put in another solvent based product to wash it out, or just drain and refill.  

And what should I refill it with?   III or IV,  do they still make the II?

Related question, my trans dipstick has the wiring for the low fluid light, and the wires snake off to somewhere, but there is no light on my dash, the location for it is blanked off.   Was this an option?  is it easy to add?  

waynep712222 waynep712222
User | Posts: 127 | Joined: 04/13
Posted: 09/24/13
02:18 AM

7835737112 4F77cedaa5 B

like that one.???

and another one bites the dust.

a few things... all you can do it change the fluid .. several times to dilute it out..

new filters each time...

or just yank it out and rebuild the transmission.. and replace the torque converter...  the torque converter probably has a drain plug in the front face..


and a HUGE HINT..

visit a junk yard .. find a late 70s thru mid 90s dodge or plymouth van. with a V8..

take off the bolt that holds the dipstick tube to the back of the head or to the transmission bolt.. its going to be either 9/16 or 5/8..

you are going to be looking for a LONG automatic transmission dipstick tube and dipstick..

stop by a transmission parts supplier and buy a dipstick tube Oring..  under 2 bucks..  swap out your old short dipstick for a dipstick and tube that can be checked from the front..  these are over 5 feet long..

please... with Torque flight transmissions.. these normally get checked in Neutral..

there is NO CONVERTER FILL on most until you have selected Neutral..

any current dextron fluid will work in your transmission..

you do NOT need the Mopar spec ATF+3 or ATF+4 that are used in later computer controlled mopar transmissions.. those have an exact quanity of rosins.. these are what creates the grip of the clutch and band friction materials against the steel clutch discs or spinning drum outer surfaces..

i would probably pick up several ONE gallon containers of transmission fluid..

each change takes 4 to 6 quarts depending on pan depth.. and more than that if you drain the torque converter..

one thing.. be very careful if you want to drain the torque converter..

and a hint.. my former boss was a chrysler master tech..  he showed me the time saving way to drain the torque converters... he pulled the drain plug and started the engine.. man.. fluid went everywhere.. including into the starter..

he believed in draining all converters.. he saved the tiny plugs that used to come in tie rod ends before you screwed in the zirk fittings..  he drilled and tapped a lot of torque converters with pairs of these 180 degrees apart..

there is also a special tool for the dust shield version of the tail housing bushing..

you can.. while you have the transmission drained.. but the new filter installed. the pan bolted back up..

on the tail housing leak...    grab the drive shaft yoke... wiggle it in the tail housing... there should be NO PLAY.. worn tail shaft bushings allow the shaft to wobble beyond the limit of the seal.. so it starts to leak

if you pull the drive shaft.. check the yoke for rust spots and for wear... where it will eat up the new seal and or tail shaft bushing..

jack up the transmission with a block of wood across the bottom of the pan..  pull the transmission mount bracket... and the speedo gear holder out..   you can unbolt the tail housing.. you will need a special pair of pliers to expand the snap ring thats hidden below the steel plate cover thats sometimes under the transmission mount.. to be able to remove the tail housing.

if the bushing is worn.. you might need to remove the tail housing to replace it and the rear seal.. please try the drive shaft thru the bushing away from the van before you attempt to install the seal.. sometimes the edge of the bushing gets mushroomed from being installed.. so the drive shaft yoke does not slip thru the beginning of the bushing..  

there is a cork gasket for the plate. there is a new tail housing gasket..

along with new seals for the speedo gear holder..  

69_340_GTS 69_340_GTS
Enthusiast | Posts: 535 | Joined: 06/09
Posted: 09/24/13
09:34 AM

a few things... all you can do it change the fluid .. several times to dilute it out..

new filters each time..."

I think that's overkill. Unless the Lucas stuff has been known to ruin transmissions? I have no evidence either way, do you? They are a good company and as far as I know make excellent quality products.  

Everything you mention might just be being caused by too high of an idle speed when hot, and a choke or fast-idle that's not working right when it is cold. I'd check both of those things before tearing apart the transmission.  

kasman kasman
New User | Posts: 2 | Joined: 09/13
Posted: 09/24/13
02:54 PM

Wayne, I've seen that one too.  No nothing quite that big.  Ours is more of a van than an RV, here is a link to some pictures the previous owner posted showing her in all her retro glory:   My wife had basically the same one growing up, so the good husband that I am, i bought it for her for our anniversary.

Thanks for the tip on the fill tube swap.

When I changed the extension housing rear seal, (dust shield version) i checked for wear on the drive shaft where it rides in the seal, all looked good,  I wondered about the bushing, I noticed that the output shaft had a little bit of play, maybe 1/32 or so. I didn't know what the spec was, but i figured the seal replacement was fairly easy (although I didn't have the special tool), that I'd just do it and if it started to leak again, I'd know the bushing was the culprit.   I'll see how it holds up.  no leak so far.

I will do the transmission fluid incl, torque converter drain, (LOL, not the running one) once and see if that makes a difference.  


My idle is a bit high, that is also a good tip.  but it was also high before and I am noticing this problem more now.  Regardless, I think that this lucas stuff just increases the viscosity of the fluid too much in the tranny.   maybe an ok product if you have a slipping transmission, but that's not the case with mine.   Hopefully diluting it down will solve the issue.  

As I said, I'm new to Automatic transmissions, so i appreciate the coaching.

I'm also on a quest to increase the gas milage on this thing.  Just picked up a set of Doug Thorley tri y headers at the local pick and pull and will be fabing up an dual exhaust.  Was also thinking of pulling the fan and putting in an electric one... any other suggestions welcome.  

waynep712222 waynep712222
User | Posts: 127 | Joined: 04/13
Posted: 09/25/13
12:43 AM

turn the idle speed down as low as possible..

search out vacuum leaks..

don't take the belt driven fan off.. you need all that cooling to push that barn down the road..

i have a bunch more typed out.. but the machine won't let me post it??  

drmopar drmopar
Guru | Posts: 1445 | Joined: 02/08
Posted: 09/27/13
08:03 PM

I am amazed at how someone assumes all there vehicles problems are from the one bottle of snake oil they bought and installed. First of all Lucas products are some of the finest. Second, your vehicles problems didn't start from one bottle of Lucas. Your vehicle most likely has a life time of neglect and problems from wear, tear, and age..
If you aren't sure, ask before you throw something in it, not that it mattered in this case. Dex 2,3, or 4 will work in your trans. A good full synthetic trans. oil for a Chrysler product would do as well. You can even put Ford trans. fluid in a basic 77 727.  
As far as your vehicles problems?? Sounds like you need a good mechanic before you waist any more time guessing what might be wrong with your vehicle..


skyeking skyeking
New User | Posts: 3 | Joined: 09/13
Posted: 09/30/13
05:05 PM

Laugh Hi there,
 I would prefer by experience  stick with the Dexron range of
 tranny oils as I have actually mixed 2 & 3 together and no problems
 with TH400 and TH700s. I ran a 904 and a BW35 on it too.
 Forget the the Synthetic oils for the early Autos.
 Cost more and achieve no more.
 Good luck with Wayne's advice. Cool  

drmopar drmopar
Guru | Posts: 1445 | Joined: 02/08
Posted: 10/01/13
04:13 PM