Speed

[GReynolds]

I have a 1991 4X4 with AT and 3. 07 rear. The max speed of my truck is about 75-80, on a good day, with the pedal mashed to the floor. Doing the speed limit (75) really makes the engine run hot and makes for bad mileage since the truck is running wide open. The truck has 215,000 miles and the transmission is getting a little tired (original). Is there an easy way to get more speed? I don't have a tach, so I don't know how many rpm's I have left. Can I use a higher geared transmission when the original finally goes? Any ideas?

 

[RDusch]

Sound like somethings definetly going south on ya.

My 93 auto with 3:53's will do close to 90mph, those 3:07's should cruze on down th road,

I put a new trans in mine afew ears ago thinking the same thing but ended up being the tourqe converter that was doing all the slipping, you might look at that first, i would'nt know how to tell you to check it with out a tack, but i'm shure somebody here can.



Rick D

 

[CBratten]

I think there is some other problem with your truck. Mine is a 91 model with the overdrive and 3:54 ratio. I have had it to 105mph

a couple of times and I don't think it was topped-out.

 

[therabbittree]

no problem with his truck!

guys he has a 3 speed auto the 727 transmission 1 to 1 3rd gear. . i have the same in my truck ( 89 1 ton 4x4 reg cab 727 3 speed with 3. 08 gears) and like he said 75=80 mph is max speed . . kinda sucks. . i've been thinking of swapping in a standard transmission. . for three reasons. . sound ha. i run stright pipes and the auto doesn't sound as sweet as my friends 5 spd. . the auto just spools up and shifts never lugs the engine . . my buddies truck with 5spd and straight pipe sounds like a tractor trailer. . lugg it down a little and exhaust sound is awesome, second is mpg. . he can get 22 mpg. . he has a 4x4 too... i can maybe get 17 usaully 15mpg, and third speed. . 75-80 sucks. . most of the time traffic is at those speeds and the engine is reved out. . need over drive... . or and i jsut thought of a 4th reason. . with the 727 3 speed transmission it doesn't have a locking torque convertor so i can't get a exhaust brake... mummn only benift of the 727 3peed is constant boost, quick acceleration. . and pretty bullet proof!

later

Deo

\x/ hillfolk!

 

[GReynolds]

Thanks for the reply. And thanks for realizing the problem I have. You are right, the transmission is bulletproof. I never would have thought that a transmission would go 215,000 miles and still be working. Also, my old truck will out accelerate my 1999 24 valve truck. I'm not complaining, I just want to go as fast with less work on the engine. It runs so hot. Has anyone put a higher geared transmission in as a replacement?

 

[therabbittree]

yeah i hear ya

i have a bunch of friends with cummins dodges 2 older first gens and 2 2001 6spd ho duallys the 3 speed auto in my truck out accelerates all of them except one of the first gens omy friend has with over drive transmission and his is turned up too. . but it beatsa the new ho engine!. . ha crazy at least till 75 mph. . sucks. . if you don't want to change the transmission looking into a overdrive add on unit... . i am checking into some allison autos too. . but the cheap ones aren't overdrive. . mummn kinda sucks

the 727's , bullet proof they are. . heck plowing and driving with your foot to the floor constant aren't easy on any transmission but this one is strong hasn't puked any fluid even when stuck offroad plowing . . spinning tires back and forth for 1 hr!. . heck that says something there. . we've blow th350s and th400 that way . . or at least puked some fluid. . but not with the 727 3 spd. . oh well i porbably just jinxed myself...

later

\x/ hillfolk!

 

[BushWakr - RIP]

You might try to run this by Bill K. From what I've read I think you'll find that the miles on the truck are well over the 'average' life of the 727 trans. It sounds like you do have slippage in the trans. A tach will be a big help in running that down, also an EGT/Boost gauge to see what kind of temps your running will help with diagnosing your fueling level. I have chickened out at about 105 MPH and still pulling hard with 23lbs boost at 750*F. You may have a combo of issues, transmission slip, governor setting not right, fueling lean, boost loss, dirty airfilter, dirty injector(s) low lift pump pressure are some.

FWIW



Regards, Bush'

 

[Steve Campbell]

Iis there any way to put an overdrive unit (Geart Vendors or US Gear) behind the 727?

 

[Fred Swanson]

GReynolds, where in Waddell are you? If you want to bring it over I can look at it for you. That high of mileage is a concern for a stock automatic.

I've got bvanetten's 90'Cummins /w a 72 Suburban body over doing a DTT rebuild on it. He already upgraded to a 94 transmission with overdrive and lockup. Since he has no PCM, they are activated manually.

 

[wrk2mtch]

It sounds pretty normal for that setup. I've got the 727 with 3. 07's and mine also tops out arount 75-80. It really sucks in going up a mountain pass, towing a trailer and only be able to do 60! I talked to someone at Jet transmission a while ago and they said that a swap to a 518 is pretty easy. I really want a W350cc though so I think I'll just leave it as-is for now.

 

[Matt S]

Try a search looking for posts from Jsimpson. He has done the swap but I believe he said he would just go with an aftermarket OD.

 

[Woodenhead]

Did all the '89 727s come with 3. 07s? It seems everyones '89 auto is good for 75mph and I can only get 65. My trucks been painted and the stickers are all messed up so I can't read the gearing off of them. I don't have a tach so I don't know what the revs are. I checked to make sure the linkage on the pump's hitting the stop. Has anyone else got a 65mph 727 'or any ideas?



Thanks

Mike

 

[Gary - K7GLD]

I have the early '91 with the plain 3-speed 727 too - and it too was only good for 80 mph on the top end. I use mine a lot for towing our 24 ft 5er, so added a US Gear OD unit behind the 727. Top speed is now 95, cruises easily at 70 empty, and I hold it down around 65 when towing. The ability to split gears with the OD is nice, but would be greatly improved with a stiffer torque converter. I plan on the TC upgrade when MY transmission gets tired, but JEEZE, *I* sure don't wanna wait ANOTHER 100,000 miles!

 

[Thierry]

I have 89 with 727 and gearvendor

Hi I live here in San Diego, and I to have a 89 auto with 3. 08 and 727, Truck was totaled and rebuilt using another 89 truck, trans planted the whole running gear, my trans had 150k and was running great, had it rebuilt for $400, trans was in great shape only the clutches were worn.

put everything back together with a gear vendor

and love it now I run down the freeway at 70mph

1900 rpm with a top speed of 90mph with governed pump of about 2550 rpm

Highly recomend installing a Vendor and you will get your foot out of the pedal ( or always be going faster)

Good luck

 

[Jim Curry]

Hey GREYNOLDS;



Take a look at the classified section of this site under engine and trans heading. Someone has a gear vendor for sale for the 727 complete with a drive shaft for $1200. 00 dollars. Don't know the condition its in but considering they cost 2500. 00 to 3000. 00 dollars new not including a cut down drive shaft, its worth looking into. You would still have your original drive shaft and be able to convert back if the need arose.





Jim Curry

 

[BillyKidd]

MY $.02 Worth

IMHO, The 727 is a great trans and I think you would really like it after a TC/VB upgrade and rebuild. THEN, add a Gear Vendor over/under aux. drive unit and you have possibly the best "first gen. " set up there is. I had that in my 74/89 conversion(74 1 Ton Crewcab w/ 89 4X4 CTD drive train) with 4. 10 gears and had good acceleration and in overdrive good top end crusing speed at reasonable R. P. M. If I had of been a TDR member then I could have "bombed" it for even better performance. BILLY KIDD