Archived It Was Just A Matter Of Time

[JTHUSKINS]

Something is slipping ! In my last 911 post everybody helped me solve my heating problem. I added power at the same time. The transmission only lasted two trips towing our camper until it began to slip in OD lockup. It does not slip in 3rd lockup. We still have one trip to make before winter and I need to figure out if this is the converter or the bands slipping. The problem does not seem to create any excess heat but is annoying having to back out of the throttle while climbing slight grades . I have never experienced a torque converter slip so I am having trouble diagnosing the problem. The same symptom occurred today with no trailer in tow at highway speed when I attempted to accelerate from 60 mph.

 

[S.Morris]

suggest you change transmission oil and completely flush system to remove burnt oil from cooler lines and torque convertor. Remove added power back to stock and see if TC will hold. If okay, be gentle on shifts and pulls and you should make the trip. If it still slips, then at the very least you are in for an upgraded TC and valvebody.

 

[Missouri Mule]

In my 96 Service Manual for the 47re and this should go for the 48re since they are kissing cousins.

Slips in Overdrive gear:

1. Fluid level low

2. Overdrive clutch pack worn.

3. Overdrive Piston retainer bleed orfice blowout.

4. Overdrive Piston or Seal.

5. Shift valve,timing valve,Accumlator malfunction.

6. Overdrive unit thrust bearing failure.

7. Overdrive check valve/bleed orfice failure.

 

[B.G. Smith]

With torque converter slip you will see up to about 300 to 500 rpm change, with clutch slip it would be worse. I had the same problem with a 99, I shortened the kickdown cable a little and that helped some, also don't use OD under 65 mph while towing. bg

 

[JTHUSKINS]

My truck was built in Nov. 97 . I never have run the VIN to identify which transmission it has but as Mr Thomas said the two are very similar. I don't have a manuel to study the mechanics of either unit. Is the OD clutch pack a band that can be adjusted or is it separate from the 2 bands? My fluid is only about 1500 miles old and is still clean so I have ruled that out. The RPM gain as I climb a slight grade is not high but as I continue to adjust the throttle to prevent slipping we loose momentum and have to downshift to third where nothing slips in lockup. I assume that all of the other possibilities listed for OD problems will be located in the valve body? Our next trip is not far from home so as Mr. Smith stated I could make the trip without OD and keep the speed down to around 55.

 

[B.G. Smith]

Quote; (I don't have a manuel to study the mechanics of either unit. Is the OD clutch pack a band that can be adjusted or is it separate from the 2 bands?) OD is a clutch pack, there are only two bands, low/reverse and kickdown or second gear. bg

 

[JTHUSKINS]

Ok guys, thanks again for the info. Sounds like the fix will be a rebuild with TC and valve body upgrades while it is down. I don't drive this truck in the winter months so after the next trip I'll put it in my shop and go to work. The power upgrades improved the trucks towing so much that I don't want to go back stock so it's time to freshen up the 115000 miles on the transmission. A thousand here, a thousand there, it's still better than a big payment.

 

[DieselLady]

Turn the power down and see if the problem goes away. While in Overdrive your depending on the TC lockup to do more of the holding. It only takes about 60 horsepower to slip a stock torque converter. When in 3rd gear you are spinning at higher rpms and the gearing does more of the work. I am betting it is the TC going away.

 

[JTHUSKINS]

I contacted a local diesel performance shop that I just located 3 days ago. This shop has worked on hundreds of 47 & 48 REs and they agree that my symptoms are classic TC slippage based on my description just as you guys & gals have stated. I feel that the last trip will be ok without using OD since it is only about 100 miles

 

[JTHUSKINS]

Just to follow up on this post for all of you who helped with your advice, I had the local shop install a new single disc billet converter, rebuild the trans with heavy duty clutches and disc,and rework the valve body to their specs to perform well with my slight mods. The truck is soooooo pleasant to tow with now with the added power and stronger transmission setup. Don't need the lockup switch anymore because the valve body setup holds second gear longer and holds lockup longer in third and OD. No slipping and all power to the pavement is great! PS it was the TC gone bad, the transmission parts were all in good shape.