First gear slip 48RE

[Superdawg]

I searched and didn't find much that dealt with this in particular so here goes. Another transmission thread....

Occasionally, on takeoff, I have a slip in first gear. It only lasts about a second and goes away.
Truck has 152k. Smarty Jr. on performance but Tq management on highest setting (most not least).
Tows a 10k 5th wheel several times per year.
20k on low budget rebuild of 48RE. A little bit lower stall tq converter with valvebody to match (trans shop sent it out, unk company).
It also has the upgraded GM solenoid and transducer but they are a couple years old.
Daily driver for 11 years.

It is due for a fluid change and filter. Try that first?
Inspect front band to see if the anchors are loose/pulled out?
Replace GM solenoid and transducer while the pan is off?

Thank you in advance,
Tom

 

[Ozymandias]

Smarty JR on Performance gives you 910ft/lb of torque, way to much for a mostly stock 48RE, even with a shiftkit its to much i was told.
And with a Trailer in the back that makes it even worse.

Set Smarty JR on Towing, that gives you 750ft/lb and do service the Trans of course.

 

[Superdawg]

Thanks Ozy.
I will set it back to stock for now. Going to try to get it into Inglewood Transmission in Fullerton for a service and see what they find.

 

[Ozymandias]

If you pull the Trans then install a better converter anyway, the OEM has also big problem to handle a modified engine.

 

[brillmtb]

I am having a similar problem. I have had the experience of solenoids going out and having it not shift from 1st to 2nd. Now after taking a trip with everything acting normally I stopped in a city to get a bite to eat. Got back in and went to take off and it felt like either slipping or starting in second with the tach going to 2K. Once in 3rd and 4th it seems to drive normal, transmission temp normal so I drove the rest of the way home. Once at another stoplight I noticed that when I shifted into 1st it didn't seem to go into first. I actually had a hard time telling if it was starting off in second or third. So now I am thinking the TQ isnt slipping then locking up but perhaps a 1st/2nd gear issue in the transmission. Could this be solenoid again or worse a band or something and is there an easy way to tell. Thanks, guess my trip next week with my son to Moab, motorcycling and having fun just got dumped.

 

[p-Bar]

Well you are taking it to the right shop . He did mine and knows what he is doing . Uses all goerend parts

 

[brillmtb]

OK, the truck displayed the P0700 code which I guess is very general. Given I cant shift into first or ? second and the transmission runs fine in 3rd/4th do you think it is the solenoid? Also, is it ok to do a full transmission flush on a dodge, one shop says yes and the other says just drop the pan regularly. I am been running amsoil so a whole flush will be expensive but perhaps it is time.

 

[Ozymandias]

Drop the pan every 20 -30 th. Mile and its fine, no need for flush if the transmission was'nt burnt up before.

 

[promisedland]

I put a 900/400 Georend TC in mine, if u tow the diff is amazing! Pulls much better!

 

[cerberusiam]

OK, the truck displayed the P0700 code which I guess is very general. Given I cant shift into first or ? second and the transmission runs fine in 3rd/4th do you think it is the solenoid? Also, is it ok to do a full transmission flush on a dodge, one shop says yes and the other says just drop the pan regularly. I am been running amsoil so a whole flush will be expensive but perhaps it is time.

It is probably the gov pressure transducer causing issues, they are the normal cause of 2nd or 3rd gear starts. The gov solenoid can also be an issue if you have not upgraded it and pulled the gov housing to clean it out. Recommend the DNC gov solenoid housing and a new transducer, if you have a lot of miles a new VB harness would be a good idea also.

Yes, a flush every 30-50k is highly recommended. The fluid will boil the additives out after so much use and the stock transmissions tend to make a lot of metal and friction dust. That all gets suspended into the trans fluid and reduces its efficacy, need to exchange it on a regular basis or rebuild the trans to limit those problems. The fluid should also be changed at least once per year regardless, it will draw moisture and contaminants no fluid can compensate for.

Dump the Amsoil and use ATF+4, dollar for dollar a much better solution than anything else. Even more so if you get rid of the inherent problems with a stock build.

 

[Superdawg]

Well folks here is the wrap up on this issue. Seems my diagnostic skills are lacking.
I took it to Inglewood Transmission. Mike was generous with his time and after experiencing what I was complaining about, he said it wasn't the transmission. Thank you Mike! Maybe driveshaft or differential.
Turns out, apparently it was rear differential chatter. Only evident on turns and when warmed up. I put two 4 ounce bottles of Lubeguard in and problem solved. I know, I read up that the AAM axle doesn't need the friction modifier but it worked.

 

[Bob4x4]

Well folks here is the wrap up on this issue. Seems my diagnostic skills are lacking.
I took it to Inglewood Transmission. Mike was generous with his time and after experiencing what I was complaining about, he said it wasn't the transmission. Thank you Mike! Maybe driveshaft or differential.
Turns out, apparently it was rear differential chatter. Only evident on turns and when warmed up. I put two 4 ounce bottles of Lubeguard in and problem solved. I know, I read up that the AAM axle doesn't need the friction modifier but it worked.

Sounds like you need to change the diff fluid more often for your duty cycle.I don't remember if you have a big cover or not,a finned cover will help to keep the fluid a lil cooler

 

[Superdawg]

You sir are correct. Stock cover.