transmission issues/questions

[TBM F350]

I've had my truck for about two months now and i am having some problems with the transmission this past week.

First off the truck has 103k on it and the transmission is a factory rebuild from Ford and was done about 8-9k miles and a little less than 1 year ago. I am guessing it had a single disc torque converter put in. For mod's so far the truck has a hypermax 300hp chip and a 5" exhaust.

Since i bought the truck i put in a sonnax kit and an external trans filter kit and flushed and changed the trans fluid.

Since i've only had the truck for a short period of time i dont know if this is normal or if there is something wrong. After putting the sonnax kit in i have noticed a sluggishness to the shifting at times. At first all of the shifts were very firm which i liked, but now them seem to be going in the opposite direction. I have had quite a few hard accelerations trying to get it to shift hard but it doesnt.

I'm guessing its the 2-3 shift, but it almost shifts like it's going into overdrive twice. In this shift the rpm's reach 2300-2500 or so rpms, then it drops down to 1500-1700 or so rpms and you hear that squishy sound and the engine gets sluggish then it builds back up to higher rpms again and it shifts into overdrive. The first shifts seems ok, but the latter shifts are starting to concern me. Under hard acceleration is the rpm difference between shifts supposed to drop that much, or is something slipping? Any ideas????

Also, under very hard acceleration when it's approaching 3000 rpm's and it is about to shift into the next gear i hear a pssssstttttttpppppppssssttstttpppssssssstt type of swooshing sound. Is that something with the tranny or is it something from the turbo. It sounds like it coming somewhere from the back of the engine or from the front of the trans.

My understanding is that the trans goes from 1-2, 2-3, 3-OD, and OD to lockup. Correct? My previous truck was a 95 dodge ram diesel auto and it had this similiar shift pattern and each shift was very distinct. And again i dont know if its just that i'm still learning the sounds of the new transmission but it is harder to notice them so far. Maybe i'm over analyzing things but i just want to make sure that something isnt going bad in the tranny that i should get looked at.

Thanks,
Tim

 

[Lord Tauk]

Also, under very hard acceleration when it's approaching 3000 rpm's and it is about to shift into the next gear i hear a pssssstttttttpppppppssssttstttpppssssssstt type of swooshing sound. Is that something with the tranny or is it something from the turbo. It sounds like it coming somewhere from the back of the engine or from the front of the trans

Maybe I can help here, but would that happen to be turbo surge? Fairly common with the factory thrust bearing turbo. From what I can understand, open element air filters really bring out the sound of turbo surge.

I thought the 4R100 was like this for shifting patterns, 1-2, 2-3, lockup, 3-4.

 

[patrickc]

the pssssttttttt pssssttttttt sounds definitly like turbo charger surge/shutter my ford does the same thing at higher rpm shifts a cold air intake makes it sound even louder if your transmission only had a single disc converter that might explain the shift patterns it should be at least a twin disc converter triple disc is better generally if the converter/transmission is slipping it will not take long to overheat the fluid it shouldnot be sluggish at 1500-1700 rpm thats right in beginning of the power band i beleive shifts are 1-2,2-3,lockup,3-4

 

[neil_04]

my truck does the same thing. my turbo also makes the same noise, everyone ive talked to said get a triple disk converter, i have a rebuilt ford trans. with shift kit and D.I. 3 position chip

 

[dpantazis]

did you install a shift plate with the sonnax kit?

aside from the other suggestions, did you torque the valve body bolts/nuts to the proper setting? if you didn;t there could be fluid leaking between the VB and the labyrinth. iirc, 100 IN-lbs for the bolts and 115 IN-lbs for the nuts.

can someone verify the TQ settings?
dp

 

[TBM F350]

I only put in the $50 sonnax kit with the new valve and the 3 springs. I torqued the bolts down to 80 in/lbs according to the wiki article i printed out.

As for the shifts i didnt mean that the 2-3 shift flet sluggish. It was doing it again on the drive home tonight. When it shifts into 3rd the rpm's go down from about 2400 ish to about 15-1700 and you hear that swoosh sound. Then it builds back up to about 2400 or so rpms and then it kicks into OD and it does that swooshing sound for the 2nd time and it's then at about 1700-1800 ish rpm's at highway speed.

Tim

 

[Glassdude]

I think the swoosh sound you hear is turbo stall. The turbo is getting rid of excess boost. Is it possible that your chip has also programed the tranny and by adding the sonnax the 2 are conflicting?

 

[TBM F350]

Well going by what dieselsite.com said about the external filter kit for the tranny that i put on, it said that the filter replacement gauge *may* show up in the replace section when it's perfectly fine if the chip you have increases the line pressure to the trans. And my filter gauge does this. So it may possibly affect the trans somehow. I bought the truck 2 mo's ago so i dont know a whole lot about its modifications and how they may interact with the truck. I'm still learning.

Tim

 

[neil_04]

its like ur talking for me, im not sure what kit i have my brother had it done they uped the pressure to, ive been thinking about just getting a brand new tranny mines been out 4 times now. its starting to get pricey! ill keep an eye on this thread, sorry ur having the same probs as me it sucks. mines getting more consistent so u better fix urs soon

 

[White Buffalo]

TBM 350,

The shift pattern for the 4R100 tranny is 1-2,2-3, Torque converter lockup (approx 35-40 mph, unless you are really getting on it),then OD. The TC lockup feels like another gear change. It sounds like your truck is shifting just fine.

The pssssttt sound you mentioned sound like turbo surge. With a chip/tuner the stock turbo will surge, mostly when towing. A whicked wheel will get rid of 99% of the surge (did for me) or you can upgrade the turbo housing to an ATS housing which will cure the surge. Surge is no good for the turbo in the long run, can lead to an early turbo death (or an excuse to upgrade the turbo!).

The woooshhh sound you hear is turbo stall. Basically what happens is that your turbo is supplying a whole lot of boost to the engine at the higher rpms, then when the tranny shifts and the rpms drop the compressed air demand goes down and the air has no where left to go but back out the turbo.

Now here's the bad news,

The stock torque converter is the weak link in the system. The stock drivetrain is not designed to handle all the extra power, especially when romping on it - which I really like to do. Check to see if your chip/programmer increases the line pressure to your tranny. Increased line pressure is no good in the long run. A valve body upgrade is a minimum for a chipped truck. If you can upgrade the tranny great, if the $ just ain't available - start stashing $ away for a torque converter. Jon Faubion (Faubion Motorsports), BTS & suncoast (and some others I can't remember) have some great units out there that can handle the extra power. I know that Jon has built many heavy duty/racing/towing tranny's for folks on this site.

Just remember - one mod leads to another! Enjoy the new hobby/obsession!!