Drivetrain shutter only 50% of the time?

[AutoVation]

I "think" it's the TC but I'm not sure. I let the Sy sit for 2 weeks (I was traveling) and when I drove it, the truck would accelerate normally until i started putting load on the transmission. When the boost gauge would get to zero, the Sy starts vibrating madly and not accelerating. When I ease off, the Sy still accelerates (but way too slowly!).

When in park or neutral, the engine revs cleanly and the boost does what is expected. Therefore I assume it's a tranny issue.

Now the strange part, I drove it again yesterday and the Sy accelerated and shifted perfectly when I got on it. Full boost shifts very clean, crisp and hard. :tup:

Then I drove it today and the same slipping issue. :rant:

I think my Sy is just mad that I didn't drive it for 2 weeks.

So, any ideas guys? Should I replace the TC?

FYI, the Sy has 38k miles on it.

 

[willyson]

Re: Drivetrain shutter only 50% of the time?

I "think" it's the TC but I'm not sure. I let the Sy sit for 2 weeks (I was traveling) and when I drove it, the truck would accelerate normally until i started putting load on the transmission. When the boost gauge would get to zero, the Sy starts vibrating madly and not accelerating. When I ease off, the Sy still accelerates (but way too slowly!).

When in park or neutral, the engine revs cleanly and the boost does what is expected. Therefore I assume it's a tranny issue.

Now the strange part, I drove it again yesterday and the Sy accelerated and shifted perfectly when I got on it. Full boost shifts very clean, crisp and hard. :tup:

Then I drove it today and the same slipping issue. :rant:

I think my Sy is just mad that I didn't drive it for 2 weeks.

So, any ideas guys? Should I replace the TC?

FYI, the Sy has 38k miles on it.

does it slip only when the trans is warm? this would indicate a slipping tc. if you have an emulator, you can disable tcc lockup for a run to see if it still slips. id get in touch with waller as hes a tranny guy near you.

 

[AutoVation]

Re: Drivetrain shutter only 50% of the time?

does it slip only when the trans is warm? this would indicate a slipping tc. if you have an emulator, you can disable tcc lockup for a run to see if it still slips. id get in touch with waller as hes a tranny guy near you.

It doesn't seem to depend on temperature. It either seems to work 100% or not.

It was colder outside when I first had the shuddering. When it was warmer today, I didn't have any issues.

No emulator.

 

[AutoVation]

Re: Drivetrain shutter only 50% of the time?

OK. I don't think it's the TC. Did you check the fluid level?

Does the engine RPM increase when it starts 'shuddering'? Ie, it's really slipping as well?

You didn't indicate what gear the trans or selector was in, but if it does it in all forward gears, regardless of shifter position, it could be the "forward" clutch. This is engaged in ALL forward gears. All power passes through this clutch.

I wouldn't think a 38K transmission would have worn out forward clutch frictions. But the piston seals could be hard, or have issues just from age. I had an S10 that had a problem with the forward clutch piston seal. I drove it for months, but I knew something was wrong. It slipped from time to time, regardless of gear. I pulled the pan, and a 1" 'sliver' of rubber was in the pan. I pulled the trans apart, and sure enough, the piston seal had a piece missing.

Double check the fluid level. Maybe pull the pan and see if you find anything in it. Holler for more help if you need it.

- Did not check fluid level.
- RPM's do increase when shuddering (feels like slippage)
- It does it in all the forward gears regardless of where the gear selector is.
- I'll try to check the fluid level and pan tomorrow.

 

[George Blake]

Re: Drivetrain shutter only 50% of the time?

Dave had really good answers. Our setup, if your program is stock is 32MPH with steady throttle, the TCC will engage. The TCC can engage as soon as you hit 2nd gear with a 700r4 because it becomes hydraulicly possible. Do like Dave said. Get on a nice long road with no stop signs. Come to a stop. Take off with steadily increasing throttle. Feel for 1-2 shift. 2-3 shift. Watch the speedometer. When you see 30 MPH come, start feeling for it. If it comes on at about 32-35 mph with steady throttle and you feel the shudder, tap the brake pedal. This breaks the circuit and unlock the TCC.

The other thing you can do finish ruling stuff out is unplug the terminal from the side of the trans. This will eliminate the TCC. If all shudder is gone and you can go through all the gears, the TC needs replaced. You should be able to get a stock style TC for around $200 to $250 from Dacco or Transtar.

 

[dgoodhue]

Re: Drivetrain shutter only 50% of the time?

I had a shudder in a high mile Typhoon. It would only shudder during Torque Converter Lockup. I added a bottle of lube guard per a transmission expert. The shudder went away.

 

[AutoVation]

Re: Drivetrain shutter only 50% of the time?

Thanks for the great info guys,

I was on the highway a couple days ago at 55mph and pressed the accelerator to load the engine and started vibrating. Based on Dave's description, it does sound like it's the TCC.

I went out and drove it this morning to try to test it and there are no issues (of course...). I will try again this afternoon. I would imagine a 700R4 TCC should be available at just about any auto parts store.

Hey George, thanks again for the previous help on my front propshaft. Your propshaft fixed the problems!