ShadowsPapa
Well-Known Member
- First Name
- Bill
- Joined
- Oct 12, 2019
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- 180
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- 29,414
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- Location
- Runnells, Iowa
- Vehicle(s)
- '22 JTO, '23 JLU, '82 SX4, '73 P. Cardin Javelin
- Occupation
- Retired auto mechanic, frmr gov't ntwrk security admin
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- 3
Simple answer to that is "BULL CRAP".One dealer has said that it's normal and the transmission "rubber bands" meaning it'll alow slip and then slap itself back into gear;
No transmission slips then grabs. That's not how they work, nor should they because slipping clutches and/or bands means heat and wear. Clutch packs are applied - not instantly like "dumping a clutch" but with the aid of accumulators and so on that allow an even, although fairly quick, application of the clutch. it's handled by pumping fluid into the chamber behind the clutch pack piston squeezing the clutch disks and plates (an alternating sandwich) against each other until there's no slippage. Once applied, they stay applied.
Same for bands - a servo, a hydraulic piston, pushes the band around a drum, gripping the drum and stopping it from moving. it's a lot of force. So much force that I've seen the servo snapped off the case when a valve in the valve body locked or wedged because of a tiny piece of lint.
It would take time and their dedication and knowledge to do so, but they CAN actually diagnose a transmission every single step of the way including information gathering such as the time to engagement, pressure to the clutch pack, pressure holding the clutch pack and more. They can tell how much pressure is getting to almost anything and how long it's taking for a clutch or band to engage and if that pressure holds or drops off (indicating leaking seals, etc.)
But they've got to get the OK to do it since it would take time - and thus $$.
Even years ago before all of the electronics, I could monitor the fluid pressures to enough places in a transmission to tell you if a clutch pack or band was being applied, how much pressure was there, throttle pressure vs. governor pressure and more. Today it's all electronically monitored.
We had to unscrew plugs from the case and attach pressure gauges with long hoses. Today, plug it in and watch the numbers.
But the idea that anything "rubber bands" is a hoot. That's just silly.
And a torque converter doesn't act that way, either. It's either in torque multiplication phase where the "pump" fins on the shell are directing fluid through the turbine or it's stalled or locked.
There are actually decent videos out there on how a TC works, explanation of how various TCs lock, stall speeds and so on. Maybe those techs need to spend some time in the books again?
If a gasser, that's lugging. They haven't got a narrow power band (it's actually pretty wide for a gas engine) but below 2,000 RPM is lugging territory, IMO. The only engine I ever let get below 2.000 RPM and try to accelerate is the 4.0 in my car because that baby can be at 1400 RPM in 3rd and accelerate up a hill and never flinch. But if my JT 3.6 was a stick, I'd not want to try it.If I'm accelerating while in 3rd but below 2,000rpm, the truck bogs but then noticeably bucks a tiny bit like it just got dumped a ton of fuel into it.
The gasser needs RPM to make torque and HP. It's not a great sub-2000 engine, IMO.
Diesel - that's another matter. Those love life in the lower RPMs
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