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[b]Launch shudder with the 4T65E transmission[/b]

[b]Launch shudder with the 4T65E transmission[/b]

[b]Launch shudder with the 4T65E transmission[/b]

(OP)
I have a 4T65E transmission in my 2000 Chevy Venture Extended Van with about 100K miles.  Recently it has developed a shudder, at moderate or aggressive launch from Stop light.   The shudder happens between 5 and 15 mph (so no TCC related issue?). Any pointers to root causes...?

RE: [b]Launch shudder with the 4T65E transmission[/b]

One of the internal clutches is going stick/slip. When is the last time the tranny fluid and filter was changed? It's probably designed to be a lifetime-fill, as a good many auto trannies are these days, but I don't buy it.

RE: [b]Launch shudder with the 4T65E transmission[/b]

Does it shift normally there after and at the correct speed? It should have the line pressure checked, if it is okay then you probably have some friction elements that are wearing out. You need to not let it slip, and get it checked out soon. It can be anything from a spring broke, sticky valve, solenoid going, some internal leakage, worn friction material.

RE: [b]Launch shudder with the 4T65E transmission[/b]

Replace the presure solenoid- but do your presure check first to verify, if you pull the pan and it looks normal for 100k you will probably fix it by replacing that solenoid.

RE: [b]Launch shudder with the 4T65E transmission[/b]

I totally believe in lifetime fill for oil in ATs.

When the oil is burnt or contaminated, that will be shortly before the end of the life of the transmission. I suspect there is a better margin on parts than there is on new cars.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.

RE: [b]Launch shudder with the 4T65E transmission[/b]

patprimmer
"I totally believe in lifetime fill for oil in ATs."


I do not believe in that at all.  The fluid breaks down.  I have been through many trans and the ones that i went through most of them never had a trans service.  The customer could not show a history and checking vehicle records.  I am a firm believer that companies are only going to lifetime on trans fluid to sell the vehicle but the trans will fail eventually (between 80,000 and 130,000).  I have seen trannys finally take a dump on abused vehicles in between 200,000 and 300,000 miles and even higher with a service at around every 50,000.  But we all have our own opinions, just going off experience.

RE: [b]Launch shudder with the 4T65E transmission[/b]

You misunderstood my sarcasim.

My inference was that the life of the transmission would be the life of the oil, not the other way round.

An early breakdown of the oil will result in a transmission failure.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.

RE: [b]Launch shudder with the 4T65E transmission[/b]

Oh, i get it.  Usually there is a "j/k" cause through words its hard to tell you are being sarcastic.  But cool, i get it now.

RE: [b]Launch shudder with the 4T65E transmission[/b]



In addition to mentioned trans issues, seized or badly worn cardan type u-joints can cause interesting low speed shuddering reacting against softly mounted center support bearings.  My RWD Volvos often need a u-joint or 4 every 100 kmiles or so.

RE: [b]Launch shudder with the 4T65E transmission[/b]

Sounds like classic torque converter lockup clutch shudder.  If it was my van I'd change the fluid first if it has never been done- and quick to prevent accelerating clutch wear, and then go from there.

A lot of folks are skeptical about 'fill-for-life' fluid claims, but such a thing is technically practical for 200K or more lifetimes in passenger vehicles.  In a previous job I evaluated the condition of factory fill ATFs from consumer vehicls MY ca. 1996-2000, having service (all in Texas so high T but no hills) of 85-135Kmi, one each of light truck/SUV and automobile each from Chrysler, FOMOCO and GM.  I compared that to similar data collected 5-6 years before. Observations were:

1) Of all the vehicles, only the 135Kmi one showed measureably degraded friction properties- though no driveability concerns- and it had experienced a fluid leak early on in it's life (would've been disqualified from the test if this was known before it was sampled, but it was reportedly serviced with factory fluid).

2) The RWD vehicle's fluids appeared marginally better than the FWD, suggesting lower severity despite possibly heavier duty cycle (towing/hauling).

3) The previous study showed generally poorer fluid durability despite the sample cohort having on average 10K fewer miles.

It was clear from the data that ATFs in routine service could last in excess of 100K, and that the performance had been improved in the factory fill fluid from the early- to the late 90's (and has presumably gone up in later specs). If the fluid's properties haven't changed but the parts are shot then it's they that aren't as 'durable' as the lubricant.
 

RE: [b]Launch shudder with the 4T65E transmission[/b]

"Sounds like classic torque converter lockup clutch shudder.  If it was my van I'd change the fluid first if it has never been done- and quick to prevent accelerating clutch wear, and then go from there."

DRWEBB, You must not have read the begining, tcc wont engage at 5-15 miles an hour.  That not correct at all.  4t65s don't have that many tcc issues as does the 96,97 and some 98 4L60e.  4t65es though do have pressure control solenoid issues.  I put my money on the solenoid from the description above.  Gm CV axles are pretty solid. If it was a mount you should get more of a clunk,  POWER brake it and give it a little gas and shift back and forth from reverse to 4 and watch and listen for abnormal clunk noises (thats for mount diagnosis).  Probably a pcs issue though.

Peace!!




RE: [b]Launch shudder with the 4T65E transmission[/b]

If the trans. uses one-way roller sprag clutches I'd suspect them.  Their loads are highest during takeoff.

Gold is for the mistress - silver for the maid
Copper for the craftsman cunning in his trade.
"Good!" said the Baron, sitting in his hall
But iron - cold iron is the master of them all.
Rudyard Kipling

RE: [b]Launch shudder with the 4T65E transmission[/b]

One-way clutches don't usually slip, they either work or they don't, meaning broke.

TCC shudder could happen if the friction material was warped or chunking off, it would be happening all the time and causing a feeling of actuation. Though the description is slipping applied friction elements, if not due to an internal leakage, then due to low control pressure, or now worn out clutch packs. Are all shifts normal? Check the simple things Vac modulator (throttle valve control) even such things as TPS and VSS that regulate control pressures.

RE: [b]Launch shudder with the 4T65E transmission[/b]

Check your front uni joint for wear and your cross member where your gearbox mounts to it as it has a rubber type dampener in it (well some do) if it has worn through your gear box could be "slapping"

RE: [b]Launch shudder with the 4T65E transmission[/b]

drwebb - I assume you measured other properties besides friction properties? I wouldn't declare an oil "good" based solely on that one number! Obviously there is TAN, water, fine particle count, varnish, etc.

I know that the latest engine oils have dramatically reduced levels of zinc for emissions reasons, but I don't know about ATF. Zinc is good for sliding friction - I have heard that hot rodders are wiping out new solid lifter cams using these new oils and the recommendation is to use diesel oil (usually Rotella) instead.

ISZ

RE: [b]Launch shudder with the 4T65E transmission[/b]

Yes the fluids were checked for elemental analysis, wear protection performance, oxidation, insolubles and a number of other properties- basically they were still in spec so were judged 'good'.  I summarized the friction results because paper on steel friction control is a primary concern for ATF fluid durability.  ATF doesn't have to cope with emission equipment compatibility like engine oils, although it is similarly trending toward lower viscosity for improved fuel efficiency. Zn is not favored for antiwear in ATFs because ash-containing chemistries can clog the paper pores reducing friction, so ashless (i.e. more costly) chemistries have traditionally been preferred.  

I'll defer to the parts and software experts on this diagnosis.  But despite my point on durability- generally speaking a fluid service as a first countermeasure for many tranny problems is a comparatively cheap & easy way to ensure one component of the system is in factory spec.

RE: [b]Launch shudder with the 4T65E transmission[/b]

TCC DOES NOT APPLY ALL THE TIME, it occures when vaccum is high and throttle is steady and most of the time in a drive and over drive ranges.  IN OTHER WORDS WHEN YOU APPLY A LOAD TCC WILL RELEASE or WILL NOT ENGAGE.  YOU GUYS NEED TO READ THE FIRST POST BEFORE REPLY-ING.

this was directed to the ones who think it is the tcc, if you lock a torque converter at a low speed it like letting your clutch out on a stick going 10 in forth gear.

this vehicle has nothing vaccuum to the tranny.

RE: [b]Launch shudder with the 4T65E transmission[/b]

There are cases when the TCC is applied all the time. Like I mentioned if the material comes loose and locks it up it is then applied all the time, or partially applied all the time. There are cases of the TCC solenoid going bad and the valve sticking and applying the TCC so that it drags the engine down at a stop and kills it. I did read before replying.

RE: [b]Launch shudder with the 4T65E transmission[/b]

I used to have a little jigger that would allow me to drive the gearbox manually. As such it was very easy to explore the torque limits of the lock-up clutch.

It is, to be honest, rather a small device, and if you keep abusing it, it will fry.

Cheers

Greg Locock

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