Real Bad Shake ?

[^_^ Gem132]

alright guys so when im driving along at a steady speed and get to around 70-75km/h my whole vl make a groaning noise and shakes really bad, and i cant go any faster ? do you guys know what the problem is ? im getting p's next month and i dnt want to be out and brake down ?

Thanks James

[rambunctious]

James, how many k's has it done ?
Is it v8 or 6 ?
Is it steering wheel shake or can you feel the shake through the seat and console ?
Is it auto or manual ?

[^_^ Gem132]

uhm it only has around 163,000 but i dont know if it has been wound back or not, cos i bought it off an old guy but could be possible, and its a v6 auto and the shake sounds like it comming from the engine and underneath me but also shakes the steering wheel,

[Munz]

sounds like tailshaft uni/centre bearing

[detox_nath83]

hmm dont u mean straight 6 they r not V6

shake could be anything really.. overdrive lockup in the auto gearbox can cause a bad shudder. over 75-80kms
could be unbalanced tyres(would do it at all speeds)
loose engine mounts and or gearbox mounts.(mainly acceleration)
tailshaft has thrown a weight(any speed)
depends on the actual Shake as u say..

but at that speed i can only think of the auto lockup converter. u can test by clicking the power button on the gear selector and drive it over 80kms. when u click the power button off and it shudders and shakes into 4th/overdrive its ur lockup converted which can be fixed by unplugging the overdrive soleniod on the box itself

[^_^ Gem132]

hmm dont u mean straight 6 they r not V6

shake could be anything really.. overdrive lockup in the auto gearbox can cause a bad shudder. over 75-80kms
could be unbalanced tyres(would do it at all speeds)
loose engine mounts and or gearbox mounts.(mainly acceleration)
tailshaft has thrown a weight(any speed)
depends on the actual Shake as u say..

but at that speed i can only think of the auto lockup converter. u can test by clicking the power button on the gear selector and drive it over 80kms. when u click the power button off and it shudders and shakes into 4th/overdrive its ur lockup converted which can be fixed by unplugging the overdrive soleniod on the box itself

it actually does sound like the auto lock converter problem because ive driven it around about 5-6 times with the power on and no problems but than i took it off to see the difference and thats when it occured, i will try and see if it only happens when i take off power and let you guys know. and also when the shake/shudder happens is this bad for the car ?

[detox_nath83]

any shake/shudder is "bad for the car as such" depends really. report back and if it is this problem and u dont care about ur overdrive unplug that sucker... u will still have 1st- 4th

[Jxw]

4th is overdrive..... give the trans a service, fresh oil and filter n see how it goes
what color is the trans oil atm? red/yellowish/brownish color? does it smell right or have a burnt smell? (if you have power steering does oil on the trans dipstick smell the same as the p/steering res as comparison) if it is burnt then i'd take it to a trans specialist to service it and they can adjust the bands also. last check was about $120-$150 to get it done professionally

i'd ask if it feel like it's slipping in gears but the jatco's feel sloppy at the best of times stock to me.....

have a look underneath at the center bearing for perishing or out of shape, push the tail shaft up and pull it down at the center bearing and uni's to check for excessive movement and play, the unis shouldn't move laterally and the center bearing will move slightly, make sure the car is secure on ramps with bricks or chocks under the wheels to make sure it can't roll off.

unbalanced tyres depending how much they're out may not shake at all speeds, 5gms you won't notice it, 10gms you probably won't notice, 15-20gms out may cause a shudder at higher speeds but feel normal lower, anything more you'll know about it

if you accelerate past the shaking shudder and back off the throttle (let it go completely) does it still shudder as it's slowing down?

hit any bad potholes lately? maybe a bent rim....... jack it up and spin the wheel and see if it "wobbles" moves in and out at the edges and check for damage to the rims, dents/flats spots etc, hows the tyre wear? uniform or feathered patchy wear in places?

i've had a cv joint fail and only make noise at around 90-100km/h on sweeping bends before as the load changed from the gforce moving the diff alignment but that was more a metallic ringing noise accompanying the underlying clunk noise and vibration as it echo'd through the tailshaft

[jatsvl]

the vl jatco trans has 4 gears, then a lockup clutch in the torque converter (overdrive), which when stuffed will make the car shudder really badly everytime it engages as detox _nath83 has stated. you can disconnect the overdrive solenoid and solve the problem or you could replace the torque converter.

[Jxw]

the vl jatco trans has 4 gears, then a lockup clutch in the torque converter (overdrive)

jatco E4N71B ratios
1st 2.458:1
2nd 1.458:1
3rd 1:1
4th 0.686:1

as 4th is less than the 1:1 straight through ratio of 3rd, it's the overdrive ratio, the tcc locking upcould be considered a fake 5th i guess if you were explaining it to the average person that owns a car with little mechanical knowledge, but it's more for fuel economy and stop wear on the trans and torque converter as the power is transferred directly through at cruising speeds, if it locked up sooner than 85ish km/h the engine would be laboring using more fuel at lower revs in order to keep the speed going

unplugging it is a bandaid approach as it's already worn, may get you a few more km's out of the box, it still has worn bits n pieces floating through it, i'd be trying to diagnose and fix it instead of being in the middle of no where and lose the rest of the gears

either way it's the largest and hardest job to replace hence why i made the suggestions of checking everything externally and easier first.

[jatsvl]

I have never heard it referred to as a fake 5th. always as overdrive.
as 3rd is 1;1 and
4th is 0.686;1 when the clutch activates would that give it the 1;1 ratio? the reason I ask is because this topic has been covered many times on here and with the testing that I have done on several vl's 3rd and 4thOD will reach the exact same top speed obviously at different rev ranges so 3rd higher revs and 4thOD at much lower revs.

also I have never heard of any ill affects from dissconnecting the overdrive solenoid, because basically all that is happening is stopping tcc from engageing so it just sits there idle. I think there are several members here that have done this including myself and there have been no bad effects that I am aware of.

[Jxw]

nah the trans is still in whichever gear you've selected, same as a 5 speed manual, 4th would be 1:1 ratio and 5th would be lower than 1:1 so the input is rotating less than the output.
when driving normally the tc by design "slips" which is great for taking off and stopping without stalling the engine
when you're up at freeway speeds if the tcc is not locked the trans is still running in the .686:1 ratio but you're wasting alot as the tc is slipping and not all the power from the engine is being transferred to the transmission.
when the tcc locks up it transfers pretty much all the power from the engine/ringgear with less loss straight into the transmission so it's no longer "slipping" so the engine revs drop by a few hundred rpm, it has no effect on the ratio of the gear selected, just a more efficient way of transferring power to the wheels and saving fuel.