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  #1  
Old 03-11-2004, 10:27 AM
alia176 alia176 is offline
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Need a little tranny education here!

Hey guys,

I need a little education on my tranny's behavior. I'm aware of the 4Eat's temperment but this is mostly a generic question. I'm not having any problems with my tranny....well at least I don't think so anyway!

1) when the car slows down to 40 mph or below, the tach needle drops to the idle position (around 850 rpm or so) as the engine disengages from the drivetrain. Is this condition known as the torque converted "unlocking"? If not, what is happening?

2) after the stop light turns green, if I'm a little too quick on the gas pedal, there's a definite clunking as the drivetrain slack is taken up by the enginen rpm. Is this condition normal? I don't think this is the toque converter locking.

3) while driving, I can let my foot of the gas pedal suddenly and reapply and then I can hear/feel the drivetrain slack. I'm used to the slack on my full time 4x4 SUVs. Is this common in the SVX or should I investigate this further.

4) does the forum have a favorite brand of ATF?

I'm aware of all of the moving parts in my drivetrain: cv joints, viscous coupler, driveshaft ujoints, tranny, transaxle and I can appreciate the combined slack from all of the parts can be tremendous. My vehicle has 106k miles on her. I've never changed the ATF since I owned it back in 1999. I was thinking of doing this this spring/summer. I hesitated this long due to the ATF fluid changin controversial on this site. However, I do understand the need for clean fluid for cooling as well clutch disc engagement. My ATF is still red and smells fine...that I know of.

Sorry for the long winded note and thanks for any inputs. I'm sure this topic has been covered before so pls point me to where I need to go. Message #, topic search, etc.

Ali
'92 SVX
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  #2  
Old 03-11-2004, 11:07 AM
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1) That's not the TC unlocking. It would be the gear clutch disengaging.

2) No matter how hard I mash the pedal, I don't hear/feel any clunk.

3) No clunk in this situation either.

4) Good question. Some seem to like synthetics, but beware of synthetics with slip modifiers. The really slippery stuff makes it difficult for the clutches to provide sufficient grab (although in some instances, its necessary to add a small amount of slip modifier to stop binding that sometimes occurs with the center diff clutch).
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  #3  
Old 03-11-2004, 01:13 PM
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When the TC locks up there is no engine rpm slip through the TC to the tranny. A slight tap on the gas peddle will show this on the tach.

My svx has the slop in the drive train only when the TC is locked up at highway speeds. As you say this is noticed by taking the foot off the gas and then reapplying the foot.

Cluncking off the line is something I have noit heard but I think it could be the transfer clutch engaging.

Have you checked the front axles and "propellor shaft" u-joints? It could also be slop in the front diff.

I would change the fluid if there is more than 20K on it.
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  #4  
Old 03-12-2004, 12:58 AM
gl1674 gl1674 is offline
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1) This is normal, it is designed to be that way. One of the one-way clutches is there exactly for that purpose. Well at least with gear selector in D. With gear selector in 3/2/1 you should have engine braking - the one way clutch should be disabled.

2) This is not normal, most likely transfer clutch or duty solenoid C. Beware of doing it, shocks are not good for the tranny.

3) Inconclusive without a test drive. Some slack is "normal".

4) No conclusive data has been gathered.
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  #5  
Old 03-12-2004, 01:01 AM
gl1674 gl1674 is offline
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Oh, yes, the fluid: there is a risk of changing it, but I would go ahead and do it. Make sure you drop the pan and clear it.
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  #6  
Old 03-12-2004, 09:36 AM
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1.) This question was already sufficiently answered by Mychailo.

2.) I would first have your tranny mount looked at. Mine used to clunk very softly sometimes when I let off the gas and it turned out that my rear tranny mount was broken. This allows the transmission to shift more than it's supposed to. Specifically it'll twist back and forth some.

3.) Same thing. Check the rear mount. It's two pieces of metal bend into a cradle shape with rubber bumpers molded in between them. If the rubber separates from the metal, the tranny can shift around and thump against its mountings.

4.) A simple drain and refill shouldn't be harmful. If it is, and your tranny fails soon after, you were headed for it anyway. Drain it, drop the pan and replace the internal screen.
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  #7  
Old 03-16-2004, 11:41 PM
Paxton71
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neutral on coast and driveline thunks

This is not good.

Mine did that "extreme" neutral thing a few times on the highway when I got it. I think it was due to HOT, OLD tranny fluid (like coasting down either side of Eisenhower tunnel on I-70 on a summer day). Please check fluid level and go ahead and change it.


The clunk is your rear transfer clutch hooking up the rear wheel drive for you. If the fluid change doesn't fix it, better go in now and replace the clutch pack. See if the clutch hub looks OK where it is welded to the "reduction" gear.
Otherwise, it will slam-engage for awhile, then you will have a FWD SVX when the clutch hub breaks off the gear.

Oh yeah, the only viscous coupler in these things is the torque convertor. The front/rear split is done by an electrically controlled, hydraulicly actuated clutch pack.


You want to hear/see driveline slop, check out my 4runner. 221,000miles of wear+2 transfer cases (one with 4.7:1 low range) = 2x the slop + lockrights(25 degrees of backlash right there!) in the 4.88 diffs. In low, low, first @ idle I can put the brakes on and stop the truck for about 1 second before all the slop winds out. sloppppppy

Last edited by Paxton71; 03-16-2004 at 11:49 PM.
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  #8  
Old 03-17-2004, 09:16 AM
alia176 alia176 is offline
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Thanks for the inputs guys. I'll start with a fluid change or two to get things rolling.

Ali
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