Auto Transmission Slip 93FZJ80 (1 Viewer)

[eaiello]

New to the forum and am looking for some advice on possible reasons for what I assume is transmission slippage. For example, when navigating a city block, the vehicle will shift from 1st > 2nd > 3rd just fine & then when slowing down to stop, it will abruptly "drop" back down into first with a loud thud. All other circumstances the transimission is smooth and seems fine. Should I be concerned about a rebuild/new transmission (171K) or could this likely be a solenoid issue, etc. Also, there is a mild "whine" when starting off in 1st and I am not sure if this is normal. I am the 3rd owner of this vehicile & it appears to be fundamentally sound and taken care of.

Trying to get a little more educated so as to hopefully avoid getting ripped off at the shop.

Thanks for any info.

Eric

 

[94LC]

I have the exact same problem in my 94. Hard downshift at around 25 to 20 mph, but it doesn't happen all the time.

 

[eaiello]

Potential Lead...

After a couple hours of searching, it appears that adjusting the Kick Down Cable may or may not help. I will check into it & report back.

 

[vjr021]

This happens in my 97... I have tried to duplicate it, so I could diagnose it, but I can't seem to get it to happen when I want.

keep us in the loop if you find something...

 

[IdahoDoug]

Also, the whine in 1st gear is normal and they did it when new. The 93/94 models have a city bus transmission and it's my understanding that 1st gear is a much tougher straight cut gear used for durability where the other gears are normal passenger car style beveled hypoid gears (much quieter as straight cut gear noise is not tolerated by civilians).

So, grease the drive shafts (do a search so you don't overgrease), and consider adjusting your kickdown cable.

DougM

 

[eaiello]

Sorry for the delayed follow up...

1. Finally got FSM a few weeks ago & tried the kick down (throttle) cable adjustment but problem still persisted. Throttle cable is way (relative) out of spec from FSM so I figured it needed replaced. Brought this to the dealerships attention and of course they want to replace the cable & throttle body...not going there...unecessary $$$

2. Broke down & took it to a Toyota dealership to get checked out & they said the front axle has about 1 inch of play before it engages with the diff & that is what is causing the abrubt knock when downshifting from 3>2>1. Makes some sense to me & somewhat of a relief that it is not the transmission. However, the dealership of course is quoting me 2K to replace the front axle, labor, etc. Is this way out of line?

3. Since this rig is a DD/Weekend warrior & I am a novice hack, I cannot afford to take on this job myself. Is 2K too much for a front axle replacement? Would it be unrealistic to look at a junkyard for a locked replacement for an unlocked 80?

I appreciate any feedback.

 

[IdahoDoug]

I think you're overthinking this. You own a 17 year old vehicle with a drivetrain that is very heavily built with less focus on consumer-levels of smoothness and noise than other vehicles in its class. It's more commercial than even a light duty truck drivetrain. When it downshifts, the slack comes out of two driveshafts, and 3 differentials and you'd expect a clunk. Yes, adjusting the shift cable may make a small difference, but with properly greased driveshafts (grease absorbs the metal to metal clunk) and filled differentials plus that adjustment you'll be fine. I think you're either expecting a smooth downshift from a bus transmission normally installed in a city bus with a 30,000 GVW that is not going to happen, or the dealership is simply egging you on that they can make it smoother with your money which will also turn out to be false after you've written the check.

My advice is to simply be sure the fluids and lubes are all done and drive it.

 

[MARLIN375]

Take it over to Doug's place and let him take it for a scrape.

Or find another 93-94 to go for a ride in.

 

[eaiello]

Thanks for the feedback guys.

Doug, I agree with what you are saying & it makes sense. However, I do not expect this vehicle to be a super smooth operator & I do believe that the abrupt downshift knock is out of the normal "accepted" range for this vehicle.

More MUD research & drivetrain lubing for me.

If you are ever bored and/or have a weekend to kill in the garage, we could accomodate you and your family here plus a fair Per Diem/Food-Beer rate to come on down to Salmon or I could pop on up to CDA.

Let me know if you would be interested.

 

[IdahoDoug]

Next time you're in CDA call me and I'm sure I can allay your concerns about slack in your drivetrain. Bring some old clothes as you'll be crawling under your truck and 3 others to grab the drive shafts and compare the amount of free play. You'll have the following:

1993 I've had since new and maintained to the highest standards with 185,000 miles
1993 my bro in law's had since new and maintained poorly with 330,000 miles
1997 I've had for 50,000 miles that has 190,000 miles

Bet yours will be mid pack and normal....

DougM

 

[tblume]

Next time you're in CDA call me and I'm sure I can allay your concerns about slack in your drivetrain. Bring some old clothes as you'll be crawling under your truck and 3 others to grab the drive shafts and compare the amount of free play. You'll have the following:

1993 I've had since new and maintained to the highest standards with 185,000 miles
1993 my bro in law's had since new and maintained poorly with 330,000 miles
1997 I've had for 50,000 miles that has 190,000 miles

Bet yours will be mid pack and normal....

DougM

that right there is what makes this page/community/world a great place.

 

[eaiello]

Driveline Clunk...

Alright, I did my research on the FAQ. Dropped both the front & rear driveshafts, greased up the splines according to FAQ posts recommendations, changed front/rear diffs & transfer fluids, re-assembled. Front diff was nasty...even though it has been changed less than 1 year ago (PO). Rear was like new.

Nasty Clunk is still there...

Not sure the best way to check the runout/play in the driveshaft (Nuetral or Park)...but in Park, the front driveshaft had about 1.5 inch of play before the diff engaged. The rear was much tighter, probably 1/2 inch of play. The FSM notes a 0.8mm runout tolerance of the shaft off the vehicle & that seemed fine. Also, I noticed that the front driveshaft was/is spitting out grease along the shaft (normal) but the rear was not & is not even after dissasembly & re-greasing. However, both splines seemed to be well greased when I took them apart. Would it still be appropriate to remove the zircs and drive to ensure that the splines are not overpacked?

So now I am not sure if the clunk is coming from the rear as there is no expelled grease on the driveline & it may be binding or if it is the front given all of the freeplay.

Doug, when we can get up to CDA, I will PM you to see if we can coordinate a LC school session. But for now, what would be the next troubleshooting steps a wise LC owner should take on?...

Thanks for the help.

Eric