LT4 Lt4 transmission shift problem

[oledocclock]

I recently purchased an LT4 with 14,400 actual miles showing on the odometer. I also have documentation showing that 14,400 is the true mileage. s The owner advised that sometimes when shifting into third gear the shift would be difficult and the gears would grind. I did a thorough test drive and had no problems with the up shift or down shift to third gear. I purchased the vehicle and have found that about sixty percent of the time I will have difficulty going into third gear and the gears will grind. Does anyone have an idea as to what is causing this problem? Do you have any advice on how to fix the problem?

 

[Hib Halverson]

1) make sure the clutch hardware and hydraulics are working properly.
2) make sure the transmission doesn't have the wrong lube in it.

With only 14,000 miles it's unlikely the transmission, a ZF S6-40, is worn.

 

[oledocclock]

LT4 transmission shift problems

Thank you for your reply. I will check the lube and other items you recommended.

 

[Wegone]

Here is some great info on the ZF hope it helps. As Hib said check the clutch master cylinder under the ECM also look for any fluid drips at the slave cylinder.

ZF S6-40 and T-56 6-speed Transmssion Driveline Specialists, Prototype and Manufacturing Services

 

[oledocclock]

LT4 transmission shift problems

Have checked everything recommended and found everything OK with no leaks found. Any other ideas. Could there be damage from an improper shift from second to third gear. The only shift problems are from second to third. Thank you for the responses. George

 

[Hib Halverson]

If you've checked the lubricant type, level and condition and you've verified the condition and operation of the clutch hydraulics then it's likely the tranmission has been damaged. If that's the case, there is no solution other than removal and repair.

And yes, it is possible that a missed 2-3 shift could have damaged the transmission.

The best guy in the country for ZF S6-40 overhauls is the ZF Doc in Cave Creek AZ.