99 yukon 4l60e problem
Mar 27, 2008 | 09:28 PM
#1
99 yukon 4l60e problem
i lost 3 gear on my old tranny i bought another one and put it on.
i noticed that the 4l60e i pulled out from my truck didnt look original.
it looked like an ls style tranny, cast aluminum with a webbed kind of design. 4l60e on the side.
the tranny i received from the yard came from a 98 with a 5.7. the guy i sold it from assured me that this was a 4l60e and i had the right one.
when i received the tranny it looked smooth not like the one i pulled out. i asked a friend who told me that the smooth trannies are like 700r4s.
anyways. the plugs and controls for the tranny i got were identical to the one i pulled out.
so i put in the deep pan of the old tranny, with the correct deep filter, new fluid, check the level hot and it was good. put in old torque converter, test drove it, shifted perfect.
the Problem. at crusing speed, say 80 km/h it shifts into overdrive like normal, the rpm dips to 1200 rpm.
at this point if i touch the throtle ever so slightly
say rev from 1200 to 1400 rpm...the truck vibrates.
it accelerates normally after that range of rpm but during that range the truck vibrates like as if driving over rumble strips.
i also noticed that the acceleration isnt the same as before.
the truck doesnt feel as stout.
sorry for writing so much, just trying to be thorough.
can you help me?
i noticed that the 4l60e i pulled out from my truck didnt look original.
it looked like an ls style tranny, cast aluminum with a webbed kind of design. 4l60e on the side.
the tranny i received from the yard came from a 98 with a 5.7. the guy i sold it from assured me that this was a 4l60e and i had the right one.
when i received the tranny it looked smooth not like the one i pulled out. i asked a friend who told me that the smooth trannies are like 700r4s.
anyways. the plugs and controls for the tranny i got were identical to the one i pulled out.
so i put in the deep pan of the old tranny, with the correct deep filter, new fluid, check the level hot and it was good. put in old torque converter, test drove it, shifted perfect.
the Problem. at crusing speed, say 80 km/h it shifts into overdrive like normal, the rpm dips to 1200 rpm.
at this point if i touch the throtle ever so slightly
say rev from 1200 to 1400 rpm...the truck vibrates.
it accelerates normally after that range of rpm but during that range the truck vibrates like as if driving over rumble strips.
i also noticed that the acceleration isnt the same as before.
the truck doesnt feel as stout.
sorry for writing so much, just trying to be thorough.
can you help me?
Mar 27, 2008 | 11:40 PM
#3
The transmission advertised as coming "from a 1998" truck absolutely did NOT. Full size trucks received the two-piece case 4L60-E for the 1998 model year. S-truck (Sonoma, S-10, Blazer, Jimmy) got the 2-piece case 4L60-E in 1997. The two piece case design was a necessary evolution for the 4L60-E to be used in the C5 Corvette with the rear-mounted transmission and torque tube. Your 1999 truck had the correct transmission, but if you look closely the input shaft and bellhousing are different from a Gen-III 4L60-E setup. (Notice the missing hole at 12:00?)
The trans you have now most likely has a valve body problem. There is an area in the case where the 4th gear apply passage is right next to the converter clutch signal fluid passage. Leakage from one passage to the other past one of the two (or both) gaskets could cause the converter to be engaged whenever fourth gear is. You can test for this by putting it into manual third. The causes for separator plate gasket blowout could be warped valvebody, improper bolt torque sequence, improper bolt torque, and/or damaged case, spacer plate, gaskets, or valve body.
The trans you have now most likely has a valve body problem. There is an area in the case where the 4th gear apply passage is right next to the converter clutch signal fluid passage. Leakage from one passage to the other past one of the two (or both) gaskets could cause the converter to be engaged whenever fourth gear is. You can test for this by putting it into manual third. The causes for separator plate gasket blowout could be warped valvebody, improper bolt torque sequence, improper bolt torque, and/or damaged case, spacer plate, gaskets, or valve body.
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