Posted: 12/29/2009 4:53:56 PM EDT
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I have a 1988 GMC Jimmy full size like the K5 Blazer with 138000 miles on it. Coming home from a family Christmas on the interstate, I noticed there seemed to be a vibration in overdrive. Also it really seemed to lug (like a manual trans in too high of a gear) and vibrate worse when it would downshift to pass or pull hills. It shifts fine if you really accelerate hard but seems to have problems with normal acceleration or with the cruise set. Driving around town or at lower speeds I do not notice it.
The transmission had the filter and fluid replaced at 130K. If I have to have it rebuilt, is there a kit to make it more heavy duty as I use this as my hunting/off road truck? How much should I expect it to cost? |
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I would guess it's not the trans making the truck vibrate. My first guess would be "U" joints, however, I just don't know.
My friend just overhauled his Ford Excursion trans due to vibration. It cost over 3 grand at AAMCO. Come to find out, it was the sparkplugs. (his vintage 5.4L is known for plug problems of all sorts). My boss made the same mistake. It was a cracked cylinder head causing the vibration problem. Another friend had a shudder when shifting. A vacuum line had fallen off the intake manifold. The car would idle fine, as the computer compensated just fine at idle. But under mild accel, it would shake. My point, many people make the mistake of "transmission problems" when in fact, it's something else (not necessarily less expensive). It's extremely unlikely that the engine would be forced to "lug" or run a lower RPM than designed when at highway speeds. Once the trans shifts into top gear and the torque converter is locked up, the gear ratio directly links engine speed and vehicle speed. |
| Before I jumped into a trans rebuild I would do a tune up on the truck and check you drive shafts. Makes sure the u-joints look good and have adequate lubrication. If all of that checks out then it may be your trans or transfer case causing the vibrations. I would find a good trustworthy transmission place and let them drive it and see what they think. That trans should be a 700r4 and they suck from the factory. I would recommend a beast sun shell upgrade and better than stock clutches at a minimum. There are lots of tricks you can do to a 700r4 to make it better. After a little thought May be the torque converter as well. Your trans guy should be able to identify that. |
| The transmission is a 700r4 and I think in 88 GM did improve/upgrade it over previous years. Last time I checked the u-joints looked good and the driveshafts were tight. I went through several drifts and unplowed roads so some snow/ice could be packed in the wheels causing some of the vibration at highway speed. |