Some time back I installed a 700R4 into my '87, it originally had the METRIC 200 in it. I had to shorten the driveshaft 3 inches and I thought all was well. I recently swapped in a 3:73 posi out of an '86 Monte Carlo and now I get a slight vibration at high speed. The shaft must be just a tad out of balance which wasn't noticeable with the 2:40 gears. I also have the shaft out of the Monte Carlo, is there any chance that shaft would be the proper length?
u joints are oriented proper and the differential was never apart, it is "from the factory" set up. Like I said, this was not an issue until the lower gears started spinning the driveshaft faster. Does anyone know if the El Camino & Monte Carlo shafts are the same length?
Make sure the bushing in the 700R4 tail housing is tight on the slip yoke. If it's not tight, you will be chasing other things to get the vibration issue solved. The higher ratio, and drive shaft RPM may be enough to set it off. That bushing is the same one as the TH350.
All drive shafts have a harmonic speed at which they will "wobble". Having higher gears will make it show up at a lower speed. the best way to alter it to a higher rpm is to change the material to a lighter weight shaft --as in aluminum or carbon fiber....It may be perfectly balanced and just be the harmonic doing it. remember the El camino drive shaft is longer than and other---short of trucks, and they usually use a two peice driveshaft to avoid the harmonic there. This is a fairly common complaint on a long wheel base vehicle...........Dan
I don't think I have ever had a car that was "FINISHED"........unless it was totaled.
http://www.iedls.com/ Inland Empire drive line service. All you ever wanted to know about drive shafts, engine and trans angles, pinion angle on rear etc,
When I'm ready for a new drive shaft for my Elco/Caddy 500 project, that's where I'm gonna get one made.
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