I'm looking for ways to improve the high speed comfort of my '80 Fairmont, which doesn't like to cruise above about 70-75 mph or so. I know that replacing the 36 year old steel driveshaft with aluminum will probably help, but I am looking into removing any other causes of vibration I can, and I'm thinking that CV joints instead of U-joints may help by removing some of the gyroscopic and acceleration based forces.
Thoughts?
Did you see this thread: https://grassrootsmotorsports.com/forum/tech-tips/cheap-simple-nvh-tool-and-write-up/117396/page1/
Ford put weights in weird places to control vibes.. I've seen weight bolted to the differential and the tailshaft housing on the trans as well as integrated into the front yoke of the driveshaft.. they even used a weird setup with 2 u joints separated by a short collar on the front of the driveshaft.
novaderrik wrote: Ford put weights in weird places to control vibes.. I've seen weight bolted to the differential and the tailshaft housing on the trans as well as integrated into the front yoke of the driveshaft.. they even used a weird setup with 2 u joints separated by a short collar on the front of the driveshaft.
The "two u-joints" thing is a double Cardan joint, and is a CV joint by design.
snailmont5oh wrote:novaderrik wrote: Ford put weights in weird places to control vibes.. I've seen weight bolted to the differential and the tailshaft housing on the trans as well as integrated into the front yoke of the driveshaft.. they even used a weird setup with 2 u joints separated by a short collar on the front of the driveshaft.The "two u-joints" thing is a double Cardan joint, and is a CV joint by design.
Which also adds a whole bunch of weight to the shaft, and can cause its own set of issues. Witness 2wd S trucks towards the end of their run.
Streetwiseguy wrote:snailmont5oh wrote:Which also adds a whole bunch of weight to the shaft, and can cause its own set of issues. Witness 2wd S trucks towards the end of their run.novaderrik wrote: Ford put weights in weird places to control vibes.. I've seen weight bolted to the differential and the tailshaft housing on the trans as well as integrated into the front yoke of the driveshaft.. they even used a weird setup with 2 u joints separated by a short collar on the front of the driveshaft.The "two u-joints" thing is a double Cardan joint, and is a CV joint by design.
That's why I was thinking CV joints.
Christ. I typoed the title. I didn't mean CC joint, I meant CV joint. I wish we could edit titles.
Here's another thought; what if I put a stupid low fifth gear in, use it as first, and put a 2.73:1 gear in the rear to lower the driveshaft speed?
snailmont5oh wrote: Here's another thought; what if I put a stupid low fifth gear in, use it as first, and put a 2.73:1 gear in the rear to lower the driveshaft speed?
At that point, just run a non-OD trans and tall diff gears. That'll get the DS speed down, although the gearing might be a little short for high speed stuff (70 mph with a 1:1 top gear in the trans, 2.73 diff and 26" tires is ~2450 rpm). It's slightly more mechanically efficient too, in theory.
Realistically, I'd figure out what kind of RPM you want to turn on the highway first, as that'll tell you the options of how to get there.
Driveshaft wise, as long as it's got good angles, there's no reason a 1 piece u-jointed (1 at each end) driveshaft can't work fine with no significant vibes.
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