RotaryBo

Well, after a year and a half sitting in a nice warm garage(the car, not me), I have finally gotten my '81 back on the road...and now the fun begins.

When I decelerate from highway speeds, the car develops a rather alarming shudder around 80km/h (about 40mph), which goes away once I get below 75km/h (30-35mph). My coworkers think that I may have either a bad Ujoint or a busted transmission mount. The car has always been a bit rough, but this 'shake and decelerate' is something new. What does it sound like to you guys?

Next issue; back before I put the car in storage, I had an alarm system installed. Being garaged, I never bothered having it on (besides, I had removed the battery). Fast forward to present day. I installed a new battery, and within a week was dead! I hooked up my inline ammeter and discovered that the only drain in my system is the alarm and it drawing 150-175 miliamps. The last time I had a drain anywhere near this was my clock(long since gone) but that was only 20 miliamps. Should I go back to the car stereo place and see if they will play nice with me, or do you think that even though the car has been in storage, they will say,"It's been two years, too bad so sad!" I think I will try my luck, just wanted some input. Thanks guys

Rx7carl

Ill assume the car is stock. Maybe your dashpot isint working. Do you have any kind of service manual to know how to check it?

Im not sure what an alarm should draw but 175 milli amps seems excessive to me.

RotaryBo

Oh dear, now I have to ask a silly question: What is a dashpot? (I probably know, but humour me )and yes, the car is stock, with the execption of an '86 FC alternator and an electric fan.

BIll Burdette

Tires? I know if my car sat for 1 week on race tires, they would develop flat spots. They would smooth out after a few miles, but your car sat much longer.

RotaryBo

I over inflated the tires a bit prior to storage in anticipation of that. Granted, after a year and a half/ two years parked, they were flat. There was some Some low speed shake initially, but most of that went away after a few days driving. There's just that shaking on deceleration on the highway that has me worried.

Paradox

iTrader: (1)

put your foot on the floor to feel for vibrations and decelerate, try it once in gear and once in neutral. see if it still does it in neutral. if it does it could be related to suspension/brakes/bearings,etc

does it feel like its a engine or drivetrain problem to you right now?

RotaryBo

My gut says drivetrain. The engine pulls good and strong, idles around 1k once it's all warmed up. It just seems to use a lot of gas. Then again, I have been driving my jetta TDI for the past two years, so that could be why the '7 seems so thirsty!

Whanrow

Dashpot is used so the throttle doesn't just chop shut. Its kind of like a round vacum diaphram and as the throttle closes, it provides some resistance so the throttle closes slowly. Its about 2 " across (at least on my -se) with a pin sticking out that contact the throttle linkage just before it closes.

As far as the vibration, my first guess would be that a u-joint siezed up during storage so sort of has a tight spot. That's assuming they were fine to start with. 2nd guess is tranny mount. First two guesses go out the window though because it sat on flat tires. A cheap trick I've done before is jack the back end up on blocks, block the front wheels, and run the car up to speed. Better yet, get somebody else to run the car, then both watch the tires to see if they have a flat spot, and try and feel the axle when it vibrates to try and see where the vibration is coming from.

Just don't come to me if you're silly enough to get a hand in a spinning tire or driveshaft! lol
Oh, and WERAR safety glasses. If a little stone flies out of the tire, it won't exactly tickle.

RotaryBo

I have some good news! It turns out that one of my neighbours used to work for the car audio place where I had the alarm installed and he was telling me that it sounded like the diode for (the alarm's) ignition relay was pooched (instead of blocking the current flow, it was providing a constant trickle, draining the battery.) As far as the U joints are concerned, they were about two years old when I put the car in storage, so they could be considered new-ish. I will still have to take the car to the auto club and get it on a lift and see for sure though.