Edmunds.com | Inside Line | Auto Observer Your Account | Help | Directory
You are here:
![[F]](http://a332.g.akamai.net/f/332/936/12h/www.edmunds.com/media/townhall/webxicons/site.gif){kind=small}
Forums
Maintenance & Repair Transmission Traumas?
2411 messages, Last post on Dec 04, 2009 at 1:19 PM
You are in the Maintenance & Repair Forum. Your Host is mr_shiftright
|
|
|---|---|
|
Well, back in those days to design and build an entirely new 5-speed was expensive...this way, you just add a unit onto the original three or four speed...a different tail shaft housing. The overdrive in the 3rd gear of a 4 speed was not intended, it's just something you got for free...often, like with jaguar or mg or volvo (1960s, early 70s) they'd only allow you to flip into overdrive in 4th gear, but you could easily by-pass that. On AMerican cars, typical overdrive was activated in the 50s & 60s by a cable under the dashboard..this worked with the typical 3-speed column shift of cars of that era. I don't recall any 4-speed American overdrives. Five speeds were rare in the 60s...mostly the exotic Italian cars had them, and that was about it. It was really the Japanese who made them commonplace.
|
|
|
But Mr. Shiftright Why do we need overdrive? |
|
|
|
|
Well, fuel economy and reduction of rpm/engine noise at cruising speeds are two benefits. It's awfully nice, especially with today's high-revving overhead cam engines, to be able to plop it down in 5th or an "overdrive" gear and watch the RPMs drop from a buzzy 3800 rpm to a melllow 3000. The downside is that people sometimes forget that the overdrive gear isn't very good for hill-climbing or any kind of serious work, so they sometimes mash the gas in overdrive and go...nowhere fast... Of course, all these extra gears and overdrive circuitry makes for more expensive transmission overhauls. |
|
| My 85 Toyota Cressida has some kind of jerking or clunking sound when I let go of the accelerator during slowing down. It's a AUTO w/ 4sp Overdrive. I think it's a u-joint needs to be replaced. The car have 185K miles on it. Any ideas ? I pray it's not the tranmission. | |
| Yes, your prayers positively answered - with a high probability it's engine mounts you have to check first. | |
| Why engine mount? Do u mean the engine mount is loose from the frame? Can u go a little more in detail. Thanks. | |
|
Engine mounts on the modern cars is two peaces of metal separated with layer of rubber. With years, rubber is wearing thin and allows more engine movement during the load changes. When You accelerate, certain forces trying to push engine indirection opposite the direction of rotating axles. With bad engine mounts engine can move as much as 1-2 inches. After You remove foot from gas, engine can bounce back under own weight, and you can hear clunk or thud, depends on degree of rubber wear - if little left, or nothing left at all. I hope it will help you understand how it works. |
|
| Thanks for the explaination, I think I understood your answer. I guess it's just like mechanical backlash when the gears are worn out. | |
| 1992 chevy astro van transmission problem no reverse or second gear. Any suggestions on how to solve this problem? | |
| Automatic transmission? Doesn't sound good. Even if it's a manual transmission, it doesn't sound good. You may need to take it in for repair or replacement. Have it checked out though, before you just walk into a shop and say "I need a new transmission." | |
You are here:
Forums
Maintenance & Repair Transmission Traumas?
New? Join Now!
Forum Tools
Search Forums
Browse by Vehicle
Browse by Board
Browse by Topic
Today's Chats
