Can engine power affect transmission life ?

[NICAT]

A friend of mine has a theory that, if two cars has the same gearbox, and one has as relatively more powerful engine , there would be less need to downshift under load or during acceleration. So This could theoritically save automatic gearbox.
From the experience i know that, if engine doesn"t produce enough power, i have to shift so frequently in order to avoid high RPM and lugging engine.
Since manual transmissions are very reliable, it shouldn"t be a problem.
But how about automatic transmissions ? How frequent shifting affect their life ?

 

[bdcardinal]

Its true to some extent. When the 2005 Mustang came out you had a choice of a 4.0L V6 and a 4.6L V8. The V6 made something like 210hp and the V8 made 300hp. The V8 actually got better mileage on models with the same rear end because you didn't have to constantly rev out the engine to keep at speed.

 

[eljefino]

So when the car does eventually downshift there's more torque involved.

In the last 15 years, having an electric throttle has done wonders for cutting engine power mid-shift, which used to be force the trans had to absorb somehow.

 

[honeeagle]

your right foot has the biggest effect

 

[CT8]

More power puts more stress on any component.

 

[Linctex]

Originally Posted by NICAT

Since manual transmissions are very reliable, it shouldn't be a problem.


Try telling that to the early Dodge Cummins truck owners.

The Getrag G360 was lousy in good situtions... and then came the NV4500 that couldn't handle the Cummins hardly at all.

I've put two NP435's behind my Cummins with a "puny" 11" clutch! (and nearly a dozen u-joints)

Summary: A LOT of torque will kill a trans just as fast as a lot of downshifting will.

There are SOME secrets to getting better life out of a trans, but it could write a book.
Like honeeagle says - your right foot has more effect on transmission life than anything.

 

[Skippy722]

I don't think it necessarily applies to modern cars. My Durango had a pretty heavy torque management system that basically cut ALL power between shifts. The 8 speeds FCA uses now handle it much much better than that narcoleptic 5/6 speed slushbox they were using.

 

[bullwinkle]

Originally Posted by Linctex
Originally Posted by NICAT

Since manual transmissions are very reliable, it shouldn't be a problem.


Try telling that to the early Dodge Cummins truck owners.

The Getrag G360 was lousy in good situtions... and then came the NV4500 that couldn't handle the Cummins hardly at all.

I've put two NP435's behind my Cummins with a "puny" 11" clutch! (and nearly a dozen u-joints)

Summary: A LOT of torque will kill a trans just as fast as a lot of downshifting will.

There are SOME secrets to getting better life out of a trans, but it could write a book.
Like honeeagle says - your right foot has more effect on transmission life than anything.

I missed something somewhere-other than the infamous 5th gear nut loosening, what issues did the NV4500 have behind a Cummins? Thought it was the one to have, since NV5600 parts are basically unobtainable?

 

[demarpaint]

Originally Posted by CT8
More power puts more stress on any component.

True, and when people have more power they tend to use it, even when it isn't needed. That can often create more problems.

 

[92saturnsl2]

Originally Posted by eljefino
So when the car does eventually downshift there's more torque involved.

In the last 15 years, having an electric throttle has done wonders for cutting engine power mid-shift, which used to be force the trans had to absorb somehow.


This is a big reason why we have 400+ hp vehicles in stock form with 6,7,8,9+ speed automatics with a trans package size about the same or smaller than the old 4 speed units. The ability for the ECU minimize shock loads has made an enormous improvement in reliability and power handling.

 

[Chris142]

Originally Posted by bdcardinal
Its true to some extent. When the 2005 Mustang came out you had a choice of a 4.0L V6 and a 4.6L V8. The V6 made something like 210hp and the V8 made 300hp. The V8 actually got better mileage on models with the same rear end because you didn't have to constantly rev out the engine to keep at speed.

Same with the 4 cyl jeeps vs the inline 6. The 6 gets the same mpg as the 4.

 

[slacktide_bitog]

only if the transmission can't handle it

 

[69GTX]

Ford tried this on the 200 hp Taurus V6's with FWD. They shoe horned that known to be weak automatic trans into the 265-275 hp 1996-2002 Lincoln Continentals. That extra horsepower and added car weight contributed to many early transmission deaths. On top of that they stuck in a really aggressive first gear on the Lincoln to help you kill it quicker....lol (final drive ratio was >10). Best thing you can do is very frequent trans fluid changes and use a feather light touch on that gas pedal.

 

[WylieCoyote]

I'm betting you'd get better transmission life from the 10A in an Ecoboost Mustang than you'd get from a Mustang GT, if you have the same leadfoot behind the wheel of both cars.

 

[BMWTurboDzl]

Originally Posted by NICAT
A friend of mine has a theory that, if two cars has the same gearbox, and one has as relatively more powerful engine , there would be less need to downshift under load or during acceleration. So This could theoritically save automatic gearbox.
From the experience i know that, if engine doesn"t produce enough power, i have to shift so frequently in order to avoid high RPM and lugging engine.
Since manual transmissions are very reliable, it shouldn"t be a problem.
But how about automatic transmissions ? How frequent shifting affect their life ?




Depends on the rated capacity for the transmission. For example there are a couple of versions of the ZF8HP (ZF8HP45, 50, 55, 70, 90, 95, etc). The last two number designate max tq (45 = 450Nm). An engine rated for the ZF8HP95 could easily cause problems if it were mounted to a ZF8HP45.

 

[badtlc]

I believe so. Take the Ford Escape for example....

if you go look at the forums for CD4E failures/issues, you'll notice all of them were V6 owners. I couldn't find one 2.3L with the CD4E that had transmission issues. I think the V6 was just too much power for that transmission for regular use.

 

[DoubleWasp]

Originally Posted by bullwinkle
Originally Posted by Linctex
Originally Posted by NICAT

Since manual transmissions are very reliable, it shouldn't be a problem.


Try telling that to the early Dodge Cummins truck owners.

The Getrag G360 was lousy in good situtions... and then came the NV4500 that couldn't handle the Cummins hardly at all.

I've put two NP435's behind my Cummins with a "puny" 11" clutch! (and nearly a dozen u-joints)

Summary: A LOT of torque will kill a trans just as fast as a lot of downshifting will.

There are SOME secrets to getting better life out of a trans, but it could write a book.
Like honeeagle says - your right foot has more effect on transmission life than anything.

I missed something somewhere-other than the infamous 5th gear nut loosening, what issues did the NV4500 have behind a Cummins? Thought it was the one to have, since NV5600 parts are basically unobtainable?


There are a lot of lies spread about those transmissions. The NV4500 is a ticking time bomb behind the Cummins engines. Issue is self destruction.

People invested in NV5600-to-NV4500 conversions for owners of NV5600 Cummins trucks have spread the mythology that the NV4500 was a bullet proof trans in these applications.

 

[circuitsmith]

10 years before the ricey f@rt cans I had an '81 Accord I modified extensively.
From in to out:
Second snorkel on air cleaner. Both routed to cold air. Warm air flap retained, set to 80F instead of 100F.
Weber carb, non CVCC head with bigger valves, stage 2 cam, recurved distributor, colder plugs,
exhaust header, gutted cat converter, 2" exhaust pipe, stock quiet muffler.
This all resulted in considerable increase in midrange torque.
After a couple years a trans bearing failed in the 5-speed manual.
A couple more years it failed again, disintegrated and knocked a hole in the trans case.
Got a trans from a Prelude, which was stronger and held up.