Hey guys, my main question here is; What is too low of rpm for my AWD drivetrain?
Here is my story... 2011 Subaru Forester 2.5X Premium with Manual 5 speed tranny. Purchased used @70,000kms, now has 100,000kms.
Last January (2017) I was cruising 5th gear, ~1,900-2,200rpm, ~50-75km/h. Because an uphill was coming I suddenly hit WOT without downshifting. As soon as I hit max engine Load/full TPS/Open Loop, engine stumble with loud sound (implosion like). Blown a bearing on shaft inside the transfer case. The transmission sounded differently, more winding sound. It got worst and worst, the bearing melted inside there, smell burnt oil for weeks after. During that time I didn't know anything about engine lugging btw.
2,000$ later I would like to take every precaution. I was told that AWD Subaru needed REVS for drivetrain to perform under high load / full throttle / high power output situations. ?
*I don't put the blame on 1 simple reason on that transmission fail. I think it is more a cocktail of; oversized/overweight tires/Engine lugging situation/low rpm/wot ***plus after the repair done, I came to conclusion that Bearings inside the transfer case was already damaged before failure!Before the repairs, my shifter stick was shaking a lot more! A lot more, but in a way acceptable for a fresh owner of subaru awd (back from Toyota Echo lol) Also there was a rattling annoying sound before when reaching the 4k rpm. Now all smooth up to the redline! Clutch was ridin hard by previous owner, had to change the clutch also.
I also tweaked the rims setup with my BFG Ko2 225/65r17. I was running the oem enkei 17 silver spokes rims, unfortunately those rims are too heavy. Swapped them with Enkei RPF1. Oem~25lbs, rpf1~15lbs, -10lbs, Ko2+10lbs, so that kinda net me close to flat.
Now I was wondering, what rpm is considered ''too low'' for a WOT in higher gear 5th ?
With my oversized tires, n/a engine, if I cruise 105 km/h~2,500 rpm I feel that rpm is not enough for full engine load. Full load on 5th gear 2,500 rpm has very low acceleration, feels like its struggling to increase speed but without any vibrations or bad sound. Its just smooth but very slow. So I think that 2.5k rpm may be to low putting stress on drivetrain/engine. Still dropping to 4th feels too much... Cruising closer to the 3,000 rpm (2,900 min) feels a lot better for acceleration and stress on hardware but I am going too fast.
http://www.subaruforester.org/vbulletin/attachment.php?attachmentid=388178&thumb=1
Here is my story... 2011 Subaru Forester 2.5X Premium with Manual 5 speed tranny. Purchased used @70,000kms, now has 100,000kms.
Last January (2017) I was cruising 5th gear, ~1,900-2,200rpm, ~50-75km/h. Because an uphill was coming I suddenly hit WOT without downshifting. As soon as I hit max engine Load/full TPS/Open Loop, engine stumble with loud sound (implosion like). Blown a bearing on shaft inside the transfer case. The transmission sounded differently, more winding sound. It got worst and worst, the bearing melted inside there, smell burnt oil for weeks after. During that time I didn't know anything about engine lugging btw.
2,000$ later I would like to take every precaution. I was told that AWD Subaru needed REVS for drivetrain to perform under high load / full throttle / high power output situations. ?
*I don't put the blame on 1 simple reason on that transmission fail. I think it is more a cocktail of; oversized/overweight tires/Engine lugging situation/low rpm/wot ***plus after the repair done, I came to conclusion that Bearings inside the transfer case was already damaged before failure!Before the repairs, my shifter stick was shaking a lot more! A lot more, but in a way acceptable for a fresh owner of subaru awd (back from Toyota Echo lol) Also there was a rattling annoying sound before when reaching the 4k rpm. Now all smooth up to the redline! Clutch was ridin hard by previous owner, had to change the clutch also.
I also tweaked the rims setup with my BFG Ko2 225/65r17. I was running the oem enkei 17 silver spokes rims, unfortunately those rims are too heavy. Swapped them with Enkei RPF1. Oem~25lbs, rpf1~15lbs, -10lbs, Ko2+10lbs, so that kinda net me close to flat.
Now I was wondering, what rpm is considered ''too low'' for a WOT in higher gear 5th ?
With my oversized tires, n/a engine, if I cruise 105 km/h~2,500 rpm I feel that rpm is not enough for full engine load. Full load on 5th gear 2,500 rpm has very low acceleration, feels like its struggling to increase speed but without any vibrations or bad sound. Its just smooth but very slow. So I think that 2.5k rpm may be to low putting stress on drivetrain/engine. Still dropping to 4th feels too much... Cruising closer to the 3,000 rpm (2,900 min) feels a lot better for acceleration and stress on hardware but I am going too fast.
http://www.subaruforester.org/vbulletin/attachment.php?attachmentid=388178&thumb=1