RPMs... do I have a different differential?
Thread Starter
Instructor
Joined: Nov 2005
Posts: 133
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RPMs... do I have a different differential?
Well not "different" per se, but with lower gears.
I spin at about 4k-4200 at 70mph, in my 3 speed... seems a bit high to me. Not sure, of course, this is the first auto with no overdrive I've owned. Any idea what ratio that puts me at?
My first gear is about 4500 at 30 or so mph.
I spin at about 4k-4200 at 70mph, in my 3 speed... seems a bit high to me. Not sure, of course, this is the first auto with no overdrive I've owned. Any idea what ratio that puts me at?
My first gear is about 4500 at 30 or so mph.
Le Mans Master
Joined: Jan 2004
Posts: 8,295
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From: one night in Bangkok you are never lonely
Sound like you have a 3.73 or lower rear gear. I had the same problem with my 81 it had 3.73 and with my 4 speed 1 to 1 it would tack 4,000 at 75mph. I changed it out to 3.08 now I can drive on the highway at 90 with out a problem. 
Tech Contributor
Joined: Aug 1999
Posts: 15,175
Likes: 3,990
From: Connecticut, USA
Depending on tire size but it sounds more likr 411's to me. With 370 or 373 gears and 225 x15 tires 3400 @65 is about right and you're higher then that.
What year is your car? typically 70's 350 with auto's came with 308 and 4 spd 336 or 308. 355,370 were an option on some but after years of who knows who working/owning them anything could be in there.
What year is your car? typically 70's 350 with auto's came with 308 and 4 spd 336 or 308. 355,370 were an option on some but after years of who knows who working/owning them anything could be in there.
