456s?

[johnnieb]

I have one of those rare 4 speed overdrive transmissions, RPO MM7 Np A833, I like it but with 33s it is very high geared I rarely get into O/D and 1st and reverse are just to high, I currently have 373s but I'm thinking the 456s may be the answer, for those who don't know the gear ratio is very close to the 700r auto. Anybody care to give me their thoughts?

 

[crazy4offroad]

Looking at a gear ratio calculator your top gear is about 1,850 rpm at 70, which is awesome for fuel mileage but could be out of ideal operating range depending on your cam profile. 4.56s would run about 2,275 at 70 mph, just about perfect compared to modern overdrives but again how radical your cam is it still might not be happy. 4.10s might be a ok at 2,050 rpms but I can't tell what the lower gears would be since they don't have this trans on the calculator. You can enter custom numbers if you want to give it a shot but I just used the 700r4 to go by for OD...
http://www.grimmjeeper.com/gears.html

 

[johnnieb]

That's a cool site..Thanx

 

[Jrgunn5150]

I have 4.56's in my DD Trailblazer with 33's and of course, overdrive. I'm quite happy with the performance.

 

[johnnieb]

what tranny are you running?

 

[Jrgunn5150]

My Trailblazer has the 4l60E

 

[littlered]

johnn i have the exact "rare A833" 4 speed od.....running 456 gears in mine and only a lil 305 engine it turns 3000rpm at 65 mph......i know this is an old post but i just seen it ...lol