Rear end gear change.... will it effect tranny?

[HOTTOGO]

I'm gonna change my 3.73 gears to a 4.56, will it have any effect on the tranny other than speedo? I have a 2300 stall t/c and I know it may have some effect on eng. combo but what if any on tranny?

 

[HellOnWheels]

Rear end gear change....

Mark,

I'm running 4:11's and a 3500 stall n/l with really no down side other than a few more RPMs and only then noticable at 75-80 mph cruise.

I'm thinking about going back to the 3:42s and lockup.

 

[HOTTOGO]

Thanx, for the reply, but why going back to the 3.42's?

 

[6PacktoGo]

It won't hurt the transmission, but you will likely find you will have too much overall low gear. Most people find an overall low gear much lower than 11:1 is too much, unless you have a tall tire. Having run 4.11 gears with my 700 and a 27" tall tire I can say low gear was real steep. Be ready to shift when you launch. If you're going to run a 30" tall slick it might work.

 

[HOTTOGO]

Thanx 6Pack, Wasn't even thinking tire size yet, I run 27' on the street and 26" BFG Drag radial a the strip which were to compensate for the 3.73's but I'd bet your right I'm gonna need taller one's to make it work.

 

[HellOnWheels]

Rear end gear change....

Mark,

My plans are to be doing more long distant crusing and wanted a better mpg.

If memory serves with the 4:11 rear gears and 28" tires would equate to a 3:82 ratio. I've read/heard pro/con as to what ratio was best. I know its all about leverage.

One person that uses steep gears is Viktor ?? on the gnttype.org, I believe he held a record (?) for a while and the only mod was a set of 5:14 gears! he also told me that if a set of 6:0 gears were available he would try them...I'm sure you could get an em on the gnttype web site.

BTW if you have a Buick Power Source Manual there is an article/graph about rpm v mph v ratio.

HellOnWheels

 

[6PacktoGo]

If you're running in overdrive, a 4.11 becomes a 2.87 final, and a 4.56 becomes a 3.42 final. Those are APPROXIMATE, not exact. Tire sizes on the back of a G Body usually run between 26.5" and 28", excluding slicks. My Cutlass did fine for several years with a 4.11 and a 700 R4. In retrospect, with a 3.06 low gear, a 3.90 rear would have been better. But a 4.11 may work great with a 2.75 low gear in a 200 4R. Just be ready to shift, especially if you don't turn more than 5500.