A Mechanic suggested changing the 3.52 gear in my Dana 80 to a lower i.e. 3.00 gear to lower the rpm so I can cruise in the operating range of my B5.7
any thoughts? I Know it will hurt my 0-60 but oh well.
Wayne

If it were I, I'd leave the 3.52 gear in (it's already the tallest I know of on a Breakaway). Your engine has already had its power upped, and going to a 3.00 runs the risk of the engine lugging, unless transmission shift points are raised - negating the change.

with the 8R tires 60 mph is 2180rpm 65 is 2360 which is at the top of the operating range.
a 3.0 would give me 1860 at 60 mph and 2010 at 65
wouldn't that be in a better part of the operating range?
Wayne

Are you sure you have a 3.52 ratio rear end on your Breakaway. Most have a 3.73. Mine has 4.1 but I have a 6 speed with a double O/D, (5th & 6th)

I can assure you, you will not be happy with a lower numerical ratio. It will be a real dog off the line and the benefits of the cruise will not benefit the cost.

Check the metal tag on the diff to make sure what ratio you have.

Dana 80 - Larger Image

IIRC, the 4th gear in your tranny is OD,so your calculations would be off.

4 speed Allison trans do not have O/D and I don't think the torque converter locks either.

Thanks! I couldn't remember. My 4L80E with .75 OD yields 1750 @ 60 mph with the 3.73.

Ed is right. 3.73 is the ratio and the 542 does not lock up.

There is or was a 3.43 available for the Dana 80. But the problem is the transmission. I had problems with my 542 overheating in the hills due to the torque converter slipping. Change to a 3.43 and it will slip even more.

I have a data sheet on a 1542 which was a 542 with a lockup converter. Tried to find one with no luck before finding my 2000. Lots of internet sites advertised they had them until you called and they had no clue what I wanted.

The only good answer is a transmission swap. Either the Allison 1000 or 2000 with work if setup right.

Has anyone looked at a 2 speed differential maybe 3.00/4.11 . Just a thought
Wk

I did. None available for the Dana 80. I went thru every thing you are now doing.

Think TRANSMISSION.

Hi Gary: you said in the thread where you were putting in the new trans, that you would do a complete write up when you finished. Do you know the link to that write up? thanks for all your help
Wayne

any idea on gear ratio on a 33 ft 454 turbo 400

My guess on the one in Findlay is a 4.11. I think that coach has 16.5" wheels. Our 31' has a 4.56, but has 19.5' wheels.