2000 Chevy Astro HELP with performance

ENDEAVORNICHE

MEMBER
2000 CHEVROLET ASTRO

Engine Performance problem
2000 Chevy Astro 6 cyl Two Wheel Drive Automatic

Hi,
We have several Chevy Astro Minivans used in an A/C Service Company. They are V-6, Auto Trans W/ Overdrive, Rear Wheel Drive.
They average about 8-10 MPG and cannot carry much weight at all or they will not make it up the steep inclines. It is a mountainous region.
The top speed limit on the island is 35MPH.
We need to be able to carry more than just our tools in the vans and get more MPG also. As it is the vans stay in first or second gear going up hill. When coming down an incline even downshifting to 2nd gear doesn't provide the necessary slow down.
Our question is; to be able to carry a normal load and be able to climb and decelerate normally as well as improve fuel efficiency, should we use a higher gear ratio in the rear differentials, or replace the overdrive transmissions with a 3 spd unit, or both, or we're open to suggestions.
Thank you.
This is a serious question with far reaching implications to a real business. Serious answers with corroboration would be appreciated.

3 Replies

JACOBANDNICKOLAS

MECHANIC
108,269 POSTS

How much weight do you carry? Also, if the max speed limit is 35, I would recommend going with the highest gear ratio available on the differential. It will provide more power and lessen the strain on the engine (more MPG). However, if the vehicles are driven at 60+ MPH, it will hurt the MPG because the engine will run at a much higher RPM.

Let me know about how much weight you carry.

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Wednesday, November 18th, 2009 AT 10:46 AM

ENDEAVORNICHE

MEMBER
3 POSTS

Hi,
The vans are loaded to capacity (sometimes over).
Since my original post, we've installed 4:56's in one van. That's the lowest ratio available for the diff. The performance with the new gears is phenomenal!
It's like a completely different van. Thanks for your reply.
Your advice is on the money.

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Wednesday, November 18th, 2009 AT 5:03 PM

JACOBANDNICKOLAS

MECHANIC
108,269 POSTS

I'm glad to help good people. I'm sure the van has all kinds of power now, but like I said, if you use it at highway speed, it will have an adverse effect on the MPG. Keep it around 35 MPH and you'll be happy with the results. In the future, I believe you can order the vans with that gear ratio. That's the way to go.

Thanks for using 2carpros. Com, and let us know if you have questions in the future. I wish you luck with your business.
Joe

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Wednesday, November 18th, 2009 AT 9:18 PM