Safe speeds

[SilentWolf8293]

So my dad tells me that the national speed limit when my eagle was built was 55mph and that's what my car was designed for. However, when I get up to 55 the engine is already straining quite a bit. one time I actually got up to 75mph and the engine was practically screaming for mercy. Is there a cheap way to alter the Transmission to make it a little better suited for modern day traffic speeds or should I just make my next 500 mile trip at 55?

[carnuck]

what size tires and what gear ratio? What motor/trans?

[BenM]

You should be fine at any legal speed limit, maybe a 4cyl would be a little loud and weak at 75, but it would still be at a safe speed.

Let us know all you know about the engine, transmission, and axle gearing.

[carnuck]

I had an '86 Comanche longbox with AMC 2.5L, Renix TBI, AX5 4x4 with 4.10 gears and 235/75/15 tires and we loaded it to the gunnels with parts, tools, 3 people, camping gear, 3 spare tires and went to Ouray, CO in '02 to the Ouray Invasion (UPS lost the steering parts of my J10 would've gone) We rolled over the scale at over 6,000 lbs and we were able to cruise 75 mph (until we were hit by a delivery truck that messed up my steering and ate all my tires by the time we got back) Still got 20 mph on the highway and even got 25 mpg for a couple tanks with 85 octane.
   Gearing correct is what you need. PS: We finished converting it to 4x4 a couple hours before we left.

[SilentWolf8293]

It's an '84 Eagle with the IL6 4.21 liters. I have no clue about the gearing and I only know that the tires are just one size larger than standard

[Amc1320]

My eagle seems most confortable at 65 on the hwy, much over that and it seems iffy

Yes, it was designed at a time when 55 was the max anyway and I think it's greared to work best at that speed, if the transmission shifted a couple more times like 4 or 5 speed like today's cars it would be fine at higher speeds I think

[recomer]

I've done up to 80 in mine in when traveling across country twice with no issues. I keep it below 70 now that I'm in Virginia as the roads really suck around here. Mines a 6 cylinder, Auto with 2.53 gears.

[Draekon]

I've cruised at 80mph in mine before.  6cyl with SR4 and 2.73 gearing.

[maddog]

I have only done this once and I would not recommend doing it but I have had my strait six automatic with 3.08's up to 120mph as for doing 70 to 75 or even 80 as long as the car is in good shape I don't see why it couldn't do it.

[carnuck]

With the AW4 my wagon with 3.08s and 235/75/15s should cruise nicely at 80 and handle higher bursts into the 3 digit zone.