Travel Speed

[GComo]

I have a "high speed" AA that I enjoy driving around town. I realize this is not a fast truck. And have no desire to make it a fast truck. My question is what is a reasonable speed to drive without hurting the motor? I usually travel around 35-38 mph and have been told this is too fast.

Thanks
GComo

[SeaSlugs]

as long as you have the high speed rearend gearset 35-40mph is perfect. If you have the low speed 20-25...

[GComo]

Thanks for the reply. That's what I thought.

[Tom Wesenberg]

I like to keep engine speed below 2,000 RPM for cruising. Sometimes you have to go a bit faster, but about 2,300 is what I would think of as red line.

[GComo]

What would that translate to in mph?

[1crosscut]

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A very comfortable cruising speed for my worm drive AA is 28 mph. I can go faster but the rpm's start to climb pretty quickly past that point. The later trucks with the bevel drive rear ends can do a bit higher speed I understand. Is yours a worm or bevel gear rear end?
Low speed worm drives will get you 10 - 15 mph.

[GComo]

I have an early 1930 with bevel gears.

[apbright]

My math says, with a stock 3.76 rear-end ratio, rpm = 41.2*mph. Thus 40mph = 1650 rpm.

I'm guess all AA-trucks have 4.11 rear-end ratios, changing the formula to rpm = 45*mph. That would make 40 mph give 1800 rpm.

[GComo]

It has 5.14 gears. Not sure how to do the math.

[SeaSlugs]

worm drive AA's are 5.14:1 high speed or 7.25:1 low speed

30/31 bevels were 5.14 high speed and 6.6 low speed

same 600x20 tires. (32" diameter)

http://www.crawlpedia.com/rpm_gear_calculator.htm

so according to that the 5.14 ratio:

30 mph is 1619rpm
35 mph is 1889
40 mph is 2159
45 your over redline at 2429rpm

for S&G heres low speed 6.6 bevel:

15 mph is 1040
20 mph is 1386
25 mph is 1733
30 mph is 2079
35 is above redline at 2426rpm

[GComo]

Thanks that helps a lot.

[Big Iron]

I have an early 30 with a high speed worm. It likes to run at 32 to 38 mph. You can tell what it likes by the sound. I run it up to about 40 quite I bit but only when I have to. It will do 47 or so but that is pushing it to hard.

[GComo]

Thanks. I've only run it up to 40 to get a run on steep hills.