I got it so HOT , it runs better than ever

Thewespaul

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Either your speedo is wrong or you have 4.55s, I’m at 83 mph in fourth at the same rpm, and 106 in 5th in at the same rpm
 

Danielle

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My truck lives on side roads. So when I drove it to the rally, it was the first time I had had it on the highway and it had never run better than when we got to the rally and back! When I tow on the highway I drive so grandmotherly that it doesn't count haha
 

Cubey

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Either your speedo is wrong or you have 4.55s, I’m at 83 mph in fourth at the same rpm, and 106 in 5th in at the same rpm

My 87s speedometer is off about 3-5mph with the stock 3.55 and stock 235s (250HD).

I had a 91 Corolla that was about the same in being off. Pretty sure a 78 Dodge van I had was the same too.

I guess they all used the same parameters to calibrate mechanical speedometers.
 

The_Josh_Bear

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Either your speedo is wrong or you have 4.55s, I’m at 83 mph in fourth at the same rpm, and 106 in 5th in at the same rpm
Well what the deuce... maybe YOU have airplane gears! ;)

I'll jack up one side and figure it out for sure then. If I do have abnormally short gearing maybe that's why reverse with a trailer(especially up hill)doesnt bug me in the ZF like it seems to bug others.

And the speedo works good, I've checked it with a GPS.
 

Thewespaul

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Well what the deuce... maybe YOU have airplane gears! ;)

I'll jack up one side and figure it out for sure then. If I do have abnormally short gearing maybe that's why reverse with a trailer(especially up hill)doesnt bug me in the ZF like it seems to bug others.

And the speedo works good, I've checked it with a GPS.
I’ve got 3.55 and 33” tires, but the old shop truck had stock sized tires and a 4.10 rear and would bury the speedo in fourth when the clutch wasn’t slipping
 

IDIBRONCO

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I’ve got 3.55 and 33” tires, but the old shop truck had stock sized tires and a 4.10 rear and would bury the speedo in fourth when the clutch wasn’t slipping
Back in the mid 90's, a friend and I had an impromptu race down the highway. He was in his 1989 F250, Ex cab, 4x4, ZF5, 235/85R16 tires. We ran down the highway as fast as we could go. I pulled out and went around him at about 105. My 75 F150, 4x2, C6, powered by a 1971 429 had more top end so I won that race. His truck would run 2100 RPMs at 60 in 5th so I am fairly certain that it had 4.10s in it.
 

austin92

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I don’t have a tach but I know I can run 80 in 4th. 245/75r16’s and 3.73’s


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austin92

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This is rpms for a zf5, 235/85r16s, and 4.56’s.

Look familiar josh_bear?


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