1978 HJ45 What is max speed

[jjliu1974]

Hello. I have a question for you all with a HJ45 with H engine. What is your max speed? I am looking to purchase a HJ45 in Costa Rica and the one that I have seen can go up to 120 kph which is about 75mph on flat ground. Does that seem about right? The engine and trans was said to be overhauled 2 years ago and had minimal whitish smoke when floored. Any info is appreciated. Thank you

 

[SteveH]

Your axle gear ratio (likely 4.11) will have an impact on this. Most vehicles of this era should probably not be driven faster than 75 mph (some would argue 55) due to brakes, steering, suspension, etc. They are tractors. With 4.11 gears and normal-size tires, 75 mph will put you well over 3000 rpm, which would seem a bit excessive for a diesel LC engine.

 

[bhsdriller]

downhill or uphill

 

[cbmontgo]

I still think the sweet spot for a 40 with 4.11 gearing is 55-50 MPH.

 

[jjliu1974]

Thank you SteveH for the reply. Bhsdriller , the 75mph was on flat even plane.

 

[Splangy]

75mph sounds pretty damn good for an H

 

[Frikkadel]

Max speed and max safe speed would be 2 very different things. I've had my petrol 40 up to 110km/h on a flat stretch, but it was white-knuckle stuff.

 

[tlaporte]

@65swb45 Mark had an HJ45 for a while and I seem to recall him talking about its overall lack of power.

For me, I find the sweet spot in my HJ47 around 60KPH/35MPH. I’m old enough now to not be in any hurry.

75MPH in an HJ45 sounds like a dog walking on its hind legs: it’s not pretty, but you’re so impressed to see that it’s even possible for you to care about how well it does it!

 

[65swb45]

@65swb45 Mark had an HJ45 for a while and I seem to recall him talking about its overall lack of power.

For me, I find the sweet spot in my HJ47 around 60KPH/35MPH. I’m old enough now to not be in any hurry.

75MPH in an HJ45 sounds like a dog walking on its hind legs: it’s not pretty, but you’re so impressed to see that it’s even possible for you to care about how well it does it!

You are correct Tom. The H is a real ‘dog’. I was never really comfortable at anything over 60, and usually drove it 55.

They say one of the signs of middle age is when you become more interested in seeing how long something will last, rather than how fast it can go. I got my HJ when I was 34, and slipped into middle age shortly thereafter! I flirted with a midlife crisis at 43 after seeing @whitey45 monster 45, dreaming of swapping the gutless wonder ‘H’ for a SBC. Got lucky and sold the truck to Ron Q before I pulled the trigger on that swap.

IMO, driving an H at 75mph is the fastest road to an engine swap.

 

[kerplunk]

Thank you SteveH for the reply. Bhsdriller , the 75mph was on flat even falling out of a plane.

I fixed the typo for you....

 

[65swb45]

I fixed the typo for you....

Yes, but can you fix the EHW (early hill warning) system that automatically slows the truck down a 1/4 mile BEFORE you get to the hill?

 

[FJ40Jim]

The design brief specified max sustained cruise speed of 100kph.

 

[kerplunk]

I've never had my FJ60 over about 60 mph (100 kph?). There are some seriously steep hills close to home, and it will coast down them that fast in neutral, but the steering starts wobbling enough that I slow.

Regardless of my own FJ40's issues, or the power issues with any particular engine. I used to have a 99 Jeep wrangler, and at a little over 80 mph, I could feel it getting light. It just simply didn't have the aerodynamics to not float up off the road at that speed. I've never driven an fi40 at that speed, but can't imagine it's not worse. (maybe the steering will stop wobbling if the tires begin floating off the road?)

 

[jjliu1974]

Thank you all for the replys. I was evaluating the power train based on exhaust smoke and performance of the engine and trans from shifts to its top speed. Thanks again.

 

[AussieHJCruza]

She'll run out of revs at circa 130 km/h

 

[reddingcruiser]

I've never had my FJ60 over about 60 mph (100 kph?). There are some seriously steep hills close to home, and it will coast down them that fast in neutral, but the steering starts wobbling enough that I slow.

Regardless of my own FJ40's issues, or the power issues with any particular engine. I used to have a 99 Jeep wrangler, and at a little over 80 mph, I could feel it getting light. It just simply didn't have the aerodynamics to not float up off the road at that speed. I've never driven an fi40 at that speed, but can't imagine it's not worse. (maybe the steering will stop wobbling if the tires begin floating off the road?)

I run my not-so-stock 40 at 70mph all the time (been to 80 mph a couple times). Never been uncomfortable, just leave a lot of negotiating room between me and traffic.