4K RPM is way to high, sounds like you have super low gears in there.
Great thread by the way
A 1990 HZJ80 mini-refurb from Saudi Arabia
- Thread starter boozewz
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
4K RPM is way to high, sounds like you have super low gears in there.
Great thread by the way
boozewz
SILVER Star
- Thread starter
- #182
That's correct. The beam is now a bit narrower, and I get a feeling a tad skewed to the left as the lenses I got are from Aus, and are marked for RHD vehicles. However, its the high beams that really blow it out of the water. Will snap a pic and post it.
4K RPM is way to high, sounds like you have super low gears in there.
Great thread by the way
Thanks! Any way I can check the gears without opening the diffs and counting? Figured with running 33s it would help. Would dropping down to say 31" tires help reduce the RPM?
Last edited:
Going to a smaller tire would make it rev higher, you'd want to move to 35's if your goal was to bring the revs down at a given speed. How fast are you going when it's revving at 4K rpm? With the 5 speed and 33's I'd guess 140km/h or so?
Wow, that is more than 1000rpm higher than my truck on 33's with the auto! I had no idea they were geared that low!
Stock gears, locked axles, HDJ81, I believe it's 4.11.
I'm running a similar setup to yours... 33s, H151, 4.11s (assuming your diffs are stock). I do 3,000 RPM or so at 120 km/h.
I'm not savy with tranny gearing, but I know 1st and 2nd gear in the H150 are different. I wonder if that makes a difference for overall transmission gearing in 5th?? 3rd, 4th and 5th are the same as H151.
I'm not savy with tranny gearing, but I know 1st and 2nd gear in the H150 are different. I wonder if that makes a difference for overall transmission gearing in 5th?? 3rd, 4th and 5th are the same as H151.
From Mark's 4wd website:
Manual Gearbox: 5-speed manual - H150F.
The gear ratios are: 1st 4.529:1, 2nd 2.464:1, 3rd 1.49:1, 4th 1:1, 5th .881:1, reverse 4.313:1
Manual Gearbox; 5-speed manual the model designation is H151F.
The gear ratios are: 1st 4.081:1, 2nd 2.294:1, 3rd 1.49:1, 4th 1:1, 5th .881:1, reverse 4.313:1
1FZ/1HD Engine & Automatic Transmission: 4-speed with lock up torque converter - A442F.
The gear ratios are: 1st 2.95:1, 2nd 1.53:1, 3rd 1:1, 4th .765:1, reverse 2.678:1
Looks to me like about 13-14% difference between the gearing of the top gears that you'll be using on the highway. Going from 33" to 35" tires is about a 5.7% difference, so while it would help, it won't get you down to where I'm revving with my auto.
How to determine your gear ratio:
What gear ratio do I have?
Jack up one tire if you have an open diff, or both tires if you have a working posi or locking differential. Rotate the tire one full revolution for posi’s and lockers and 2 full revolutions for open diffs. Carefully count the number of full revolutions the driveshaft makes. This is your gear ratio. In other words, if the drive shaft turns 3 ¾ turns, you probably have a 3.73 gear ratio. Turning the tire for twice the number of full revolutions and dividing the drive shaft revolutions by two will give you a more accurate reading.
Edit: added the H151F data, based on what Nick is seeing, I'd check your axle gear ratio cause there's about a 1000RPM variance that's unaccounted for here.
Manual Gearbox: 5-speed manual - H150F.
The gear ratios are: 1st 4.529:1, 2nd 2.464:1, 3rd 1.49:1, 4th 1:1, 5th .881:1, reverse 4.313:1
Manual Gearbox; 5-speed manual the model designation is H151F.
The gear ratios are: 1st 4.081:1, 2nd 2.294:1, 3rd 1.49:1, 4th 1:1, 5th .881:1, reverse 4.313:1
1FZ/1HD Engine & Automatic Transmission: 4-speed with lock up torque converter - A442F.
The gear ratios are: 1st 2.95:1, 2nd 1.53:1, 3rd 1:1, 4th .765:1, reverse 2.678:1
Looks to me like about 13-14% difference between the gearing of the top gears that you'll be using on the highway. Going from 33" to 35" tires is about a 5.7% difference, so while it would help, it won't get you down to where I'm revving with my auto.
How to determine your gear ratio:
What gear ratio do I have?
Jack up one tire if you have an open diff, or both tires if you have a working posi or locking differential. Rotate the tire one full revolution for posi’s and lockers and 2 full revolutions for open diffs. Carefully count the number of full revolutions the driveshaft makes. This is your gear ratio. In other words, if the drive shaft turns 3 ¾ turns, you probably have a 3.73 gear ratio. Turning the tire for twice the number of full revolutions and dividing the drive shaft revolutions by two will give you a more accurate reading.
Edit: added the H151F data, based on what Nick is seeing, I'd check your axle gear ratio cause there's about a 1000RPM variance that's unaccounted for here.
With a manual trans, unless your clutch is slipping the wind (or any other outside factor) CAN'T affect the RPM at a given speed. IP can't affect this either, it could cause the engine to not rev/run properly, but not what speed you're doing at a given RPM.
What size tires are you running again? You'd said 33's, right? What size specifically.
What about the t case? You have the part time case, does it not have a 1:1 ratio?
boozewz
SILVER Star
- Thread starter
- #195
Where can I check that @gnarlynick2072
I wouldn't have a clue. I'm dumb when it comes to t cases. lol!
@IanB could probably point you in the right direction... he's been on the ball in this thread so far.
I'm dumb on TC's as well, lol. That is a factor I hadn't considered though, how would @boozewz figure out what case he has? Paging TC gurus...
Well he definitely has the HF1A part time case. I'm not sure what the specs are though...
Was that info earlier in the thread? Isn't there also a part time case with PTO for 80's?
I just found the specs in the FSM... part-time case also has a 1:1 ratio... so no go there.
