Post by heyitsmike on Dec 30, 2018 17:29:48 GMT -5
Hello all,
We’re currently looking into the possibilities of adding “low range” to our 88 4x4.
We’ve taken ours out and have had a blast with it. Unfortunately, it’s downfall was the lack of torque and slow control over the more technical parts of the trail, which resulted in a clutch failure.
[a href="
(Neat video of my GF tearing it up 👍🏽
You can see the car start to struggle a bit towards the end on some of the bigger rocks)
Anyway, what the car lacks that other 4x4’s have is low range. So as a little pet project, and a slight exercise in the “just because i can” mentality, we’ve started looking into how to give the justy a bit more low speed grunt, ideally without loosing the ability to drive over the road.
As i see it this can happen in a few ways.
1. Smaller tires (yeah right what’s even the point)
2. Adding some sort of low transfer gear
3. Changing final gear ratios
4. Custom transmission gearing
Unlike a traditional 4x4 where you have power from the motor passed through the transmission, to a transfer case, then separately to the front and rear axles through driveshafts, the justy is a transverse motor and transmission setup with some interesting engineering taken into consideration.
Like other Subaru’s and and many other “all wheel drive” cars, the front differential is integrated into the transmission. In the case of the justy, it uses a power-take-off from the layshaft of the transmission to turn the rear driveshaft and subsequently the rear differential.
All this being the case, there isn’t really a “transfer” gear that directly transmits power to both axles. The “split” in power happens from the transmission directly. so in order to create some sort of low range without having to redesign the entire driveline setup, the change in gearing needs to happen before that point where it splits off the shaft in the transmission.
After researching some about this, i found out that other similar cars have done something like this; the Toyota Tercel 4x4 and the Honda Civic pt4wd. Both implemented an “extra low” first gear that was usable when 4wd was engaged.
My thoughts now, as a machinist by trade, And a mechanic by hobby, replacing the existing 1st gear with a custom made lower gear may be our easiest option.
In the meantime, I’ve found a spare donor justy that i can use for parts and essentially pull apart the transmission and do some investigating.
The existing 1st gear ratio is 3.071:1. I would like to bump it up to somewhere over 4:1, but as big of a takeup gear as i can fit in the case would be ideal, hopefully somewhere around 5:1.
I’ll be sure to update what i find here, for anyone who might be interested. I’ll also be able to share technical data and how or process was done in case anyone else has an interest in doing something similar in the future!
We’re currently looking into the possibilities of adding “low range” to our 88 4x4.
We’ve taken ours out and have had a blast with it. Unfortunately, it’s downfall was the lack of torque and slow control over the more technical parts of the trail, which resulted in a clutch failure.
[a href="
http://instagram.com/p/BaIRSw7Bb3U[/a]
(Neat video of my GF tearing it up 👍🏽
You can see the car start to struggle a bit towards the end on some of the bigger rocks)
Anyway, what the car lacks that other 4x4’s have is low range. So as a little pet project, and a slight exercise in the “just because i can” mentality, we’ve started looking into how to give the justy a bit more low speed grunt, ideally without loosing the ability to drive over the road.
As i see it this can happen in a few ways.
1. Smaller tires (yeah right what’s even the point)
2. Adding some sort of low transfer gear
3. Changing final gear ratios
4. Custom transmission gearing
Unlike a traditional 4x4 where you have power from the motor passed through the transmission, to a transfer case, then separately to the front and rear axles through driveshafts, the justy is a transverse motor and transmission setup with some interesting engineering taken into consideration.
Like other Subaru’s and and many other “all wheel drive” cars, the front differential is integrated into the transmission. In the case of the justy, it uses a power-take-off from the layshaft of the transmission to turn the rear driveshaft and subsequently the rear differential.
All this being the case, there isn’t really a “transfer” gear that directly transmits power to both axles. The “split” in power happens from the transmission directly. so in order to create some sort of low range without having to redesign the entire driveline setup, the change in gearing needs to happen before that point where it splits off the shaft in the transmission.
After researching some about this, i found out that other similar cars have done something like this; the Toyota Tercel 4x4 and the Honda Civic pt4wd. Both implemented an “extra low” first gear that was usable when 4wd was engaged.
My thoughts now, as a machinist by trade, And a mechanic by hobby, replacing the existing 1st gear with a custom made lower gear may be our easiest option.
In the meantime, I’ve found a spare donor justy that i can use for parts and essentially pull apart the transmission and do some investigating.
The existing 1st gear ratio is 3.071:1. I would like to bump it up to somewhere over 4:1, but as big of a takeup gear as i can fit in the case would be ideal, hopefully somewhere around 5:1.
I’ll be sure to update what i find here, for anyone who might be interested. I’ll also be able to share technical data and how or process was done in case anyone else has an interest in doing something similar in the future!