93 locking axles swap to 97 FZJ80

[stvrn6]

Hello,
I parted out a 1993 FZJ80 with a blown engine and decided to buy a dirt cheap 97 that I have built up so I basically got a set of locking axles, wiring harness and locker ecu for free. I have had them sitting out for a while but today I finally took the truck out to hit some trails for the first time in Calico California and let me tell you. I FELL IN LOVE!
I'm on 315s and the truck did not struggle one bit, but there was a trail I wanted to hit but I was told I would need lockers or someone to winch me, so I'm going to swap them in now.
The 93s have probably around 400k miles and no history of maintenance. what should i do before installing? Was going to regear to 4.88s but not in a rush for that. been driving the truck on stock gears on 315s, fully loaded and its been alright, some struggles on steep hills but no rush to regear.
So is there any tips for doing this swap?
What should i change on the axles while they are out?
is there any concern for how high the mileage is?
and finally what would a set of non locking 97 axles with 210k miles and no rust be worth? since ill end up selling them after the swap.
*pics of my truck today and the 97 F/R axles for reference. *
Thank you guys in advance!

 

[Rusty Marlin]

On the fronts, rebuild the knuckles, check the spindles for uneaven wear. Might as well pull the thirds and change the pinion seals. Check the ring and pinion for back lash and end play, adjust as needed per FSM.
I put 4:88's in mine and I'm only on 33's. Amazing slow control off-road and makes a huge differance hauling trailers.
There is a spray dye penatrant that welders use, you might want to use on all the welded flanges, to check for cracks around them. Cheap insurance.

 

[Broski]

IMO at 400k on them you should just do the gears now with a new install kit that way everything gets a refresh. If there the originals the birdfield are going to need to be replacedede, I would hate to do a knuckle rebuild only to find the burfield's clicking.
You need to check the drive flanges for ware as well as the spindles, the rear one's are not replaceable so pay close attention to those.
New axle seals front & rear
If it was me I would replace all knuckle/drive flange hardware to include cone washers.
As Rusty Marlin suggested check for cracks especially around the front control arm mounts.

A built locked 80 becomes a almost unstoppable beast my guess it was some jeep guys that said you couldn't make the trail not many tuff Trails in Calico.

Your axle look clean probably $1200 to 1500 for the set.

 

[Kabanstva]

On the fronts, rebuild the knuckles, check the spindles for uneaven wear. Might as well pull the thirds and change the pinion seals. Check the ring and pinion for back lash and end play, adjust as needed per FSM.
I put 4:88's in mine and I'm only on 33's. Amazing slow control off-road and makes a huge differance hauling trailers.
There is a spray dye penatrant that welders use, you might want to use on all the welded flanges, to check for cracks around them. Cheap insurance.

Do you do alot of high way driving with 33s and 4.88s? I’m curious how you like that type of gearing going 70mph+?

 

[Rusty Marlin]

The Roll-on torque is incredible.
I typically limit myself to 65-68MPH on highway, but if I need to get around someone, 65-80 is quick.
Around town I get 11.8-12.8 MPG on any given tank.
Cruising around the country side at 55-60 I get 12.5 to 13.5 and if I'm on the hywy at 65 to 70 I get high 13's to low 14's.
Hauling a trailer gets me down around 10-12, but the rig easily pulls out into traffic and gets out of its own way. On stock gearing hauling a trailer was a terrible and terrifying experience. Could hardly climb a grade in the NC mountains. Now it gallops up the same slopes and doesn't feel underpowered.

 

[stvrn6]

On the fronts, rebuild the knuckles, check the spindles for uneaven wear. Might as well pull the thirds and change the pinion seals. Check the ring and pinion for back lash and end play, adjust as needed per FSM.
I put 4:88's in mine and I'm only on 33's. Amazing slow control off-road and makes a huge differance hauling trailers.
There is a spray dye penatrant that welders use, you might want to use on all the welded flanges, to check for cracks around them. Cheap insurance.

what rpm do you sit at highway driving?

 

[stvrn6]

IMO at 400k on them you should just do the gears now with a new install kit that way everything gets a refresh. If there the originals the birdfield are going to need to be replacedede, I would hate to do a knuckle rebuild only to find the burfield's clicking.
You need to check the drive flanges for ware as well as the spindles, the rear one's are not replaceable so pay close attention to those.
New axle seals front & rear
If it was me I would replace all knuckle/drive flange hardware to include cone washers.
As Rusty Marlin suggested check for cracks especially around the front control arm mounts.

A built locked 80 becomes a almost unstoppable beast my guess it was some jeep guys that said you couldn't make the trail not many tuff Trails in Calico.

Your axle look clean probably $1200 to 1500 for the set.

Damn good point i might just have full regear and service done. and thanks for the pricing!

 

[Rusty Marlin]

what rpm do you sit at highway driving?

I want to say 2k at 55 50 and 2400K at 60 and ~2900k at 70. (looked on the way home) I noticed a while ago that the tach and speedo needle run parallel to each other in top gear.
And yes, those are correct values on the speedo. I have a Lutz Auto speedo correction device and it's tuned to GPS speed.

 

[Rusty Marlin]

I want to say 2k at 55 and 3K at 70. I noticed a while ago that the tach and speedo needle run parralle to each other in top gear.
And yes, those are correct values on the speedo. I have a Landcruiser 70/80/100/105 & LX450/LX470 Speedometer Calibrator/Correction Device | Lutz Auto - https://www.lutzauto.com/product-page/80-series-landcruiser-lx450-speedometer-calibrator and it's tuned to GPS speed.

 

[smritte]

I run the same setup. 4.88 and 33's. ~2600 rpm @ 65mph (same speedo calibrator). 4.10-4.88 I went up about 500 rpm. Put it just over stock rpm, right in the sweet spot of the power band. Last weekend was the first long trip since install. 2200# trailer and I think I actually picked up 1ish mpg towing. Haven't calculated non towing yet, just got the gears broken in.