That is a great question!
What I think I know (i.e. what the internet told me):
The axles are 26 spline and the weak link for the rear axle.
The axle shaft limit (working?) is 3575 ft /lbs.
The diff has a 6.9 inch ring gear with oem ratios that range between 4.3 and 5.6:1. The strongest gear set based on tooth count should be 4.62 with the fewest number on the pinion and ring for thicker teeth (8/37) but the diff is not the weakest point.
All the sidekicks, trackers, x90, samurai, etc use the same diff and axle shaft and housing size for the rear until 99 or so, with the sami having a greater offset diff(shorter and longer axle).
The tire size limit for offroading/crawling is 32-33 inches. I assume this is with a manual trans, locking diff, numerically higher ratio (more torque multiplication), and reasonable caution climbing boulders.
The ’87 tbi 2.8 v6 torque is 150@2400 compared to 94@3300 so about 47% more torque at the trans. However, the 700r4 first gear is 3.06 (3.06x5.13x150=2355ftlbs) where the tracker was 3.65x5.13x94=1760ftlbs for 25% more torque at the pinion.
To mitigate the 25% torque peak increase:
Curb weight should be less than the 4dr 4wd hard top version of 2,434 lbs. I’m expecting about 2300 lbs.
The 235-65-16s are 28 inches, hard compound.
I won’t be offroading or fitting slicks.
I have an automatic for reduced shock loads compared to a manual.
I have an open diff so the limited traction can act as a mechanical fuse.
Other options ranked by cost:
The center section swaps easily so for about $75, I could fit an automatic tracker 4.30 diff which should be stronger and reduced peak torque to the axles (3.06x4.3x150=1974) to an increase of just 11% off the line.
99 and newer vitara have larger 28 spline axles and an 8 inch diff (a 2.7l v6 is an option), but the axle is likely wider and the suspension is a 4 link so not a direct swap but it can be done cheap.
The early jeep CJ/DJ rear axle (dana 44) has the right bolt circle and width, comes in 3.07, 3.54, and 3.73 with a limited slip.
Any other axle for more fab/cost to narrow and drill to match the bolt circle.
Not so cheap is to replace the axle shafts with a more spring-like alloy such as 300m and cryo treat and/or rework
the housing for full floating axles so now the diff is the weak link.
There are also custom housings that fit larger everything.
The plan: I’m going to see how this goes and maybe swap to a 4.30 eventually for comparison.
I love this little digital inclinometer I bought on ebay for $10. It has a zeroing function that makes checking driveshaft angles very quick plus I can read it. Mine are set to 1.7 degrees on both ends, no trans shimming required.
I have a working shifter now to select all positions but fine tuning angles/arms for more dexterity in gear selection, then reinforcing the long shift arm for rigidity since I think it is slightly spongy/springy so when the detent in the trans is overcome, it unloads and tries to overshoot to the next gear position. I should have widened the tunnel a bit before because I have less room than is normal. I don’t think a lokar shifter would have fit without mods. EDIT: I just realized I didn't install the front bolt on the shifter base. That might help
Fan brkts made and mounted. It’s such a big, heavy fan I don’t want to use the zip rods through the condenser so it bolts on like the original and the brkts bolt to the fan with 1/4x2.75 bolts.
Zeroed in on the best position for the rad and made brkt blanks that still need to be fitted. There was only one good spot and angle for the rad to clear everything.
The speedo cable was fun. It uses the original s10 inner without modification. A couple feet of the zuki housing at the speedo end is used so it will fit the speedo. The s10 housing is cut down so the overall length remains the same. The housing ends are slightly different OD. ½ inch tube is split and squeezed around the housings just enough to grip and keep them aligned but not pinch the ID, then heat shrinked. There is a rubber oring that goes inside the zuki cable end that was cut down to fit with the s10 plastic end. Because the s10 cable is much shorter than the zuki cable, it runs through a floor grommet then up the inside to the cluster. When the zuki cable is cut for the housing, the firewall grommet is separated and fit with a ¼ bolt and washer to plug the cable hole and refitted to the firewall. The cable housing was cleaned with brake clean, then the cable lubed with high quality synthetic wheel bearing grease.
It turns out this speedo has a 2k output to the ecm like the s10 so I will have a vss input.
Since the cluster had to come out for the speedo, I pulled the tach to calibrate to a v6 input. I ordered some pots to find the right resistance and 30 ga solid jumper wire. No adjustment on the zuki tach.
The vertical brkt behind the grill would not clear the new fan so the upper end was cut off and a 1/8 strip was welded and bent to hug the back side of the grill then welded to the removable cross member. Grill mounting tabs were cut off the old and rewelded to the new removable cross member. Running out of room in the front for the trans cooler but I will probably hang it off the bottom of the removable cross member.
Ground the ferrules off the NOS ac hose and found the fittings are .570” od (14mm-ish). I ordered #10 ferrules and standard barrier hose along with a 180 bead lock due to the hose bend radius. Having to recurve the large hard line for clearance and best angle.
Some pics:
Login
Register
FAQ
Members
