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Grabbed an iron front diff from a zr2 this weekend. Grabbing a rear also. Gonna swap them into my 01 non zr2. I’ll be running the 3.73s with the 235/75 tires. Hoping it’ll help a little with towing my seadoos over the summer. Anyone else running 3.73 gears and 235s.
or my other idea was into my truck and regearing to 4.56s and 6” lift with the 3” body lift and going with 33-35s
I have 3.73:1 gears in my non-ZR2 with 30 in. tires. I use it to tow 2,200 lbs of boat and trailer. It does feel it though.
With the tires larger than stock, my effective gear ratio is reduced to 3.59:1. I bet you should be fine towing your Seadoos with stock tires.and 3.73:1 gears.
Regarding the ZR2 axles, I thougIt they were all 4.11:1? Also, I'm not sure they will easily bolt up to a non-ZR2 frame. You'll want to check if I'm right or not. I was pretty sure the ZR2 Blazers had a wider front subframe or at least different control arms.
All that said, I'm sure the swap can be done. I think there was a member doing this to a 4 door Blazer.
Last edited by christine_208; Nov 27, 2023 at 03:20 AM.
I have 3.73:1 gears in my non-ZR2 with 30 in. tires. I use it to tow 2,200 lbs of boat and trailer. It does feel it though.
With the tires larger than stock, my effective gear ratio is reduced to 3.59:1. I bet you should be fine towing your Seadoos with stock tires.and 3.73:1 gears.
Regarding the ZR2 axles, I thougIt they were all 4.11:1? Also, I'm not sure they will easily bolt up to a non-ZR2 frame. You'll want to check if I'm right or not. I was pretty sure the ZR2 Blazers had a wider front subframe or at least different control arms.
All that said, I'm sure the swap can be done. I think there was a member doing this to a 4 door Blazer.
yes they will bolt right in no problem. I’ve done all that research. Just wondered to guys with 235/75 tires how the driving was with 3.73 gears. And no the zr2s did not have 4.11s. All were 3.73s.
Can confirm that the ZR2s came stock with 3.73 gears, and any different gears were custom options.
The rear axle and front diff will bolt right in place, although the front diff to CV connections were different 95-97 (bolt on style) vs 98-05 (splined plug in style). The CV axles are 2-3" longer on the ZR2s though, and are not compatible with a non-ZR2. Christine is correct that the ZR2s had different frame mounts for the control arms, moving the locations lower, and outboard to give the ZR2 higher & wider stance, necessitating the longer CV axles.
Keep in mind too that the ZR2 rear axle is 3" wider than the non-ZR2 4x4 axle. Swapping the ZR2 axle into a non-ZR2 truck will make the rear track about 1" wider than the front track width.
Last edited by El_Beautor; Nov 27, 2023 at 02:16 PM.
Reason: Clarification and spelling
Can confirm that the ZR2s came stock with 3.73 gears, and any different gears were custom options.
The rear axle and front diff will bolt right in place, although the front diff to CV connections were different 95-97 (bolt on style) vs 98-05 (splined plug in style). The CV axles are 2-3" longer on the ZR2s though, and are not compatible with a non-ZR2. Christine is correct that the ZR2s had different frame mounts for the control arms, moving the locations lower, and outboard to give the ZR2 higher & wider stance, necessitating the longer CV axles.
Keep in mind too that the ZR2 rear axle is 3" wider than the non-ZR2 4x4 axle. Swapping the ZR2 axle into a non-ZR2 truck will make the rear track about 1" wider than the front track width.
thank you for the info. Everything I already knew however. lol. But no one has actually answered the original question.
.. I’ll be running the 3.73s with the 235/75 tires. Hoping it’ll help a little with towing my Sea-Doos over the summer. Anyone else running 3.73 gears and 235s.
Regarding your question, I've been towing my 2,200 lbs of boat and trailer with 235/75R15s and then 30x9.5R15s and it has been fine. The lower gear ratio will make towing easier if also at the cost of lower mileage. As such, I'd guess you'd have no troubles towing a couple of Sea-Doos.
What I have done to help with the towing is add an oversized all aluminum radiator and an extra transmission cooler. I'd recommend at least the latter. I have the Hayden 699 which is the largest they make and has a thermal bypass to prevent overcooling. (It can get cold here in Idaho!) I added the cooling upgrades because I often find myself towing up some steep grades on hot days, e.g., 1,700' in 6 miles at 105'F. Depending on your situation, you should be fine. Just be sure to tow only in D and not Overdrive. If you tow in overdrive, you could overheat your transmission and burn out the 3/4 clutch pack. That was a lesson I learned the hard way.
BTW, I also got an OBDII gauge reader so that I could monitor the transmission fluid temperature. This confirmed that the extra cooler really did help.
I just wanted to share a little info with other ZR2 blazer owners.
-Driver side CV : NCV10207
-Passenger Side CV: NCV10206
When I first got my truck I was given the wrong ones multiple time. Regular blazer CV's will shred every time.
I hope this saves some of you a major head ache in the future.
Zr2 iron front diff
