ZR2 rear axle upgrade.

JaVeRo · Post by **JaVeRo** » Sat Jan 26, 2008 12:28 pm

If you knew you had to replace your rear axle and had the money to do it right, what would want to do?

Rebuild the old alxe with new bearings and a locker of some sort?

Replace with a new GM axle of the same type as stock?

Replace with a 10 bolt 8.5 modified to fit the width you want?

Replace with a Dana axle to have more options available for a new locker?

From my limited knowledge right now, I am leaning toward a Dana axle with a Detroit (Eaton) Electrac locker and use the brakes from the old axle.

I don't know yet that I need to do this and I don't know that I will have the money to do it "my way" if I do. I'm just curious what others would do if they could.

James

Post by **HenryJ** » Sat Jan 26, 2008 12:51 pm

I would go with a rear from ZR2. The 8.5" rear is wider to match the track of the front without spacers. Disc brakes and ABS sensor to match the braking system. Good availability of parts. Eaton G80 gov-loc and gears to match mine. Lots of aftermarket support. Requires less horsepower to operate than other options, other than stock.
You would lose some ground clearance due to the larger center section. That may be a good reason to stick with the stock 7.625" diff. I have invested in a good cover, rotors and pads for that rear end, so I am in no hurry to switch.

gocntry · Post by **gocntry** » Sat Jan 26, 2008 12:57 pm

JaVeRo wrote:If you knew you had to replace your rear axle and had the money to do it right, what would want to do?

Rebuild the old alxe with new bearings and a locker of some sort?

Replace with a new GM axle of the same type as stock?

I Would Think Buying A New Axle Would Be A Huge Cost, If The Old Housing Is Still Good Just Replacing The Worn Parts Would Be A Better Way To Go

JaVeRo wrote: Replace with a 10 bolt 8.5 modified to fit the width you want?

I Have One Of Those Waiting To Go In My Truck, I'm Not Gonna Modify The Width And It's Supposed To Be A Bolt In. I Know I checked The Part Numbers For The Brake Pads And Such And It Uses The Same Parts As My Current 7.6" Axle.

JaVeRo wrote:Replace with a Dana axle to have more options available for a new locker?

Only If Your Gonna Put A Dana Up Front Too

F9K9 · Post by **F9K9** » Sat Jan 26, 2008 2:05 pm

It really depends on your long range goals on your rig. If, you don't have SFA plans then do as Brule suggests.
I was going to go with the ZR2 rear axle but, am going to wait and do everything at once when my extended warranty expires in May '09. I have it scheduled into a shop of a ZR2USA.com member in NC. I am currently taking my time shopping for a HP D44 for the front and a Ford 9" .

1TFROT wrote:...............'77-79 f150/bronco

or f250 of the same years will get you 8 lug and a D60 rear instead of the 9"

both sets can be found pretty cheap. my D44 was $75 and the 9" was the same price. bought them separately.

'77 is the ideal year for the D44 so the wedges are welded on (easier to get rid of) the '79s have cast wedges and are a bitch to work around.

JaVeRo · Post by **JaVeRo** » Sat Jan 26, 2008 2:58 pm

My goals are simply to get the rear wheels at the same width as the front, get a better axle, and get a better locker.

I am not planning on a lift kit or a solid front axle.

I like the idea of the Electrac but it is only made for the Dana axles and since Eaton bought out Detroit, It doesn't look like they will be expanding the product line any.

Brule brought up a good point, I didn't know the zr2 was an 8.5/8.6 axle and 3" wider. I just thought they used different backspacing on the wheels.

James

F9K9 · Post by **F9K9** » Sat Jan 26, 2008 3:09 pm

JaVeRo wrote:..............I like the idea of the Electrac but it is only made for the Dana axles and since Eaton bought out Detroit, It doesn't look like they will be expanding the product line any.........

I've not seen many people have good about things to say about electric lockers but, I run in a small circle. I have seen one or two lockers for the 7.6 but, not much else. I don't even know if, I could find it again. Not much help, sorry.

Post by **HenryJ** » Sat Jan 26, 2008 3:14 pm

Do you need more than the G80 will provide? If your trucks sees more than 80% offroad there are better ways to go. If the reverse is true, the G80 is really a good way to go.
If you really need locked and have an extra $1000 to spend we can give you some recommendations.

drperry · Post by **drperry** » Sat Jan 26, 2008 4:43 pm

There's a fair amount of lockers out for the 8.5" thankfully...

If you can't find a ZR2 rear axle, then the rear from any 5-speed S-series should be the 8.5" and you can get a set of 1.25" spacers.

F9K9 · Post by **F9K9** » Sat Jan 26, 2008 4:48 pm

drperry wrote:.........then the rear from any 5-speed S-series should be the 8.5" and you can get a set of 1.25" spacers.

Are you sure of this? This is the first that I have heard this but, you may be absolutely correct.

JaVeRo · Post by **JaVeRo** » Sat Jan 26, 2008 10:08 pm

HenryJ wrote:Do you need more than the G80 will provide? If your trucks sees more than 80% offroad there are better ways to go. If the reverse is true, the G80 is really a good way to go.
If you really need locked and have an extra $1000 to spend we can give you some recommendations.

My wife runs a 115 mile mail route with about 30-40 miles being dirt roads, some of them sand, others are slick red clay. Many of the road are narrow enough that you have to find a wide spot to pull over when you meet someone. On many occasions she has had to pull someone out of the ditch just to get past them. Usually oilfield workers driving 3/4 or one ton trucks. They tell her that her truck won't pull them, she just tells them to hook it up and lets go. It has been a wet winter.

So far the G80 locker has held up good. Her truck has 142,000 miles on it now, hoping to get 200k. I bought a 2002 crew that is the same color. After her truck is worn out, I can pull the axle and put it in the next one. Then I will have a complete parts truck with fenders, doors and all.

Being able to push a button and know the axle is locked would be a real advantage. The 2002 she will be using next is kinda finicky about locking up. Something just ain't right.

I'm all ears on any recommendations.

James

drperry · Post by **drperry** » Sat Jan 26, 2008 10:34 pm

f9k9 wrote:
drperry wrote:.........then the rear from any 5-speed S-series should be the 8.5" and you can get a set of 1.25" spacers.
Are you sure of this? This is the first that I have heard this but, you may be absolutely correct.

99% sure on it... There might be a few that didn't get it... But most did.

As far as I know, all 5-speed Blazer's got them, anyway... And the 5-speed 4x4's got the iron front diff.

There's a few fleet 4 door Blazer's that have the 8.5" axle as well...

I can't remember what RPO code it is, though...

F9K9 · Post by **F9K9** » Sat Jan 26, 2008 11:44 pm

drperry wrote:..........99% sure on it... There might be a few that didn't get it... But most did.

As far as I know, all 5-speed Blazer's got them, anyway... And the 5-speed 4x4's got the iron front diff.

There's a few fleet 4 door Blazer's that have the 8.5" axle as well...

I can't remember what RPO code it is, though...

I am still a little shady on this. Maybe Miles will chime in.

drperry · Post by **drperry** » Sun Jan 27, 2008 2:57 am

So long as it's 5-speed, it should have the 8.5" and 3-button 4x4 gives you the iron front diff

ZR2 or not.

If it doesn't it's a factory freak

The Iron Front Diff Poll on ZR2 USA should help out

F9K9 · Post by **F9K9** » Sun Jan 27, 2008 5:43 am

drperry wrote:So long as it's 5-speed, it should have the 8.5" and 3-button 4x4 gives you the iron front diff ...............

I am familiar with Jeremy's research on the cast iron front differential. Perhaps if, you had stated that any 5 speed "4WD" S/T series was an 8.5 or 8.6" rear diff, I might not have been confused. I'll go over the thread again and see where I may have gone astray

Thanks for info.

Post by **HenryJ** » Sun Jan 27, 2008 6:14 am

Probably need to clarify that these are second gen. First gen may not have the 8.5" rear. My '86 Sport did not.

drperry · Post by **drperry** » Sun Jan 27, 2008 6:17 am

Oops! Forgot about that...

It is indeed for second gen... 1st gens only got the 7.5" and later on the 7.625" (same casing)

99+ trucks got the 8.625" apparently... Same casing, slightly larger bearings, IIRC. Either way, it should be stamped on the axle somewhere

killian96ss · Post by **killian96ss** » Sun Jan 27, 2008 7:20 am

I would get a ZR2 axle and a detroit Locker or True Trac.

The 5 speed 4x4's got the larger rear axle and iron front diff because of "shock loading" from clutch engagement which is harder on parts that the automatic trannies.

Steve

drperry · Post by **drperry** » Sun Jan 27, 2008 8:27 am

Or, if you can't find a ZR2 axle... One from a 5-speed S-series and 1.25" wheel spacers for it

F9K9 · Post by **F9K9** » Sun Jan 27, 2008 10:28 am

I learn something new every day. Thanks!

JaVeRo · Post by **JaVeRo** » Sun Jan 27, 2008 11:17 am

Thanks for the input fella's. Hopefully next weekend I will have time to pull the differential cover and see what it looks like.

James

F9K9 · Post by **F9K9** » Sun Jan 27, 2008 2:35 pm

I think we need to address the original problem. What is the reason that you seek an alternative? No locker at all? Something is amiss when you want to pull the diff cover for a " Look-see"!

drperry · Post by **drperry** » Sun Jan 27, 2008 2:38 pm

Also, unless you wanna have to carry two spares, you're not gonna want to switch to the dana axle

F9K9 · Post by **F9K9** » Sun Jan 27, 2008 3:22 pm

drperry wrote:Also, unless you wanna have to carry two spares, you're not gonna want to switch to the dana axle

Wait a second here. Maybe, I misunderstood you again. I wheel with junk on D44s, D60s and a bunch of different axles. I witnessed a 3/4 ton 44 (with a Moser alloy Dana 44 MAX Front axle) go to hades this spring. I towed him out with a Lincoln locked Chrysler rear 8.25". Extra axles should be a requirement for any serious trail rig!

drperry · Post by **drperry** » Sun Jan 27, 2008 3:56 pm

I meant spare tires, lol.

The Dana's will have a different bolt pattern. Unless they have a 5x4 3/4" option, which I don't think they do...

JaVeRo · Post by **JaVeRo** » Sun Jan 27, 2008 4:29 pm

f9k9 wrote:I think we need to address the original problem. What is the reason that you seek an alternative? No locker at all? Something is amiss when you want to pull the diff cover for a " Look-see"!

I guess I should explain myself a little better. The 2001 rear axle seems to be doing good but has 140k miles on it. The 2002 I bought used a few months ago only has 65k miles on it but has a grinding or growling noise coming from it. It sounded like a dry bearing on a hay baler. I thought it would be the parking brake shoes wore down to metal and be an easy fix. It also had a leaking intake gasket but that is a whole nuther story. I don't like buying used but they don't make the S10 any more and the colorado is wider. Wide is not good on the mail route.

The disk brakes were fine. I checked the parking brake shoes. They were a little rusty on the drum from not being driven but not metal to metal. I cleaned them up but it made no difference. I put the truck up on jack stands and put it in drive trying to trace the source of the noise. With the engine running and exhaust flowing I could still hear it but couldn't find the source. At this point I also noticed once that only one wheel was spinning. That is the basis of thinking the locker is not working. I pulled the driveshaft and the noise went away. The tailshaft bushing looked to be worn on the lower side so I replace it and the seal. After putting it all back together, the noise was still there.

My next step is to pull the parking brake shoes off and try it again. If the noise is still there I plan to pull the rear cover and check for metal shavings. I have never been inside a G80 before but if I can pull the c-clips and then pull the axles, I will check the wheel bearings. From this point I can pull the driveshaft again and should be able to trace down any bad bearings by feel (I hope).

My thinking on my original post is that if it has carrier bearing going out and the locker is bad, I might be better off getting another axle. If I get another axle, I would like to have the track width the same as the front and have a locker that locks solid at the flip of a switch.

Sorry to be so long winded but that is my logic so far.
If you have an easier way of tracing down a bad bearing, I'm open to any and all suggestions.

If I do get a better locker, I considered putting that axle in my wife's 2001 and putting her axle in mine until her truck is retired. Then I would put it in the 02 and she can wear it out.

ICBW MWSIUA
James

drperry · Post by **drperry** » Sun Jan 27, 2008 4:50 pm

Yeah, there's not much in t the way of lockers for the 7.5"

A ZR2 axle, or a regular s-series 8.5" with wheel spacers is the way to go for you, then.

A non-ZR2 axle is probably easier to find...

Actually a ZR2 axle will put the rear wheels a touch wider than the fronts, lol... I can't remember by how much, though.

gocntry · Post by **gocntry** » Mon Jan 28, 2008 4:00 am

drperry wrote:Actually a ZR2 axle will put the rear wheels a touch wider than the fronts, lol... I can't remember by how much, though.

I Believe The 8.5" Zr2 Axle I Have Is 4" Wider Than My Stock 7.6" Axle

okie s10 · Post by **okie s10** » Sat Feb 16, 2008 11:07 pm

So a ZR2 rear will lay right up in a CC? Spring perchs in the same place? Reason I ask, I got a line on one of these rears and if it works out, it will be very resonable(almost cheap). It's a good rear but I didn't know what all was involved in the swap. Need some input guys.

drperry · Post by **drperry** » Sun Feb 17, 2008 1:43 am

Take some measurements to make sure the perches line up just right.

I can't remember if it's a direct bolt in or not... Should be, but always nice to double check.

okie s10 · Post by **okie s10** » Sun Feb 17, 2008 2:46 pm

Well DUH! Am I stupid or what? Gonna measure anyway, but it just dawned on me with ZR2 frame 4" wider than other S10's, odds are the springs are out a little further on the rear. Won't be able to do the mearsure for a couple of days, anybody know right off hand?

F9K9 · Post by **F9K9** » Sun Feb 17, 2008 3:29 pm

okie s10 wrote:Well DUH! Am I stupid or what? Gonna measure anyway, but it just dawned on me with ZR2 frame 4" wider than other S10's, odds are the springs are out a little further on the rear. Won't be able to do the mearsure for a couple of days, anybody know right off hand?

I don't think that the frame is that much wider at the rear. You can poke around here. It hurts my head every time I try to find the differences!

Post by **HenryJ** » Sun Feb 17, 2008 3:36 pm

okie s10 wrote:... it just dawned on me with ZR2 frame 4" wider than other S10's

Actually the frame is the same width. I can not say that for the mounting points though.

killian96ss · Post by **killian96ss** » Sun Feb 17, 2008 4:16 pm

I can measure the distance between spring perches on my Z this evening and post the #'s if it will help any.

Steve

roadrunner · Post by **roadrunner** » Sun Feb 17, 2008 4:41 pm

Just a little off topic but is the rear track on my stock CC (01) narrower than the front? If so, how much and would it handle better in mud/snow if it matched the front?

Post by **HenryJ** » Sun Feb 17, 2008 4:59 pm

roadrunner wrote:Just a little off topic but is the rear track on my stock CC (01) narrower than the front? If so, how much and would it handle better in mud/snow if it matched the front?

Stock specs from our website
2.1 inches narrower in the rear. There are many suggestions as for why. I think it handles just fine stock. Adding a wider rear makes up for the odd look we have with the Isuzu fender bulge. This really magnifies the difference.

roadrunner · Post by **roadrunner** » Sun Feb 17, 2008 5:13 pm

HenryJ wrote:
roadrunner wrote:Just a little off topic but is the rear track on my stock CC (01) narrower than the front? If so, how much and would it handle better in mud/snow if it matched the front?
Stock specs from our website
2.1 inches narrower in the rear. There are many suggestions as for why. I think it handles just fine stock. Adding a wider rear makes up for the odd look we have with the Isuzu fender bulge. This really magnifies the difference.

Reason I asked is I have to travel a lot in severly rutted roads when muddy and the rear axle seems to want to "hunt" all the time. Rather a driveability problem not to mention feeling like you're getting beat back and forth in the cab when you're trying to hold it in a single track on one side and out of another on the other. Most 4x4's in this area are full size and they leave a wider track than I do with my CC. An advantage when the ruts get really deep since I can keep one side "up" and one in the track. And no you can't just straddle the ruts cause it's too slick and you'll just end up in them anyway. Isuzu fender bulge???

killian96ss · Post by **killian96ss** » Sun Feb 17, 2008 5:19 pm

roadrunner wrote:Isuzu fender bulge???

S10 Crew Cabs have Isuzu beds.

I have no idea why GM did this.

Maybe because they partially own Isuzu and the parts were available which saved them money?

The rear door handles use the same GM thinking.

Steve

Post by **HenryJ** » Sun Feb 17, 2008 5:21 pm

You might get away with adding spacers to widen it out closer to the fullsize. I don't know the difference there.

Our bed came from the South American Isuzu Crew Cab. The faux flare was added to make it look like the S-series bed. Check out an Hombre next time you see one. It has the same Isuzu fender bulge on the rear fenders.

roadrunner · Post by **roadrunner** » Sun Feb 17, 2008 5:24 pm

killian96ss wrote:
roadrunner wrote:Isuzu fender bulge???
S10 Crew Cabs have Isuzu beds.

I have no idea why GM did this.

Maybe because they partially own Isuzu and the parts were available which saved them money?

The rear door handles use the same GM thinking.

Steve

Which Isuzu model do they match up to?

Probably the usual reason to do it $$$$$$$$$. Main reason any of the makers do things.

drperry · Post by **drperry** » Sun Feb 17, 2008 6:38 pm

HenryJ wrote:You might get away with adding spacers to widen it out closer to the fullsize. I don't know the difference there.

Our bed came from the South American Isuzu Crew Cab. The faux flare was added to make it look like the S-series bed. Check out an Hombre next time you see one. It has the same Isuzu fender bulge on the rear fenders.

From what I've read, for non-crew S-10 4x4's 1.25" puts the front and rear almost equal... Close enough that you'll only be able to tell by measuring, or knowing exactly what to look for...

The crews should be the same...

roadrunner · Post by **roadrunner** » Sun Feb 17, 2008 6:47 pm

Where and what size spacers are available and do I need longer wheel studs to use them?

Post by **HenryJ** » Sun Feb 17, 2008 6:51 pm

roadrunner wrote:Where and what size spacers are available and do I need longer wheel studs to use them?

Have you seen the sticky?

roadrunner · Post by **roadrunner** » Sun Feb 17, 2008 6:59 pm

Thanks HJ. No but I will now.

quickbiker · Post by **quickbiker** » Mon Feb 18, 2008 9:08 pm

When I had my stock 7.5, I put a Detroit in it, and it worked great, but then I went to 35's and didn't want to chance it, so I got an Isuzu D44 rear now. The 7.5 did great for me while I had it, and I ran 31's on them for a long time. Detroits are a bit radical, but I like them and run a detroit in my D44 also. There is nothing tougher. But there are some posi's for 7.5's also out there.

okie s10 · Post by **okie s10** » Wed Apr 02, 2008 8:53 pm

Just finished last week the install of a ZR2 rearend under my CC. Was a snap, except for those darn ubolts. Those puppies were rusted on tight and needed a good long cheater bar on the ratchet. Everything lined up just like it was made there, brake lines and all. 1'5" spacers on front and almost perfect widthwise.

green02crew · Post by **green02crew** » Thu Apr 03, 2008 8:36 am

Pictures of it would be nice!

F9K9 · Post by **F9K9** » Thu Apr 03, 2008 3:33 pm

okie s10 wrote:Just finished last week the install of a ZR2 rearend under my CC. Was a snap, except for those darn ubolts. Those puppies were rusted on tight and needed a good long cheater bar on the ratchet................

Soaking fasteners daily, for a week or longer, with PB Blaster or Sea Foam Deep Creep helps with those rusted puppies. Anytime I am preparing for a mod I use that Heep advice.

04crewvt · Post by **04crewvt** » Thu Apr 03, 2008 4:38 pm

Gee I just break them off and replace with new ones and use anti-seize.

gocntry · Post by **gocntry** » Thu May 15, 2008 10:35 am

okie s10 wrote:Just finished last week the install of a ZR2 rearend under my CC. Was a snap, except for those darn ubolts. Everything lined up just like it was made there, brake lines and all. 1'5" spacers on front and almost perfect widthwise.

Okie , Did The Factory U-Bolts Work? Axle Tubes The Same Size? And Did The Driveshaft Bolt Right Up Or Did You Need Different (pinion?) For The Zr-2 Rear??

Thanks

green02crew · Post by **green02crew** » Thu May 15, 2008 6:38 pm

I'm still waiting on the pictures!

okie s10 · Post by **okie s10** » Wed May 21, 2008 7:08 pm

Sorry for delay, been out of town. Yes, factory u-bolts worked. Tubes are same size as our stock CC. Only thing different with the Zr2 unit is extra width. All brake cables hooked right up as did driveshaft. But did have to get a different u-joint from pinion to shaft. Got it at local parts store. Didn't make any pics when doing this, never thought about it but it was an easy swap. Unhook driveshaft, brake lines, u-bolts, un hook rear shackles and drop the rear of the springs. Remove stock rear and replace with new unit and bolt everything back up.

F9K9 · Post by **F9K9** » Wed May 21, 2008 8:30 pm

Sounds great. I assume that you will take a few moments to take pics next mod if, you have a digital camera. I have been guilty myself but, photos help new members or potential wrenchers that are afraid of a mod that might sit well with others.

gocntry · Post by **gocntry** » Thu May 22, 2008 3:57 am

okie s10 wrote:But did have to get a different u-joint from pinion to shaft.

Thanks For The Update, Do You Have A Part # For The U-Joint? Or Did You Just Get A U-Joint For A Zr2 Model Instead Of A Standard Model?

My Rear Is Out Of An Older Zr2 It's A '98 I Believe. I Don't Know If This Would Make A Difference Or Not?

Thanks Again

gocntry · Post by **gocntry** » Fri May 23, 2008 12:38 pm

Ok After Some Snooping Around I Came Up With The Following From Autozone's Books.....

Standard S-10 U-Joint: Part #2-3011 Saginaw 44 Type

ZR2 S-10 U-Joint: Part #2-0053 Spicer 1350 Type

So You Either Need A Different Yoke For The Rear End - Switch Driveshafts Or A Hybrid U-Joint

Part# 2-1153 Seems To Be The U-Joint # It's An S44/1350 Conversion It's 1 Part 2-3011 And 1 Part 2-0053 So It Should Work.

The Book Does Not Recommend This U-Joint For An Aluminum Driveshaft Though, Reason Is It Does Not Have The Factory Coating To Resist Corrosion Between The Aluminum And Steel Surfaces.

I'm Guessing By Applying My Own Coating This Should Work As Well As The Factory Coating?

Post by **HenryJ** » Thu Jan 21, 2010 9:37 pm

Bringing this one back from the dead.

My research shows that the U-joint is the same. I have yet to confirm this is indeed the case. Tomorrow I will compare my 2001 S-10 to the axle assembly from a 2003 ZR2.

I am going to tear my truck down in the morning. I have had a very worrisome whine in the rear axle for a little over a week. It is loudest while coasting. Almost gone under acceleration or deceleration. I suspect either pinion or carrier bearings. It could as easily be axle bearings. Maybe just a loose pinion.

I am in a bit of a pickle here.

I have invested in the stock axle. It has a truss cover and 3" spacers. I hate to lose those.
If the repairs are not too expensive or extensive, common sense says fix it and move on. My axle has 88k miles on it now. I should have twice that before any major work is needed. The little 7.625" axle offers better ground clearance, but is known to be a bit flexy. I have had no trouble with the same axle on my old S-10.

ZR2 axle assemblies are readily available now. There are three here locally. They are a good improvement in durability. One inch larger ring gear, bigger bearings, better aftermarket support.
I have lined up a 2003 ZR2 axle assembly with 71k miles for inspection. Just in case I do need it. The problem with installing a used axle, besides the extra cost, is that it may not be far from needing repairs too. I would probably need a set of 1.25" spacers to match the front. All together a pretty expensive option.

I am torn. Do I abandon ship and install the ZR2 axle? Do I repair and stay with the stocker?

If the stock rear end needs axles and bearings, that could easily exceed $600. The ZR2 axle is $500 , but it too may need $100 worth of parts to put it in good shape. Given that scenario, the answer is easy. Upgrade.
The hard part is when to say when. Wheel bearings and seals are less than $50. If that is all the stock axle needs. Do I invest $100 in it? Do I cut my losses and go bigger now.

I guess the morning will offer more light on the subject. Tear it down and see what it reveals.

F9K9 · Post by **F9K9** » Fri Jan 22, 2010 3:59 am

What about gear ratios? I thought ZR2s had 4.10s.

Post by **HenryJ** » Fri Jan 22, 2010 5:48 am

Nope, the ZR2 is 3.73 just like mine.
The older first gen Sport and Baja packages received the 4.10 ratio in the 7.5" differential.

green02crew · Post by **green02crew** » Fri Jan 22, 2010 9:03 am

All I have invested in mine is a set of spacers. When mine goes, I have every intention to put a zr2 rear end in it. Why not go larger and stronger?

Post by **HenryJ** » Fri Jan 22, 2010 9:10 am

green02crew wrote:Why not go larger and stronger?

Exactly my problem.
I tore my stock axle down and it all looks good. Very good. The pinion was loose. I see a shiny crush sleeve. That may mean that it has been loose. Perhaps not torqued enough from the factory?
Less than $50 to put all the parts in to fix it right. New seals and bearings. Axles are good, gears good.

I think it will hinge on the condition of the ZR2 axle.

I am tempted to swap. However , if I were making recommendations for someone else, or a customer. I would probably just fix what I have. Do I really need a bigger axle?

Post by **HenryJ** » Fri Jan 22, 2010 9:23 am

UPDATE: I found the reason for the loose pinion. The shim is crushed and broken.

: shim.JPG (91.18 KiB) Viewed 32065 times

That tips the scale to the side of the ZR2 upgrade.

Post by **HenryJ** » Fri Jan 22, 2010 1:11 pm

Only eight nuts to remove from the point I was at , so here it sits:

: rearup.jpg (102.07 KiB) Viewed 32065 times

I will see what the ZR2 axle looks like this afternoon and make the decision.

Post by **HenryJ** » Sat Jan 23, 2010 12:28 am

The ZR2 axle did not look the best. After rotating it, I had doubts. I pulled the cover at the yard and took a look /feel. It seemed ok. It was very dirty and muddy. The brakes horribly rusted. It took quite a while to strip it down and clean it up. The axles looked really good. They are significantly stronger.

Nearly half an inch larger in diameter the splined end is as big as the bearing surface on the 7.625" axle. A full two inches longer.

One wheel seal was leaking so it received new axle seals. I found it easier to install the rear axle assembly the same way that I took the old axle housing out. From the inside with the springs attached. Slip one side up and over the spring. Slide it over and lift the other side up and over.

Once in place and the U-bolts tight I slid the brake backing plates into place. they are a direct swap. The left side cable is a little tight at full droop, but it makes it.

The U-joint is indeed the same. The driveshaft bolted right up with no modifications. The brake lines are not the same. The right side rubber line from the caliper must be changed and both steel lines, as they are longer. The left side caliper hose will interchange and worked just fine.

it is all in and going. The ZR2 axle assembly is 63" mounting surface to mounting surface.

Total cost= $509

What did I learn? Get a friend to help lift the axle assembly into the parts washer. My arms are fried. Take out the fill plug before you install the axle assembly. This one was seized and I came close to the old drill and tap. Heat and quench, beat and heat. it finally broke loose.

The trip home felt smooth and quiet. I guess all that slack has been there for a while. It sort of snuck up on me. It is noticeably tighter now.

F9K9 · Post by **F9K9** » Sat Jan 23, 2010 6:18 am

Lots of good info there, Brule. Needs to go into the mods section with a short write up.

Post by **HenryJ** » Sat Jan 23, 2010 8:43 am

I'll keep that in mind. We still need to get the website pages moved and translated. I might do something after that.
It took all day to do the swap. That included cleaning up the old differential and parts as well as a five hour wait for the ZR2 axle to arrive.
I would estimate the swap took about 10 hours with all the careful clean-up and a couple parts runs. I am sure if you have ducks that float, it would go faster. It seemed that every time I turned around I had yet another problem.
Knowing what I do now, I am sure it would go faster.

I was a little disappointed to see the condition of the 2003 axle. somehow I just imagined that it would look better. The internals were good, but the last seven years were not kind to it. My axle was in much better condition.
I guess the availability is better, but the condition is deteriorating rapidly. A good thing is that with the abundance of them now available, prices are coming down. I saw prices ranging from $250-$750. I probably could have played watch and wait to get a better price and perhaps better condition, but I was in a bind and needed to get this done on a schedule.

I would say if this swap is in your future , by you I mean anyone, find the ZR2 axle. Time will not be your friend now.

Post by **HenryJ** » Sun Jan 24, 2010 2:29 pm

I am running 33" BFG TAKO tires on the ZR5 wheels. I did a little measuring today. The rear tread width side to side is 66" outside lug to out side lug. No adapters or spacers on the rear at this time.
I have 1.25" wheel adapter / spacers on the front. The width there measured 67".

To get things back to where I had it , I need to add some 1" spacers to the rear. It just looks better to me with the rear slightly wider. That evens out those Isuzu fender bulges.

s10 again · Post by **s10 again** » Sat Jan 30, 2010 4:13 pm

Tax money is in so now Monday I get to try to find a zr2 rear.

So now that I'm ready I'm Going to try my local JY and see how much a complete zr2 axle will cost me. They told me 850.00 a couple of weeks ago i'm guessing that was stripped. But now I want to see if they can get one with the following. Panhard bracket for brake line(thanks HJ),uncut parking brake cables,both calipers,Both rotors. Is there anything else needed to make this a bolt in deal? I have had people tell me not to reuse u-bolts but I have a few times and never had issue. What you guys think?

I will pop the cover and inspect as well as replace lube. Is there something that could safely be used to flush out the diff or should I even mess with it other than lube change?

Does that cover it or have I missed something.

Chris.

Post by **HenryJ** » Sat Jan 30, 2010 5:14 pm

Take a look above again, I refreshed the photos. I used all my own brakes. If your rear brakes are usable there is no reason to worry about replacing them. That means you don't need parking brake cables either. You do need the steel brake lines from the Tee in the middle to each side and the rubber brake line from the steel line to the caliper on the right side.
Plan on spending $10 on a pair of new seals and a cover gasket.
As long as the U-bolts are not damaged or stressed, I reuse them. Have another option should you need a U-bolt. Soak them all down with penetrating oil at least a week before the swap and you have a chance of not twisting one off. If you do, I have my originals for sale. I took them off when I did the BSW kit.

Just wipe out the diff as best you can. If it is really bad you can use some mineral spirits to clean things up. Just be careful not to use something that will swell or damage the pinion seal.

s10 again · Post by **s10 again** » Sat Jan 30, 2010 6:09 pm

As badly as I would like to reuse as much of what I already have I need to get this as simple as I can. This because I'm going to be counting on my wife,daughter,and son in law to help (Who am I kidding do this with my instruction). It will be 8 weeks minimum before I regain any use of my right arm. I will get the gear oil changed and while there look in the cover to see what shape it is in. But if the bearings are tight and seals not leaking I'm just going to get it bolted in. If I need to replace the seals later then that is not a bad job with the axle in the truck and both arms working. I'm going to put the stock axle in the shed so brake parts will be there if I need them later.

Chris.

Post by **HenryJ** » Sat Jan 30, 2010 6:15 pm

Understood. You may need to drop the leaf springs loose at the rear shackles then.

I can't say which is easier. If you have to drop the hats to check the parking brake shoes, you are only nine bolts , two c-clips and a center pin from changing the backing plates. That requires no messing with parking brake cables or adjustment. You don't need to drop the springs either.

Just another option, I guess.

s10 again · Post by **s10 again** » Sat Jan 30, 2010 8:10 pm

Thanks again HJ,

I was thinking about dropping the springs at the shackles already to try to save some lifting. If we get lucky we use my dolly to roll the old axle out and the zr2 back under. But we all know were a well laid out plan gets us. Anyhow I might take advantage of the springs being dropped and try to sneak in some lift shackles. Then I think I can handle a TB crank even one handed. After that I might be able to sneak in an alignment and some 30x9.50s but more on that later.

Chris.

Post by **HenryJ** » Sat Jan 30, 2010 8:56 pm

That is not a bad place to be. I really liked Mark's truck and all the others set up like that.

killian96ss · Post by **killian96ss** » Sun Jan 31, 2010 11:50 pm

HenryJ wrote:To get things back to where I had it , I need to add some 1" spacers to the rear. It just looks better to me with the rear slightly wider.

I still have a set of 1" spacers from my CC if your interested. I used to have them on the rear to match the front track width. I don't know why I have hung onto them so long

, but I would take any reasonable off for them.

Steve

Post by **HenryJ** » Mon Feb 01, 2010 6:14 am

PM sent!
The price on spacers has come down nicely. I think they are about one quarter the price that I paid for my first set. A nice used set would be perfect for me though.

s10 again · Post by **s10 again** » Mon Feb 01, 2010 7:05 pm

Zr2 axle payed for and will be here tomorrow eve.

Chris.

Post by **HenryJ** » Mon Feb 01, 2010 9:15 pm

Thanks to Steve I should have some spacers soon. Thanks.

Chris, You know we like photos and details.

How many miles, what year and model is the donor?

That reminds me that I need to research my 71k mile 2003 ZR2 donor too.

S-10CREWCAB.NET

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