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Buzz 02-06-2018 10:51 AM

Jag IRS pinion seal
 
Hi guys. I recently picked up a 3:31 Powerlock Series ll rear suspension assembly out of a '73 XJ6. It has a Salisbury 4HU case and was sitting in the shop yard fully intact in its suspension cage covered in old oil which the shop owner had poured over it to preserve it from the elements.

He offered to clean it up and pressure wash it so I could verify the axle ratio before I committed to buying it, and in the process he apparently tried to get it turning by applying a torque wrench to the pinion nut. The diff was not turning because the brakes were all gummed up and fused, so he ended up loosening and re-tightening the nut.

I knew the family who originally owned the car it came out of and verified that it was really low mileage before it was wrecked. After being cleaned up, the diff tag showed it was a 3:31 and since it all looked in pretty good shape, I got it for a very reasonable price and took it home. I figured worse case scenario is that I would have a fresh set of control arms, uprights and half shafts to rebuild my damaged old Series l 3:54 Powerlock axle.

Once I got it stripped down to the bare differential, using bolts and a crowbar on the pinion flange, I gradually rocked the pinion back and forth before turning it fully. At first, the output flanges rocked in opposite directions, leading me to the disappointing conclusion that it was an open diff, but it suddenly loosened right up and the flanges both rotated the same way as a powerlock should. Turning the output flange on one side also rotates the other side in the same direction, so I assume that it is indeed a locking diff.

My main issue is that there is a fairly steady drip from the pinion seal when I turn it, and on reading up on replacing the seal I see that because of the crush sleeve in the input shaft, great care must be taken not to loosen or tighten that pinion nut without reference marks or the bearing preload will be affected and a full diff teardown and rebuild will be needed. The diff is still full of fluid and turns smoothly and quietly in both directions with no discernible play of any kind in the pinion or output flanges.

There is no one down here with the know how to expertly rebuild a Jag differential, so the entire thing would have to be shipped out which involves a ton of paperwork, time and import/export duties, levies and taxes that I would prefer to avoid.

Is there a safe way for me to just replace the seal, clean up and re lube the differential without a full rebuild? Can a "safe range" for the pinion bearing preload be established by torque required to turn the pinion? I guess it's obvious what answer I'm hoping for. %/

EDIT: Just for context, once I decided to buy the axle, I went ahead and ordered a complete Team CJ Bronze bushing set and new calipers, rotors and pads, and I'm awaiting the exact shortening measurements from Alan at Unique Motorcars before I head to the machine shop to get the pieces chopped.

EDIT 2: I suppose while I have everything apart, I might as well replace the axle shaft U-Joints. Does anyone know which high quality replacement joints I should order?

redmt 02-06-2018 11:59 AM

Buzz , on the pinion flange torque,,, Slip the yoke off and replace the seal. Then tighten the pinion nut down to around 150 and check for bearing resistance and end play. If it's still turns freely take it down another 50 to 200. If it still has the same perceived torque rotation on the pinion then you should be good. Best case is to drop out the carrier and set the pinion pre-load around 10 inch pounds or rotational torque with the start and stop of rotation being smooth with out any jerking.
Spicer makes some decent u-joints.

patrickt 02-06-2018 01:08 PM

Here, maybe this page will help: Replacing the pinion seal Now, I've never done it, but it doesn't look all that hard.;)

EDIT -- Try and avoid Step 16 Remove car from ramp and road test. If final drive is noisy, overhaul procedure 51.25.19 MUST be carried out.

Buzz 02-06-2018 02:40 PM

Thanks John - I'll do that and see how it works out. I called and checked all over the island for positrack compatible differential lube or the additive - no luck. I'll have to order some in. Life in the tropics... :MECOOL:

Patrick - thanks. I read that page before and it's step 4 that had me worried:
"Mark nut and pinion shaft so that in refitting, nut may be returned to its original position on shaft."
The seller loosened and re-tightened the pinion nut with no markings for reference, so I was concerned that I would have to do a full rebuild as a result.

patrickt 02-06-2018 02:56 PM

Quote:

Originally Posted by Buzz (Post 1437896)
Patrick - thanks. I read that page before and it's step 4 that had me worried...

Yeah, hmmm... well, if it was me, I would try putting my dial indicator on it and just shoot for about .001" to .004" float. That seems to work on most other bearings in the world....

Buzz 02-06-2018 03:12 PM

I don't currently own a dial indicator, but I have been boning up on Jag diff rebuild videos and instructions, so if I hear any noises or feel anything odd after trying John's suggestion I might just have to order some new tools and have a go at rebuilding it myself.

joyridin' 02-06-2018 03:28 PM

I rebuilt mine and converted it to a Dana 44 set-up instead of the Salisbury with 30 spline axles. It was not hard. I just took my time. I replaced every bearing and the LSD unit with a torsen style LSD.

800 miles and all is well.

redmt 02-06-2018 03:43 PM

Buzz the basic setup is already done. If you don't have to change anything except the seal, it's only a matter of getting the nut tight enough and the pre-load correct. It is possible to overtighten the nut. Somewhere around 250-275 the shims can start it crush and deform and somewhere upwards of 300 you will find out the integrity of the pinion. The ones that are a real PITA are the 9" Ford and similar that use a 1 time use crush sleeve. Tackle one of those and you find out what a 3' breaker bar is for. OH!! and NEVER use an impact wrench. never ever.
BTW, end play is far more critical than backlash. You want zero end play. If you turn the pinion by hand and can feel it but not see it, that's close enough. If you feel it AND see it, it's time to check the pattern and either move the carrier over or sink the pinion deeper depending on what the pattern looks like. This is where the rotational drag come into play. You can't actually measure an negative so the next best thing is the bearing resistance , rotational torque. You probably don't have a dial inch pounds torque wrench. Grab the pinion across the flange with your thumb and little finger. If you can turn the pinion , it's too loose. It should take a light to moderate amount of twist to rotate it.
I hope that all makes sense,,,,,

Grubby 02-06-2018 04:45 PM

The purpose of the crush sleeve is to set pinion bearing preload. It has nothing to do with float. If the sleeve has been further crushed as described, it MUST be replaced. You will cook the pinion bearings if you don't.

A sleeve that is crushed too far will have excessive bearing preload. This is very bad.

You need to replace the pinion seal, crush sleeve and nut. They are all one time use. This is straight forward. The manuals are on line and on the ERA web site.

Remove the ring gear install new crush sleeve and set the correct bearing preload and then finish putting it back to together. The rest of the shims should be fine since nothing else has changed. I like to use my floor jack handle to get enough torque to crush the crush sleeve. I am not man enough to do it with just my breaker bar.

You simply tighten the pinion nut in small increments and check bearing preload with a inch pound torque wrench. Preload is the torque required to rotate the pinion only.

Replace the O rings on the stub axles while you are at it. They are cheap and leak from age.

Don't take a short cut. It will be harder when it is in the car.

John

DanEC 02-06-2018 04:55 PM

Not sure how similar the Salisbury unit is to the Mopar 8-3/4 rear set up - if it is, you don't want to tighten it to the point of further crushing it to meet pre-load, as it can collapse and break. Guaranteed to howl and whine then due to the pinion play.

redmt 02-06-2018 04:57 PM

What John (Grubby) said is %100. I was working from my feeble memory on the Jag setup. I don't remember it having a crush sleeve but having to shim the races on the pinion to achieve pinion depth and preload.

Buzz 02-06-2018 05:15 PM

Grubby - is there an easy way to tell if the crush sleeve has in fact been over tightened? I only know that the nut was loosened and re tightened. I don't think he had a breaker bar on it - just a torque wrench from what he showed me.

EDIT - Another question: Will the 3.54:1 gearset from my series 1 case swap into the newer series 2 case? Both are Salisbury units. If I'm going to have to pull the ring and pinion out, I'm considering the swap as its automatic to assume the taller ratio will work better with my .68 5th gear.

Grubby 02-06-2018 05:18 PM

Some Dana 44s use a spacer and shims to set pinion bearing preload. The two Jags that I rebuilt both had crush sleeves. The last one was a series II from an XKE.

From a manufacturing stand point the crush sleeve is the cheapest easiest way for the automakers to assemble them quickly.

John

Grubby 02-06-2018 05:58 PM

Buzz,

Pull apart including removal of the ring gear/carrier. Remove the pinion nut before pulling the carrier out. Clean up everything, inspect bearings for any damage. Use a magnifying glass to look for marks or indentions in the roller bearings. Replace if they show any damage.

Lightly oil the pinion bearings, install the pinion, slinger and everything else you removed from the pinion. Install the new seal and tighten the new nut to 200-220 lbs / ft. You either need to make up a tool to hold the yoke or install the carrier and stub axles so you can torque the pinion nut. Then use a lbs / inch beam type torque wrench to measure the torque to keep the pinion turning. Your target is 20-40 lbs / inch. If the crush sleeve was crushed too far the number will be much higher. Have the carrier and ring gear removed when checking preload.

If pinion preload is within spec, then clean up the carrier bearings and stub axle bearings, replace O rings and reassemble.

Keep all shims where you find them and note the stub axles are also shimmed. Keep the stub axles on the side they are on with the shims they have.

Let me know if you need further details.
John

Grubby 02-06-2018 06:04 PM

Buzz,

You can swap gears, but you will need to follow the full book process to shim everything. It is a big job. It takes me about 8 hours to set one up, but I don't do it everyday.

What is the benefit of swapping to a series II? If not big benefit I would save the head ache and stay with the Series I with the 3.54s.

Don't Series Is have ball bearings in the stub shafts and Series IIs have tapper rollers?

John

Buzz 02-06-2018 06:07 PM

Thanks Grubby - and I really appreciate the help from everyone. I will update on how it all goes.

Buzz 02-06-2018 06:14 PM

Quote:

Originally Posted by Grubby (Post 1437914)
Buzz,

You can swap gears, but you will need to follow the full book process to shim everything. It is a big job. It takes me about 8 hours to set one up, but I don't do it everyday.

What is the benefit of swapping to a series II? If not big benefit I would save the head ache and stay with the Series I with the 3.54s.

Don't Series Is have ball bearings in the stub shafts and Series IIs have tapper rollers?

John

I thought the series 2 is supposed to be better because of the tapered roller bearings in the outputs being less prone to failure. My old series 1 has a lot of miles on it and its easier to find brake parts, etc. on line for the newer axle. I guess its all moot now that I'm faced with tearing the diff down now if not for the fact that I have a bunch of new parts already in transit for the series 2.

joyridin' 02-06-2018 06:52 PM

Series 1 came both ways. Early models had tapered bearing. Then in 68, they went to ball bearing. Maybe around 73 or so, they went back to tapered bearings.

Most of the early versions with 19spline axles used ships to set preload. From the early 70’s onward, they used a crush sleeve.

Buzz 02-07-2018 01:57 AM

Double post

Buzz 02-07-2018 02:02 AM

Quote:

Originally Posted by joyridin' (Post 1437918)
Series 1 came both ways. Early models had tapered bearing. Then in 68, they went to ball bearing. Maybe around 73 or so, they went back to tapered bearings.

Most of the early versions with 19spline axles used ships to set preload. From the early 70’s onward, they used a crush sleeve.

Joyridin' - Interesting. I didn't know that any Series 1 diffs used tapered rollers. There really is a wealth of knowledge here.
PS - Any tips or issues I need to keep in mind about the use of the Team CJ Bronze bushing set, or is it really as straightforward as it's touted to be?

For others contemplating a Jag IRS rebuild/refresh, this realy looks like the way to go. Team CJ system bronze


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