Limited Slip Time?

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1979bettywhite
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Limited Slip Time?

Postby 1979bettywhite » Tue Mar 13, 2018 7:44 am

So I have a vibration occurring at about 55 mph. So I replaced both u-joints in the rear shaft, had an alignment done, and balanced all the new BFGs by a very reputable shop that does on-car balancing. The do most of work to a lot of dedicated track cars around town.

Still continued to have some vibration. So next stop was to a strictly driveline shop. Very well respected shop. When there is a driveline issue, all the good shops send their customers here. The had the Chief for about a week. The basically went through the whole driveline and get it back up to basically brand new. The extended the front DS 1-1/4", checked all the u-joints, and confirmed all were fine. Rebalanced both the front and rear D/S. Checked all angles and said everything was fine there.

Still had a vibration both at 55 and when slowing to a stop. Shop was determined to find the culprit. Said they could hear a little noise almost like a wheel bearing coming from the rear. So they put it up on the lift and spun it up to speed. Noise seemed to come from the diff. So off came the diff cover.

Found a little play in the cross pin, enough believed to cause the vibration at issue. Wheel bearings seemed to be fine. Said it is not dangerous to drive like it is, but probably need to consider either rebuilding the open diff or swap out to a limited slip etc.

Now this is to my knowledge the original carrier and gears. Open diff 3.54 in the Dana 44. So I wanted to reach out to you guys to get opinions on what I should do regarding what I should swap in. The plans for the Chief are to be a fairly reliable 2-3 hour highway driver to get me to the mountains to explore some light wheeling, get to the camping spots for me to hunt down native trout :) .

Tech at the driveline shop said I should swap in a limited slip at minimum if I am going to change things out. Question is, which one? Fairly new to this but have done a decent amount of reading. Can I keep the ring gear and pinion that is in there and just swap carriers? Should I stick with the 3.54s? Should I keep the axle shafts and just do a bearing and seal replacement while we have the carrier out? Currently running 33x12.50x15s on a 4" lift and feels ok running around 60mph on the highway. Of course a little sluggish on startup, but not bad. The vibration is just annoying and doing a 2-3 hr trip with that does not sound like much fun.

Thanks in advance for the input!

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Stuka
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Re: Limited Slip Time?

Postby Stuka » Tue Mar 13, 2018 8:44 am

What year is your Jeep? I am assuming its a 70's model based on you stating 3.54 gears. Do you have an automatic or a manual?

EDIT: I see your name has 1979 in it, so pretty sure thats the year :)
1981 J10 AMC 258 with HEI and Weber 32/36 DGEV Carb, T176, NP208, D44/M23 with 4.56 gears and Detroit Locker, 6" lift, 33x12.50 Cooper STT's, BJ's Offroad Rear Dozer Bumper.
2017 JKU Rubicon Stock, but not for long!
Pevious Jeeps: 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

1979bettywhite
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Re: Limited Slip Time?

Postby 1979bettywhite » Tue Mar 13, 2018 11:15 am

Actually it is a 78. 360, auto, TH400, quadratrac. Basic Chief setup.

The 1979 in my sig references my CJ5, which is a 79 and white. Hence her name, Betty White.

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tgreese
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Re: Limited Slip Time?

Postby tgreese » Tue Mar 13, 2018 12:29 pm

Yes, you can reuse the gears if they are not damaged. The time-consuming part will be setting up the gears to have correct a correct mesh pattern and clearances with the new parts in place.

The shop is telling you to install some kind of traction device (LSD or locker) if you are going to pay to have the gears set up. The labor costs will be high, but a new LSD case will still be many times the parts cost of a replacement open case. All the Quadratrac Jeeps came with open differentials front and rear. Are you still full-time? If so, I'd ask about any possible strange performance issues with a LSD in the rear axle. I recall the TrueTrac got very positive reviews. You could also go selectable, if it's within the budget.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
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1979bettywhite
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Re: Limited Slip Time?

Postby 1979bettywhite » Tue Mar 13, 2018 12:38 pm

Yes, still on the stock full-time 4wd setup. I thought that if I needed to rebuild the open case, why not go ahead and just swap out to a limited slip? Seems logical to upgrade at this point instead of just repairing the open diff. I know the labor can get expensive on this, but I thought I might pick up the new carrier at one of the online places to take advantage of sales and deals.

Also figured the labor might not be much more on installing an LSD when they would have to remove the carrier etc to refurb the open carrier and spider gears. Maybe I am wrong about this (I know they would have to reset pinion/backlash etc. with the LSD). I am still learning regarding differentials etc.

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tgreese
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Re: Limited Slip Time?

Postby tgreese » Tue Mar 13, 2018 12:44 pm

Labor will be the same. Parts price will be much higher for LSD or locker (selectable or not).

Look at Randy's http://www.ringpinion.com for prices. Looks like the a Truetrak is $750-ish and I'd guess an open case is less than $100, and a selectable would be $1000-1200-ish.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 FCA Jeep Cherokee KL Trailhawk, ECO Green

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dodgerammit
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Re: Limited Slip Time?

Postby dodgerammit » Tue Mar 13, 2018 10:47 pm

I'll vouch for the true trac. Very mild mannered. Great in snow. Great to use up front since it doesn't mess with steering.
I used it in my old Dodge truck's front 44 with very positive results.

For light wheeling, or even moderate with no wheels in the air, the truetrac is awesome.

However, if you have been fine with an open diff and see no reason to do the upgrade, I'd save the extra $600.
84 Grand Waggy-Radio Flyer (Garnet Red with Honey interior) AMC 360/727/229 TFI conversion, MSD streetfire ignition, D44/AMC20 Serehill tailgate and headlight harnesses Relays! Relays everywhere! :fsj:

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Tatsadasayago
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Re: Limited Slip Time?

Postby Tatsadasayago » Wed Mar 14, 2018 3:46 am

After reading your comments, I am thinking the source of your vibration is elsewhere. Why? Because vibrations you can feel are mostly caused by longitudinal forces rather than lateral. Before you drop coin on expensive changes, you might want to look at the engine and trans/transfer mounts and input/output shaft slop at the transfer case. I've driven many vehicles with bad axle and carrier bearings an they never did cause much vibration--they caused noise. Also, I agree with the others, the moment you add an LSD or locker to a full time QT rig you destroy the best abilities of that transfer case.
1977 Cherokee Chief - The Blair Jeep Project III
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Stuka
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Re: Limited Slip Time?

Postby Stuka » Wed Mar 14, 2018 6:17 am

I also don't think a cross pin is causing this. I have driven things were horribly worn diffs and not had vibrations. There just isnt enough mass in a carrier to cause a vibration like that.

Out of curiosity, do you have hub centric or lug centric wheels? I had a vibration on my old JK that was a result of having lug centric wheels. The tires balanced out fine, and it would only happen between 47-53mph for me. Once I got hub centric rings, vibration was gone.
1981 J10 AMC 258 with HEI and Weber 32/36 DGEV Carb, T176, NP208, D44/M23 with 4.56 gears and Detroit Locker, 6" lift, 33x12.50 Cooper STT's, BJ's Offroad Rear Dozer Bumper.
2017 JKU Rubicon Stock, but not for long!
Pevious Jeeps: 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

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fulsizjeep
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Re: Limited Slip Time?

Postby fulsizjeep » Wed Mar 14, 2018 6:36 am

Anyone considering axle traction device(s) with a stock QuadraTrac should probably read this:
http://jubileejeeps.org/quadratrac/qt_review.pdf
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Embracing the Borg Warner QuadraTrac since 1980 http://jubileejeeps.org/quadratrac
88 GW, 401/727/208, 5" lift, D44s/4.10s/locked up, 35s, a few Evil Twin mods, http://eviltwinfab.com and a few TT's Fabworks mods, http://www.ttsfabworks.com
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Fast Eddie
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Re: Limited Slip Time?

Postby Fast Eddie » Wed Mar 14, 2018 7:20 am

1979 BettyWhite, You do NOT want to use a limited slip diff in your full time QT JEEP!!!! I worked at AMC for years, I owned a QT Cherokee Chief back in the day! Special T/C fluid and NO Limited Slip diffs! Good way to tear up your Q/T!
There was a Doug Nash conversion kit back then to convert your QT to part time and you could install locking hubs and T/L in rear, but not STOCK!!! These guys are telling you the REAL DEAL!! Don't listen to these shops who have no idea and want to sell you parts!!!
Last edited by Fast Eddie on Wed Mar 14, 2018 7:36 am, edited 1 time in total.
1979 J20, 360 w/NV4500/D300 Twin Stick/3.73 axles :fsj:
1978 Cherokee Chief W/T Levi interior, 360 Q/T. SCRAPPED
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1979bettywhite
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Re: Limited Slip Time?

Postby 1979bettywhite » Wed Mar 14, 2018 7:27 am

Stuka - I think your response has been my thought process the whole time as well. The current wheels that are on the Chief are the two-piece Centerline convo pro's in 15x8.5. I believe these are a lug centric style wheel. I have been considering ordering up a set of these:

https://www.summitracing.com/parts/usw-70-5860

Closest thing I have found to the old original white steelies. But I believe these are also lug centric as well. So maybe I should get a set of hub centric rings at the same time?

Tats - thanks for the reply. I know that they had both driveshafts out when refurbishing and they did not find any slop in the outputs on the tcase. Engine mounts are new and trans mount is solid as well.

After reading comments, it seems as though a LSD or locked diff is not really necessary when using the QT transfer case. It seems as thought it would not really improve things. So I may just rebuild the open case.

I think looking into the wheel issue might be a better starting point, now that all the D/S issues are taken care of.

1979bettywhite
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Re: Limited Slip Time?

Postby 1979bettywhite » Wed Mar 14, 2018 7:41 am

Thanks once again guys for continuing my education of the Chief.

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Re: Limited Slip Time?

Postby SJTD » Wed Mar 14, 2018 8:49 am

If the rear diff is suspect couldn't you pull the rear driveshaft and lock up the TC for a test drive?
Sic friatur crustulum

'84 GW with Nissan SD33T, early Chev NV4500, 300, narrowed Ford reverse 44, narrowed Ford 60, SOA/reversed shackle in fornt, lowered mount/flipped shackle in rear.

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Stuka
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Re: Limited Slip Time?

Postby Stuka » Wed Mar 14, 2018 9:28 am

1979bettywhite wrote:Stuka - I think your response has been my thought process the whole time as well. The current wheels that are on the Chief are the two-piece Centerline convo pro's in 15x8.5. I believe these are a lug centric style wheel. I have been considering ordering up a set of these:

https://www.summitracing.com/parts/usw-70-5860

Closest thing I have found to the old original white steelies. But I believe these are also lug centric as well. So maybe I should get a set of hub centric rings at the same time?

Tats - thanks for the reply. I know that they had both driveshafts out when refurbishing and they did not find any slop in the outputs on the tcase. Engine mounts are new and trans mount is solid as well.

After reading comments, it seems as though a LSD or locked diff is not really necessary when using the QT transfer case. It seems as thought it would not really improve things. So I may just rebuild the open case.

I think looking into the wheel issue might be a better starting point, now that all the D/S issues are taken care of.


A set of hub centric rings is about 10 bucks. You can get them on amazon. You just need the bore size of the wheels, and the hub size. Then find a ring with the correct ID and OD. And I advise the plastic ones, not the aluminum ones. The aluminum ones are more durable, but they also tend to corrode.
1981 J10 AMC 258 with HEI and Weber 32/36 DGEV Carb, T176, NP208, D44/M23 with 4.56 gears and Detroit Locker, 6" lift, 33x12.50 Cooper STT's, BJ's Offroad Rear Dozer Bumper.
2017 JKU Rubicon Stock, but not for long!
Pevious Jeeps: 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

1979bettywhite
Posts: 184
Joined: Tue Jul 25, 2017 8:14 am

Re: Limited Slip Time?

Postby 1979bettywhite » Wed Mar 14, 2018 11:03 am

I learned a while back that aluminum and steel don't play nicely with one another. Had to "burn out" an aluminum seatpost from a steel frame bike with some caustic soda. Fun science experiment, but would rather not have to deal with that again, lol.


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