Shim adjustments to remove backlash in Dana 35


RonT

Member
Joined
Aug 31, 2018
Messages
32
Location
Maine
Anyone ever make shim adjustments to remove backlash in the drive train YouTube makes it look easy . Any tips would be appreciated. Thank you.
 

JMT

The Jeep Guy
Supporting Member
Ride of the Month Winner
Joined
Feb 27, 2017
Messages
10,981
Location
Earth
There are a few on here. @Rob5589 is a gear guru, done thousands of gear setups. @ErikOffroad is active here and a good source too.

You just need to get various shims, remove the carrier and add or subtract to get within the right tolerances.Know your tolerances, know how to read your backlash indicator and know how to interpret the pattern. Post up pics and let the gear experts take a look.
 

someguysjeep

TJ Addict
Lifetime Supporting Member
Joined
Nov 17, 2019
Messages
1,705
Location
ohio
it depends on what your dealing with here.
is the diff assembled fully??
whats leading you to believe you need to adjust the backlash?
 

tworley

Bent Currie Club
Supporting Member
Ride of the Month Winner
Joined
May 23, 2018
Messages
4,803
Location
Morrison, CO
X2--why do you need to remove backlash? Was it set up incorrectly?
 

Lou

TJ Enthusiast
Supporting Member
Joined
Jun 16, 2016
Messages
918
Location
Long Beach
It’s my understanding it’s not the best practice to adjust backlash once the gears have been set up and ran.

what is your backlash at now?
 
OP
R

RonT

Member
Joined
Aug 31, 2018
Messages
32
Location
Maine
it depends on what your dealing with here.
is the diff assembled fully??
whats leading you to believe you need to adjust the backlash?
I bought the Jeep new in 05, it's a six speed 4.0L and has had a sloppy drive train since the day I drove it off the lot. If you're not smooth when shifting gears or shifting to quickly there a dead spot where the drive train is not engaged and the jeep bounces forwards and back until positive contact is maintained at the rack and pinion gear. Sounds to me like a shim adjustment is needed to close up the clearance between the two gears. Youtube shows a shim adjustment to tighten up the slack. Youtube always makes it look easier than it actually is. I just wondered of if someone has tackled this project and can tell me "watch out for". Thanks all for the input.
 
OP
R

RonT

Member
Joined
Aug 31, 2018
Messages
32
Location
Maine
A certain amount of backlash is required. Don't mess with it without knowing what you're doing.
I'll be well informed before I dismantle that pumpkin. This is why I'm fact finding right now. Thanks for the input.
 

Jerry Bransford

TJ Guru Moderator
Staff Member
Supporting Member
Joined
Nov 9, 2015
Messages
15,855
Location
Escondido California
I bought the Jeep new in 05, it's a six speed 4.0L and has had a sloppy drive train since the day I drove it off the lot. If you're not smooth when shifting gears or shifting to quickly there a dead spot where the drive train is not engaged and the jeep bounces forwards and back until positive contact is maintained at the rack and pinion gear. Sounds to me like a shim adjustment is needed to close up the clearance between the two gears. Youtube shows a shim adjustment to tighten up the slack. Youtube always makes it look easier than it actually is. I just wondered of if someone has tackled this project and can tell me "watch out for". Thanks all for the input.
Don't confuse the ring & pinion gears inside the axles with a rack & pinion (steering system). Both are always engaged, decreasing the backlash between the gears just makes it harder for the gear lube to get in between the gears which is the purpose of having a certain amount of "slop" (backlash) between the gears. It doesn't sound like your issue has anything to do with the a amount backlash between your axle's ring & pinion gears.
 

Lou

TJ Enthusiast
Supporting Member
Joined
Jun 16, 2016
Messages
918
Location
Long Beach
Yeah you definitely do not have to “remove backlash”.
 

Indy

TJ Enthusiast
Supporting Member
Ride of the Month Winner
Joined
Apr 15, 2019
Messages
411
Location
Roseville CA
Does it have an automatic locker in the rear? How much is the slop if you turn the driveshaft by hand?
 

someguysjeep

TJ Addict
Lifetime Supporting Member
Joined
Nov 17, 2019
Messages
1,705
Location
ohio
the jeep bounces forward and back? it's bucking?

if you not smooth shifting gears or shift quick it happens?
sounds more like a clutch problem than a diff issue.
 

jjvw

Everything is great. No issues.
Supporting Member
Ride of the Month Winner
Joined
Feb 17, 2018
Messages
13,671
Location
Colorado, USA
I'll be well informed before I dismantle that pumpkin. This is why I'm fact finding right now. Thanks for the input.
You can measure the R&P backlash with a dial indicator. There ought to be between .006-.010" of movement. You can feel it click more than you can hear it.

Let us know what you find.
 

Rob5589

Certified video trained differential rebuilder
Supporting Member
Joined
Aug 29, 2016
Messages
6,692
Location
W Sacramento, Kalifornia
I bought the Jeep new in 05, it's a six speed 4.0L and has had a sloppy drive train since the day I drove it off the lot. If you're not smooth when shifting gears or shifting to quickly there a dead spot where the drive train is not engaged and the jeep bounces forwards and back until positive contact is maintained at the rack and pinion gear. Sounds to me like a shim adjustment is needed to close up the clearance between the two gears. Youtube shows a shim adjustment to tighten up the slack. Youtube always makes it look easier than it actually is. I just wondered of if someone has tackled this project and can tell me "watch out for". Thanks all for the input.
It's not the backlash causing the issue. Backlash runs from about .006 to .010. there is no way you are feeling that while driving.
 
  • Like
Reactions: jjvw
OP
R

RonT

Member
Joined
Aug 31, 2018
Messages
32
Location
Maine
It's not the backlash causing the issue. Backlash runs from about .006 to .010. there is no way you are feeling that while driving.
Thanks everyone for your feedback.
I understand tolerances between 0 .006 and 0.010 Rob but, if the clearances between the gears exceed the specification the slack will be there. Given this issue has been there since the Jeep was brand new, then I conclude the differential was never properly set up. U-joints are fine as is the 6-speed transmission. The only other place to consider is the differential. If I coast while approaching a red light and it turns green and I accelerate, until those gears are maintaining steady contact, the Jeep will buck a couple of times . I haven't changed gears now. I saw a fellow on YouTube re-shim his differential in order to remove back lash. It makes perfect sense. My initial inquiry was, is there something in particular I should be aware of? Your thoughts!
 

someguysjeep

TJ Addict
Lifetime Supporting Member
Joined
Nov 17, 2019
Messages
1,705
Location
ohio
open the case then..................................................
go get some gear oil and gasket maker and open it up and inspect it.

it drives ok, it coasts fine, but the problem occurs when you put in in gear and hit the gas? it bucks......and you don't think it could be clutch related, more than the diff?

have you had anyone else try and diagnose this problem, like maybe a mechanic?
 
  • Like
Reactions: Lou

jjvw

Everything is great. No issues.
Supporting Member
Ride of the Month Winner
Joined
Feb 17, 2018
Messages
13,671
Location
Colorado, USA
Let's assume for a moment that the problem really is the R&P. If the backlash has been perceptively sloppy from the driver's seat for 15 years and however many miles during that time (let's conservatively say 50k miles), would the R&P still be alive today?
 
  • Like
Reactions: someguysjeep