68RFE sprag failure with explanation

https://www.youtube.com/watch?v=qKvByzA5CL4

 I'm going to concentrate here on the 68
RE sprag for those of you that don't know me I'm Ethan Patterson at WP developments we concentrate in you know
performance and heavyduty uh diesel Transmissions um one of our biggest sellers is the 68
RF big problem that we have and some of you have seen magazine articles or
videos on YouTube or um some podcasts that I have done in the past that kind
of covers this topic but not this in depth um a lot of shops reach out to me
having the old uh one two shift
fault um this is going to be you know your first gear right this is a problem
here in your first gear not normally not this one they're called a roller sprag
we don't use those we use the factory style sprag and this video is going to tell you why y um what a sprag is is
imagine your ratchet you know 38 ratchet and it goes one way when it's on the
tighten position so that's basically the same thing as frag de you hold it in the middle it free Wheels clockwise and it
locks counterclockwise so that's what a sprag is and when you have problems is
when this thing maybe locks in both directions so it can't Freewheel one way
and it locks the other way or um if you strain like a factory one enough um what
it will do is it will actually flip the sprag inside and it will Freewheel the
wrong direction so it'll free whe in the counterclockwise Direction and lock in
this Direction that's where you're going to get a really tough bind up so your
one two shift is going to either bind and throw a code and say hey look
you know um the input shaft speed versus the output shaft speed did not correlate
with this shift in time and we're going to fault you to fourth gear um a lot of
calls that I get um as well is going to be I have
a inconsistent 21 downshift so when it's
coming from two down to one either they're getting a flare or a har
shift um so I'll kind of explain both of these a flare is going to be that the
brag isn't catching um there's a delay from when it comes from two to one when
the low reverse clutch will actually come on there's a hydraulic delay in the
SSV and then if they are getting a hardship then that sprag is stuck right so that
thing is not wanting to free wheeel or it's stuck in both directions um
normally when you have a sprag issue as well you're going to have a delay so
when you drop it from park down to drive it's going to be a
delayed engagement so you'll notice that probably first as it starts what I
considered wiping away and there's some important keys to this
sprag right so a sprag has an internal
I'm not an artist so don't make fun of my drawing so this is let's just not even put spines in it this is going to
be your internal race and then you're going to have an external race and if
you look closely in one of these I do believe it's in one or two spots in the
sprag I can very verify that real quick um yep it's just one one
spot so one spot we're going to feed oil in right so when this thing is free when
it's free spinning it's metal on metal creating heat worst thing you can have
the more cooling you have the better off you are things don't expand the the
clearances don't get super tight and start wearing materials much so we're we're wanting to
lubricate inside here so we don't wear this race this race is super picky like
we're talking like a thousandth of an inch of wear can
cause this thing to fail so a lot of people went to a roller
style a roller style instead of having something that looks kind of
like I call them dog bone like I said I'm
not a artist so a dog bone style is
going to lock the pressure is going to be here and the pressure is going to be
here on the high ridges right so when that thing grabs what this does is
there's going to be these elements all the way around the outside and they're going to grab here
and here now when it goes into Freewheel so free wheel is going to
shove it this way which is going to be in a low spot which allows it to Freewheel right so it's going to
back it's not going to have a lot of drag in there um and that allows it to Freewheel one
way so in a nutshell like that's how the factory sprad works the one thing that
the factory sprag lacks that I've heard through the grap Vine now I have not
verified this with Mopar but it makes total sense um is they had Bor it's a
Borg Warner brand so obviously you guys have heard of Bor Warner they don't just
make turbos they don't just make clutches they don't just make solenoids they make a lot for these
Transmissions one of these things is the sprag in the back um when
moar went to do basically their their uh strain test so say they they put I'm
just imagining this is how it goes they put some type of machine on the back and say okay this thing took um you know 15
foot- pounds to turn so they can equate that value out to fuel mileage right so
the amount of drag that's in this transmission they have a set
goal and you know OB obviously as they're put up with the EPA and they
have set points of mileage they have to meet um you know they I'm sure you know
they they had to do something so this did not meet the the sprag drag test
right so this sprag was originally a smaller o outside
diameter uh I shouldn't say outside diameter because the outside diameter is what is on on the clutch so it's it's
like it's the Inside Edge of this outer sprag Grace right so
the Inside Edge is where your dog bends are going to be and then you have
an inside diameter so that's what
goes on here so this is your outer race on the outside with the splines and this is your inner race with the inside of
the splines okay and so what they did to meet to meet this uh you know drag test like the
resistance of how much that sprag had was they took that they took that
outside diameter or the outside race inside diameter and they opened it up
now remember in the first part of the video we said a huge thing is a
thousandth of an inch a lot of people can't even measure that closely with the tool they have in their shop right so a
thousand of an inch can make or break this dog bone what I consider the dog
bone flipping over backwards and having a reverse operation which is total
failure right so you're stuck in the mud and this thing really grabs right it
really grabs hard and gets kind of stuck in there so it wedges itself between the inner and the outer and then all of a
sudden second gear comes and this thing has to go to free wheel so it has to you
know spin this the other way like that and this thing's stuck so it has a bind
so when it does that it gets it gets inertia and it will actually flip it over right it flips it past and all of a
sudden your low spot ends up being your high spot and makes this thing work in the opposite direction and now you got
that first gear incorrect ratio code all I was is stuck in the mud
right there's another problem here and a
lot of people think they fix it in tuning and bless their hearts they do a really good job at making sure like in
that file that it does read that it has
low reverse clutches on the entire way through first
gear but it's as a transmission
our team has went in and we said okay well that's crazy because there's what
they call pressure switch right so if there is fluid in a
circuit and that fluid is fed into a pressure pressure switch in your
solenoid pack at 23 PSI of pressure pushing up it connects a
contact and sends a signal back to the ECM okay that tells the ECM hey we're on
this this was commanded on this is how long it took and then when that pressure
comes off it takes it takes 11 PSI less than 11 PSI to turn off that
pressure switch okay so what we've seen was in everybody's low reverse fixed
tuning this pressure press switch was still turning off regardless of the output shaft speed right so this BL
reverse clutch itself that's based on the outside that helps hold this
thing hold this thing from spinning in the middle it holds it is releasing
prior to your one two
upshift right so this thing's trying to go up and the reason they have to do
this is that the valve that has created this thing to be a headache right and
everybody should know this valve it's the one valve it's one of three valves in your valve body right this 68 is a
pretty simple valve body it has three valves this one is considered the SSV
okay so that switch valve is duty is to
basically I'm covering more than I wanted to but it all pertains to one
thing so the SSV itself its duty is to
Cut N mosquito and its
March so the purpose of the SSV is to cut fluid and utilize one solenoid so your
low reverse solenoid
is equal to Locka so instead of Dodge putting an extra
solenoid in like they did in the 2019s they said we got this bright idea we'll never need lock up in first gear so
let's double duty this thing right so this SSV directs fluid to the low
reverse clutch and first gear but it has to
hydraulically shut that off and start its motion to stroke it prior to the one
two shifts so no matter what your tuning does there is a hydraulic delay in the
actual movement of the SSV and we've proved it like we have it on data we put
pressure ports in every single clutch circuit and tried every single type of low reverse fixed tuning and it
absolutely 100% pulls off this low reverse clutch prior to the
upshift you're like well that's kind of out there you know why are you saying this here's why because think of
somebody on tug of- War right like we're we got two people versus two people and
we're both pulling our hearts out right and the guy behind me you know we're
getting there we're almost we're almost winning and he lets go what happens it strains me right I'm trying to do the
work of two people's job that's not terrible if you start out
doing the work work a two person's job but as you're going there and he
lets go I'm going to get shock loaded right that's the same thing that happens here and if we shock load the strain so
it's grabbing but say it's at 50% holding capacity and then I drop this
clutch out that's helping hold it it's going to shock
load over this little hump where it holds it on the race right
what do you think is going to happen and then second gear is coming on
and this thing's stuck and it flips it the other way and it's done for right
so in the aftermarket World they decided that you know let's
uh let's get this cleaned off here they decided that the upgrade is going to be
a roller style right so there's 14
rollers I'm doing 10 my circle isn't that great and just imagine you know there's
there's ramps right so there's there's ramps at each one of these
rollers so
again there's nobody here that is super good at drawing so you're going to have
to get with me here and these rollers are used in lighter Duty Vehicles so if
you want to really know where this idea came from it was a 45 RF right and then
they made a 54 45 RF so that's where a 14 roller frag came
from why didn't they use the HD sprag well the HD sprag doesn't necessarily
like the RPMs so if you have a gaser that can spin you know
7,000 RPM and then you have a diesel
that can go you know I take my diesel to like 6,000 but different story but you
have a diesel that goes to you know most people aren't going to go over that 4,000 RPM we're dang near half of the
RPM and like I said before the problem with the dog bone is that it can create heat right and then start Machining
stuff out well imagine if that things is freewheeling faster these rollers take
the RPM so much better right that's that's good
but this isn't good this has a ramp that you know then the outer race you know
comes over here and then you got your clutches on the outside and then they
got Springs they got Springs in between them right so these these Springs in
between each roller sprag and I wish I had one I could show you um but I don't
so I guess the guys decided to throw them all away so the sorry I'm trying to take
apart a sprag so you guys can see kind of how this sprag is on a dog
bone without a spring really there is Springs in there but they're not really
part of the roller so these things are going to be the same length so dang near
3 of an inch tall spring in between and then there's a plastic housing that goes
in here that hosts them so perfect we're going to keep it in the free wheeel
position when it's not being used it's a roller it can spin like perfect but the
problem is going to be these things are no stronger than
what our dog bone is what are they good for Reon existence of showing failure a
a factory one fails once and you know it a roller style it can fail a thousand times and
you're starting to get that delay into first and you're like man huh I wonder what's going on so you check your fluid
and you ask your Builder and you're like you're you're pulling your hair out right like you're you're just wondering
why is this thing just got a delay going into reverse so what happened s is these
Springs compress right they get you can hold that spring in your hand and and
actuate it for a lifetime and it's never going to lose its spring rate but if I
take a hammer and stick that spring on a hard bench so if I smack it real
hard all of a sudden that Spring's compressed right so you can imagine if
this roller is able to float back and forth up this ramp the higher it goes up
the ramp the more tension it puts between the inner and the outer Rays so what
happens right every once in a while that that roller is
grabbing going down the road like it's trying to it's trying to grab so and
then when we get into it and you start to down shift from second to First and
this roller is just hanging out cu it doesn't have any spring on it and this
roller is doing the same thing and that roller is doing the same thing and then this roller is doing the same thing now
we're down to half our rollers does it still work yes it does until you strain
it really hard right so okay we strained it really hard again and lost a couple
more Springs now all of a sudden instead of having 14 rollers we have four right
so F there 10 of these things are just hanging out there they're not starting
up the ramp at the same time to grab each individual area
right so all of a sudden we have less than half of the rollers doing the duty
and what do you think happens it fails you can't rely on four
of these rollers and the bad part about a roller sprad when it fails is it takes
out the entire rear gear
train and you'll be lucky if it doesn't take out your case with it so we at WP
developments have put in maybe a handful of these roller sprangs um but our
goto is the factory Style what I consider the dog bone sprag there's 36
of these elements in here and there's 14 of your rollers in your heavy duty sprag
assembly now what the shops are seeing is that they did proong a problem right they they they
can fail multiple times and have maybe one or two Springs and for the normal driver that doesn't get stuck all the
time or is snow plowing or spinning the tires they have worked for many years but the
more abuse they get the more they wear these Springs out and then we're not
even going to get into I have to do the calculation still and that's why I wrote down these numbers
um it's the surface area of say if we had 14
rollers applying you know out on each area we have have this Gap in between
right like this Gap here is unused portion of the race as to where
if we have you know a normal doin style
where these things there's 36 of these
elements pushing out so your pounds per square in is evenly
applied so imagine I guess I don't know that's just messed
up but listen I'm just trying to trying to make this as simple as possible but
imagine you know I have 36 points of pressure right so I have pressure here
here here here here and and my area in between is less so instead of Imagine
under super high torque and I know it's hard to imagine like this thick race
here which there is a calculation for sprags and I don't remember the
calculation I have it written down in my notes but there's a certain like
the outside race has to be like 1.9 times the height of the race it's kind
of like when you calculate for a bolt strength right like the diameter of the bolt times 1 and a half that's as far
down as it needs to go in order to make the full strength of that bolt so
there's the same calculation for your sprag Graves I did the calculation on the factory spag Grace it is pretty far
off I mean it it doesn't have enough meat to really support the amount of
pressure that's on each one of these to keep it from expanding but if you could
only imagine that we have this spr gra and we have 14 points of pressure I mean that's
that's literally like double the pressure over double the pressure per point so this thing under load is going
to look like this and I know that's hard to even
imagine right like each one of those points of fours of your roller is
doing this this and this air gap in here isn't
moving right so your point of contact is
greater but if you could imagine you're trying with a with a finer it's like a
finer Toth ratet right so we got 36 elements here 36 points of contact
you're trying to expand this entire outer R Heavenly you
don't have a lot of air gap in between right and so one we've spread out the
force over a bunch of different dog bones rather than concentrated on 14
rollers we put it against 36 right so that your amount of PSI which is pounds
per square inch is a lot less Duty on these and it's
magnified at least times two on your roller compared
to this so I know a lot of people are going to say well you know the hardness
of that roller and the hardness of this race and a lot of people don't check
that like a lot of people don't check the hardness of the race on these races
there's actually an RA finish the same as you would check on per se your head
surface for your block you know to seal up the head gasket an MLs gasket
takes a dang near a polished finish right so this is the same way like we
want a mirr finish right so it's the same way with any race like any sprag
has to have dang near a mere finish it can't have any High edges can't retain oil you know that thing is a barning and
and that's what they technically column is a oneway bearing so um after so long and you get dirty
fluid and and you start grabbing here you know in 14 spots and you start doing
this stuff you'll you'll take that apart and most guys will look at it like oh it's just scuffing well no it's not it's
not scuffing it's actually this this bearing material is harder than your outside race and if you run the old
fingernail trick right I learned that when I was doing Motors like you know if it catches your fingernail probably need
to take it to the Machine Shop same Theory like this thing here you can see where each one of these rollers has
grabbed that outside race that thing is no good at all you can't use it and I
get calls I bet four times a week so every day but one day I'm guessing about
a sprag issue I I get them nonstop and I
want to tell them all this information but as you can tell like this video is long enough and and I don't have that
kind of time to sit there and explain this that's why I'm doing this tonight so instead of eating dinner I've I'm
with my my YouTube guys um you know and
I I hope to be able to do this more often and you know my next my next thing
I want to get into maybe is like how to get the overdrive clutch you know to hold power um stuff like that definitely
if you have any questions on the failure of the sprags why we don't
use the roller type verse the dog bone style we'll call them
the dog bone style um as well as our dog bone style is I got into that
earlier they had to open up this outside race to get less drag so less Freewheel
drag so board Warner makes the actual first sprag they made for the the
68 RF that has a tighter outside diameter or tighter raise clearance that
keeps the dog bone from flipping over the wrong way so we do run those um in
all of our units we get it it used to be a black nitrated outside brace uh really
nice piece they've since discontinued it and they just call it the Borg HD sprag
I think they realized like the black nitrate probably didn't add a whole lot lot of benefit um I have some out there
as soon as I get those units out I'm going to start testing like the mileage
and the wear that we're seeing on that and see if it's worth you know offering that to the public again um if it is we
will we will obviously offer that um but this is kind of like the how does the
roller sprag dog bone uh why the dog bone was prone to failure was most had
Bor Warner open up the clearance a little bit to create less drag um so you can get the one that was tighter
clearance yes it does create a little bit more heat you're not going to see it probably on your on your gauge um you
know the the more the more fluid we get in you know in that area here and in
here to lube everything you know the better we got right so that comes back to changing your fluids you know if you
work this truck who cares we're going to throw a filter a couple filters and some
oil at this thing we really work this thing this last 20,000 miles it isn't
going to hurt anything the guys that are getting hurt on what they've you know
invested into are the guys that say well I bought this built transmission it was
$10,000 this thing should be able to go $60,000 miles of pure abuse you know
flat foot it up Mountain sides and and in reality it doesn't matter who builds
your transmission you have to have a service pattern so if you use it hard
and you use it for a work truck you're going to have a couple hundred bucks and it's going to save you
a headache you know most of the time you drop it at 20,000 miles if you're really
working this thing hard 30,000 miles you know whatever you feel comfortable doing
I always tell everybody you know we never flush them we just drop the pan we change the fil we refill with what came
out that is is peanuts compared to what this investment you have cost you and if
you're not willing to put in you know that there's no transmission on the market and I've been in probably every
single heavyduty transmission in a diesel pickup I I know I have um from
manuals to automatics to the brand new stuff um that is across the board like
filtration on these units if it doesn't filter it out that micro you know piece
of metal is in there on the SSV we talked about it's in here taking your
polish off of your outer race you know that is huge and a lot of people don't
understand it like if we could get like a two micron filter in there great you know but in reality it would suck
because a two micron filter doesn't flow enough to keep up with the volume that we need um and it would just plug up
super quick so I'm done with my rambling I really
appreciate you guys stopping in like I said it's my first YouTube video I'm
glad to be doing them I have tried and tried and tried to break away I just have to do it after hours the Shop's
super busy the guys always need you know me to do something and I get pulled away
from a lot of different uh jobs and tasks um just trying to help everybody and on top of
that you know they are kind of loud um so hopefully we can do this like on a
set week night um and get you guys some more information of you know how to
think about this this stuff um how to lay it out in your head to make it un
make you understand it that's and that's the biggest thing like if you understood
how each one of these worked and what the failures were and why we don't use what we don't use and why we use what we
use and why they used what they used in in the gas versus the diesel you know