Help! TF727 behind a YJ 4.0- how do I do it?!?!?

fbpd227

Active Member
Joined
Jan 12, 2007
Location
Smoky Mts. WNC- Sylva, NC
I need some good clear tech info, please! I have burned up 3- TF999's ( 32RH ) in just over 3 years! They SUCK ( with MY setup anyhow )!!!! I was wondering IF/HOW I could upgrade to a stouter transmission without having to buy a $1000 in adapters to put a GM auto in it? I am on a VERY poor man's budget- and will have to what ever I can to get this thing running again! I have paid @ $1200 for each rebuild- WHEN I HAD A JOB- and can't afford that route right now- so...is this possible/ easy- bolt up? to both the 4.0 AND the stock transfer case ( 1993 YJ ), I have heard something about relocating the crank sensor on the back of the 4.0 to the front - but that's all I have ever over heard? I am desperate guys! ANY and ALL help/ advice would SOOOOOOOOOOO appreciated!!!! Thanx- A desperate wheeler!

ps; also- from day one after each rebuild all the way through till they died- IF the jeep had been sitting for a few days, when I put it in gear it would go in "sluggish"- kinda like VERY slow to engage the desired movement (IE forward or reverse) is that a common problem to TF transmissions? I once had a FS grand Wagoneer and it also did the same thing....maybe I just have crap luck with TF auto's?!?!?!?!? LOL
 
Go lower on axle gearing? Add a cooler? Lose some reciprocating mass (wheels, tires)?
 
IIRC, they're normally pretty stout, but have heard missing or misadjusted TV/kickdown cables will burn one up quick. Are you running without an external cooler or running in deep mud/water alot? What's actually failing on them?

Outside of length issues, maybe it's time for a tranny that doesn't require cables & band adjustments to run normally?

FWIW, a TH400 out of a Jeepster/Commando/Waggy/J-truck (NOT the QT models) with an AMC motor will work. You'd need the castiron bellhousing spacer/adapter, the crank spacer, & flexplate. A V8 flexplate might need rebalanced, but a 258 flexplate (OEM Commando/Waggy/J-truck w/ 258) should work fine. The downside is the bastard 15spline output, which equates to being stuck with a D20 TC or swapping another output shaft (32spline) for D300 input ($150+ input required)... no idea if the later D-side drop TCs (NP231/241/xxx) will accept 32spline...

With the same bits above + a plate adapter from Summit/Jegs, a GM (4x4) TH400 gets you 32spl. output from the start. Either would require aftermarket or GM 208(?) adapter to mate up.

Hesco & AA both make CPS relocation kits.

Unfortunately, none of this is going to be much cheaper or simpler than another 999 rebuild...
 
Thanx for the info. I have used 3 differen't shops- so it's NOT a rebuild issue ( I don't think?) and I have no intentions of going basck to wimpy- so the rolling mass (IE 37" IROKS" will stay as well. As for going to lower gearing- also not an option...I'm already running 3000 at @ 60 MPH so I don't wish to scream it an higher- and to add to ALL of the crap stacked against me- I live in the mountains and have a driveway at 30-35 % slope for around 800 feet- none of this is helping me- thats why I am interested in doing the HD TF727 swap. I am in an even deeper chit sandwich since I don't have a job anymore- WC ACL and meniscus torn- surgery and 8 months recovered- so good enough to get around- but still can't do what "normal " people do ...yet... So alas I turn to the NC4X4 guru's for help!
 
fbpd227 said:
The adding of a cooler would most certantly help me out- and I WILL add one this next time around- FOR SURE!!!
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You'd have thunk the folks taking your $$ would have made that recommendation. OTOH, why would they at $1200 a pop? :shaking:

A temp gauge (plumbed to your choice of output/input), would also let you KNOW when/if it enters the death range!
 
Caver- IN a perfect world I would be running the TH400 - like I had in my 79 CJ. That wouldn't die! and believe me....I was hell on it! and the best part was- like you said- it diodn't have ANY crappy cable or band adjustments! All I had was a small vac line running down to it and that's it! It was truely Bullet Proof! ( but was also a very expensive project at the time...lol...400 HP 350, th400, dana 300 60's f/r and 39.5 boggers- sweet- wish I NEVER sold it!!!!!!!!!!!!!!)
 
The last tranny rebuild I paid for was in Anderson, SC at AMCO- $1187.00- so I got it in the kester just as bad there as I did in some of the NC shops I have used....Just doesn't seem to matter where you take a jeep ( or any 4x4 for that matter ) it WILL be over $1000 ( Paid almost $1500 for a Chevy 700R4- mostly labor to pull/ re-install) NO MORE! I will spin my own wrenches and stab as many used junk yard tranny's as I can find in it for way less than these shops are hitting me for! LOL
 
I just don't want to re=build another anemic 32RH slush box just to watch it die- exactly anytime after the 12 month warranty is out. It just seems to me that IF I can do this TF727 resonably- myself- that it would be a WAY better tranny - much heavier duty and much longer lasting!
 
I ran 999's (32rh's) for years with no issues. I mean total thrashing, forward to reverse at 4000 rpm, beating the piss out of them. Never any issues at all. In 10 years of building trannies at my dealership, we have never been into one at all.

Mine was behind a worn out 4.2 and later behind a very stout 360.

If it was built correctly, with a GOOD cooler, it will last for years and years. Proper TV cable adjustment is of utmost importance on any TF tranny.Was it properly adjusted?

Something definately screwy with the build or lack of cooling.
 
Cooling very well could have been the biggest issue- I have an 800' +/- and all at 30-35% grade- running 37" IROKS, 4.88 gears, and the 4.0 ho- so just about every day I am driving this thing up or down steep grades and under load ( of tire size ) so it's very likely alot of heat is momentarily generated- but over a period of time I'm sure the short hard bursts of driving under that load ( to get to my cabin) takes it toll. As far as the TV cable- I couldn't tell ya? It was built ( the last time ) by AAMCO in Anderson, SC ( a year and a half ago- and I have driven it almost every day ( short distances- 25-30 miles or less ) so I couldn't elaborate on if part of the problem lies there as well. My thoughts were to go with the much stouter TF727 BECAUSE of the terrain ( mountains- as you know )around here-hoping that might last longer than 1- 2 years/ 32RH. I WISH I had your shop build mine in the first place- so I wouldn't be writing this right now! Candler is Not very far away from me- what's a QUALITY rebuild gonna run me over there for a 32RH (999) that WILL last me?
 
The 727 is only marginally stronger than the 999. The 999 can be built as strong as a 727 w/o much cost. Plus, the 727 does not hace a provision for the crank sensor. There are ways around this, but not easily.

The 727 is also wider than the 999 with a higher first gear. Something else to think about.

I am out of the building business for now. Sorry, cant help ya there.
 
Oh yearh- the first trans I have no idea what killed it- it was replaced just before I got it- and went out ( under warranty) and was replaced again prior to me taking posession of the Jeep- the next one @ a year and a half later- was a rear sprag ( I think that's what it was called- hard part failure) then the next one- this present one to die- has just killed clutches- no forward movement- unless reved real high and on flat ground- pulling it out will determine more acurately- just my best estimate ( from past exp ) of what's happened this time. I think I was actually given a "warning" sigh last week- when I went around a few corners ( cold still ) it "slipped" for a second. So there went my chance at figuring this out while it was still driveable to the shop! LOL. Guess I'll be pulling trans/ tranny as soon as it warms up this week. Thanx for responding and offering tips/ help/ exp.
 
On the same notion, does anybody run a tf999 with a manual valve body? Thinking about getting mine done this way when I have it rebuilt. To my understanding, this also does away with the kickdown cable.
 
Sprags break when doing forward to reverse shifts while under power (or vise versa). They are a common weak link in any TF tranny. There are HD sprags out there, I had one in mine.

Your current issue could be a number of things. Low fluid, low pump pressure, failed pump, converter, etc. You can actually diagnose it in vehicle. Rent a pressure gauge to test the pump and VB. Perform air pressure tests with the VB removed to test the clutches.Inspect bands. You may be able to repair it w/o major repairs.

Its like your engine, just because the water pump leaks, it doesnt mean you need a new engine. Parts fail, find out what and why. Then go from there.

There is a wealth of info out there on these trannies. Many drag racers run the 999's relative the 904. Look at how to beef them up and apply it to the 999.

Gotta get back to work now...
 
336wheeler said:
On the same notion, does anybody run a tf999 with a manual valve body? Thinking about getting mine done this way when I have it rebuilt. To my understanding, this also does away with the kickdown cable.
Click to expand...

I looked into it, but you will lose compression braking, which IMO is needed off road with an automatic.

I went with a Level 3 drag racing shift kit in mine. Couldnt have been happier. Shifted crisp even with 40's and 42's. Temps never got above 175* crawling, driving or under any conditions.
 
fbpd227 said:
I need some good clear tech info, please! I have burned up 3- TF999's ( 32RH ) in just over 3 years! They SUCK ( with MY setup anyhow )!!!! I was wondering IF/HOW I could upgrade to a stouter transmission without having to buy a $1000 in adapters to put a GM auto in it? I am on a VERY poor man's budget- and will have to what ever I can to get this thing running again! I have paid @ $1200 for each rebuild- WHEN I HAD A JOB- and can't afford that route right now- so...is this possible/ easy- bolt up? to both the 4.0 AND the stock transfer case ( 1993 YJ ), I have heard something about relocating the crank sensor on the back of the 4.0 to the front - but that's all I have ever over heard? I am desperate guys! ANY and ALL help/ advice would SOOOOOOOOOOO appreciated!!!! Thanx- A desperate wheeler!
ps; also- from day one after each rebuild all the way through till they died- IF the jeep had been sitting for a few days, when I put it in gear it would go in "sluggish"- kinda like VERY slow to engage the desired movement (IE forward or reverse) is that a common problem to TF transmissions? I once had a FS grand Wagoneer and it also did the same thing....maybe I just have crap luck with TF auto's?!?!?!?!? LOL
Click to expand...
Why not just go with a junkyard AW4 from a cherokee? Sounds like you could use the OD anyways with your deepish gearing. Google AW4 swap.
 
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