Converter Snout Loosening up?

Hoping someone in the ITA crowd has been through this frustrating issue:

Application is a Lenco with Bruno drive behind a Chance NXS converter (has bolt-on snout held in place by qty 7 x 5/16-24 bolt pattern). On multiple occasions, after a weekend of passes, I get a trans fluid leak in the bellhousing area. On disassembly (involves pulling trans and motor), the converter snout has loosened up and the fluid is coming out between the converter front cover and the snout.

Talked to Chance, they said they use green Loctite on the snout fasteners and dont have an issue. I tried that the last two times and still have had the issue.

On mockup assembly this time, I checked snout runout. I'm within +- .003". I do not know what the runout was on previous installs, as I didnt know to check it at that time.

I think the correct order of assembly for the bruno/torque conv/bellhousing is to bolt bellhousing onto Bruno, slide torque conv into Bruno (with snout engaging the pump) and then mate that up to the block--with the final step being bolt the torque conv onto the flexplate. Problem is i cannot check torque conv snout runout once everything is bolted up that way--no access through the titanium bellhousing.

Anyone know of any tricks here? Should I be bolting torque conv onto flexplate first, and then carefully engage Bruno onto the snout? I've always placed converter onto Bruno first to ensure proper spline and pump engagement.

 

I can't speak to the specific issues but green loctite isn't for fasteners its for bearing and shaft fits. The red is the stuff you want. It used to be 262 now its 271. Permanent thread locker.

Corey

 

Maybe a bit of a forensic workup is needed? When you pull things apart, are the fasteners actually loose? Are you torqueing the fasteners to a given spec before hand? Does the snout have any signs of irregular wear or contact around its outer surface? Is this a lockup converter or an open converter? When you butt the converter up against your flex plate, does it seem to touch evenly at all points or does it give you the impression that it is cocked versus the plane of the flex plate? Do you shake and pedal a lot during a run? Theoretically those bolts should just be experiencing mild shear loads if all is aligned. There's got to be something else going on? Has this been a problem since the beginning, or did it appear in coincidence with some other change or event? Do you support the rear end of your trans, or is it all just hanging there as a big canti-lever bending load? Have you ever mounted the crank and flex plate, and then dial registered that to the back of the block? I'm going to make a guess that you either have some nutating excessive side loads, or bad vibrations, or a combination. Everything points back to an alignment problem.

 

This is a point where I will respectfully disagree. I am an industrial mechanic and on gas compressors ,turbines etc the green stuff just won't hold up, the red IS the strongest only heat can remove it. Like I said, no disrespect here but I am going to stick with my original statement. However the green sets up faster so unless you have 24 hrs for cure then maybe the green is better in this application. (between rounds and so forth)

All my honest opinion
Corey

 

I would indicate the bellhousing to see if maybe it is off some. If you are unable to find anything I would either drill the heads of the bolts and safety wire them or machine up some sort of a locking tab ring that will not allow the heads of the bolts to turn. If it uses a countersunk type bolt I would tighten them up and then bang each one with one of those impact drivers to really seat that taper in there good, it’s amazing the difference they make. Keep in mind if you “fix” this problem, the real problem may show up in another area.


The problem with using loctite on items that have the potential to get really hot is heat is used to break It down for easy removal, which leads me to the next questio; How hot does the converter get on a regular basis?


I have used the green for various things over the years but can say that I didn’t have good luck with it in high heat, side load situations.

 

I had a similar issue and it turned out it was my bellhousing centering on the crank that was the biggest issue. I made two offset dowel pins for the block to center the bell housing on the crank center line. I can usually get the bell housing centered to +- 0.002 or slightly less. The way I assemble is

1) clean crank and flex plate, check with machinist straight edge to make sure everything is flat.
2) bolt flex plate on crank, torque to 90 ftlbs and use loctit 242
3) Mount a dial on the block and check the flexplate back and forth "wobble" it is less than 0.001 in on my setup after torque.
4) Mount the converter and torque to 65 ftlbs (no loctite)
5) Mount the dial on the block and check the converter snout, should be less the +- 0.002 in. If it not take the converter of the flex plate and rotate it and recheck. Once the snout run out is good mark the converter and flex plate with a sharpie. Make sure you can see the mark through the bell housing opening.
6) take the converter off and mount the bellhousing and mount the dial on the flex plate and dial the centering of the bell housing to less than +-0.002

Now I go through the same steps you are to mount the bruno.

One thing you might want to check is the centering of the bruno case and pump with everything mounted. You can take the bruno apart and dial on the inside diameter where the pump normally is. It is very tight but it can be done. I had to fix my bruno where it centers in the bell housing.

The bruno pump bearing will tell you if you are misaligned.

I have a suspicion about heat cycles and the converter snout bolts.....

Hope it helps !! If everyone has something to pitch in on the above please do I... Love to learn

Thanks

 

Green loctite is significantly better at holding converter to flexplate bolts. Widely know fact and I've seen it myself. Only thing you have to make sure is the bolts and holes are clean and you get them torqued within about 2 minutes of application.

 

Does your snout mate into a register step of any sort? Or is it just one flange against the other (2-flats) with taper bolts holding everything concentric? A machined step would make things stronger for sure, however acknowledged it is hard to reverse engineer a manufacturer's existing product. Would be really interested to know your assembly clean up/off procedure for your snout, and what if anything you add for a sealant upon reassembly, and what your exact torque procedure is during assembly. If your fasteners are into aluminum, and if you have had multiple issues, are your AL threads now maybe compromised at this point due to repeated events? Thread-Serts maybe? Back to one of my earlier points, is this a new problem or has it always been ongoing?

 

Thanks very much for the input ITA--as always great input and awesome ideas for me to check out.

Most parts involved were new when first assembled (now about 12 passes total). Only item not new is the block (KB stg 6 hemi). They all fit very nicely and tight, doesnt seem like there is great potential for extra slop. This problem occurred right from the start. I would say that the last weekend out, the problem was the worst. All converter snout fasteners were loose, and 4 of the 7 fasteners were backed out--one of them all the way so that it rubbed on the Bruno seal/bearing. Definitely seeing high heat loading, thinking that heat cycling pretty much takes care of anything either red or green loctite would have to offer.

I'm leaning toward a misalignment issue which causes side loading of the snout--but it is going to be near impossible to check the alignment. The bellhousing offers an inspection port that is about 1.75"w x 5" long--very little area to reach in and do any runout measurements. By bolting up the bellhousing without the converter in place, I might be able to indicate the Bruno input shaft with the crank centerline. But that is going to be a real challenging exercise to get any measurements that are decent enough to draw conclusions.

I will mock up the assembly and measure as best I can--also post a pic or two. Thanks in advance for anymore suggestions!

 

Loctite (red or green) works poorly in the absence of ferrous material, including aluminum & 300 series stainless. Use primer or XX3 series pre-primered Loctite.

Chris Saulnier - Team Tigges
Mechanic Falls, Maine

 

Can I ask what temp the fluid in the Bruno is getting up to ? Do you use an off board cooler after a run ? Is it possible that the Bruno is getting too hot for the "Loctite" ?

 

My Bruno goes to 273 degrees every run and I've never had that problem with my Chance NXS. I don't use a cooler but I do cool it with a fan after the run. Whatever Marty put on the threads is still there.

 

The converter snout (which the fasteners bolt into) is a carbon based (magnetic) steel, most likely pretty hardened--so loctite should do a fair amount of good. Threads seem fine, the bolts "take" torque like normal.

HOWEVER heat is definitely the enemy. The fluid does get very hot--i dont have data, but at one point after a couple quick turn test passes, I did see Bruno case temps of over 225 after towing back to pits (scorched fluid, most likely over 300degs).

Next week i am picking up my new Kool Solutions external cooler--I will not put the Bruno through that temp cycle again.

 

it sounds like maybe heat is the problem , have a look into the fluid you are using and how hot it gets. We had a similar issue with heat and the viscosity of the fluid changed because of the heat. maybe this is the issue that is affecting the "Loctite"...... just my thoughts

 

Great thought, Will. I will measure thread depth vs fastener length when I get back to the shop. I do know the fasteners are "custom length", as in I can tell the ends were ground down from their original length. Maybe they weren't ground down quite short enough . . .

 

When I had an misalignment issue the bruno pump bushing and plate behind the pump would show signed of a lot of heat. i think this is where the heat is generated and transferred to snout and snout bolts that will see a higher load than when everything is square and in alignment.

Just for comparison I have a temp sensor in the pan right next to where the return dumps into the pan. I see roughly 10 F increase in temp during a run.

 

Mike & Corey and anyone who cares.......
Never speak in colors of Loctite !!! We need to learn by part #'s!
If you get your hands on a late book, you will find over 200 #'s for red,
anywhere from why bother, to it ain't gonna come apart.
Over 100 #'s of Blue, same results!
Over 80 #'s of Green, again same results.
We recently had a welcomed visit by a Loctite engineer and High up long time salesman to answer questions I had for our Billet 9"-9.5"- 10" Ford case while they were across the street at my supplier. They wanted to see our application and were extremely knowledgeable. I was using #271 for steel studs to aluminum that should never have to come out period. They recommended # 263 that is made for an OIL environment ! I also changed my Blue #242 to #243 also made for OIL ! NEW Technology marches on ! They also asked me to please throw away my CRC Stud Locker (label says compares to Loctite 271) Grin.........