2G Balance shaft sprocket and seal weirdness

[406_Talon]

i am putting together my front case, I have one that previously had the shafts deleted and I am putting them back in before installing. The oil pump side goes fine, but the front balance shaft binds up completely when I tighten it. I am assembling everything correctly, the seal is in all the way and it is riding on the little seal boss sleeve as it should, but when I tighten it to the specified torque, it will not turn. I deduced that the gap between the flange and the sleeve seems to be too small, however this balance shaft spins just fine in the case it came from, which does not appear any different dimensionally, although I haven’t measured it. That case has a water oil pump housing though, so it’s trash. I put a washer underneath the seal boss to give it some more space and it works, my question is twofold: has anyone ever had this happen? And should I run it with the shim/washer in there, or buy a new front case?

 

[19Eclipse90]

@luv2rallye has some experience he might share with you on this.

 

[406_Talon]

Is there a thread of his I’m missing? I’ve been searching and I can find hardly anything that isn’t a bs delete thread . I try to be diligent about searching first haha. I’m gonna go find a shim, I think. That’s my current plan anyway. My backup is just pull my whole front case and bs out of another known good stock rebuild.

 

[19Eclipse90]

We had a conversation about it. He was trying to put on a new case and ran into the same issue with the front shaft locking up. I believe he ended up using the old case again but it's been about a year ago I may be a little off with my memory.

 

[406_Talon]

Well I tried to find a washer that would fit but they don’t seem to exist . Back to the drawing board.

 

[luv2rallye]

... the front balance shaft binds up completely when I tighten it. I am assembling everything correctly, the seal is in all the way and it is riding on the little seal boss sleeve as it should, but when I tighten it to the specified torque, it will not turn. I deduced that the gap between the flange and the sleeve seems to be too small, however this balance shaft spins just fine in the case it came from, which does not appear any different dimensionally, although I haven’t measured it. That case has a water oil pump housing though, so it’s trash. I put a washer underneath the seal boss to give it some more space and it works, my question is twofold: has anyone ever had this happen? And should I run it with the shim/washer in there, or buy a new front case?

Ah yes. I had the exact same problem 3 months ago and was wondering how long it would be until someone else saw it. My problem ended up being the new front case I bought (brand ECCPP from Amazon) had a slightly different dimension in that area than the Mitsu original (see measurement pics [hint: hold mouse pointer over each pic to see what you are looking at], 0.889" vs 0.865"). It took a long time to figure this out as the 2 cases look identical. So when the front balance shaft bolt was tightened, it pulled on the balance shaft until it butted up against the case rear and then wouldn't turn. {I ended up finally just paying the megabucks for a new real Mitsubishi front case (which then worked) as I also wanted to replace the oil pump which is part of it. And I returned the ECCPP case.}. In your case I suspect your engine probably came with the ECCPP case which worked fine w/o the front balance shaft. And now when you tried to install the front balance shaft you came across this issue. The classic problem with aftermarket parts (probably China as usual) never being exactly the same as factory parts. And the 2 cases look identical (with no identification markings) so you can't tell them apart. So you probably either will have to run w/o balance shafts, or get a real Mitsubishi front case if you want balance shafts.

I also tried using a shim/washer (which then allowed it to turn) but decided against it because the gear hole opening then doesn't fit snug enough on the shaft end to get a good grip (out farther by the shim thickness). So I was worried it would elongate the gear opening (destroy its shape) and start turning on the shaft. It already wasn't even all the way on and the opening wasn't very snug. I made sure to use red lock tight on the bolt due to this.

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[406_Talon]

This is exactly the issue I’m having. I’m gonna use a low mile oem front case I have and see how that goes. Did you give any thought to having a machine shop try to shave the boss on the front case? That was my other idea to still be able to use this case with a front BS.

 

[luv2rallye]

No I didn't.
{But what are you going to shave and how would you know how much? Are you going to keep bringing it back shaving off another 0.001" each time? And would you shave the case risking it won't then crack under operating conditions? Or shave the spacer which means you'll have to shave the gear too since it will hit the case (and then risk not having the B belt fully on the gear)? Or what...?}

 

[406_Talon]

Hmmm I’m not sure I guess I would just try to measure the difference with calipers and probably take it off the inside.

No I didn't.
{But what are you going to shave and how would you know how much? Are you going to keep bringing it back shaving off another 0.001" each time? And would you shave the case risking it won't then crack under operating conditions? Or shave the spacer which means you'll have to shave the gear too since it will hit the case (and then risk not having the B belt fully on the gear)? Or what...?}

Hmm, I’m not sure I guess I would measure the difference and just take it off the inside of the case, that way the gear wouldn’t interfere and I think it would be ok. if it’s thicker than stock I wouldn’t be concerned turning it down to stock thickness in that small area.

 

[406_Talon]

So, I have my rotating assembly in, everything is good, I have my front case with balance shafts installed and everything, and I slide it in and the oil pump shaft is fine, but the B shaft is tight enough I have to turn it with a wrench. It is not binding on the case, everything turns freely until the B shaft (front Balance shaft) engages the last half of the rear bearing. I popped the balance shaft out, flip it around and verify the front bearing is fine by inserting the front journal of the BS in the front bearing, backwards, and it’s smooth as silk at all points. It’s definitely the back bearing on the front shaft. I looked with a small camera and it was a tiny bit marred from installation. (Although not bad enough I thought it would cause the issue.) So I knocked that bearing out just to be safe, and ordered and installed a new one. I used a bit of thin oil and it drove in straight and looks fine, but it’s still the same tightness. I’m just testing it with the shaft by itself now, and the last 1/4” or so of the shaft feels hard to install. It spins freely all the way up until I pop the last 1/4” in and then it gets hard enough that it takes a wrench. I mean, just like barely using a wrench, it takes maybe 1-3 ft-lbs on the ol’ biological torque-o-meter. And it does spin smoothly. I can’t find a spec for the oil clearance on these bearings, but my old motor the case came from was really easy to turn the shaft with two fingers...nobody seems to make a oversized bearing for the BS either. I’m the bearing is not ridged or mushroomed or scratched at all, and the oil hole is lined up right. I’m baffled. I was giving some thought to “honing” it with metal polish and a spare balance shaft, does anyone think that seems ok? How would I know when I’ve removed enough? Just by feel? Should I just have the shaft turned down .0005-.001? Should I just try to have a machine shop line home the balance shaft bores and get new bearings again? I hate that idea, I just got the rotating assembly in. (I’ve learned my lesson there too, make sure the damn BS works before putting pistons in!) Or, finally, should I just give up and delete the shafts? I have a GSC elimination kit and I could just put that in. I’m trying to keep the BS for the sake of the synchros in my Jack’s built trans I just got. It’s just a full synchro build box and I REALLY don’t wanna trash it.... Any advice would be very much appreciated!

I am gonna throw in the towel tonight but tomorrow I’m gonna mic out the two balance shafts I have, I’ll post the numbers. Unfortunately I can’t measure the bearing ID because my bore gauge is not long enough. Maybe I can rent one. For the clearance, based on the size of the shaft I would imagine a clearance of .0015 +/- .0005” would be appropriate, right? Would I be better a bit loose on the BS bearing since it has basically no load?

 

[luv2rallye]

I don't have any answers to those questions but am interested in how this all turns out. Just FYI I replaced the front case with the engine still in the car! So anything is possible when you set your mind to it.

 

[steve]

Just FYI I replaced the front case with the engine still in the car!

 

[luv2rallye]

So you did too huh Steve. Is that from your 91 GSX?
Here's my 99 GST.

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[steve]

Yep, Last TB change I pretty much stripped the front side to replace the seals, water pump, and do the BSE.

 

[luv2rallye]

I’m trying to keep the BS for the sake of the synchros in my Jack’s built trans I just got. It’s just a full synchro build box and I REALLY don’t wanna trash it....

I'm curious about why you think you need the BS for the sake of the synchros. Do you think the extra vibration with no BS will damage them somehow or...?

 

[406_Talon]

Well, I have been in limbo but I found part#s for .001 oversized BS bearings:
MD082301 = left shaft front bearing
MD082302 = left shaft rear bearing
MD103723 = right shaft bearing.
I ordered them, then got the dreaded “this part no longer exists” email from the retailer. I tried a couple more places, same result. Only the one I need is unavailable. I have an order in with STM, but they said it’s back ordered. So I tried one last time, found an eBay listing for one new in box in Puerto GD Rico and it should be here today or tomorrow. I think my block needs a BS line hone, perhaps distortion from the main and head studs has caused a slight misalignment. Like I said the BS bearing takes some serious shoulder to hammer into the seat on this block, maybe it’s just a crap casting. I will update as soon as I get the bearing. If its still tight I’m gonna have a machine shop turn .001” off the bearing ID. I also considered turning the shaft down .001” but that’s gonna be my last resort. Well, second to last. Last resort is deleting the BS.

I'm curious about why you think you need the BS for the sake of the synchros. Do you think the extra vibration with no BS will damage them somehow or...?

I dunno, Jack’s seems to think the harmonics contribute to clutch drag, I just got this trans and I don’t wanna F it up. I also just feel like the BS belt isn’t necessarily a big problem, I have had a 6 and 7 bolt with BS and I never broke the BS belt in a lot of miles between the two cars. I don’t want a buzzy car, either. I’ve ridden in a GS-T that was BS deleted and it was super buzzy but it was also a total shitbox, so I don’t know if it was a good indicator . I suppose that maybe deleting would be a better call than doing the oil clearances by feel though. I dunno. Shit thing is I can’t measure the ID of the installed bearing, and they fit on the shaft fine right out of the box so maybe I should just delete the BS.

 

[luv2rallye]

I ordered them, then got the dreaded “this part no longer exists” email from the retailer. I tried a couple more places, same result. Only the one I need is unavailable. I have an order in with STM, but they said it’s back ordered.

Ya I run into this all the time. Mitsu dealers list it as available (or even in stock) when it isn't. And calling them asking if it really is gets you nowhere. Many say it's back ordered but you'll never hear back from them. I called each month for 3 months waiting on a so called "back order" until I demanded a real answer for the delay and one guy (but not others I asked at the same place) finally disclosed it's unavailable.

 

[DSMPT]

IIRC, OEM oversize bearing is only 1.0mm. ACL can also be an option for oversize balance shaft bearing set. They have 0.25mm and 0.5mm.

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Just for in case, did you check the shaft straightness?

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[406_Talon]

So it would appear that my part numbers are incorrect the MD082302 that I got does not have an oil hole so that’s the incorrect one. I’m gonna try having bearings turned down at a shop or I’ll try a set of ACL’s next, the other part numbers for the OEM appear to be unobtanium. And my shaft is perfectly straight, I have two sets from recently running engines. I can’t really measure them but they both spin fine in my spare 120000 mile factory shortblock. And even in the tight bearing they spin uniformly all the way around, no binding.

 

[DSMPT]

So it would appear that my part numbers are incorrect the MD082302 that I got does not have an oil hole so that’s the incorrect one.

Yes. I think you got confused when you placed the order. What you needed to order was a MD082301 and MD103723. Those two are the RH oversize bearings with oil feed hole.

 

[406_Talon]

I just realized I should have updated this thread, I ended up having my local machine shop take .001 off the ID of the rear BS bearing, and it's in the motor now. If it was a bad idea I'll make aure to post the results.