Allison 5sp: Harsh 4-5 shift or harsh lockup?
- Thread starter Devon
- Start date
The one in your truck works the best. I used your OS in my '04 LB7 for 6 years and loved it. I didn't have use of my O/D cancell button with it but I didn't care. Your O/S is the dumbest one out there and that's what makes it so good.
Now that u guys mentioned about the OS George had said something about me maybe having to switch Os's i guess the earlier os will shift funny .. but from what i rember him telling me it was down shift from 2-1 and if i was in tow haul he said its brutal to the point were abs kicks on...? Again guys im new to this whole thing so i havent got a clue about os's and such:thumb:I dont even know if i have a early os or not or how to even check i do have efi live so if any of you guys could explain what to do id be real happy with that:hug:
I know 100% I have an 01 OS in mine, and it's a crapshoot wetehr it unlocks or not under a 4-5 WOT shift. It does some wierd stuff sometimes, but shifts the most consistent of the ones I've run.
Ive run an 01 os for years, never had unlock on me, shifts the best by far, my next favorite is the latest updated 05 tcm file, it acts pretty reasonable other than seems to wanna jump up through the gears to quick when just crusing...but maybe that just me!
A little update, changed Allison spin on, and fuel filter today. The truck feels like its shifting through the gears alittle better. Not defueling as hard as before. But that could be because of a old fuel filter. The Trans still bucks between 3-4 though. Between needing the taps reset and some new tuning, I think it will be better. Hopefully!
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Curious to see the outcome. My truck seems very similar to what you're describing. I realize its gonna lock up hard, but I don't think it should be this way. I figured I had something wrong with the C3's, but looks like others have the same issue.
Also, I have a bellhousing leak and I'm fairly certain its the converter. It came directly from Precision around November of '11, was there a "leaky" batch around that time?
Thanks for your time,
Blaine
Also, I have a bellhousing leak and I'm fairly certain its the converter. It came directly from Precision around November of '11, was there a "leaky" batch around that time?
Thanks for your time,
Blaine
Well I just realized that the abs can effect the Trans is a negative way as well. My abs light has been on since I bought the truck last week. I read on some page that it effects the way the Trans can shift and also TC lockup. So I have to find the problem with that an then go from there. I'm going to flush ye Trans fluid out, put a new internal filter on aswell.
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no allison OS will ever unlock the converter during a WOT UPshift. If you stomp on it, the converter locks and will stay locked through all of the shifts.
early TCM OS's unlock the converter on a WOT DOWNshift, then relock....but upshifts, its all locked.
Mine will sometimes, just like sometimes it will defy teh lock-up tables and hold lock-up in 4th down to 28 when it downshifts to 3rd, and all kinds of other wierd crap. Maybe it's because mine doesn't see all of the normal inputs a truck would.
this is exactly what mine does day in and day out. As i found out, if you have a HARD 3-4th up shift and the trans was built by one of our very reputable trans builders here, better start looking at your ECM tuning.
I'm beginning to think it is in the tuning. The PO said he had robs dsp5 tuning on here. I have had robs tuning as it ran a lot better and shifted better than this does. I'm going to be buying another v2 or autocal in the next couple weeks and put the stock map back on the truck and reset taps and relearn and see what happens.
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I bet your tcase chain is jumping teeth. Had a guy that thought his rear end had busted a tooth or 2 off the pinion and thought his pig was done. I drove the truck and wasnt sure what was going on with it but I popped the cover and to confirm my initial thought it was the tcase. So I pulled the tcase after we got it to my shop and it had anhilated the guts in the case. Shift forks trashed bearings trashed and what it ended up being was the tcase chain jumping teeth from the bearings being bad. Did not do it at lower speeds but once you got her up to highway speed it started jumping about every 5-6 seconds. Made the truck bang and shudder and then was smooth again for a few hundred yards. Check the oil in your tcase if it's trashed id say your tcase is junk.
On edit I realize your having trouble when the tranny is shifting but maybe your 85mph clunk is the tcase.
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