Allison 6sp: first time allison build c1 clutch issues

Jan 28, 2014
33
7
8
hey guys im having issues with my trans i just build worked great for about a day and then it started binding in reverse and really clunking into reverse and it had a few second delay when shifted into drive and it kept getting worse and started going into limp in! so i took the trans out i was suspecting it was a problem with the c1 clutches and sure enough the brand new c1 pack is fried i did some investigation and realized i had installed the clutches friction down instead of friction up like the instructions clearly said. any way i know this is obviously a problem but i just wanted to cover my bases and make sure this doesnt happen again. my thinking is that as long as they where installed steel to friction (which they were) they should work or is there something im over looking hopefully one of you transmission experts on here can help me out
 

IOWA LLY

Yes, its really me
Feb 23, 2007
2,275
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What was your clearance? How did the C1 stack start? And how did it end? Meaning if they were all friction side down, was the first plate internal, or external spline?

What was against the backing plate? Internal or external?


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Jan 28, 2014
33
7
8
i failed to check the spec on the c1 clutch pack... ya i know rookie mistake and i beleve i started with an inside spline and ended with outside spline
 

onebaddmaxxx

Active member
Feb 22, 2009
1,212
1
38
Cecil County Md
That would have been fine if the friction side was facing up. if it was facing down it should have been external down first against apply plate, ending with an internal against the backing plate.
 

IOWA LLY

Yes, its really me
Feb 23, 2007
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ok so i guess that was my problem then? just curious why that makes a difference?



Seriously? You can't look at it and see why?

The reason is this, since the back plate is "internal spline", and you ended with an external spline plate, you had metal on metal parts spinning against each other......


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IOWA LLY

Yes, its really me
Feb 23, 2007
2,275
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Also, not checking clearance is a terrible mistake.

You should probably have a professional go through and redo it at this point honestly.


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JRein

Aircraft Mechanic's Hero
Sep 26, 2015
212
0
16
LRAFB, Arkansas
I'm no expert but a few words of advice is go slow, place removed parts as they should be installed, triple check your work, and with today's tech take pictures to help yourself later.

This will probably be a very expensive lesson but I wish you the best of luck with it.

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THEFERMANATOR

LEGALLY INSANE
Feb 16, 2009
3,890
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ZEPHYRHILLS, FL
ALWAYS check clearances. I don't care if you're reusing a pack that you have previously checked, CHECK YOUR CLEARANCES! Crap happens, and checking is a good way to find mistakes before they get REAL expensive. You also need to be pay close attention to things like the c1 stack and metal to metal spinning against each other. You also need a manual so that you know HOW to check the stack's for clearance.
 

Blackmax123

Member
Aug 2, 2014
683
1
18
central Pennsylvania
I have always double and triple checked clearances. I also did take pictures with mine and worked in steps. Before I did my first one I went though the manual and made notes in the manual using the directions from suncoast on what they wanted for clearances and what order they wanted the plates stacked and how many they're were compared to stock.