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Discussion Starter #1
hi guys looking for input on this one. I BUILT a c-4 for a customer he has a 2800lb mustang with a small block on nitrous and the trans did great for two months and he brought it back with the forward burnt in it . now i put the early steel forward drum in it and blue clutches and this was the the only clutch pack hurt in it any ideas please ?
 

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Must have a good Positive shift pattern where the linkage hits the arm detentes perfectly or you can take them out quick...been there-done that.
 

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I burnt up the high gear clutches in my old C4 2 seasons in a row. I was using blue clutches in the stock drum. My tranny guy put in a Coan 6 clutch drum this last time....no more issues. I was running the C4 behind a nitrous 347 that made about 600hp in a 3050lb mustang using JD Hyguard in it.
 

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I had that problem ounce burned up 2sets of forward clutches high and band looked great. Talked to JR at dynamic he had me set clearance little tighter .020 by adding one thick steel and I went back to type f fluid never burnt a nother one again car ran 9.80s not aure on hp but 2960 lbs car
 

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If it is the forward clutch as in the clutch that is on in all forward gears a fluid leak is the only way it can burn. Unlike the direct the forward gets applied pulling the tranny into any forward gear so it never applies with big power on it.
Any time I have burnt it it is a sealing ring/ pump groove issue. Steel rings will wear the groove and new rings try to seal against a worn surface and leak likke crazy. Not enough pressure get thru to keep it from slipping.
Need teflon rings and probably a new pump.
 

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If it is the forward clutch as in the clutch that is on in all forward gears a fluid leak is the only way it can burn. Unlike the direct the forward gets applied pulling the tranny into any forward gear so it never applies with big power on it.
Any time I have burnt it it is a sealing ring/ pump groove issue. Steel rings will wear the groove and new rings try to seal against a worn surface and leak likke crazy. Not enough pressure get thru to keep it from slipping.
Need teflon rings and probably a new pump.
Agreed, not enough pressure on the forward clutch. Besides sealing rings, other things causing low pressure could be poor piston seal or in one case that happened to me, the check ball wouldn't seat completely and would bleed off pressure.
 

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I agree had high clutch prob dads trans inside of drum was wore I always use teflonseals on pump but bought trans used at swapmeet was a dynamic trans had allm good stuff in it just some wear in drum got overlooked by previous owner trans has a lot of passes on it now also did U check bellv washer got .080 snapring on bottom on bell washer I ussually get 225 psi at about 1800 rpm
 

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Discussion Starter #12
thanks for all the input the sealing rings are teflon i am suspecting the piston leaks if it were a pressure issue over the whole transmission the high gear would be burnt but its not . i am going to replace stator rings also .
 

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Its really amazing how critical fwd clutch clearance is on a trans using a belleville spring apply. Do some testing and you'll notice how much piston travel is required when you alter the cl;utch pack clearance by .010". Maybe you just started out with too much and it went downhill from there.


Hutch
 

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He sent you here to post that he suggests cast rings as the cure? Is that what you said?


Hutch
LOL ................... they are the cure alright ......................................................................... for something. :smt119
 

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He sent you here to post that he suggests cast rings as the cure? Is that what you said?:p


Hutch
Funny! I don't know him and have never spoken with him. All I do is try to provide good advice and try to make a living.:-D
 

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We had another companies C-4 come in a while back with a similar problem, we found they used narrow rings on a wide sealing grove pump, thus leaking by. We have seen this happen before. We found that different years used narrow or wide seals in the forward sealing ring area on the end of the front pump. Put the correct, wider seals in this area, problem solved. Burt
 
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