Glazing high gear clutches on the street?

Posted By: whiplash

Glazing high gear clutches on the street? - 05/04/10 02:10 PM

Just had my trns freshened. 727 behind motor in sig. the trans guy told me that the high gear (3rd) clutches were ok but glazed. He said every high stall converter with a high hp motor on the street glazes the 3rd gear clutches. His reasoning was that the converter is stalling at 3500 rpm and your cruising at 2000, so your always slipping, causing heat and glazing the clutches.

Not wanting to argue with him, I wanted to understand this reasoning more with you guys. I don't necessarily agree with the theory, unless the heat in the fluid around the clutches, not in the pan, gets hotter due to the slipping converter?
Could it be that there isn't enough line pressure at low rpms?
Does the slipping converter effect line pressure?
What do you guys think?

Posted By: maximum entropy

Re: Glazing high gear clutches on the street? - 05/04/10 03:25 PM

it would be good to put a temp gauge in that thing, but, the direct clutch may be slipping, which has nothing to do with your converter. is it an automatic valve body? is your throttle pressure linkage adjusted properly? it could be a line pressure issue, inadequate clutch disc clearance, or possibly a clutch piston seal problem, among others. fwiw, i have a "high horsepower high stall" car that gets driven on the street- a lot!

Posted By: Dragula

Re: Glazing high gear clutches on the street? - 05/04/10 04:41 PM

Lack of a deep trans pan causes the pan to go dry on the upshift from 2-3 and then it kills the clutches. 1-2 will be ok, but it need more oil for the 2-3 especially if you have a shift kit, after market VB or tend to shift at higher rpms.

The clutches do not slip when just driving on the street, only during gear changes which should be nearly instant if you have an after market VB. The convertor is the slip link between the motor and trans, and the clutches should always be locked up. Anyone who tells you differently doesn't have a clue.

Posted By: whiplash

Re: Glazing high gear clutches on the street? - 05/04/10 05:21 PM

thanks guys, the above post is how I understand the workings of it. So the glazing could be happening from not enough line pressure, or if the 2-3 shift is not instantaneous.

FWIW, the trans is an auto valve body, deep pan, trans temp gauge never goes above 180 (sending unit in pan), has a cooler on it. The shift linkage is set correctly. The trans itself was originally a TCi super street fighter that I recently had rebuilt(not by TCI), so the VB has some mods to it by TCI.

Posted By: JohnRR

Re: Glazing high gear clutches on the street? - 05/04/10 05:43 PM

Quote:

thanks guys, the above post is how I understand the workings of it. So the glazing could be happening from not enough line pressure, or if the 2-3 shift is not instantaneous. {b] Only if you have a huge overlap issue and it has alot of miles on it

FWIW, the trans is an auto valve body, deep pan, trans temp gauge never goes above 180 (sending unit in pan), has a cooler on it. The hottest fluid is coming from the convertor , it's the line at the front of the trans , I'd put the sender for your guage there .

The shift linkage is set correctly. The trans itself was originally a TCi super street fighter that I recently had rebuilt(not by TCI), so the VB has some mods to it by TCI. TCI stands for total [Email]CR@P[/Email] Inc.

Posted By: Dragula

Re: Glazing high gear clutches on the street? - 05/04/10 06:20 PM

Says you have the deep pan, but do you have the deep pan pick-up or an extension on the stock one?

As stated TCI sucks, and I completetly agree, and think the words sucks is a little mild for the crap they put out, but this is a family site so we will keep it semi-nice.

Posted By: dOoC

Re: Glazing high gear clutches on the street? - 05/04/10 06:25 PM

Me thimks your trans-guy should go back to school and take ..... Transmissions-101 !

HEAT would contribute-to maybe .5% of glazing of clutches. SLIPPAGE or a severe overlap of the 2/3 shift is the remainder 99.5% of potential probs.

Slippage ....due to low line pressure OR worn sealing rings OR leaking rubber seals and/or excessive clutch clearances.

Posted By: MR_P_BODY

Re: Glazing high gear clutches on the street? - 05/04/10 06:35 PM

I'm not a trans guy but its not due to the conv...
when you are street driving and are taking off with
just part throttle your engine isnt making the torque
to stall it at the higher stall point so its acting
more like a normal conv(it takes torque to have them
stall at thew higher point)... might just be the lack
of line pressure

Posted By: John_Kunkel

Re: Glazing high gear clutches on the street? - 05/04/10 09:39 PM

Quote:

Me thimks your trans-guy should go back to school and take ..... Transmissions-101 !

HEAT would contribute-to maybe .5% of glazing of clutches. SLIPPAGE or a severe overlap of the 2/3 shift is the remainder 99.5% of potential probs.

Slippage ....due to low line pressure OR worn sealing rings OR leaking rubber seals and/or excessive clutch clearances.

Listen to Doc.

Posted By: dennismopar73

Re: Glazing high gear clutches on the street? - 05/04/10 11:55 PM

never liked tci junk
i have hade several
buddy had acomplete trans /convert from them
bolt in with fluid
burned up in less than 300 miles and jegs didnt warrenty it because it went into a 'race car'
but
i agree with the above line pressure,
or miss adj bands

Posted By: turbobitt

Re: Glazing high gear clutches on the street? - 05/05/10 12:46 AM

Quote:

never liked tci junk
i have hade several
buddy had acomplete trans /convert from them
bolt in with fluid
burned up in less than 300 miles and jegs didnt warrenty it because it went into a 'race car'
but
i agree with the above line pressure,
or miss adj bands

I just rebuilt a TCI(Total Crap Inside) and found a mismatch of parts. This transmission had badly worn front and rear cluches and a stuck PR valve. The pump was a late model with wide bearing journal and the drum was an early type with narrow bearing.
Allan G.

Posted By: whiplash

Re: Glazing high gear clutches on the street? - 05/05/10 05:39 PM

ok thanks Doc, that's what I was thinking. 2-3 shift overlap due to less than adequate line pressure for whatever reason.

Yes it has the deep pan with the deep pan pickup. It started as a TCI trans, but I had it rebuilt with "better" parts (not getting into whta was changed cause it will cause a pi$$ing match and was not part of the problem).