c-4 engagement problem

c-4 engagement problem

Joined: August 23rd, 2011, 8:59 pm

August 23rd, 2011, 9:16 pm #1

I purchased a used c-4 and convertor for a 32 5 window cpe i am building installed it behind a 302. The transmission is full of new fluid type F . The engine has to be reved up b/4 the transmission will engage which it does so suddenly. is this a convertor problem, pump problem or does the forward band need adjustment ? could it be that the servo o ring is sticking after sitting ? Thanks for some one answering this ?
Last edited by mrputz1 on August 23rd, 2011, 9:37 pm, edited 1 time in total.
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Joined: July 17th, 2011, 7:07 pm

August 24th, 2011, 12:26 am #2


How does it engage in reverse?

The forward engagement is via the FWD clutch pack, not the band. The front band is used for 2nd gear.

Common problems with C4 forward engagement ranges from low oil level, to misadjusted linkage, to internal trans troubles.

Knowing how it engages in reverse helps to troubleshoot the problem. When asking for troubleshooting advice, its best to provide as much info as possible about all aspects of trans operation. That helps us narrow down the trouble.
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Joined: November 18th, 2004, 4:20 am

August 24th, 2011, 2:25 am #3

I purchased a used c-4 and convertor for a 32 5 window cpe i am building installed it behind a 302. The transmission is full of new fluid type F . The engine has to be reved up b/4 the transmission will engage which it does so suddenly. is this a convertor problem, pump problem or does the forward band need adjustment ? could it be that the servo o ring is sticking after sitting ? Thanks for some one answering this ?
I think the key word here is "USED".

But yes knowing how it engages in Reverse will help lots.

Just for the heck of it, undo a cooler line at the rad and fire it up.

If there is a good flow that means the pump is working.

If there is weak or no flow that means the pump may have been compromised.
Last edited by stuart40a on August 24th, 2011, 2:27 am, edited 1 time in total.
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Joined: August 23rd, 2011, 8:59 pm

August 24th, 2011, 2:27 pm #4

How does it engage in reverse?

The forward engagement is via the FWD clutch pack, not the band. The front band is used for 2nd gear.

Common problems with C4 forward engagement ranges from low oil level, to misadjusted linkage, to internal trans troubles.

Knowing how it engages in reverse helps to troubleshoot the problem. When asking for troubleshooting advice, its best to provide as much info as possible about all aspects of trans operation. That helps us narrow down the trouble.
I will follow your advice about reverse Sorry i didn't give a more complete description.
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Joined: August 23rd, 2011, 8:59 pm

August 24th, 2011, 2:29 pm #5

I think the key word here is "USED".

But yes knowing how it engages in Reverse will help lots.

Just for the heck of it, undo a cooler line at the rad and fire it up.

If there is a good flow that means the pump is working.

If there is weak or no flow that means the pump may have been compromised.
thank you for this tip . More information to follow.
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Joined: August 23rd, 2011, 8:59 pm

August 25th, 2011, 7:43 pm #6

I think the key word here is "USED".

But yes knowing how it engages in Reverse will help lots.

Just for the heck of it, undo a cooler line at the rad and fire it up.

If there is a good flow that means the pump is working.

If there is weak or no flow that means the pump may have been compromised.
No flow at idle at all. Only when engine is reved up. Reverse no operation sometimes it trys to lurch back
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Joined: July 17th, 2011, 7:07 pm

August 25th, 2011, 9:11 pm #7


As Stuart said in his above post, pump may be compromised (read worn out or NFG).

The symptom is no pump pressure at idle, the causes might be...

1. Low oil level

2. Pump sucking air due to blown valve body gasket or blown pump gasket. (not too common, but does happen)

3. Pressure regulator valve stuck wide open. (due to other damage/debris in trans, if the valve is stuck, you can bet there is other damage)

4. Pump damaged due to improper torque convertor installation. (pump gear drive flats not aligned when tran and convertor bolted up to engine, causing immediate "wipeout" of the pump when engine is started)

#4 would be my guess...
Last edited by galaxiex on August 25th, 2011, 9:12 pm, edited 1 time in total.
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Joined: August 23rd, 2011, 8:59 pm

August 25th, 2011, 9:17 pm #8

Jegs has a TCI trans pt#511238 its for the later years of 1970 26 spline small bell hsg b/4 ordering will it adapt to the 157 tooth flex plate and it appears that i will have to shorten my drive shaft also to use it in place of the early c-4 any help here would be appreciated
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Joined: November 18th, 2004, 4:20 am

August 26th, 2011, 6:39 am #9

$799.99 is quite a chunk of change.

It does not come with a bell housing so you would have to put yours onto it.
I don't notice mention of a convertor. That would be another hunka moola.

As for length, unless yours has a bolt on flange it should be the same.

Aren't there transmission shops where you are that could build this one for you?
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Joined: August 23rd, 2011, 8:59 pm

August 27th, 2011, 5:53 pm #10

Its more like $1137.00 with the shipping and torque convertor. I have the Bad shoe rebuild DVD's and have reviewed them 6 times now. having never rebuilt an automatic i was a little intimated but Ken's dvd is very through. So i went to Transtar and bought a rebuild kit and bands SO HERE WE GO. I do think i will get a rebuilt torque conv. I have a trans that i got which some one didn't install the torque correctly and brokr the large splined shaft off by drawing the thing up with the bolts. I bought a pump from transtar and will use it . In ken's video he slips the nbr 1 thrust washer between the pump on mine the thrust washer is a little thicker than the the space since the nbr 2 washer sets the 8 to 42 tolerance is it ok to use the thicker nbr and adjust using a smalle ror larger nbr 2 ? Thank you for your help George
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