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Username Post: 1957 Treadlevac (i think)        (Topic#348210)
boybowser 
Forum Newbie
Posts: 5

Reg: 02-05-17
11-14-17 05:43 PM - Post#2714393    

Need some help restoring a 1957 4dr HT which has seen better days, although it is looking more like it did in 1957. Having some difficulty with the tredlevac power brake system I cannot put my finger on. It was not functioning and looked pretty rough when I found the car, since then I have rebuilt it and off the car it seems to function as expected, on the car I am unable to get the pedal to return and am beginning to believe the pushrod itself may be the issue, what is the correct length for the push rod on a 1957 Chevy Belair tredlevac. Also how to tell the tredlevac is correct for the car. Any help is appreciated.

Thanks



 

Jalapeno 
Senior Member
Posts: 9631
Jalapeno
Loc: The Republic of Texas
Reg: 04-30-00
11-14-17 05:51 PM - Post#2714395    
    In response to boybowser

Welcome to Chevy Talk.

Pics of the Treadle Vac would help ID it. TriFive T-Vacs were a bit unusual in that the vacuum tee was on the passenger side; most T-Vacs it was on the driver side.

55, 56 and 57 units were interchangeable installed on the car, as far as function goes. They were very different internally.


Jalapeno


 
Jalapeno 
Senior Member
Posts: 9631
Jalapeno
Loc: The Republic of Texas
Reg: 04-30-00
11-14-17 05:58 PM - Post#2714398    
    In response to boybowser

As for the problem you are getting, where the pedal does not return all the way: it is VERY important that the pedal return fully, especially the last fraction of an inch.

A couple of common causes:
The inner surface of the booster is corroded, it must be really smooth,
New leather seal for the vacuum piston is sometimes way too stiff, use an original one if it's in good shape,
Lubricate the leather seal and the booster with neatsfoot oil,
The large spring can get weak and compressed over time, try stretching it out a little,
If all else fails, use a non-PB pedal return spring on the pedal.

Jalapeno


 
boybowser 
Forum Newbie
Posts: 5

Reg: 02-05-17
11-14-17 06:09 PM - Post#2714401    
    In response to Jalapeno

The vaccum tee is on the (I am presuming you are referring to the tee which on the power cylinder itself and it is on the passenger side, not sure how to post pictures on this site yet, most of my activity has been on the tri-five forum.



 
boybowser 
Forum Newbie
Posts: 5

Reg: 02-05-17
11-14-17 06:15 PM - Post#2714403    
    In response to Jalapeno

This begs another question, from your response I am presuming the master cylinder plunger would not be at fault. The inside of the canister is clean and smooth, I used some emery cloth on it.



 
Jalapeno 
Senior Member
Posts: 9631
Jalapeno
Loc: The Republic of Texas
Reg: 04-30-00
11-15-17 08:19 PM - Post#2714577    
    In response to boybowser

The last fraction of an inch of the pedal return should move the tipper valve. The tipper is located at the bottom of the reservoir. With a flashlight you can look in the MC cap hole and see it.

The seals in the MC are stationary, it's the MC rod that moves.

Did you use a new leather seal in the vacuum piston? Did you use any lubrication on it?



Jalapeno


 
boybowser 
Forum Newbie
Posts: 5

Reg: 02-05-17
11-16-17 08:28 AM - Post#2714628    
    In response to Jalapeno

To answer, yes leather on vacuum piston is replaced lubricated and seems to move smoothly in canister., regards the tipper valve are you referencing the master cylinder, i presume you suggest remove the compensating valve, if so and I see no valves in that area. On another question, how loose should the plunger in the MC be I have some slop, do you know where I can purchase a sleeve if needed or will it need to be manufactured. The kit I used to rebuild came from Harmon Classics and had a fair amount of seals but not everything, at over $200 I expected a more complete kit than what I got. Also the push rod does not say in the valve plunger as described in the assembly manual, should this be a problem.



 
boybowser 
Forum Newbie
Posts: 5

Reg: 02-05-17
11-16-17 09:30 AM - Post#2714641    
    In response to boybowser

Okay, another question, do you have a measurement for pedal to floorboard (metal not carpet when pedal is fully retracted I have 3 1/2 inches, does this seem correct or should it come higher?




 
Jalapeno 
Senior Member
Posts: 9631
Jalapeno
Loc: The Republic of Texas
Reg: 04-30-00
11-16-17 08:43 PM - Post#2714719    
    In response to boybowser

  • boybowser Said:
To answer, yes leather on vacuum piston is replaced lubricated and seems to move smoothly in canister.,
What lubrication? Neatsfoot oil? Regular light oil is NOT recommended, it dries up quickly. And again, new leather seals can be too stiff, and will not allow that last bit of return , which is critical.

regards the tipper valve are you referencing the master cylinder,
Yes

i presume you suggest remove the compensating valve, if so and I see no valves in that area.
No, I am not suggesting removing anything. I was explaining why the last fraction of an inch of pedal return is important.

On another question, how loose should the plunger in the MC be I have some slop,
Slop in what way? There is a lot of play around the rod, there is nothing hard holding it in place, you can wiggle it pretty good before assembling the booster and vacuum piston.

do you know where I can purchase a sleeve if needed or will it need to be manufactured.
No, it is a custom sleeving job. New MCs are available, and cost about the same as a quality sleeving job, about $200.

Also the push rod does not say in the valve plunger as described in the assembly manual, should this be a problem.
Do you mean "stay"? And do you mean the the push rod that comes out the back with the eyelet that attaches to the lever/link/pedal? Or..?




Jalapeno


 
Jalapeno 
Senior Member
Posts: 9631
Jalapeno
Loc: The Republic of Texas
Reg: 04-30-00
11-16-17 08:48 PM - Post#2714721    
    In response to boybowser

  • boybowser Said:
Okay, another question, do you have a measurement for pedal to floorboard (metal not carpet when pedal is fully retracted I have 3 1/2 inches, does this seem correct or should it come higher?




No measurement but that sounds about right.
Can you physically pull the pedal up to get it to return all the way?


Jalapeno


 
Jalapeno 
Senior Member
Posts: 9631
Jalapeno
Loc: The Republic of Texas
Reg: 04-30-00
11-16-17 08:49 PM - Post#2714722    
    In response to boybowser

  • boybowser Said:
not sure how to post pictures on this site



Here's a good explanation on posting photos:
http://www.chevytalk.org/fusionbb/showtopic.php?ti...

Jalapeno


 

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