Packard Forum Index » V-8 (1955-56)

JP, what does the steel liner(sleeve) accomplish? The T-V has no rubber cup and so is not required to have a complete smooth surface. Perhaps they sleeved the vacuum cylinder which many times has rust and corrosion??

QUote:
"...for what it's worth that Karps did fit a stainless steel liner into my treadlevac -..."

Yes, very well worth mentioning because, without detailed analasys, this is a major source of confusion relative to the BTV MASTER CYLINDER only.

THe BTV SUPPOSEDLY is "sleeved" or "liner installed" by rebuilders only at the seal bore in the very back of the master clylinder.

Conventional master cylinders have the full length of the piston bore lined.

NOTE: that the internal workings of the BTV is unorthodox compared to nearly all other master cylinders ever produced in the last 60 to 70 years.

See post #74 on page 8 of this thread regarding BTV sleeving and some of the posts prior to and after post #74 by Eric.

JP -

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I have long maintained that, because of the ram method of fluid displacement, the BTV did not require sleeving - at least not like other conventional master cylinder (single or tandem).

However, I see that I have to modify that position WRT to the fixed rubber cup seal.

The 55-56 shop manual clearly advises:

Quote:
I can see where scores or porosity issues in this location would cause leakage into the vacuum shell and, thus, require sleeving. However, none of the units that I've personally rebuilt with my own tow hands have needed it.

Meanwhile, IIRC, the high-mounted BTV's in tri-five Chevies had, essentially, the same innards as the units on our Packards. Of course, the cover was redesigned to accommodate the horizontal, rather than angled, orientation.

Lets consider a sleeve for the fixed rubber seal at the back of the BTV master cylender:

I've not done the math on it but if ANY edge or portion of an installed sleeve is subject to the tremendous pressure that any master cylinder can produce then it is certainly feasible that the pressure could push the sleeve OUT or dislocate it. No???

If the fixed rear rubber seal entirely covers the sleeve and no edge of the sleeve is exposed to pressure then it would stay in place.

"...IIRC, the high-mounted BTV's in tri-five Chevies had, essentially, the same innards as the units on our Packards."

The chevies used a 3 or 4:1 pedal ratio which means that the ram or piston would have been some 1" or larger compared to the 5/8" in the Packard with 1:1 pedal ratio.

IF the Chevy high mounted BTV was 1" RAM or larger then how did they seal it at the back of the MC???? It would have required a very large seal bore for a much larger seal.

It could not have been a 1" or larger ram type piston because the back of the MC is not large enuf to allow for such a larger fixed rubber seal.

We know there were at least two types of BTV--the poppet valve type we use and the hydraulic reaction type that Chev apparently used. If anyone knows Ed Strain or any of the other BTV rebuilders, wouldn't it be simpler to call and ask if there is any other internal differences in BTV units -- size wise, cup wise or any other wise rather than endless guessing.

IIRC, the rubber seal on the ram is backed up by a fiber and steel washer held with a snap ring in back, and of course, the ram and bore on the sides. I don't think it could be dislocated in the conventional sense--leaked past, yes.

Perhaps, then, I am confusing this with some other horizontal application of the BTV. Yet, I'm certain it had the same basic casting for the hydraulic section as the units in our Packards, but with a sloped cover.

ok. The snap ring would hold the sleeve in place. Good point.

As for the Chevy high mounted BTV vs the Packard toe board mounted BTV:

"...at least two types of BTV--the poppet valve type we (Packard) use and the hydraulic reaction type that Chev apparently used..."

--*-- Yes i agree to the extent that the chevy BTV is significantly different enuf from the Packard BTV so as to cease argument over any similiarites relative to any failure analysis or any other comparison of two different BTV's.

--*-- At this point I believe and any reasonable person can believe that the BTV as OFFERED ON PACKARD (no other makes) is significantly different from all other BTV applications.
Apparently so different in some way and the unusual failure rate of PACKARD BTV application that the Packard application of the BTV is inferior beyond any redesign, rebuilding or any other remedial endeavours by any mortal entity.