Dynaflow Problems

[old-tank]

If you remember the transmission exchange went well r&r dynflow

But the performance suffered: Right away I had problems when it got hot like chattering in low and reverse. It had low oil pressure (verified with a gauge and compared to a known good transmission in one of my other cars: 150 at the front pump vs. 200+). Anyhow I tried a few things like swapping the valve body (no joy) before I pulled it back out and took to the builder. The only visible problem so far is with the front pump. The driving gear has worn a groove in the front pump cover (yes the gears were installed correctly). Now we know why the oil pressure was low, but what caused this?? During the rebuild the front pump was replaced with a rebuilt unit (TRW) and the front pump cover was replaced with a new part. Also every bushing and thrust washer in this area was replaced.

(The transmission was originally from one of my parts cars and when first torn down was very worn and abused. The reason I had this one rebuilt was to do quick swap so the car was not out of service for a long time) Anyhow when inspecting the original parts there is a similar groove worn in the front pump cover.

I checked the engine crankshaft end play and it was within specs (0.005 in) and the flywheel/flex plate runout and it was ok (0.008 in).

This week I will pick up the torque converter and bell housing and attach both to the engine and check the runout on the hub.

I have a complete transmission for parts or rebuild, but would like to get a diagnosis before hand.

Any guidance is appreciated.

Thanks

Willie

[old-tank]

Well it is going back together with a

used pump and plate from a '61. The tolerances check

out and it has been tested in service. Never could

find an obvious reason for the failure. Maybe it is

that TRW rebuilt unit was rebuilt from a bad core or

may have something to do with the way they modified

the bushing on the driven gear.

These really are simple transmissions and I have

learned a lot and I think I could dissasemble and

reassemble another one now, but hopefully not mine!

[Guest imported_MrEarl]

Sorry to hear you're having these problems Willie. I'm sure it's got to be frustrating.

Excuse my ignorance but what is "TRW"

[Guest JT]

TRW was an aftermarket parts supplier.

[Guest sixpack2639]

Lamar, this is TRW. http://www.trw.com/

[Bhigdog]

Used to be named Thompson Ramo Wooldridge then got yuppified and changed name and logo.

[old-tank]

I got the trannsmission back late yesterday and spent the day installing which is about 2/3 finished.

The car needs to be Wa-a-a-y up in the air so that the tranny can be removed and replaced. This is higher than my jack stands and the upper limits of my floor jack so it had to be lifted and lowered in stages, the result of which made me nervous.

Here is a shot of a pile of tires under the rear 'just in case...'

and shots of the jackstands on top of 6x6's

and a shot of the bumper jack used to crank the torque tube and rear end back

I did just enough assembly to be able to roll the car over my service pit where I can finally stand up.

I hope to finish tomorrow and give you folks a favorable report and post some pictures of my favorite tools.

Willie

(don't be discouraged if the pictures don't load...this is another experiment: I set up a web server on an old Compaq 486 and so far it works, but let's see what happens if it gets lots of 'hits'.)

[JohnD1956]

Whatever you do, don't show these pics to your Mom.

JD

[Bill Stoneberg]

Or MaryAnn !!!

[70Wildcat]

A burp,fart or a sneeze and your history.

Mark Lewis

BCA#41402

65&70 Wildcats

[old-tank]

Got it installed and...no joy. Problem with reverse and the pressures are still not good. Trying to drive in reverse is like driving with the brake applied. I will call the rebuilder tomorrow and start crying.

Following is a shot of the transmission on the jack and the back of the engine...looks like I will see this view again...

Willie

[Guest imported_MrEarl]

Hey Willie, how's the new tranny jack work. Does it jack it into place as high as the car was.

[old-tank]

Lamar the jack works great. The car had to be that high so that there will be room to slide the tranny and jack under. You even have to tilt the bell housing down as depicted in the picture to clear the frame rails. And yes it does lift that high. I think the range is 6-32".

Willie

[Guest imported_MrEarl]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">A burp,fart or a sneeze and your history.</div></div>

I guess this means Willie was darn lucky then!!!

[Mrbuick714]

When a Dynaflow does not back up well,check the reverse ring gear and the supports in the case below it, If there is a ridge in the case where the ring gear rides,replace the ring gear AND case.

[old-tank]

Yesterday I swapped the valve body with a known good unit and there is no change...still locked in R until you give it lots of gas, then it jerks and shudders before moving normally; and then when coasting to a stop in R it jerks and shudders again before stopping abruptly.

Anyhow I took to the rebuilder the transmission that I removed from the car to rebuild completely using none of the parts from the troublesome unit. I have had all of the fun that I can stand.

Willie

[leishear]

I'm getting ready to fix up the 56 Special my brother rebuilt the engine

for 15 years ago. He said the engine is fine but that the car doesn't move forward. I'm guessing he meant "direct drive" wasn't working.

He said he thought a torque converter sprag would be the cause of this.

I'm planning on getting the engine running and then test out the Dynaflow to see if I have reverse, low, direct drive, etc.

Any thoughts on this please let me know. I figured since this post was on not reversing well somebody might have an idea about not going forward well

Thanks

[old-tank]

Get it running first then report back on abnormal noises and function along with pressures.

Willie

[leishear]

Thanks for the reply. I'll do that.

I'm looking over the pics of jacking one up since I'll probably have to jack it up like that. I have some 2.5 ton jack stands and a 2 ton floor jack but I haven't seen how far up those will get me.

Jon

[Guest sherlok]

Hi,

Stupid question, but I've been trying to get design info on a service pit such as you have. I'm building a new shop.

Did you design it yourself? What are its dimensions?

Thank you,

[old-tank]

sherlok

The dimensions are 32"wide x 58"deep x 8'long. I designed it and dug it larger to allow for later forming of the walls and floor. The depth is about right, but it could be longer if you don't want to have to move a car around to get to all of the underside. The width will handle all vehicles large and small.

Willie

[old-tank]

Jon

The jackstands are adequate as long as you can get the car at least 18' higher than the low point of the transmission jack....I had mine 25" high. The floor jack is OK for jacking the car (do it in stages), but don't use it on that heavy tranny (might get squashed like a roach).

Willie

[Dan O]

Hello all - this is a little late but has anyone had experience with putting a 1953 dynaflow orque convertor into a 1949 dynaflow? An old friend of mine, Pete Lefchek, from Bynum, Tx told me that if you used the '53 TC the older '49 would burn rubber!

Pete new his Buicks and had rebuilt many a car and was active in the hobby as a seller of old Buicks exclusively so I think he may have been right.

Comments?