1950s 1953 Hydromatic reverse issues

[CRAIG LEWIS]

Well I checked the specs for 1951 should be 11 inch pad. I will double check the front pads as they are supposed to be the same. If so then this may be the issue. When relined should have checked the work closer they may have made the pads too big. If that is the case we will slice them down to size to match the front pads. Hope it is that simple a fix.

[CRAIG LEWIS]

Sooo it isnt the shoes I measured wrong they are indeed 11 inch shoes. No modification needed there. will see what happens in neutral pushing back by hand later in the week to come.

[PHIL WHYTE CLC 14192]

Craig, I'm still not clear whether the wheels are locked up after the 7 miles of driving or not. Also are the front wheels locking up as well. If the wheels aren't locked up then it isn't the brakes. You have to use a clear process of elimination. Phil

[CRAIG LEWIS]

Phil they locked up in reverse only after the 7 mile drive but at 5 miles they were not locking up. Today I spent more time pondering and testing. What I have now determined is that the primary shoe is catching on the passenger side at the bottom 2 inches of the shoe. The drum rotates freely but as i used my feeler gauge it caught at the leading edge of the primary only when spining the drum backwards. I could not get a .015 guage in between the shoe and drum in this one spot. I even went to .025 and had free movement in and out of the drum through the slot with the feeler gauge all the way around except the spot I identified. I am thinking the heat expansion is enough to cause full lock up due to the disparity in the gap between the shoe and drum in this spot. Since the primary is responsible for the braking in reverse and pushes the bottom of the primary shoe against the drum (I think I am correct in this action?) and the last two inches is already rubbing the heat expansion adds to that and locks it up.

After many attempts to correct it I took a dial indicator and determined the drum is out of round. I have not checked the driver side yet but it is likely the same issue. Warped or out of round. I dont feel any issues like a chatter or braking symptoms in foward from them being out of round which is a little confusing but...  this whole issue has been a head scratcher.

[PHIL WHYTE CLC 14192]

When you installed the shoes did you do the major brake adjustment as specified in the shop manual?
Also if the fronts are also locking up at the same time it could well be the master cylinder pushrod is over adjusted - this would cause the brakes to pump up over a few applications as there is not enough movement to clear the relief passage in the master cylinder.

[CRAIG LEWIS]

i have done the master adjustment. the front brakes are not loking up. I have an old rusty drum lying around that is in spec and used that this morning to see how it moves on the drum. the more I thought about it the more the drum does not seem the answer or it should rub on the shoe as it travels all the way across to be just one area of the shoe has to be the shoe. I am posting some pics if anyone sees something I am missing. the tape marks the spot the feeler gauge moves in and out freely and where it seemed the hub attachment was out of round but further checking indicates not an axle issue just the casting is off on the outer side but the inner part that the inserts into the wheel itself is not out of round. Hope that makes sense. 1st picture clearly shows where the primary is reubbing hard on the drum but past that point I have an easy .025 clearance so if I adjust to .015 it will only make it worse. Shoe does seem arched correctly but perhaps the lining should be thinner at this point on the shoe?

[dn010]

Are you using the 1951 brake drums or 1952 drums?

I am seeing that 1952 takes 12" shoes but I read you used the 51 bolt. I'd put the 52 bolt back in with proper 52 shoes and see what happens. You're mixing parts from two different years with differences between the two. I would suggest making it all 1952 brake parts.

Last but not least, I would also pull the wheel cylinder to make sure there are no issues with that somehow not retracting after you're braking once things warm up. If that shoe is dragging on the drum, things will get hot fast.

After all that, I would then do the major brake adjustment and see what happens.

[CRAIG LEWIS]

Thanks Dan to clarify, this issue first appeared while using a 1951 rear end complete but it basically ruined the axle bearings and pinion seal from torquing the rear so hard downward in reverse ( we did not know it wa doing that for a bit) We had a 52 lying around for parts and took the rear out of it which had good seals and bearings and popped it in. We used the 51 drums, wheel cylinders,  shoes and anchor pin from the 51 so basically all we had was 52 axles and backing plate which are the same. We also comparted the 512 drums to the 51 and they are the same size. The only difference really was the anchor pin which for the 51 was a larger pin and the shoes wont work with a 52. we set it all up and it drive and stops fine up until it heats up after about 7 miles or so of driving. Thne in reverse only we get lock up. Long story short if you read the whole thread we have chased this for a while.

Today we learned one of our mistakes was thinking the anchor pin wa eccentrical like the manual and all other drum setup I have seen calls for. But indeed this is not the case, theis one has a slot and only moves up and down in the slot once you lossen the nut and relieve tension on the backing spring. so whith much time and tedious checking on and off we think we have centered the shoes properly. We also lenghtned the bevel on the lower leading edge of the primary shoes since that was the hangup which allowed us to better adjust the shoes to center. we also adjusted the assembly back instead of foward since we had at least .035 clearance in the secondary and were closer to .010 in the primary.  Not there yet but getting closer.Tomorrow we will test drive and see if it helped. then we will perform fine tunning adjustments and cross our fingers.  There seems to be no issues with the front brakes. Seems

[PHIL WHYTE CLC 14192]

Craig,
The major brake adjustment involves loosening the anchor pin to centre the shoes. If you don't have the manual I do have a 51 manual somewhere and can scan it. From memory it is the same on other 50s Cadillacs.
Phil

[dn010]

Thanks for the information. Everything I've seen told me most 1952-1959 brake parts were interchangeable but not backwards to 1951. I don't know what exactly the differences are but I assumed there must be a reason they don't list it 1950-1959 interchangeable. Maybe someone else knows the differences?

Anyway, if you need the shop manual, multiple years can be found at the link below.

https://cadillac.oldcarmanualproject.com/

[CRAIG LEWIS]

The 1952 rear (only the rear are 11x2.5 front are 12) brakes are indeed the same as the 50-51 except the eccentric anchor bolt for 51 was different so the shoes are like the 1950 set up. Since we had the same issue with the 51 rear when it was installed I dont see how the change over would impact that. Everything isis 51 except the rear end which is interchangeable but may have a gear ratio difference.  After test driving today we know for sure the rear primary is stilllocking up but still dont see why. on the road we adjusted the brakes all the way in so we essentially had no rear braking contact and the problem is gone. Does anyone know if the 52 wheel cylinders are pressurized in such a way that they must go in specific to right and left sides. I am looking at that possibility as we sse more prssure applying to the secondary than the primary and perhaps the primary is hanging up under expansion and not retracting in enough. we are going to give the whell cylinders a goover and then swap them around and see whats what. Again front brakes are no issue. just double checking here but the rear are the primary stopping brakes not the front as is found in newer cars? with this issue we are relying mostly on the front right now.