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Would wish to correspond with PAS members who have had experience with refurbishing/rebuilding the Steward Warner Power Brake unit. Have many questions as to what would be the best procedure to follow in order to be aware of possible pitfalls and best material for relining clutch.
WJF
Bill,
Scott Stastny in West Chicago did a reline on my 1247. He has a beautiful 836 Brougham and is very familiar with these units, having done them also for Bill Morris and others. He can also help you understand adjustment for the desired pedal feel & response after the unit is relined. Scott’s in the roster. If you want you could send the unit to him or just ask for his guidance.
There is good info in the PASB’s on these units, including the Stewart-Warner Manual. There have also been previous discussions on the message board that you can go back to here on the website.
Hope to see you in Warwick in July!
Dave
Thank you Dave, I will contact him. One of the larger questions I have is, can the unit be worked on without it’s removal from the car and if not what should one beware of on its removal?
They come out very easy, I would pull the trans and clutch at the same time to check them out.
Just pull the driveshaft, [8 bolts/nuts] then remove output yoke off the rear of the transmission. The rear cover of the power brake unit comes right off. This exposes the disc. The Stewart warner manual says that this is all that is needed.
Slide the old disc off, the splined shaft. There are special washers on the shaft too, take your time, and look at each part, take photos, or put in a row in order of removal. Reinstall the new, relined disc.. or take photos as you go and send the disc to Fort Wayne Clutch for relining.
The hub is not symmetrical, look at it and take a photo. There is one side that needs to face into the trans.
Other than the need to take photos as you go, or make sketches. The only other item is the trans oil leaking out for hours and hours, even when you drain it first.
Use only sulphur-free gear oil to refill the trans and power brake unit.
On a lift, I can swap the disc in less than an hour.
What are your symptoms ?? are you sure the power brake disc is worn??
My symptoms when the disc friction material is worn to the rivets is that upon the first application of the brakes, they seem normal, powerful. Then in just a few seconds, the pedal pressure needed to keep the same braking effort increases, sort of like brake fade.
If this isn’t what you are experiencing, then the brake system needs a proper adjustment and check over for stuck levers, centered shoes. etc..
Greg L
The biggest problem is that the unit leaks a great amount of oil and requires filling after each usage. It stops fine but the adjustment is at end of travel on the pull rod. Since it must come apart to stop the leaks it would be prudent to reface the disk. In reading many entries regarding repairing of this unit, having Kevlar installed on the disk does not seem to be the answer. Third but not least is the return spring seems to be wrong, it appears to be a substitute. I need information on this spring and how its mounting to the car. I have obtained what should be the correct one but would desire to verify it as the tension is extreme compared to one on car. Would like to be able to accomplish repairs as, indirectly indicated by the S/W write up. That is with out removing transmission or unit from car. This seems to be possible and is one of the reasons for this inquiry to verify our estimation. From the point of my health limitations and accessibility removing it, if avoidable, seems to poses no obvious advantage. Also the cable hangers are missing from the car and I know that they are L brackets but how are the cables attached to them? Are springs placed around the cables and hooked to the brackets? Thank you Edgar and Greg
Bill
I need to go look at my 836 to be sure, but I think the ‘L’ bracket is used on an oil pan bolt, I’ll go out to the shop and look at and take a photo..
OK, my car only has springs and wire loops holding up the brake cables. The photos show the two springs.
I’m not sure if my cables are supposed to have some sort of bracket on the steel sleeve around the cable. My car is not an original-condition car. Many things are not ‘just right’ on the car.
As for the leaking of the trans lube from the trans, is the oil leaking from the rear output shaft, just ahead of the front universal joint? Or is the leak from the two seals around the brake application shaft on each side of the brake unit ?? My brake unit and rear seal do leak a bit, but after the usual 4-500 miles of touring at a PAS meet, it usually only takes about a cup of fluid to bring the level back up to the bottom of the fill hole.
If the leak is around the seam of the two halves of the brake unit, this can be sealed with ‘Ultra Black’ RTV sealant if the sealing surfaces are CLEAN, no oil at all on them. The sealing surfaces must be cleaned with Brake Klean or Carb Cleaner or similar solvents. a VERY thin layer of sealant on each surface on the clean surfaces, then assemble the halves.
Hope this helps.
Greg L
Seems to be leaking from the out put shaft on the r/h side of unit facing forward. Requires quarts of oil after a short rum, and leaks while sitting in the garage. As you mentioned it is not a perfectly original automobile but rides nicely and is a pleasure to drive. The information received has been invaluable. I thank you all for your input. Any information before dealing with an unknown is of great value and adverts tragic problems. Thank you Greg for taking the extremely helpful pictures as proper adjustment according to S/W requires springs to be in place
My output shafts also leak some, but not like what you are describing. I’ll try to get a photo of my Stewart brake unit that is for parts. I might be able to see the type of seal used on the shaft. There may be a way to reduce the leak rate, or use some type of modern seal on the shaft.
Greg L
There are some seals listed in the parts directory.
Have obtained the seals indicated in parts section from Olcar Bearing and a spare disk to be relined. Now awaiting a little warmer weather after the holidays.
Bill
Bill can you post a photo and the info on who relined the disk when you get it back? Also after a few hundred miles an impression of how the disk is working? I may have my spare relined if yours works out ok. Ed
No problem. I have done a lot of inquiry on possible material used for the disk and have not found a modern substitute for it yet. At present there may be at least one clutch re-builder in N.Y who can, and is willing to re-face with an original type of asbestos material. They still have a limited supply in stock. I need to send them a packet with pictures and all the specifications on the disk or the disk itself. They want Size, thickness and oil viscosity used in unit and any information applicable. From reading through passed PAS bulletins the inference is that Kevlar has not functioned without some limitations. I had hoped that a member who has had success with this or some other material would have answered my inquire. FYI, on Modern seals. Listings and substitute’s are readily found, if the National part numbers in the PAS parts reference are prefixed with a 4 converting them to 450084/450695/450058 a newer National part number system. They now can be cross referencing with the on-line Timken catalog cross reference, or order them from Olcar with original PAS listed numbers. Items sent from Olcar are, Standard 43-228/ National 450695 and 50047. Pn# 50047 that cross references to National 473426. Also using updated numbers most can be ordered from Rock Auto online at about 1/3 the cost. Hope this information helps someone else. As I had difficulty obtaining seals using the numbers listed in PAS parts section
Bill
Hi Guys,
Bill has brought up a good example with the new Part Number system and shared the info on the Message Board. I have taken Bill’s new numbers and added them to the record in the Parts and Services Directory. It is through sharing of information like this that we can improve the refresh the information available to all PAS Members.
Thanks for sharing, Bill. Good luck with your brake rebuild project.
Happy Motoring,
Chris
The Stewart-Warner unit and the transmission to which it is attached in the 1933 to 1935 cars should be serviced with straight mineral gear oil. This is SAE type GL-1. Originally, this would have been SAE 90 or SAE 160 depending on the climate temperature. Currently, SAE 140 is easier to obtain and works well. Under no circumstances should a Hypoid gear oil be used.