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MG TD TF 1500 - Brake Drums Rubbing Wheel Cylinders
|Purchased a new set of rear brake drums with the wire wheel conversion and they are rubbing my new Delfi wheel cylinders. |
Anybody had this happen before? Wondering if it's the drums or the cylinders at issue.
|Dan, If you lay a straight edge across the old drum, open side, measure down to the area where the drum is rubbing, then take the same measurement from the new drum. If they are the same, I would assume the problem is the cylinder is setting too proud. If the depth is less on the new drum, then I would say it's the drums. Just a guess, all I can give at this point. PJ|
|Paul S Jennings|
|Paul, you may have hit on the problem. All I have to compare to is the disc wheel drums and comparing the two I get approximately 1/4" difference. That's a BIG problem. The Delphi wheel cylinders also measure a little larger. |
I can't be the only one to have had this issue come up. Our west coast supplier must sell a lot of these. Mmmmmmmmm
|They probably do, and yet they just keep selling...|
|Wire wheels have been fitted to TFs since time immortal. First question I ask are the TF drums different to those fitted to a TD, second have the Delfi wheel cylinders been fitted to a TF with a successful outcome?|
|How much rubbing- just a drag/light rub or locking up? How much thicker/wider are the new cylinders? All TD/TF disk hub/drums same (exc very early TD), the wire components and hubs same also. Not sure the above measurement is totally valid. The final installed position and resulting depth (ie measurement of the inner face of the drum's outside surface to the backplate)is what matters most. That would depend on the one piece hub/drum where it seats on the taper when tightened, the wire where the hub seats on the taper, then how the drum seats on the hub, etc. So it could be a machining problem with the hub also.|
I took a measurement from the bottom of the spine seat and one from the top. Identical to the disc wheel. No miss match as the pieces came new as a unit.
When I set the drum and hub (before torquing) there was just a slight rub on the brake cylinder. I took a grinder and knocked a little material off and all seemed fine. Not so on the other side. Drum won't turn at all. That tells me things are to close to let stand.
I do believe the cylinders are a bit taller. Without removing them it would appear they are about 1/8 to 3/16 larger. Which would be enough to clear...I think.
The photo attached is where I took the measurement at the point of contact. Pretty close to 2"
|And from here it's about 1-1/8"
|Check the diameter of the taper at the point where 3" is in picture 2 against the old one. A slight miss machining at this point will displace the hub by a large amount. I came across this on a TF where the halfshaft nut was loose allowing it to fret at the seal taper. When tightened up the drum fouled on the brake shoes.|
Ray TF 2884
|My brain is turning to fudge!|
Simply remove the tapers and fit into new hubs and measure against the old.
|Ray, took your advise and checked the tapers. Measures the same on both drums. Checked the brake cylinders more accurately and there is no significant difference. |
I did buy a 4.3 exchange with new high strength axles from Dave Clark, but aren't all of these axle housings pretty much the same?
|That 7/8" difference is huge? But the distance of the drum surface to the shoes/backplate is set by how far the taper fits into the hub or drum. I suggest taking the spit collars off of the axle, then place it into the various drum and hub tapers, then measure from the flat back of the split collar to the inner drum edge. That will tell if the tapered hole in the hub is too deep, too wide (which would allow it to seat deeper, thereby making the drum too close/locking up) or something else was mis-machined. You could also try switching the drums side to side to rule out something with just the drum. Of course eyeball how far out the axle sticks from the hub and drum and make sure one split collar is not shorter, etc. Hope that makes sense. George|
|I have measured and re-measured every piece and all matches within hundredths. But when I put the disc drum in place (looking through the brake adjuster hole) I have about 3/16" more clearance than with the WW drum. Yet they measure out exactly the same.|
Has me stumped.
Thinking of shimming out the tapper collar.
Thank you all
|Dan , You mentioned the new axles--- Did you remember to install the spacer on the axle before fitting the bearing etc. Part 15 in MOSS catalog .|
|Yes Richard I did. That was the first thing I checked. Knowing me, it was a strong possibility.|
Since all fits well with the disc drums it just has to have something to do with the hub/drum assembly. I will be checking with my supplier in the days to come.
Thanks for your thoughts
|Something somewhere machined incorrectly.|
|I did not have any issue when I did the conversion 10 years ago.
|Something really stinks with this problem of mine. I went to Moss today and they referred me to Lawrie Alexander. Lawrie responded with his suggestion which was to have material removed from the drum and grind away some of the wheel cylinder as well. Without the manufactures agreeing to this drastic measure I don't think I want to do this. If it where anything but brakes I would give it consideration. |
Tonight I am thinking about shimming the split collar about 1/16 and placing a full diameter shim between the hub and drum with another 1/16". Going to cost a few bucks, but I'm running out of ideas.
Anyone care to share their thoughts and opinions.
|I'd like to see some pictures of the cylinder on the back plate...front and a side view. I have a couple of old ones out in the shop on some back plates with shoes we can compare with.|
I have compared and measured my old (original) cylinders and the measure exactly the same. When in place on the backing plate they are maybe a few 100's higher.
Here are some pics of what I sent Moss and lawrie
|And one of the backing plate with the new Delphi cylinder
|From the front
|Dan I must have been tired...ya that's it tired. The drums I have on the shelf are for steel wheels so there is no value in comparison there. |
What I see in the photos indicates the problem is not with the cylinder or the assembly.
What I can say is that when I did mine 10 years ago the drums I received (from Moss) were clearly made from two different castings. Each pair had different faces...sorry no photos to show. I would have to believe that one of three things is going on here.
1. The new axle shafts were incorrectly machined. I'm not sure if Dave has had some new ones made or if he is still selling the inventory he aquired. I'd quiz him about them but since he is up north for the summer he won't be able to check his stock I would guess until the fall. He may however know non the less.
2. The hubs were incorrectly machined. A real possibility, particularly if a new source is being used for them.
3. The drums are incorrectly machined. See item 2 above.
In any case I would be very reluctant to grind or modify any of the parts at this point. I think I would try and find out the source and the dates of manufactures for the hubs...if they will give you that info. I then think I would contact another source for both parts and ask the same questions. It's a possibility that another source may have correctly fitting parts. It's also a possibility that there is only one supplier but I'd be digging into it myself.
Abingdon Spares? They seem to swap parts with Moss so maybe not a good lead there as they most likely use the same source. But maybe not. Depending on what the new owners got with the deal..maybe they have some original pieces to compare with?
Hendix Wire Wheel. I think they do a conversion kit.. I'd give Allen a call and see what he has to say.
B & G in the UK
Also Moss UK... they are a separate company from Moss USA and even though they have a close relationship, they may use another source for the parts in question.
Thats just my thoughts.
|Since one side is a reasonable fit why not temporarily swap the drum/hub assemblies from side to side? This may give an indication if the problem is the drum/hub assembly or is the wheel cylinders (or half-shafts).|
I have tried swapping the drums/hubs from side to side with no significant difference. I did take one of the drums you sent me for the front and they clear just fine. That leads to believe the problem is with the drums. If I request another set from Moss I am likely to receive ones from the same manufacture and then what. If I order a set from another supplier, will they be compatible? Aren't they machined as a unit?
I did speak with Dave and he didn't feel the axels were the problem. He's never had it come up before. I have set them side by side with the originals and see no measureable difference
btw, he spends his summers about twenty miles from me. We both live in NW Washington.
|If the disk wheel drums/hubs work fine, not the axles. If I understand correctly, another drum from Hugh works fine? Been a long time since I have fiddled with a wire wheeled setup, but it looks like there is a lot of thread left sticking out when the nuts/locktabs are in place. That would be the case if the recess is turned too deeply. I wouldn't shim, grind or anything. Moss needs to take ownership of this problem. George|
|It would appear that we have it narrowed down to the drum.. maybe. Take that same drum that Hugh sent you and try it on the rear. If it works then you know for sure. If it doesn't then the issue is with the hub. Again I'd contact some of the other vendors I mentioned and see what there source is. This isn't the first time that Moss has had a manufacturing issue with parts. It may be all they can get from China? But I'd go looking around for something else. Or tell Moss to grind or better..machine the things to fit correctly.|
|Yes LaVerne, I agree.|
It does appear the drum is the major culprit. Simply removing some of the casting around and near the affected area would probably do the job. It does feel a little bit thicker than the original drum. Without knowing the strength of the casting I am not about to chance it. I feel this must be worked out with Moss. I am attempting to work with them, but it seems they are very busy these days.
Interesting to not though, the box the drum came in says "Made in the UK". Mmmmmmmmm
|They make mistakes there also...they just seem to be more frequent from the other place.|
|Just had a look at a recent conversion and there is much more thread sticking out of the nuts on yours. It looks as though they are machined too deep or the hub flange is too thin. Photo 1 from yesterday shows there is not enough meat to machine to clear the cylinder. The supplier needs to replace these with the correct parts.|
As the wire drums are the same back and front I would measure them all to see any variance.
Recently a friend bought new front drums (disc wheel) when tightened up they locked up. The bearing shoulder in the drum was wider than the spacer putting high load on the bearings. I believe people think CNC machines are infallible and don't check.
Ray TF 2884
I have and will again (today) try to get the supplier to make a decision.
A note about the bolts.....my original set received from Hugh Pite measure about a 1/4" shorter. I'm thinking that is why the bolts are showing longer.
When I measure the hub and drum dimensions, they are very close to the original in just about all respects except for the side wall thickness of the drum. The originals are about half as thick in the affected area. If I had better measuring tools it would help.
We'll see what Moss offers up for a solution.
Thank you all for your comments and suggestions.
|Thought you all might like an update on this issue. |
I alerted the supplier of the situation and they have tried to reproduce the situation in their shop. Apparently they have some old examples of where material was removed from the cylinders in an attempt to provide adequate clearance.
So after several back and forth emails it apparently was decided that I should remove material from the brake cylinder. I questioned this because I see the need to remove approximately 3/16 to 1/4 inch of material. This doesn't set well with me.
So I asked about removing a little from both the cylinder and the drum. Their response is as follows:
"I donít know if removing material from the drum will be necessary or not. It would be much easier to modify only the cylinders.
The amount that I saw removed from old cylinders was significant, so I donít foresee any issue with getting aggressive with your filing."
Additionally they stated this has been standard operating procedure for sometime. In my correspondence with Lawrie he also suggested I remove material as needed although he had never encountered this situation before. Mmmmmm?
Have any of you guys had to remove material to make yours work?
If there is some history of this I might feel better about doing it.
Your thoughts are once again appreciated.
|Hi Dan. I can't offer any technical assistance to resolve your problem, except to say I too would be loathe to remove any meat from the cylinders. Once you start altering their gear the problem becomes yours not theirs. There is a service here where original brake cylinders are relined with a stainless sleeve & are every bit as good if not better than the originals. That would eliminate the cylinder contributing to the problem. I think LaVerne's suggestion is the way to go. It seems Moss is just dumping their problem back onto you. I'd be looking to source the components elsewhere & seeking a full refund from Moss including shipping both ways. Cheers|
Peter TD 5801
|I know it is a PITA but if you have the old cylinders then trial fit them back, if the problem persists then the drum manufacturer is at fault.|
If it goes away then compare the dimensions of the old/new cylinders
I don't think there is enough material to take away what you need. I would be very wary of weakening an hydraulic cylinder, panic braking can build up one hell of a pressure.
As an engineer I seemed to spend most of my time correcting other peoples cock-ups.
Ray TF 2884
|Dan, Have you tried checking the thickness of the drum mounting flange against an old one? Sounds to me like the new drums are screwed up, to put it lightly. PJ|
|Hi Fellas, thank you for your thoughts.|
Yes Ray I did retry the old (original) cylinders and they made a very slight difference, so I'm comfortable saying its not "just" the cylinders. The comment that sanding off material from the cylinder is "standard operating procedure" seems odd to me. Especially if no one here as heard of it.
Yes, I have checked the flange thickness and just about every other possibility that I could think of. After all of my measuring I conclude that its most likely a combination of the hub taper, drum thickness (at the affected area) and maybe, just maybe the wheel cylinder. I do believe the drums are the primary culprit however. I don't have the means to properly measure the hub taper so I cannot confirm either way. I did place an old original WW drum (I purchased form Hugh) on the new hub and things did improve, albeit only slightly.
It appears to me that if I want wires I am going to have to find a way to make this work. As in machining and grinding until they fit.
Anybody have an old Delphi wheel cylinder that could measure the wall thickness at the affected area?
If I take a 1/16th for the cylinder and an 1/8th from the drum (its rather thick in the affected area) I think all should work and still be safe.
After allowing Moss to investigate my problem they came back with the suggestion that my Delphi wheel cylinders were too large. On that advice I purchased two 180-075 aftermarket units from them and to my disbelief the problem went away - almost. With these units in place their is now approximately 1/8" clearance (before torquing) without grinding away any material. I'm not entirely comfortable with this so I will be taking my drums to the local machine shop and have a 1/16" or so removed. The new drums are considerably thicker than the originals so it shouldn't be a problem.
Does anyone see a problem with this?
Seems odd that no one else has had to deal with this issue before.
|Just seing this thread for the first time. |
When I re-assembled my axle after the 4.3 conversion (no half shafts changed or anything), I had a lock up. When disassembled the axle, I found that one back plate was between the inner and outer axle bearing covers instead of onthe outside. When I investigated the problem, I found that the brake pads were 6mm larger than they should be (43 vs 37mm). Interestingly, on the other side, there was no locking problem. Suggests that the half shafts/collars are not exactly manufactured for the same distance.
After fitting correct width brake pads, I still have a slight scratching on that drum that I have yet to follow up. It is 6 times /rev, so it must be the hub nuts touching somewhere.
This is also with WW drums that I exchanged several years ago against steel wheel drums with no problems whatsoever at that time.
Seems there are quite some tolerances in that area that lead to problems when the wrong combinations meet...
This thread was discussed between 03/07/2015 and 20/09/2015
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