Rear Brakes Binding

[jbuckl]

Jeff, it it comes to it I have a NOS driveshaft (without hub), never fitted, which I assume to have a straight stub axle. Also a collection of hub and axle parts salvaged over years which I believe to be ok, at least for testing purposes. You'd be welcome to borrow.

Wow, what an offer… very considerate & kind.

Imho may not yet be the issue but who knows… it’s definitely a bizarre one.

Have the stuff here to split, rebuild & check rear hub runout.

most people seem to be raving about the C.C.D. New hubs thesedays.

[JeffW]

An update.

Rebuilt the brakes on the bench with another new set of pads, new springs and a new refurbed backplate from TD Fitchett. Took the drive shaft out and swapped the rebuilt brakes over, reinstalled the drive shaft (I didn't bother hooking up the new brake cylinder) and put the drum on.

Still binds and feels exactly the same as it was before.

So that's pretty much it save for drive shafts. I will contemplate buying the complete CDD driveshafts to be done with it all, but they are a lot of money.

jbuckl - Julian if I go with CDD's I am happy to send you these to play with if you like.

Thanks all for your assistance and hope you have a great Christmas.

Jeff

[jbuckl]

An update.

Rebuilt the brakes on the bench with another new set of pads, new springs and a new refurbed backplate from TD Fitchett. Took the drive shaft out and swapped the rebuilt brakes over, reinstalled the drive shaft (I didn't bother hooking up the new brake cylinder) and put the drum on.

Still binds and feels exactly the same as it was before.

So that's pretty much it save for drive shafts. I will contemplate buying the complete CDD driveshafts to be done with it all, but they are a lot of money.

jbuckl - Julian if I go with CDD's I am happy to send you these to play with if you like.

Thanks all for your assistance and hope you have a great Christmas.

Jeff

Thanks… without being able to be 100% certain, the drive flange could be bent due to too much force previously used to separate the taper? Have seen that happen before. Usually easily spotted though.

I think I’d be right but maybe not, in saying if the hub was removed , turned through 180 & refitted the binding might change spot possibly?

[JeffW]

Very good question Julian - I assume so but definitely worth trying. I will do so over the holidays and let you know.

If it does not, then I truly have no idea what it could be.

Jeff

[staggering]

Jeff,
Bit of a long shot but do you remember if this one side only binding happened before you did all this brake work. My very long shot is that possibly the new brake cylinder on the binding side may have a "tight" piston - very unusual but that would not let the shoes return as they should. This would be more apparent if the binding is worse immediately after pressing the brake pedal - apologies if a blind alley thought.

Cheers
Ian

[JeffW]

Hi Ian

Nope, but a very good idea. Unfortunately I did all the work after I was alerted by NeilR on another post that it was binding. I first did shoes, drum and springs, then did the cylinder and now today another new set of shoes and a new backplate.

I also tried old shoes and drums with no effect.

Thanks for the thought though, appreciated.

Jeff

[JeffW]

And a boxing day update.

I swapped over the two drive shafts. Less binding, but I noticed that it binds much more when the drum set screws are in place as opposed to just holding the drum pressed against the backplate whist rotating. I can only think the drive flanges have been bent as jbuckl Julian has suggested and the set screws bring the drum against the hub and the bent portion becomes more prevalent.

And rotating the hub 180 creates witness marks on the bottom of the shoes, so I think I am at the end and will have to replace the drive shafts and hubs.

Arrrgh

Jeff

[jbuckl]

Sorry for asking…. Theres 82 posts to trawl now…. When were the hubs apart last?

….as an aside, many moons ago I witnessed someone separating these types of hubs apart on a large press.

popped at a huge tonnage & rendered scrap.

have built a couple of threaded type splitters to avoid the distortion / tonnage.

4 bolts through the flange stud holes & an M 20 fine thread.

tighten whack, rinse, repeat.

no reports of damage.

[JeffW]

Sorry for asking…. Theres 82 posts to trawl now…. When were the hubs apart last?

….as an aside, many moons ago I witnessed someone separating these types of hubs apart on a large press.

popped at a huge tonnage & rendered scrap.

have built a couple of threaded type splitters to avoid the distortion / tonnage.

4 bolts through the flange stud holes & an M 20 fine thread.

tighten whack, rinse, repeat.

no reports of damage.

Ask away Julian!

No idea - I bought the car as assembled by the previous owner. I believe the assembly was done by a non-Stag specialist as there have been a series of badly bodged finds, so I would not be at all surprised if there was damage done to the drive shafts/hubs/drive flanges.

And sorry for all the posts, hopefully they will at least help someone in future!

Jeff

[jbuckl]

It’s been a good thread.

although the drive flanges can be skimmed true, it’s possible there’s other hidden things that might have occurred during the previous operation…. Tapered shafts have high stress raising transitions …. Have been known to fail.

some say due to fatigue…. My guess is overstressing of those areas during dubious disassembly methods though.

[mole42]

As I mentioned in post #18, I had a shaft that had been bent by someone removing the hub so even if you have the flanges skimmed you could still get problems. If you get replacement shafts and hubs it’s best to check that they run true before fitting!

[MandM]

You could check the run out on your rear flanges?

P1070613.jpg

,
You don't need a DTI to check the run out on the flange face just an axle stand ,a clamp of some sort, a pointer and a set of feeler gauges, fix the pointer to the stand and touch the pointer on the flange in a similar position to my photo earlier, slowly by hand spin the flange , you are looking for the gap, you may have to move the pointer back if you just happened to have mounted it at the lowest point , with a bit of giggling you will find that the pointer touches in one or a couple of places and then there is a gap somewhere else, measure this with the feeler gauges that is your run out. The triumph flange was a cast item and not all the faces where machined to a high degree , so will see some bobbing on the outside edge. someone may be able to explain this method better than I

[022Dave]

Brakes can be funny old things, but they’ve never had me giggling!

Happy New Year when it arrives.

Dave

[jbuckl]

,
You don't need a DTI to check the run out on the flange face just an axle stand ,a clamp of some sort, a pointer and a set of feeler gauges, fix the pointer to the stand and touch the pointer on the flange in a similar position to my photo earlier, slowly by hand spin the flange , you are looking for the gap, you may have to move the pointer back if you just happened to have mounted it at the lowest point , with a bit of giggling you will find that the pointer touches in one or a couple of places and then there is a gap somewhere else, measure this with the feeler gauges that is your run out. The triumph flange was a cast item and not all the faces where machined to a high degree , so will see some bobbing on the outside edge. someone may be able to explain this method better than I

Great illustration…. Yellow paint optional?