Jump to content

Juddery Brakes


Iain T
 Share

Recommended Posts

Another on my to do list is my juddery brakes, they're fine at lower speed if not applied harshly but at higher speed it's similar to an abs on/off judder. There isn't a wheel wobble and I can't feel anything untoward at the steering wheel. The brakes do stop me but they don't install confidence.

So as I have a dti I'm going to measure any run out of the front discs (0.15mm max) but while I'm there is there anything else I should be testing or prodding? Note I have tightened the hub nut as specified and am reasonably sure this is not the problem.

As it's going to be brakes week I'll also take a peak at the rear drums. Is there anyway to check them for roundness with a dti? Can you mount them pointing out or is it impossible to get concentric on the hub? 

The brakes are standard with club Mintex 1144 fitted and when I looked last year everything was dry.

Cheers

Iain

 

Link to comment
Share on other sites

You can check the drums by just spinning the wheels when off the ground, pull the handbrake on a little and they should rub all the way round. Almost certainly there will be a high point or two as cast iron drums are notorious for going out of true over the years but has to be excessive to affect braking. Have you changed any brake system components recently?

Link to comment
Share on other sites

3 minutes ago, johny said:

Have you changed any brake system components recently?

Apart from fitting Mintex and new fluid earlier this year no. The judder was there before fitting the Mintex so it's not them. As to the drums I remember it was not an even rub when the handbrake was applied/adjusted. I can't remember if I have self adjusting fitted as it was a couple of years ago and a lots happened since then!

A friend has a lathe and I could ask him if I can check them on it for roundness but the judder feels from the front end. 

Link to comment
Share on other sites

Its difficult to machine drums as really you need a mandrell. There used to be loads of places in the good old days but no longer however I found a shop with a big lathe and they had a go at mine by just mounting in the chuck. It wasnt perfect but made a big improvement at a very reasonable price. I would have bought new but 2L Vitesse drums are expensive and I wasnt confident the new pattern ones wouldnt go out of round as well...

I suppose discs can go out of true maybe after very heavy breaking but ours are pretty chunky! Muck underneath their mounting wouldnt be good but both of these issues can easily be checked with even a home made dti☺️

Link to comment
Share on other sites

It looks as though both front discs and rear drums were replaced when the PO had the car restored 10 years ago so both probably made from iffy spec materials. I'll check the front first then go from there.

 

Link to comment
Share on other sites

Thruppenny bit rear drums will transmit the vibration feeling to the fronts 

on discs you need to measure the thickness variation as well as the general runout of a face 

hub face runout will again  transmit to disc runout 

drums on a lathe must only grip on the centre hole but the mounting face must be accurately perpendicular to the braking surface 

or you machine even more run out   chuck grip on the outer will produce a lobed brake surface  ( very common)

Pete

 

Link to comment
Share on other sites

Im really tempted to have a go at a home drum regrind.

With the car supported the drum is bolted using the studs to the hub but reversed so that with a home made frame holding an electric drill and grind stone you can machine the drum inner surface. Probably need an assistant to rotate the axle while the 'machinist' moves the drill in to cover the complete area....

Link to comment
Share on other sites

14 minutes ago, johny said:

Im really tempted to have a go at a home drum regrind.

With the car supported the drum is bolted using the studs to the hub but reversed so that with a home made frame holding an electric drill and grind stone you can machine the drum inner surface. Probably need an assistant to rotate the axle while the 'machinist' moves the drill in to cover the complete area....

Just run it in gear? 

Link to comment
Share on other sites

16 hours ago, Iain T said:

It looks as though both front discs and rear drums were replaced when the PO had the car restored 10 years ago so both probably made from iffy spec materials. I'll check the front first then go from there.

 

Hi Iain, to check the rear drums clamp off the rear brakes and see if the vibration stops. It is safe as your back brakes don't do a lot anyway. It wont work if you have braided hoses though.

Tony.

Link to comment
Share on other sites

19 minutes ago, poppyman said:

Hi Iain, to check the rear drums clamp off the rear brakes and see if the vibration stops. It is safe as your back brakes don't do a lot anyway. It wont work if you have braided hoses though.

Tony.

Or simply pull on the handbrake when driving to see if the vibration is there and of a similar frequency.

Gully

Link to comment
Share on other sites

Measuring done. 

Both discs have a max thickness variation of 2 thou measured at several places. This is within spec? 

Run off is 5-6 thou on both sides. 

I checked front/back and top/bottom movement of the wheel and there was virtually no movement on the drivers side but a good 1-2 mm on the passenger side. I checked the hub and adjusted to give about 3 thou end float. The wheel now has no front/back movement and a small amount top/bottom (more than the drivers side). 

No point taking it out for a spin now as its goin' 'ome time and the roads are very busy. 

If this doesn't improve the judder I'll have to turn my attention to the rears. 

Link to comment
Share on other sites

6 hours ago, johny said:

With the car supported the drum is bolted using the studs to the hub but reversed so that with a home made frame holding an electric drill and grind stone you can machine the drum inner surface. Probably need an assistant to rotate the axle while the 'machinist' moves the drill in to cover the complete area....

A friend machined his huge Daimler drums using a vertical mill and a rotary table to turn the drum. He said they were way off and it worked a treat. 

Link to comment
Share on other sites

2 hours ago, Iain T said:

A friend machined his huge Daimler drums using a vertical mill and a rotary table to turn the drum. He said they were way off and it worked a treat. 

 Not sure I can stretch to making a vertical mill and rotary table with my electric drill and assorted bits of angle iron though😌 

Link to comment
Share on other sites

As part of a very comprehensive aprenticeship (Millwright) in the late 50`s early 60`s. I had extensive training and usage of Lathes, Borer`s Mill`s Grinder`s Etc; Machining the types of Castings used in brake drum`s is no easy exercise, even new material can be difficult to get the required level of finish without access to specialised equipment and tooling. "Used" and by definition, work hardened surfaces are the worst. Often by the time you get an acceptable surface finish, too much material has had to be removed. Accuracy is again, dependant upon the Machinery (and the operator skills).

I have a "Vintage" (1945) Drumond Lathe, which in theory could carry out the task, on the relatively small Drums fitted to "our" cars. Might be an interesting exercise one day, all I need is a few "scrap" drums to practice on!!!.  Any Offers?.

Pete

Link to comment
Share on other sites

A club member here in Aus race's a TR7 and his rear drums were out of spec, his research indicated that the Fox body Mustang (4 stud 9in) rear drums could be adapted, with some machining to the rear lip face and the centre flange hole enlarged to 71mm, and a spacer made to fit.

So with all our cars we may have to become resourceful in the future adapting other car bits.

Wish I could get Alfins for the Vitesse, the Spits converted, as Pete L says a 'must have' that isn't really reqd, but they look good!

Link to comment
Share on other sites

53 minutes ago, johny said:

might be able to help you there if my cunning home made drum grinder doesnt work out.....

Johny

When you're looking for thou's everything has to be held rigidly and accurately and must be registered from the centre. I would be surprised if anything could be done with the drums on the car. Not saying it can't but......

Iain

Link to comment
Share on other sites

2 hours ago, johny said:

You could be right but doing on the axle is potentially the most accurate way

I had my wheels balanced on the car, made a huge difference after getting them done twice off the car. 

Link to comment
Share on other sites

yes  as on car balancing takes into account any weight runout on drums discs etc

one silly thing that can distort drums is if the silly drum (dont really need it )  retaining screw head is proud and fouls the wheel 

its enough   to distort the drum when tightening the wheel nuts 

pete

 

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...