Front Brake Vibration

[Zeke_]

Hiya,

When braking from higher speeds, 40mph+, there is a strong judder in the front left wheel. Have already scoured the forums and replaced the tie bars as it was quite worn on the left side as well as all the front bushings. This did not help with the vibration at all. I have also replaced the front drums and shoes to no avail. When adjusting the brakes I can feel the brakes bind at one point in the wheel rotation and then the drum be completely free at another part, almost as if the hub and the drums are rotating out of alignment, but this does not seem possible with the way the front brakes are designed. I have also tried another front brake drum and this binding still occurs even on a brand new part. Considering converting the front to disc brakes to alleviate this issue but would rather avoid all the hassle if possible.

Any suggestions are very much appreciated,

Many Thanks

Zeke
1970 4 Door Saloon (Almond Green)

[King Kenny]

Sounds like it could be an oval brake drum. You can get them skimmed but frankly I wouldn't bother. I would (and did) go with the disk brake route. It is not difficult and you will thank yourself in the future.

[oliver90owner]

The issue, if an out-of-round drum, should not persist after changing the drum (unless both are substandard.

The definitive test is to swap drums from near- and off-sides. If the symptom moves with the drum, it is that at fault. If the fault stays with the same side, it’s not the drum at fault.

[myoldjalopy]

The OP having changed the drum (possibly twice?) with no success, then I agree with Mr. Oliver's advice.

[svenedin]

The OP having changed the drum (possibly twice?) with no success, then I agree with Mr. Oliver's advice.

Yes. I’ll be interested to hear the results of that test. I suspect we will hear that it is not brake drum related.

[kevin s]

Have you checked the hub and wheel bearings run freely with no play?

Might also be worth swapping the wheel and tyre with a spare to see if the issue changes.

[Zeke_]

Thank you for all the replies, going on holiday for the next week but will swap the drums over and test, and wheels also, when I get back. I can’t feel any play in the hub or wheel bearing and the hub bearing feel and sound solid. Can’t feel any play in the suspension at all either. Will definitely keep you all updated.

[oliver90owner]

Thank you for all the replies, going on holiday for the next week but will swap the drums over and test, and wheels also, when I get back. I can’t feel any play in the hub or wheel bearing and the hub bearing feel and sound solid. Can’t feel any play in the suspension at all either. Will definitely keep you all updated.

I read that as making one change, followed by a test, before making a second change and test. If not, please only change one thing at a time. I suspect a tyre fault if judder is cyclic - I’ve suffered with cheaper-range faulty boots in the past.

[geoberni]

Seeing as how you've change the drums twice (if I read this correctly) it's a bit of a long shot, but has the car been stood without moving for a long time? Flat spots on tyres may be the problem

[Zeke_]

Hi All,

I have an update:

I got myself a run-out gauge to see if the drums were oval and found 0.2mm runout on the driver side and 0.3mm runout on the passenger side, looking elsewhere online it seems that both sides have a run-out within specification for the brake drums and just testing a spare brand new drum that I have on hand, that also had 0.3mm of runout on the passenger side so I think I have eliminated oval brake drums from the equation.

During testing, I also found a small amount of play in the passenger-side bearing, which could only be felt with the brake drum mounted in reverse, and I am planning to replace both front wheel bearings.

I also have another hypothesis about where the vibration could be coming from. When I replaced the Tie bars, the passenger tie bar bracket was worn in a keyhole shape however I did not replace this due to the welding required. However, seeing as I have now eliminated almost everything else it could be am now leaning towards this as being the main issue.

I also have switched the front wheels around and will test drive tomorrow to see if any changes have occurred.

Also replying to geoberni, The car very recently went for a respray (which took 10 months) however the brake vibration was happening before it went to paint so don't think flat spots on the tyres would be an issue

[geoberni]

Hi All,
Also replying to geoberni, The car very recently went for a respray (which took 10 months) however the brake vibration was happening before it went to paint so don't think flat spots on the tyres would be an issue

Fair enough, it was very much a long shot.
I just knew a guy decades ago who brought a 'new' car but it was an end-of-model at a cut price, because the new version with some new styling was now available. Basically he brought a Stock Clearance car.
He had a vibration problem, with the dealer changing drums etc, but eventually tyre changes on advice of the manufacturer's dealer support staff sorted it.
They admitted the car had been stood in storage for almost a year and all 4 tyres had distinct flat spots....

[svenedin]

So you have found the passenger side tie bar bracket worn into a keyhole shape. The question is whether this is the cause of the brake juddering on that side or has been caused by the juddering on that side. Either way, that bracket needs to be repaired and the tie bar and bushes replaced if damaged. You have a suspect bearing and will be replacing that which is a good idea. I would suggest also looking at the front suspension for worn bushes, worn trunnions, worn swivel pins etc. Basically anything that is allowing excessive play. All of this could be made worse by a damper that is not working. It sounds quite a serious problem if it has worn the tie bar bracket and you definitely need to find the cause. Is there unusual uneven tyre wear?

Personally I would not be driving that car until you have found and rectified the issue. You did call it "a strong judder" and clearly it is.....

If your tie bar bushes were completely worn out that could cause the juddering on braking and the tie bar to wear a hole in the bracket.

Stephen

[svenedin]

It would be great if you could post some pictures of your tie bars (including bushes) and the worn bracket. I don’t think we have any real idea of the general condition of your car, especially the suspension. The forum has a habit of rotating photos but if you edit (crop) them first they should stay in the correct orientation.

Stephen

[philthehill]

The problem with the Minor tie bar is it is badly engineered. Tie bar articulation is in more than one plane/direction.
To be effective there does need to be articulation at the rear as well as the front of the tie bar.
Later or after market tie bar front bushes do not help as they do not have the central rubber boss which fits into the central hole of the cupped washer of the tie bar bar mount bracket. The central rubber boss protects the tie bar and the tie bar mount bracket. The later tie bar bush relies on the cupped housings of the tie bar mount bracket to keep the bush central to the hole. This does not happen which results in the tie bar rattling against the tie bar mount bracket central hole causing the hole to enlarge and wear the front end of the tie bar.

[svenedin]

Actually Phil certain aftermarket poly bushes DO have the central boss but I agree that the rubber ones available now do not. The poly bushes with the central locating boss are Superflex. £13.50 for 4 but only 2x needed and 2x rubber. This is what I fitted (poly bush in front, rubber bush behind). Even if I had wanted to there is no way I could have fitted 2 of these poly bushes per tie bar. They are just too incompressible and it would not have been possible to fit 2 per side.

Stephen

IMG_9163 2.jpeg (429.03 KiB) Viewed 1469 times

[philthehill]

Thank you for the reply.
Those Superflex poly bushes certainly have a pronounced centre boss which is good for keeping the tie bar and mount bracket apart.
Fitting the poly bush to the front of the bracket for braking resistance and a rubber bush to the rear of the mounting bracket for articulation is the way to go.
Phil

[Zeke_]

Thank you all,

I've decided (as the plate needs welding to be replaced) to send the car into a garage to get this and the wheel bearings sorted. I'm also going to get them to put in all new poly bushes (plus 1 rubber for the tie bar) as well and also get a wheel alignment and new ball joints installed (may as well as already have replacement parts). I'll also get them to do a good check over of the suspension to make sure I haven't missed anything.

The tires were new when I bought the car 2 years ago and have only done about 4k miles since then so there is no real wear on the tires. The only thing that suggests the car needs alignment is that the car wants to steer to the left when driving but it's fairly minimal so haven't felt the need (or had the trust to send it to a non-classic specialist garage) to get this done.

I have attached pictures of the old tie bar so you can see the wear on this. The car is assembled at the moment and so can't show the keyholing at the moment, although next time I'm working on my car, I will remember to take photos for documentation.

https://flic.kr/p/2oTx8yF
https://flic.kr/p/2oTy3bc
https://flic.kr/p/2oTx8yL