Steering Judder

[lee_rob]

Hey guys

I have a frustrating problem with my moggy. I have developed an alarming judder which comes through the steering when braking. It is worse when at around 40mph and gently apply the brakes to slow down to 30. I though at first it might be an oval brake drum. So I replaced the drums and since the shoes too as they were a little low. I now have better brakes with a firmer pedal but the judder is now worse than before.
So I then decided the tie bar bushes might be worn so I took them off and indeed the rubber bushes were very tired and loose. So I have replaced them with poly bushes and it all feels much tighter under there.
Took the car out today and the judder is still there.....I am confused.
I have checked the trunions and there seems to be no appreciable wear in either the top or bottom pins, could this be due to bad wheel bearings?? I have only had the car for a couple of months but I have a bill in the paperwork for replacement front bearings about 5000 miles ago, I would have thought a bearing should last longer than that..

Does anyone have any bright ideas??

[bmcecosse]

Top king pin bushes in good order ? These are MUCH better in polyurethane and easily fitted. Also check if the top arms are loose in the damper body - and are the damper fixing bolts good and tight. And - I suggest you drain and refill the dampers - with SAE 40 oil (which is NOT 10W40)...... Also - steering rack track rods and track rod ends all ok? And is the tracking correct at ~ 1/8" toe IN.

[lee_rob]

I have new bushes for the top pins ready to fit I just gave up today as the weather wasnt playing, I will also check the damper mounts while I am at it.
The dampers were overhauled 5000 miles ago so I would imagine the oil was changed but I will check, and yes I am aware that SAE 40 is not 10W40 i run vintage cars so I use a lot of straight oils.
No play in the track rod ends that I can see.

[bmcecosse]

Hmmm - well it's hard to think of anything else. Obviously since it only does it when braking, I would suspect the brakes.....but you say all ok there. I believe some have reported problems with new drums not running true....... May be worth checking.

[lee_rob]

I did wonder whether a wheel cylinder might not be working and hence only one shoe working but they seem to be working ok. It did it with the old and the new drums so I would suspect that the drums are ok but again I will have a look.
What size are the two front wheel bearings? I thought about putting new ones in but they seem very cheap from most of the common suppliers of minor bits. I want to put decent ones in, any recommendations?

[bmcecosse]

Some suppliers seem to be selling cheap bearings with excessive clearance (C3 type) - best to stick with the good old ones ! They really don't normally give any problem........ Wheel cylinder sticking gives powerful pull to one side - not judder.

[Dominic]

Checked for a loose back plate?

[C6Dave]

Have you tried swapping the front wheels for the back to rule out a wheel problem i.e. buckled or in balanced?

[kennatt]

have you checked the eye bolt/chassis conection.

[lee_rob]

The wheels have all been balanced and are running true. What is the exact bearing size of the fronts so I can look at suppliers?

[bmcecosse]

Unless you can feel play in the front bearings - they are not the problem.

[lambrettalad]

hi do you have a dynamic wheel balance garage near you,they can run the wheel up to speed and then gently apply the breaks and see the results ,might be worth a try

good luck

[bmcecosse]

The judder is only reported when braking - therefore it's NOT wheel balance. Frankly - it could just be the new brake shoes - file a wee chamfer on the leading edges of each shoe - and take the car out and give the brakes a GOOD workout.........

[lee_rob]

It's NOT the brake shoes it happened with the old ones hence why I replaced them and I already filed a chamfer off them as I always do when fitting new shows. I have taken the hubs and it is the bearings. They are a very loose fit on the stub axle so I would think they are cheap bearings which are not machined to the correct size. Hopefully it hasn't damaged the stub axle, but I can't see any signs of wear or blueing so they should be ok.

[bmcecosse]

As mentioned earlier - there are some entirely unsuitable C3 fit bearings being sold these days. Maybe that's what you have - but play in the hubs should be easily detected - you didn't mention it earlier. I believe the numbers are 7303 and 7205 but make sure they are not C3 suffix..... Someone recently came up with a taper roller bearing set that fitted........you can do your own search for it!

[lee_rob]

Clearly if the play in the hubs was so evident I would have diagnosed it earlier but neither myself nor 3 other people who deal with Minors regularly suspected that this was the problem as there was not discernible play by moving the wheel or hub.
I appreciate your contribution and advice, but what you might consider to be an easy problem to diagnose may be difficult or others. After all we are all here to learn new things

I shall be looking into new bearings and if anyone knows a reputable bearing make that they have used I would appreciate the advice.

[bmcecosse]

But if there is no discernible play in the assembled hub - I can't see it is the cause of your judder! Just buy decent bearings at your local bearing supplier. eg http://www.simplybearings.co.uk/shop/?g ... tAodNkYC-Q

[lee_rob]

The play is not evident because its not the bearing that is actually loose between the inner and outer races thats fine. Its the inner race that is too loose on the stub axle. This means the bearing can turn on the axle and I would imagine cause a vibration or judder in the steering.
Its the only conclusion i can come to after going through the whole front suspension today and meticulously checking each component.

[bmcecosse]

Hmmm -well I have always been able to just pull front hubs off the stubs by hand - so don't judge that as being 'loose' - it's fine ! If they really are loose - I doubt new bearings would make a difference - the inner races are hard as hell.... so any wear is likely to be on the stub axle - which is also pretty hard of course! You could degrease thoroughly - finish off with celly thinners - and then apply some Bearing Loc. But hope you don't want them off again any time soon.....

[lambrettalad]

bmc in my earlier answer.
thats why i said apply the brakes to see if the cause of the vibration could be seen ,not to balance the wheels, you may be able to see where the judder emanates from