Rare but violent brake vibration

[TheGreenVan]

Hello,

I've just started having some braking problems I can't diagnose with my 1982 VW T3. Braking sometimes -- but only sometimes! -- leads to extremely violent shakes throughout the van. The shake is similar to going in 4th gear at 25 km/h, just more bouncy. It does not seem good at all and would be a disaster in a hard-brake situation, so I'm trying to diagnose before driving much more.

What's strange is that it's rare. The first time it happened I immediately tried to recreate it for 30 minutes and couldn't. The brakes seemed perfect. Then it suddenly happened again 30 minutes later. No clear relation to turning, speed, and so on. Since then it's happened a few more times as well, maybe more often at slow speeds.

Some background: I recently got the front left wheel bearing replaced + a cleaning of the brakes. A month or so ago I had the brake pads, brake discs, and left brake caliper replaced. Since replacing the bearing I've driven about 8hrs. The van seems more wobbly/shaky than normal after the bearing replacement, which could be related.

Any help very appreciated. And thanks a lot to this forum, it's been very helpful for me with other problems before ever registering.

[Oldiebut goodie]

The obvious answer is that the wheel bearing has been replaced incorrectly.

[cobblers]

Definitely jack the van up and check the wheel for play as a matter of urgency!

[Gavrilo]

Make sure you have the right size wheel bearing fitted, the stub axle spindle on the early vans is a smaller diameter than the later vans, the bearings will fit but the hub and wheel will wobble around, depending on how tight the hub nut is it could give the symptoms you have, is an easy thing to check anyway

[TheGreenVan]

Thanks for the replies. All three of you were correct. I jacked it up and found significant play in the left wheel. The whole thing was loose. Turns out the garage installed the wrong wheel bearing. Considering myself very lucky to have found out like this.

If anyone knows how to approach this situation with the last garage I'd be happy for suggestions.

[R0B]

Take the wrongly fitted bearing back to the garage and explain their mistake to them, and how they left you in a very dangerous situation. The least they can do is refund the fitting cost. Do you have a professional mechanic who can confirm it was the wrong bearing? 

[TheGreenVan]

Yep, the van is at another mechanic now for the new wheel bearing (still learning how to do all these things myself). Should be easy to get them to write something about the problem - the guy kept repeating "this is life-threatening" as we looked at it!

I'm in a different country from where the original repair was done now, so can't go back there in person, but a call should do it I suppose. And again, thanks for the comments - almost made a long trip before getting it checked out and the comments here made me reconsider that. Very thankful I did.

[mioba]

Thats scandalous. If you have basic tools its easy to do the wheel bearings. Noting the ping when you hit it home is the key and plenty of grease slobber.

Best to do both sides at the same time tbf.

I got mine from GSF last year at ridiculous cheap price about 12 quid a side (FAG).