Have had a bit of a frustrating problem with my coupe over the last month… mainly frustrating because it’s not always present!
Anyway, first noticed a month ago on a trip down the M4. The car was handling/behaving absolutely fine for 20 mins or so, but when I sped up to join the motorway and got up to around 80ish, all of a sudden it felt like I was going over those rumble strips you get approaching a roundabout - one of these:
The car still steered straight and isn’t pulling to one side.
The weird thing is, after about 5 mins, it disappeared and was back to normal.
And it stayed that way for a good 20 mins, until I hit the brakes on the slip road coming off the motorway. Then the vibration was very strong and stuck around a little longer before disappearing again (rest of the journey was a b road, but I did push on).
This all happened before I took my car in for its service last month. The garage took it for a test drive and could see what I was referencing, and on inspection they thought that the front wishbone rear bushes seemed pretty knackered, so they replaced them.
I genuinely thought this had fixed it - I took the car up and down a dual carriageway near my house and slammed on the brakes from high speed to try to get it to come back. Before I went to the garage, after about 15 mins of doing that I would get the heavy vibration under braking - but post the bushes change I wasn’t getting it.
However yesterday I replicated the exact route I went when I first picked up on the problem, and sure enough it reappeared immediately after joining the M4 around 80mph - then disappeared 5 mins later. Only to reappear under decent amounts of braking leaving the motorway.
Anyone have any idea where to start with this one??? If it was only under braking I’d suspect warped discs, but it’s not constant. Likewise if it was constant I’d be thinking wheel balance/alignment or a buckled wheel - but surely the symptoms would be pretty consistent if that were the case?
Also it seems to not appear unless I’ve driven a certain amount of time.
I’d also wondered if it was a sticking caliper or something, but it doesn’t seem to be pulling to one side.
Maybe it’s a different part of the suspension? Control arms? I honest don’t know - and the fact it’s intermittent (yet consistently showing up at the same point on an identical route) is bizarre.
Cheers for any help! Desperately needing to get this sorted, I’ve got a rather large European road trip coming up in July…
