Floaty / boaty at speed... what should I suspect, or replace / upgrade?

[TriumphZ3]

I've done 55 miles in the 1.9 Z3 since purchase so took it on a motorway today to burn off the cobwebs; at 70 mph it was becoming very boaty, apt to drift about and not what I expected from this type of car. I stayed at around 60 mph for most of the thirty mile trip. No rattles, bumps or other harshness from the suspension and apart from wind noise there was nothing to indicate any wear anywhere. I suspect that in a 25 year old car a lot of the components are about that age, or at least close to it. What would the experts recommend to tighten up the drive? What should I look at first? Just passed MOT yesterday, no advisories ( we don't get them over here!) and I'm happy to do my own mechanic work, but one job at a time especially the urgent stuff and before I replace anything unnecessarily because I want to, I'll ask what I might need to. Any thoughts?

 

[PCD]

My 1.9 was very drifty at speed when I first had it last year. The Pirelli tyres were worn but not illegal. I found that the previous owner had fitted one odd Falken tyre and when I put a new set of Avon’s on it was completely different and felt as you would think a z3 should handle.

 

[Pingu]

Get it on a ramp, and twist and pull on everything that's bushed with a long lever. Replace anything that needs it, and replace in pairs.

I always fit the tyres recommended by RealOEM, but I drive an M, and sometimes go as close to the limit as I dare.

 

[Rudyrov]

My 98 2.8 just got a new set of rear shocks, and it made the car feel much more planted and firm, next I may tackle the stuts up front and perhaps put in a strut bar in the engine compartment.

 

[t-tony]

My 98 2.8 just got a new set of rear shocks, and it made the car feel much more planted and firm, next I may tackle the stuts up front and perhaps put in a strut bar in the engine compartment.

A strut brace under the bonnet is a waste of money if you haven’t replaced the front shockers if they’re the originals. They look good but only disguise underlying issues which are far more important.

Tony.

 

[Rudyrov]

A strut brace under the bonnet is a waste of money if you haven’t replaced the front shockers if they’re the originals. They look good but only disguise underlying issues which are far more important.

Tony.

Agreed, I replaced the A rams and the A-arm bushings (at drivers/passenger feet) a while back. Everything else looked good whn I did it but it needs another look. I don't drive much because I travel for work so Uber is my ride or a rental.
I like the strut brace for looks mostly. Tures are coopers and they are good as well. I try to stay up with the maintenance and usually use it on weekends when I have time.
Haven't done much to the rear rubbers, I should look there as well.
What I really need to look at right now is the AC, since I live in Arizona, it lost its charge so have to figure that one out.
Thanks, Tony

 

[t-tony]

Wow, I bet you are missing the AC, I know we needed it in Florida2 weeks ago. My money is on the front shocks being very tired. Hope the AC doesn't prove expensive.

Tony.