Thunk on Braking

[kkemerait]

I'm not very mechanically inclined, so any help will be appreciated. On my 1978 Fiat 124 Spider, whenever I come to a stop or slow down...as I apply pressure to the brakes I can hear (and almost feel) a "Thunk" coming from the front of the car. The only work that's been done recently was a repair of the rear brakes, rotors, pads, calipers and hoses.

What should I be looking at ... it makes me nervous

Thanks in Advance

[So Cal Mark]

I'd look at the control arm bushings as well as the front caliper bracket mounting bolts

[kkemerait]

Thanks Mark ... Happen to know a reputable FIAT mechanic in the Portland, Maine area?

[So Cal Mark]

no I don't and I wasn't aware that Portland had left Oregon and gone east either!

[mbouse]

Can't answer your question directly about the FIAT mechanic out east.... but i'd like to offer two suggestions:
1. front end suspension on a Spider is no rocket science. any competant mechanic could easily determine which component is not right with your car.
2. there is a huge concentration of FIAT-LANCIA-UNLIMITED members out east, maybe one in your neighborhood. consider joining up with FLU and get the benenfit of the club experience.

[kkemerait]

Mark... the Portland out west was the prototype.

[punes]

I had the exact same issue on my 79...check your motor mounts....I could visibly see that mine were sagging and therefore not providing enough stability for the engine.

Every time I hit the brakes, I guess, everything else under the hood pushed forward a bit..

I really had no idea that new mounts would solve that issue, but it did.

The mounts should look like 2 or 3 hockey pucks stacked together...mine were not a perfect tower so the upper part of the mount was leaning outward.

Fixed mine up and that Thunk was gone.

Frank
Canada eh?
79 Fiat Spider

[kilrwail]

I suggest looking at the two large studs that attach the cross beam to the unibody. Their nuts can work loose over time, resulting in the exact symptom you've described. Make sure they're tight before looking for a more complicated problem.

[sptcoupe]

How does the car brake under pedal? Can you "feel" the think through the brake pedal? A caliper hanging up will cause a thunk. By hanging up, I mean the piston that does not move initially, and then slams home as you increase pedal pressure. Had this problem on several cars. Caused by old/worn seals that let moisture/dirt get in and score the cylinder surface, causing it to hang up until enough pressure is applied. Not all that uncommon.

[kdog]

I had a similar problem and like Mark suggested, it was a loose brake caliper mounting bolt. You do not have to be a mechanic to check it. Climb underneath and look behind the front wheels. The calpiers are held on by only two bolts. If one is loose, the claiper will rock back and forth every time you hit the brakes. If it is a loose bolt, you should be able to tighten it without even taking the wheel off.
Keith