Violent Twitch on braking - MK1 MX5

[snowen250]

Hello,

Now I think I know what the problem is, but i'd like to ensure I have all the bases covered before I chuck the thing at a garage.

I have a '94 Mk1 MX5 (actually a Eunos but...) It recently came back from the garage from having some general work done, this included a new right rear calliper (drivers side.)

Since it returned it has been pulling to the right on braking (not every time...but often) and if you dare to apply the brakes while also turning a corner it tries to swap ends on you! It steps to the right, violently, then back to the left.

The front right disc is also disproportionately warm compared to the others.

Now I presume the front right calliper is sticking, or maybe coming on too hard (oo-er) and is thus causing the car to shimmy and pull, I am also finding that both fronts lock up very very easily now. But the garage said they checked that calliper and found no issue.

So is there anything else it can be? The brakes work fine in general use, it pulls a bit but nothing awful. But as soon as you increase speed it becomes more pronounced, and as I do track days in it at Brands there is no way I could currently drive it round a whole lap.

Any other suggestions what the issue may be? Bias? Dodgy disc? Brake Lines?

Thanks!

[snowen250]

They also did:

Gearbox and Diff oil.
Full alignment and tracking done.
Various gaskets and seals replaced in engine, it was leaking some oil.


I may ask them to replace the bushes as well then, doesn't sound an expensive job (I have no room at home to work on the car myself sadly)

Thanks

[snowen250]

JM said:

snowen250 said:

They also did:

Gearbox and Diff oil.
Full alignment and tracking done.
Various gaskets and seals replaced in engine, it was leaking some oil.


I may ask them to replace the bushes as well then, doesn't sound an expensive job (I have no room at home to work on the car myself sadly)

Thanks

Surely they would have spotted worn bushes when they were doing the alignment and tracking.

Yes, I would expect so. I asked them to check these so I can only presume. They are a good garage who have carried out a lot of work for me in the past and I've never had any issues. But bushes do wear out, so il ask how worn they are and if it is a job that will need doing in the near future il get them to do it now to cross it off the list.

I can drive round most issues. but not scary brakes....

Thanks for your responses.

[snowen250]

Thanks for the replies. The garage is also an MOT centre, so will ask them to do the check as suggested.


Finishing Touch - yeah it probably is the same thing, that's me being dense, not them!


Car doesn't have ABS, so will add that to the list to be checked, it certainly feels unbalanced and as I said, having the front wheels at an angle when pressure is applied certainly exacerbates the issue.


No worries on it having a complete check over, I've said i'm willing to throw ££ at it til it is sorted. It is otherwise a very quick little MX5!


Thanks again for the help, on a recent track day I did manage to boil the fluid. It has since been changed (obviously) but would this affect the master cylinder, and then cause issues like this?

I am pretty certain it is a binding calliper, just want to cover all the bases.

[snowen250]

SonicShadow said:

snowen250 said:

I have a '94 Mk1 MX5 (actually a Eunos but...) It recently came back from the garage from having some general work done, this included a new right rear calliper (drivers side.)

Since it returned it has been pulling to the right on braking (not every time...but often) and if you dare to apply the brakes while also turning a corner it tries to swap ends on you! It steps to the right, violently, then back to the left.

This is almost certainly why, and this is why you should always replace calipers in axle pairs. You've most likely got a very mediocre caliper on the rear left. This means the braking force on the rear right is significantly higher, leading to wayward behaviour under braking. The fact it's pulling to the side with the more effective caliper almost confirms this.

Thanks everyone, I shall get them to replace all the callipers that aren't new (ish) Worth doing the discs and pads at the same time? As with anything MX5 related, they aren't exactly expensive....

[snowen250]

Ok guys thanks, il have them do the:

Callipers

Discs

Bushes

on the tyres front, they are equal across the axles, with Rain sports on the front that are just over a year old and Rain sports on the rear that are around a month old but only a few hundred miles if that. So I don't think it is tyre related?

[snowen250]

The Tea Boy said:

There's a possibility you don't even need new calipers, sometimes just striping down and sorting the slider pin sorts it out.
You can bust the kits on fleabay for a few quid.

Ok thanks, the calipers don't seem to cost much either, so for the sake of a few ££ I think just going new may be easier, less labour costs too then I guess.

I'm dropping the car in tonight, so I shall update the thread when the find the culprit part/s

ta!