Q&A Tech­ni­cal is­sues solved

Michael Clev­er­ley of Clev­er­ley Re­paired Cars, ex­pert on all things MX-5, an­swers your ques­tions

Total MX-5 - - CONTENTS -

You ask, we an­swer. This month: ig­ni­tion is­sues, sticky brakes and more

IG­NI­TION SWITCH ANGST

Q Help please: my 1989 mk1 1.6 has a strange elec­tri­cal fault – driv­ing along, some­times the heater, wipers and lights stop work­ing and then start again. It’s quite fright­en­ing when it hap­pens and I daren’t drive at night. Can you give me an idea of what may be the prob­lem?

A Elec­tri­cal faults, par­tic­u­larly in­ter­mit­tent ones, can be frus­trat­ing. How­ever, in this case with so many sys­tems af­fected, it’s likely to be the ig­ni­tion switch it­self. We have seen this a few times on early cars and a wig­gle of the key of­ten gets things work­ing again tem­po­rar­ily.

Luck­ily it is easy to re­move the switch from the rear of the ig­ni­tion bar­rel. Take the lower kick panel off us­ing a Phillips screw­driver, and re­move the steer­ing col­umn cowl­ing as well. With the bat­tery dis­con­nected you sim­ply un­plug the ig­ni­tion switch multi-plug. A sin­gle screw is all that holds the switch as­sem­bly in. Work­ing care­fully (springs and balls can drop out…) dis­man­tle the switch – the con­tacts can then be cleaned us­ing fine abra­sive pa­per. Re­assem­ble and the prob­lem should be fixed.

If you don’t feel con­fi­dent enough to dis­man­tle the switch, then sim­ply pur­chase a brand new re­place­ment.

STICK­ING STOP­PERS

Q A few times in the last weeks my brakes have been stuck first thing in the morn­ing, and can be noisy when I’m driv­ing. What’s up?

A This is a prob­lem usu­ally re­lated to weather con­di­tions or pres­sure wash­ing! It has been very wet and salty [in the UK] for a while now, so mois­ture gets onto the discs and pads. Overnight, light sur­face rust forms on the discs which can be enough to lock the pads to the disc mak­ing mov­ing the car tricky.

The fix is to jack the car up and re­move the wheel that’s seized; a light tap of the brake caliper with a ham­mer should un­stick it very eas­ily. As soon as you drive you will hear scrap­ing sounds from the wheels – th­ese should lessen and stop with a few ap­pli­ca­tions of the brakes: the pads clean the rusty disc. The noise may alarm you but it’s ac­tu­ally noth­ing to worry about, as­sum­ing the brakes are not worn out! Leav­ing the hand­brake off and en­gine in gear overnight will re­duce the prob­lem (chock the wheels if the car is on a slope).

In cold con­di­tions it is good prac­tice to leave the hand­brake off in any car, as mois­ture in the ca­bles can freeze solid leav­ing the hand­brake stuck on un­til it thaws. Which is an­noy­ing…

QUAR­TER-LIGHT QUANDARY

Q My oth­er­wise im­mac­u­late mk3 is suf­fer­ing from un­sightly rust at the base of the quar­ter-lights – can you please ad­vise how to solve this?

A This is a rel­a­tively com­mon com­plaint and is caused by slight move­ment of the quar­terlight’s frame, mak­ing the plas­tic weather seal chafe against the metal, re­mov­ing the paint and al­low­ing rust to take hold. It looks hor­ri­ble, but is eas­ily re­paired.

Mazda sells new quar­ter-light frames sur­pris­ingly cheaply, and if you look closely at them, a small square of pro­tec­tive plas­tic has been added to the vul­ner­a­ble area. You can have the orig­i­nals pow­der-coated, but this costs a sim­i­lar amount to new ones.

The door card comes off eas­ily by re­mov­ing three screws and pris­ing off the clips around the edge. One screw is in the cup-holder, and the sil­ver top of the door pull prises off re­veal­ing a sec­ond screw: the fi­nal screw is be­hind the door han­dle (hook out the plas­tic trim to re­veal the screw).

With the three screws re­moved, work around the edge of the door card with a trim tool or screw­driver to re­lease the clips and the card comes off. As you re­move the panel, the door open­ing ca­ble and wires to the win­dow switches etc must be dis­con­nected. Next re­move the win­dow glass by re­leas­ing three fix­ing nuts and two limit stops (note the po­si­tion of th­ese). The glass lifts out eas­ily.

The quar­ter-light can now be re­moved by un­do­ing three bolts. You have to un­bolt the quar­ter-light glass from the frame and swap the rub­bers and glass to the new frame. Put back to­gether in re­verse or­der and your car looks as good as new.

BOOST BOTHER

Q My su­per­charged mk2 keeps throw­ing off belts: I’ve fit­ted new ones but it keeps hap­pen­ing. What can I do?

A The belt-drive is of­ten the Achilles’ heel of su­per­charged Maz­das. Both align­ment and ten­sion are crit­i­cal. On most in­stal­la­tions I’ve worked on, shim­ming of the su­per­charger mounts to en­sure that the drive belt is per­fectly in line with the crank pul­ley is pos­si­ble and very im­por­tant. Belt length se­lec­tion must be right to al­low the of­ten lim­ited move­ment of the ten­sioner to work cor­rectly. Too much ten­sion can wear the rub­ber­bonded crank pul­ley, mak­ing it run out of true, ag­gra­vat­ing the sit­u­a­tion. Too lit­tle ten­sion re­sults in lost boost at higher revs and huge amounts of rub­ber dust in the en­gine bay from the rapidly wear­ing belt.

It doesn’t help that the stan­dard Mazda belt width is less than most su­per­charg­ers re­ally need. Wider pul­leys are avail­able, but be­ing ex­pen­sive are not of­ten used. A smaller di­am­e­ter pul­ley on the su­per­charger to in­crease boost also gears the sys­tem up and in­creases the load even more.

So ba­si­cally, get the belt run dead-straight and the ten­sion tighter than a nor­mal drive belt – but not too tight – and ex­pect to re­place the belt more of­ten than on a stan­dard car, and you should have a rea­son­ably re­li­able boosted car.

WITH­OUT A PAD­DLE…

Q A cus­tomer re­cently com­plained about the clutch jud­der­ing badly on his mk2, spoil­ing the plea­sure of driv­ing the car, par­tic­u­larly in traf­fic. He asked if we could fix the prob­lem.

A Mk2 MX-5S are well known to suf­fer this way, par­tic­u­larly when re­vers­ing. As long as the en­gine mounts are in good con­di­tion, fit­ting a new high qual­ity clutch, and pos­si­bly hav­ing the fly­wheel refaced, cures the prob­lem. How­ever, on re­mov­ing the gear­box of this car, we were sur­prised to see a pad­dle clutch in­stalled.

Th­ese are in­tended for com­pe­ti­tion use or high­pow­ered cars. De­signed to re­duce slip un­der ex­treme loads, they can be used on the road but of­ten will be very grabby and have a bit of an on/off ac­tion. The torque of highly-boosted cars may make the use of such a clutch nec­es­sary, but the draw­backs have to be ac­cepted. Some do work much bet­ter than oth­ers, but for a nor­mal MX-5 it is com­plete overkill!

With this car we in­stalled a stan­dard-spec Exedy clutch (as fit­ted from the fac­tory) and it’s a plea­sure to drive again. For boosted cars we tend to in­stall Exedy stage 1 up­rated clutches – driven with a de­gree of sym­pa­thy, they do the job well and are smooth in op­er­a­tion.

Even light sur­face rust can cause your discs and pads to stick to­gether. A ham­mer helps…

Some elec­tri­cal prob­lems are caused by a faulty ig­ni­tion switch – it’s rel­a­tively sim­ple to re­move and clean, which will hope­fully put things right again

Rust­ing quar­ter-light frames can spoil the looks of your oth­er­wise tidy car. Re­place­ments from Mazda (above right) are supris­ingly cost-ef­fec­tive – or well priced, as we used to say. But you need to re­move the door-card to fit them

To pre­vent your su­per­charger throw­ing off its belt, the belt must be per­fectly in line with the blower’s pul­ley, and have just the right ten­sion

Un­less your MX-5 has a se­ri­ous amount of power, a stan­dard-spec Exedy clutch is per­fect for the job

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