Mono­coque mat­ters

Classic Car Weekly (UK) - - Buying Guide -

The mono­coque shell can be weak­ened by rust. Her­itage bodyshells aren’t avail­able for the MGC but all exterior pan­els ex­cept the bon­net are shared with the MGB, as are the sills. These are a key area to check and they are tricky to re­place. Other ar­eas to keep an eye on are the front in­ner whee­larches (see if the box sec­tion at the top is in­tact), the outer whee­larches, spring hang­ers and bat­tery trays. The top of the fuel tank is cor­ru­gated for strength but col­lects wa­ter, then rots. Road­ster and GT fuel tanks are in­ter­change­able and the same as chrome bumper MGB units. On GTs the double-skinned tail­gate rots along with the scut­tle where it meets the base of the wind­screen. Also check for rusty door bottoms – MGC doors are the same as post-1968 MGB items. Mar­que spe­cial­ist Paul Dep­per adds: ‘Crash dam­age can be an is­sue, es­pe­cially in the nose. But it’s not al­ways ob­vi­ous, so make sure ev­ery­thing lines up prop­erly.’

En­gine ex­am­i­na­tion

Al­though the en­gine is based on the Austin 3.0-litre six-cylin­der unit, the valves, springs and sump are unique to the C. It’s a tough old en­gine but the pis­ton rings wear so watch for oil be­ing burned. Rocker shafts also wear so lis­ten for a clat­tery top end. Don’t as­sume it’s just a ques­tion of ad­just­ing the valves.

Get into gear

Gear­boxes are weak – the layshaft bear­ings wear, re­sult­ing in the shaft drop­ping and putting pres­sure on the cogs. Lis­ten for whin­ing, as worn gears will be noisy even if the bear­ings and align­ment are fixed. Many own­ers fit a Ford five-speed con­ver­sion of­fer­ing lower trans­mis­sion losses so econ­omy is im­proved. They also have bet­ter ra­tios, qui­eter op­er­a­tion and the abil­ity to ac­com­mo­date a faster clutch change. Bud­get £2500 for a pro­fes­sional con­ver­sion or £1000 for the parts. Gear­box ra­tios var­ied – early non-over­drive cars are the same as the B but over­drive brought a close-ra­tio gear­box. Then from Novem­ber 1968 all cars got this unit and the dif­fer­en­tial ra­tios were changed. Ini­tially nonover­drive cars fea­tured a 3.07:1 ra­tio with over­drive and au­to­mat­ics get­ting a 3.3:1 unit. This changed in 1968 so au­tos and non-over­drive cars got the 3.3 unit while over­drive cars got a 3.7:1 dif­fer­en­tial. Vi­bra­tion from the driv­e­line sig­ni­fies one or both of the prop­shaft uni­ver­sal joints (UJs) has worn; con­sid­er­able gear­stick move­ment sug­gests worn or bro­ken gear­box and/or en­gine mount­ings. Re­plac­ing UJs is easy while re­new­ing mount­ings is fid­dly but straight­for­ward.

Sus­pen­sion sus­pi­cions

Un­less the king­pins are greased ev­ery 3000 miles they’ll wear, so jack up the front of the car and rock the wheel top and bot­tom while some­body ap­plies the foot­brake. Any de­tectable move­ment means the king­pins need re­plac­ing at £140 each plus fit­ting

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