I have a 1.2 that came with 14" steel wheels. I put heavier 17" alloys on it along with spacers and a few months later my gearbox casing cracked. Mechanic said the wheels are too heavy and because they are spaced out it put my gearbox under pressure and broke it. I do not drive the car hard at all. I've had a lot of people tell me since that what he said is bull and I know a lot of people who have the same car as me and put the same wheels on with no problems. Alloys are currently sitting in the shed with brand new tyres on them and just refurbished. Should I put them on the car or do you think that will cost me another gearbox?

So according to the mechanic, you can't carry passengers in the car as the gearbox won't take it. That's what he is saying by referring to the weight of the new wheels. I think the gearbox cracking is a totally unrelated issue to the wheels.

So according to the mechanic, you can't carry passengers in the car as the gearbox won't take it. That's what he is saying by referring to the weight of the new wheels. I think the gearbox cracking is a totally unrelated issue to the wheels.

Yeah I agree. I think what he was trying to say was that it's not the weight alone that does any damage, it's that the weight is in the wheels which need to be turned by the diff. And the diff cracked the gearbox casing or something like that. I wouldn't know enough to tell if what he was saying even makes sense! 

Have you actually weighed one of the 14" Steel and Tyres and the 17" Alloy and tyre to see what difference there is in weight, 

maybe the steels are 18 kg and the alloys are 19 kg per wheel / tyre.

 

http://kouki.co.uk/utilities/visual-tyre-size-calculator

Were you actually running the same Rolling Radius / Total Diameter tyres when the 17's were on, 

because that is more likely to be an issue. (not a major one though. But it will be interesting to know what the 14's were and what 17" tyres you have.)

Then driving style might have some contributory factors to how the car stands up to things.

He may not have explained very well? The much bigger alloys unless you are runimg a tyre profile with a 3" lower side wall will effectively gear the car up making it need to work alot harder to move it along - 1st becomes more like pulling away in 2nd or 3rd.. that wil lunch a gearbox after a while. Not so much the weight difference unless each each alloy needs a forklift to move..

There is also the fact that a lower, wider tyre is more "sticky" and that too will put extra strain on the diff.

I haven't actually weighed the wheels. I will though. By lifting you would know that the alloys are a good bit heavier.

 

The rolling radius is the same. The tyres on the 17s are 205/40 and extremely similar in size to the rolling radius of the 14s.

Okay weighed one of the alloys and the spare. Alloys are 6 or 7 kg heavier. Wheel sizes are 185/65/14 and 205/40/17. 10mm spacers on the front and 20mm on the back. Car is a seat ibiza 1.2 mk4 and the wheels are the mk4 cupra alloys.

So did the 14" steel wheel and tyres only weigh around 12 KG ?

No real size difference other than the width of the tyre.

 

Anyway that really is not an issue.

As plenty use 205/40 R 17's on Ibizas, Fabias & Polos.

 

Maybe leave the spacers off,

you do not need them on to get the 17's to fit, or do you?

I haven't actually weighed the wheels. I will though. By lifting you would know that the alloys are a good bit heavier.

 

The rolling radius is the same. The tyres on the 17s are 205/40 and extremely similar in size to the rolling radius of the 14s.

! Wrong one: s/be: Okay weighed one of the alloys and the spare. Alloys are 6 or 7 kg heavier.

 

Not full of drugs or concrete are they?

Could be why they're 'spaced out'

Speaking of which, how much offset on the spacers?

Post #8.

Spacers are 10mm front, and 20mm rear.

Steel wheels were 15kg according to my scale and alloys are 22kg. Scale possibly off?

 

Yeah spacers are purely for looks, not needed to make the alloys fit.

Would I be correct in thinking that spacers on the rear wheels wouldn't make any difference as they're not the driving wheels?

Does your insurance company know what wheels you have on?

 

Mk2 Fabia vRS Gigaro wheels with 205/40 R 17 tyres are 19kg so your scales might be a bit off.

(or as suggested there is something in your tyres, 'Maybe the famous thick air.')

 

Rear spacers will make no difference, but then neither will those on the front.

 

?

What power output is this 1.2 engine?

Edited 2 January, 201610 yr by GoneOffskiroottoot

I'd say my scales are off. 64hp as far as i know haha

Does the gearbox feel how much the wheels weigh? I'm thinking that the ground supports the wheels, not the gearbox.

 

(Maybe there's an argument about the extra unsprung mass, the spacers, and the angular momentum of a heavier wheel further from the gearbox? Or the extra moment due to the spacers alone, depending on how much 1 cm is compared with the rest of the suspension dimensions? But if the wheel is applying enough moment to crack the gearbox I think that might feel noticeably terrible inside the car.)

Driving the car feels no different. Ride is a bit harsher due to the low profile tyres but other than that, no difference!

Does the gearbox feel how much the wheels weigh? I'm thinking that the ground supports the wheels, not the gearbox.

(Maybe there's an argument about the extra unsprung mass, the spacers, and the angular momentum of a heavier wheel further from the gearbox? Or the extra moment due to the spacers alone, depending on how much 1 cm is compared with the rest of the suspension dimensions? But if the wheel is applying enough moment to crack the gearbox I think that might feel noticeably terrible inside the car.)

If the 1cm additional torque / moment force is enough to to make the gearbox have an anurism... then my old cordoba shouldve shat its pants long before the engine died on the bsais of some of the weight i put in that thing (also a 64bhp 1.2 engine..)

Edited 2 January, 201610 yr by mac11irl

Yeah think I'm going to put them back on. Cheers everybody!

Yeh the gearbox breaking is nothing to go with the wheels. More likely the rivets falling out of the cwp