NCT Test Results - A Query

Poulgorm

A relative of mine has a 2012 Honda CRV (170,000 Km) & I brought it for the NCT this morning - the car passed the test.

But I am curious about these figures:

Side-slip/Alignment Test: Rear axle: December 2024 result: -12.0 m/Km December 2025 result: -3.0 m/Km.

Allowable: +18 to -18 m/Km. So, the December '25 result appears to be better than the December '24 result.

How is that possible?

I don't know if the tyres have anything got to do with it - but same tyres and same pressures (33 psi).

Any explanation?

easygoing39

it's all down to the callibration of the equipement at the NCT centre,sometimes a car will fail on a lane,put it on a different lane and it'll pass.

almostover

https://www.boards.ie/discussion/2058428218/nct-test-results-a-query

Tracking was done on the car when it got the new tyres?

mk7r

One pothole can significantly alter the alignment

hhmmm?

12m per km is a serious pull. You'd know if there was a problem last year. Inconsistent testing and improper use of testing equipment is par for the course for NCT. Probably driven across the slip tester at an angle

Poulgorm

https://www.boards.ie/discussion/comment/123980145#Comment_123980145

Same tyres. No tracking done.

L1011

All wheels on the same corner as last year?

9935452

https://www.boards.ie/discussion/comment/123980951#Comment_123980951

Totally agree with you on that.

I had a 09 A4 with electric handbrake. Which failed for no handbrake on the lhs. Tester said it started with no handbrake whatsoever but they got the rhs working. . Test result showed practically zero . Booked it in elsewhere and it passed no problem . Should have made a complaint but didn't bother at the time

hhmmm?

https://www.boards.ie/discussion/comment/123981191#Comment_123981191

Sure they can do no wrong.

I'm showing my age now but when the NCT was first being rolled out they contacted Mazda Ireland wondering if the MX5 should have 3 seatbelts. Mazda advised the car was a 2 seater and the challenge from NCT was that when the roof was down sure somebody could sit on the shelf.

Great bunch of lads .

almostover

https://www.boards.ie/discussion/comment/123981138#Comment_123981138

Misread by me!

Tantalum73

https://www.boards.ie/discussion/comment/123980951#Comment_123980951

"12m per km is a serious pull" …. ??

https://www.boards.ie/discussion/comment/123981191#Comment_123981191

So your validated your own theory of nothing wrong with the car just because it has passed in another centre without any investigation of potential faults as to why this has happened … there was 100% an issue with your parking brake, simply cannot get one side to work and the other not .

https://www.boards.ie/discussion/comment/123981213#Comment_123981213

Come on , that sounds like absolute horse manure.

@OP , what was the difference between the front axle side slip readings between tests

hhmmm?

https://www.boards.ie/discussion/comment/123982608#Comment_123982608

12m/km on the rear axle is practically crabbing.

In relation to the MX5, I was in the office when the call came in.

Tantalum73

https://www.boards.ie/discussion/comment/123983224#Comment_123983224

Thats another assumption . A high sideslip can be high total toe but equal on both sides , wont crab nor "pull" as you say.

As for your mx5 story , im gonna call that bull

9935452

https://www.boards.ie/discussion/comment/123982608#Comment_123982608

A bit more information on the handbrake issue .

Firstly it's an electric handbrake . They throw faults when there is anything wrong with them .

. Car was scanned. No faults for handbrake . No stored faults eithre.

The results was practically zero on the lhs.

I brought the car home and jacked up . Put on handbrake and put a crowbar through spokes and couldn't turn eithre side

Let off handbrake everything free. Repeated a few times. No issues.

Talked to a few lads at work who are vw skoda mechanics . They reckoned machine was faulty or car wasn't on the rollers correctly. Which to be fair there was a high end sports car being tested at the time that all the testers seemed to be distracted by.

All advice was to test elsewhere.

1st test centre only had 1 lane . Part of the reason for going else where was they could test it on different lanes if needed..

Car passed .

hhmmm?

https://www.boards.ie/discussion/comment/123983847#Comment_123983847

Don't mind him, he must work for the NCT 😂

hhmmm?

https://www.boards.ie/discussion/comment/123983324#Comment_123983324

Tantalum73

https://www.boards.ie/discussion/comment/123983847#Comment_123983847

For instance if the lefthand roller doesnt rotate in sync to the rightside it trips a machine fault and wont operate the rollers at all . Also the lhs was working for your front axle and rear axle service brake , rear axle service brake is tested after your parking brake..

For the rollers to operate , the vehicle weight has to be on the safety bars and it obviously was positioned ok if rear axle service brake was done without issue… positioning is really not an issue on a brake test.

Mechanical components can be weird at times but electro mechanical components can be even harder to diagnose if you have an intermittent fault or reason for not operating. Fault codes are only as good as the ecu monitoring so depending on such fault you may not throw a code or even pending one etc .

I come from over 20yrs of automotive/commercial fault finding and diagnosis experience and operate the same MAHA equipment doing tests daily.

I see so many people jump to the conclusion that something was wrong on the previous test when the car passes at another time or centre etc . Thats no way to validate a theory the car is not without an underlying or intermittent fault

Tantalum73

https://www.boards.ie/discussion/comment/123984018#Comment_123984018

Your salty replies say it all !!

Poulgorm

https://www.boards.ie/discussion/comment/123981142#Comment_123981142

Yes

Poulgorm

Tantalum73: @op , what was the difference between the front axle side slip readings between tests?

Side-slip: Front axle: December 2024 result: 8.0 m/Km: December 2025 result: 11.0 m/Km.

Allowable: +14 to -14 m/Km.

Suspension Imbalance: Front axle: December 2024: 14%. December 2025 result: 7%

Rear axle: December 2024: 8%. December 2025: 7%.

It looks like the suspension imbalance improved all by itself too!

The only service done to the car between the 2 NCT tests was a routine one - i.e. oil and filters.

Same tyres - and in the same corners. Tracking not touched.

BrianD3

https://www.boards.ie/discussion/comment/123984029#Comment_123984029

There are issues with the precision and accuracy of NCT results, whether it is the equipment itself or how it is being used is unclear. I've had a car with kerb weight of just over 1000 kg gain 250 kg from one test to the next, then magically lose that 250 kg a week later when retested. Nothing to do with the car. Same NCT centre, same lane, some variation in weight of testers but nowhere close to a 250 kg difference.

Also I've had cars pass that should have failed which makes me question the competence of the testers. The most recent one was where I deliberately set the car up to fail by removing two number plate bulbs and a brake bulb - reason was I wanted to pass emissions, brakes etc but book a free retest a few weeks later which would have given me a longer cert due to the 3 month rule. Car passed first time. As well as the bulbs, I'm pretty sure that the tester didn't bother testing the windscreen washers or the horn