MOT Exemption Expert for ZClub? | The Z Club of Great Britain
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MOT Exemption Expert for ZClub?

Discussion in 'Anything and everything' started by Jay., Oct 22, 2018.

  1. Jay.

    Z Club Member

    So I've been looking into what awards the Z cars (40+ years old) an MOT exemption and for most people it's fairly straight forward - as long as it's not "significantly" modified and 40+ years old then you're good to go.

    The grey area comes to modifications, primarily (for me at least) engine changes. The old rules didn't penalise engine changes nearly as much as suspension, brakes, etc, but that's now gone and it's been replaced with this document which is fairly vague:


    And here:

    Now I've always assumed that because the engine in my car has been swapped (from a 70's 2.4L to a 90's 2.5L) then I'd fall under the "not exempt" category. Except apparently that's not always the case. A few friends that own various classics (Land Rovers, Mini's, Porsche, Lotus etc) have all had pretty lenient exemptions. The following points hold true:

    • changes were made to running gear in order to improve efficiency, safety or environmental performance
    • the changes were made to preserve a vehicle where original parts are no longer available
    • Alternative cubic capacities of the same basic engine and alternative original equipment engines are not considered to be a substantial change.
      • For example, for us I imagine that means going from an L24 to an L28, or rebuilding your L24 (or L28) to 3.0L etc.
    Now obviously there's a lot of grey lines and therefore they suggest to contact an expert clarification. I contacted the legislation experts over at FBHVC but they were unable to give specific advice and suggested I looked for an in-house expert here at ZClub.

    Does the club have a resident expert that people could talk to with regards to VHI status? I figure it'd be ideal to get something sorted out as this will be a pretty common question for anyone that wants to get a VHI but have modified their cars in whatever way.
  2. Woody928

    Z Club Member
    Staff Member Moderator

    slaphead likes this.
  3. uk66fastback

    Z Club Member

    The 'rules' seem fairly open to ambiguity which is never a good start.
  4. Mr.F

    Z Club Member
    Staff Member Moderator

    Surely this is becoming clear now for S30 and S130 models.

    Engine swaps within the L6-series family, tuned or otherwise, injected or carburetted, turbo or not will not be seen as "a substantial change", Supercharging - maybe as no precedent set within the manufacturer's range or motorsport modifications.
    Engine swaps outside of L6-series family = "substantial change", i.e. RB, V8 etc...
    Minor body mods, e.g front air dam, rear spoiler, ZG-style arches will not be seen as "a substantial change".
    Full body kits, extended arches other than ZG-style. Ferrari replicas (and others) = " a substantial change".
    Any changes to suspension which utilise the original design primciple of coilover strut type front and rear will not be seen as "a substantial change".
    Ford 9 inch, four link drag set-up, Jaguar independent cage = "a substantial change".

    No-one is going to change from a rack and pinion steering on an S30, but addition of power steering is not "a substantial change".
    S130 early steering box conversion to later rack and pinion is not "a substantial change" as later S130 had it anyway.

    S13 / S14 gearbox, and differential ratio changes, plus addition of LSD or Quaife is not "a substantial change".

    Feel free to disagree or add any examples of your own that I may have missed. Some S130 "substantially changed" examples below (just for fun):

    Attached Files:

    slaphead, Paul_S and AliK like this.
  5. Paul_S

    Z Club Member

    ...probably a very daft question, but I guess RHD conversation is a substantial change?
    slaphead likes this.
  6. Mr.F

    Z Club Member
    Staff Member Moderator

    I would suggest not.

    Sent from my SM-G950F using Tapatalk
    Paul_S likes this.
  7. richiep

    Z Club Member

    Mike’s on the same page as me with all above points he makes. Most of the changes people make to the typical Z do not reach the bar of constituting a substantial change, given the flexibility of the criteria. RHD conversions typically use all factory components and replicate the factory bulkhead without a change in identity (identity is an entirely separate issue from the MOT criteria anyway). The only thing that really excludes a car from the MOT exemption is a non-L-series engine swap, or significant and obvious bodywork and running gear changes that are not in keeping with historical precedents. I.e. ZG arches OK as they were in period Nissan options and modifications, in some cases factory-executed. Not OK - tubular front subframe replacing original front end or doing something like replacing the floor/tunnel etc with a 200SX floor to run a full rear end. In fact, extreme cases such as those should even trigger a car losing its reg and needing an IVA if DVLA found out...

    Interpretation favourable to our cars is in the interests of the club and owners. Thus, if asked officially (I took up the responsibility for this at the general meeting earlier in the year and am a contact for the FHBVC), I would give a take giving the greatest realistic and evidence-based latitude.

    OP - your car will likely be fine for VHI if that 2.5L you mention is just a modded L6.
    Paul_S likes this.
  8. Jay.

    Z Club Member

    Brilliant reply, both Mike and Richie.

    Mines a non-L series motor so mine doesn't classify for VHI - thanks for clearing that up :)
  9. slaphead

    Z Club Member

    The rules themselves are fairly black and white, the grey areas creap in where and how you apply/interpret the exemptions.

    For example in your case wasn't there a twin cam varient of the L series engine? Therefore couldn't it be put forward that your RB (developed from the L20 fitted to the fairlady Z originally) is the same basic layout as the original engine, by the same manufacturer?.

    I'd certainly be interested in helping out with any of the work to do with this.
    Last edited: Oct 24, 2018
  10. jonbills

    ZClub Administrator
    Staff Member Moderator

    Getting an MOT seems easier
    slaphead likes this.
  11. franky

    Z Club Member

    When it all goes wrong, which it will at some point, I'd be much happier with an MOT as a backup instead of standing in court trying to play ignorant.
    slaphead and Paul_S like this.
  12. Albrecht

    Albrecht Well-Known Forum User

    You might need Rumpole of The Bailey to help you get that one past a beak.

    There was no 6-cylinder twin cam version in the Nissan L-gata engine family, only 4-cylinder. The bloodline of the RB-series engines can be traced back through the FJ-series to the S20 and (with Rumpole's help) you might even link it tenuously to the Prince G7, but it's pushing it a bit.

    The RB certainly wasn't "developed from" the L20 six. The team which conceived and developed the RB-series engine family had their roots in the Prince Motor Co. part of Nissan's bloodline.
    Mr.G, slaphead, richiep and 1 other person like this.
  13. slaphead

    Z Club Member

    Oh dear Wikipedia (which I do take with a pinch of salt and then some needs correcting it seems). I personally stand corrected though I was confusing the engine fitted to the Z432R, which I thought was a DOHC.
    Last edited: Oct 25, 2018
  14. Pete

    Pete Active Forum User

    I think there was also an error on the Nissan heritage site as well, but they seem to have fixed it. I posted this on the 'missing model from line up thread', which was info copied and pasted from the original links

    'OK. I'll be stupid.

    Fairlady 240Z-G (1972 : HS30)
    Sport Car / Special Spec Car

    Overall length / width / height
    Tread (front/rear)
    Curb weight
    L24 (6-cyl. in-line, DOHC), 2,393cc
    Engine Max. power
    110kW (150PS)/5,600rpm
  15. Albrecht

    Albrecht Well-Known Forum User

    It's a mistake, that's all.

    Welcome to my world. If you try to correct enough obvious mistakes, people start taking exception to it.
    slaphead likes this.
  16. Pete

    Pete Active Forum User

    Ah, OK , thanks. Thought it was maybe me being wrong!
    slaphead likes this.

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