mx5 6 speed box

[Scottnoble]

Hi, please can anybody tell me if you can change a 2007 mk3 1.8 5 speed box for a 6 speed?.Also change the diff for a lsd.Thanks

[roddo]

To change the box you need the prop, clutch and gear lever also.
The diff is a direct swap

[Scottnoble]

HI thanks for the quick reply if was to replace the diff only would this raise the gearing? this is what iam trying to do .also does the diff need to be from a 2.0 mx5. Sorry about this but i know little about mx5's this is my first one! Rgds Scott.

[knitware]

Scottnoble said:

HI thanks for the quick reply if was to replace the diff only would this raise the gearing? this is what iam trying to do .also does the diff need to be from a 2.0 mx5. Sorry about this but i know little about mx5's this is my first one! Rgds Scott.

Probably not too helpful but could you sell the 1.8 and buy a 2.0?

[Scottnoble]

Hi please can anybody tell me if a 2.o lsd diff from a mk3 is a haigher ratio than a std mk3 1.8,and what parts are needed ie half shafts etc etc. Thanks.

[roddo]

Depending on year a 2.0 sport 6 speed diff will be a 3:7-1
a 1.8 5 speed diff will be a 4:3-1

All the drive shafts are the same.

[Scottnoble]

Thanks Roddo, Is the 2.0 3:7-1 higher than 1.8 4:3-1 ? Also do you know what year of diff i need to get.cheers for the help.

[roddo]

What are you trying to achieve?

Feel free to call me for a chat.

[Scottnoble]

HI Roddo,i was thinking of upping the gearing to try and get the revs down a bit,trying to get a bit more mpg.My mx5 1.8 seems to rev at about 1500 rpm in 5th at about 30 mph.I was thinking about getting it down to about 11 to 1200 rpm in 5th at 30 mph.

Thanks again for your help and advise.

Scott.

[VladD]

As far as I understand it, and I'm no expert, the ratio is how many times the wheels turn in relation to the prop shaft. So in your 1.8, the wheels will turn 4.3 times for each prop shaft revolution. The 2.0 has a 3.7 ratio, so if we divide 4.3 by 3.7 we get 0.86. Use that as a multiplier. The speed you used to travel at 5000 rpm will now be achieved at 4300 RPM with the 2.0 diff.

Using your example, 30 mph in 5th would now be at 1290 rpm instead of 1500.

[Scottnoble]

Thanks for the advise,do you know what year mx5 2.0 i need to get a diff from. Cheers.

[VladD]

I don't I'm afraid. Call Roddo. Do a google for Roddisions Motorsport.

[Scottnoble]

Will do thanks for your help.

[Bertrum]

Scottnoble said:

Thanks for the advise,do you know what year mx5 2.0 i need to get a diff from. Cheers.

Any post 2006 Diff will fit. They are interchangeable between all models.

[MX-5 Lazza]

I doubt you are going to achieve what you are after. By fitting a 2.0 dif you will lower the revs but the 1.8 doesn't have the torque of the 2.0 so the engine is going to have to try harder to keep the speed.
Also, 1500 isn't high at all. Are you coming to the MX5 from a modern turbo-diesel?

[Scottnoble]

Hi Lawrence,how did you guess,i see what your saying about the engine working to hard ,would it help if i had the car re-mapped?apparently a re-map will give it +9 bhp and +17 torque without using any extra fuel,do i try a re-map on it's own? or do i just leave it as it is.I was just try to get a bit better mpg.Cheers

[Ninja59]

Hmm my daily is a 3.0 diesel and the weekend ironically a 1.8 mk3 mx5...

I must admit for a moment i feel a total pleb revving it out and the higher revs.

The only thing you have missed is what MPG is the car currently achieving? (I have seen some improvement with mine by removing the battery for a few minutes which then gets the car to reset it idle, but in conjunction with that at times I have seen improvement in MPG). I no longer monitor mine with such a degree because it does only a few miles now (for the record it is currently sat at 31 only because the weather this weekend has been awful and I have been polishing it).

[ikarl]

Scottnoble said:

Hi Lawrence,how did you guess,i see what your saying about the engine working to hard ,would it help if i had the car re-mapped?apparently a re-map will give it +9 bhp and +17 torque without using any extra fuel,do i try a re-map on it's own? or do i just leave it as it is.I was just try to get a bit better mpg.Cheers

Do a quick calculation, how much would you improve the mpg by? How many miles do you do per year? How long would it take to recoup the cost of the initial modification?

I'm gonna bet it would take many many years if you're only saving a couple of mpg

[hornetrider]

As above. Abandon this idea, for it is foolish.

[MX-5 Lazza]

Take Roddo up on his offer and give him a call to discuss it. He is the guru on all things Mk3. I think you are driving it wrong though. All MX5s, regardless if the engine, are about revs. They all love to be revved, thrashed in fact. You just can't kill them with revs as long as the servicing is done regularly and you keep an eye on oil & coolant levels. None of them like trickling along at close to idle speed. A small, normally aspirated engine just doesn't have enough torque at those revs.