Group buy / order: 0.65 / 0.643 5th for TDI

Thanks for all the work you have done so far on this Mike.

It will be interesting to see how you get on with it over the next few weeks doing some mixed driving and also to get Adrians '75' report in due course.

I think if you do most of your driving on the motorway, it is a no brainer of a decision, I just question that with mixed driving the incresed rpm in 4thwill negate any gains in economy.

Anyway, hats off to you guys for your pioneering work and helping the likes of me to make the right decision.
 
Last edited:
Thanks Mike, It all seems to confirm my own calculations. Putting aside cost the 0.681 ratio is probably the ideal gearset for the sort of use I put my car to however the the additional cost over the 0.659 or a used 0.700 is just stretching the finances a step too far.

How did your car perform in the 'new' 5th on the M62? Especially on the long uphill sections?
 
Absolutely no problems Adrian. The long straight uphill section from Brighouse to Huddersfield was a doddle - bimble along at 70mph and foot down saw 90 before you knew it. It's actually a little deceptive at the moment, as I'm still used to the noise associated with 70mph, so I tend to think I'm doing less than I am!

I doubt you'll be using 4th for long periods in an uneconomical way - from the graph you can see that a change up at 2250rpm is all that's needed to go to 5th and you're still doing an economical 1850rpm (or 1750 for 90 owners) at 40mph.

I tend to think that the 0.659 will be the most popular for owners who want the best spread, but are not big motorway users.

Cheers,

Mike
 
Hi Mike,

Are you in a position to quote a price for this job?
An update to the OEM ratio prices would be useful too.

Many thanks.

Will
 
Anyone else got near to fitting their gearsets yet? Particularly interested in how the 0.65 works on a mapped 75...
 
Skipton autos fitted my gearset today, well worth it for me and thanks Mike! will post a review tomorrow, am just home from a long day and knackered.... zzzzz
 
To update on my post last night. The difference is obvious immediately on changing to 5th and the hardest part is learning to change up at slightly higher engine/road speeds. On the m/way the new gearing is ideal for me, giving quieter running yet still having plenty of power to accelerate uphill. On urban roads with a lightly loaded car I can take the roadspeed down to 40 and still accelerate slowly. It will 'trundle' at 35 but is possibly not advisable unless you are running in a line of traffic on a flat-ish road. This weekend I will be going away for a couple of days with passenger, dog and luggage so I will get an idea of how it performs with load on board. It is too early to report on economy gains but I am hoping for around a 5% improvement. My situation is complicated by the possibility of a suspect MAF and imminent fitment of aero bits and new tyres.

In summary I agree with Mike it is as far as I would go with a mapped 75 and for some owners the 0.68 gearset is probably a better alround compromise. An unmapped 75 will simply not cope and would suggest simply going for a 0.700 gearset from a '90'.

The work itself is not overly complex IF you have the tools AND a clear understanding of the details of correct assembly (particularly of the synchro mechanism) which could easily catch out the unwary. I would highly recommend Skipton autos for this and now Mike has converted 2 cars he has also a better idea of the potential problems (and as a result of mine now has the modified gear puller.....!)

So all of you who were signing up to this a few months ago now is the time to go for it......:D

In summary i am very pleased with this conversion and would have no hesitation in recommending it as a way of improving the driving experience with the added benefit of potential savings at the fuel pump.
 
Thanks for the report Adrian. Do you have any rpm reduction figures? Also you said it was quieter, can you possibly give a bit more detail. For me, I know there will be an economy gain but as I will be doing a lot of Autobahn/autostrada miles, noise and the reduced wear and tear from lower RPM is what really appeals.
 
I'd imagine that revs will be as per the graph I posted some time ago, but at 70mph, I'd expect a reduction of around 300-400rpm if going from a standard 75 box to the 0.659 ratio.

Thanks for the write-up Adrian. Yes, the job isn't that complex, but you do need some specialist tools and as you say, the re-assembly of the synchro gear has to be precise - get one of the springs out of position by a couple of millimetres and you'll eventually lose it in the gearbox, possibly wrecking it (the gearbox, not the spring!!).

So, to all the 20+ people who signed up for the mod, what are you waiting for!!??

Cheers

Mike
 
As Mike says the reduction in revs is exactly as the graphs show. As for noise reduction it is difficult to quantify without having test equipement however there is definately less engine noise which gives a more relaxing drive. You seem to be going slower because your mind is accustomed to a certain level of noise at a given speed! For you travelling across Europe it has to be a distinct benefit, I too dislike noise and find it one of the most tiring aspects of long distance driving. The slight downside is you become more aware of tyre and wind noises. I drove over 150 miles yesterday from Mikes across to Chesterfield, upto Wetherby, across to Otley and then home to Skelmanthorpe. This journey includes just about every form of road/driving, fast cross country, motorway, country lanes, urban/city roads, flat to steep (1 in 7) hills and most;y familiar territory so have a good before/after comparison.

One aspect of my car i forgot to mention is when Mike removed the oil drain plug the 'box was somewhat lacking in oil, about a quarter of what should have been in it and no sign of any leakage..... having now used a fuly synthetic oil of the correct quantity I imagine there will be a slight reduction in gearbox generated noise.....

I expect lots of orders now for the gearset.......

So next for my car are the new wheels/tyres this afternoon, Sebring exhaust, aero parts, RARB, softer rear springs, Awesome mats and maybe the bodykit...
 
With respect Will, mine is already spoken for, but I believe MLarner is having the new ratio installed, so he is the person to ask about a used 90PS gearset.

Cheers,

Mike
 
Got my gears sat at home allready to go in, just waiting to get time to fit them could have done with having them fitted early this month but i don't think that will happen now (i've got a trip to Manchester then a trip to sheffield over 2 days) so this would have saved me some fuel and money

Glad to get your feedback Adrian as i'm going down the same as you(gear size) but not doing the 15" wheels

Cheers Phil
 
You must log in or register to reply here.
Back
Top