6 speed to 5 speed

[Julian H]

Hi

I have  the 6 speed and am thinking I really should change to the 5 speed. I love the 6 speed for the Sunday morning blat (trackdays are now in my past) so much but as I get older also love touring in my 7 too so the 5 speed would probably be the better option.

Is my only option the ford? I have a K series? Could I have a Mazda box which I hear so many great things about. The 6 speed is electric, I don't want to miss it too much!

Cheers, Julian

[7 wonders of the world]

The ford will give you the best option for ratios, and is lighter too, even more so if you opt for an alloy casing, you current prop and gear lever will go straight in to and it will fit your tunnel cover, clutch etc too.

Full helical, semi helical and straight cut options here - without doubt the best ratio options for a 7 out there, bear in mind the 6 speed was normally mated to a 3.64 final drive, this could be retained with careful selection and could benefit you for touring, a lot depends on what power your running etc

Steve here will build you a really nice ally 5 speed box

https://www.tracsport.com/

 

[K7 VCT]

Think the mazda box is wider, so only fits metric chassis ??

[7 wonders of the world]

and you would need to source a suitable adaptor as the bellhousing is semi integral 

[Wrightpayne]

Julian,

You will need to change the diff too as the 5 sp usually runs a 3.9 diff.

Have you looked at changing the diff ratio to say a 3.38 (rather than the 3.62) which should drop the revs a bit. I think there is an even lower ratio?!

Perhaps have a play around with a spreadsheet / gear calculator to understand revs / speeds etc with the 6 speed ratios and different diffs Vs the 5 speed

Ian

 

[Julian H]

That very useful thanks. I currently have a 3,9 LSD which i will keep long term. My 7 is super quick but super revvy! So the ford gearbox is the only option but with different innards to choose? i didn't realize I could choose different ratios?

i have dva k with 205bhp, probably too much 

[Julian H]

Too much for me :-o

[Julian H]

Too much for me :-o

[Roger Ford]

Who's been saying great things about the Mazda box?

In racing applications, they seem a lot worse than the Ford Type 9 box. Mine needs rebuilding for the third time, and I've only had it three years and about 12 race meetings.

[rgrigsby]

I've got a BGH Geartech 5 speed with a 3.92 LSD on my Duratec, it's the uprated box BGH do with a longer 1st and shorter 5th. It's been brilliant. Certainly worth a chat with them as there are a LOT of options.

[Englishmaninwales]

+1 on BGH Geartech. 

Note - When you install, the Type 9 five speed needs a gasket between the bellhousing and g/b along with sealant, otherwise it'll leak oil from the selector rail hole in the front face of the g/b. The six speed doesn't require this, but otherwise it's a straight swap.

Malcolm

[Wrightpayne]

I've noticed the 5speed ford boxes creeping up in value £400+ on ebay :-0

[John Vine]

Re #11:

The six speed doesn't require this...

To clarify, it doesn't need the gasket but it does require sealant around the selector shaft O-ring:

JV

[Drumster]

Julian, 

Also think about the 5 speed with SPC rocket ratios. Long 1st and 2nd and shorter 5th. You're welcome to pop over to me in Heathfield for a ride.

Chris

[Roger Ford]

There's nothing much wrong with the standard ratios. Yes, a higher first gear and a lower fifth are handy, but the standard ratios work just fine most of the time. This thread makes it sound like you've got to have custom ratios in order to use a Type 9.

If the six speed comes with a different diff, that might be an issue, but if you've got a non-LSD diff it's probably easier to change the diff and fit a standard gearbox than it is to try to match the box ratios to the current diff.

[Drumster]

Roger,

Nothing wrong with standard ratios, after all, my 7 managed 86k miles on the standard T9 (Sprinting & touring) just fancied a change with more emphasis on the sprinting, although I've still toured with the SPC gearset. I find driving it a lot more enjoyable though with closer ratio gears. One man's meat.........

[Wrightpayne]

I had the 5 speed originally and fitted a 6 speed and 3.6 diff(1.6 K supersport). I really like the fact the 6sp keeps the engine on the boil and makes the drive quite involving though I can see a point where I'd find longer distances tedious and will possibly revert (like the OP)

[7 wonders of the world]

The standard 5 speed ratios are fine for a Sierra with a family on board towing a caravan - but are shocking for a 7

OE ratios                                SPC Semi Heli

3.65                                          2.29 (opt 2.48)

1.97                                          1.61                                

1.37                                          1.22

1                                                1

.82                                            .87 (opt .82)

There are touring ratios and SC options too

 

[Roger Ford]

"shocking"? Amazing how all those Caterham race cars managed with such useless gearboxes.

[7 wonders of the world]

The gearboxes are not useless, merely the ratios are not correct for the car.

Racers moving beyond Grads fit the SC CR gearkit that is permitted by the regs, didn't see them sticking to the OE ratios.

 

[Golf Juliet Tango]

The ratios feel better with the Crossflow Supersprint and somewhere over 150bhp than with the VHPD K series (about 190bhp) in the 21.  I need first in the 21 quite a lot but not much in the Crossflow.

Whether the expense of changing the ratios in the box is worth it for a difference in feel, I'm not sure.  I'd hate to go to the expense of swopping everything over to find the differences marginal for the way I use the cars.

[Roger Ford]

Megagrads used CR internals but that class is obsolete. SigMax uses standard Type 9 ratios and 150 class (which is a slightly more flexible version of the Caterham 310R spec) uses standard Mazda ratios. 

The Mega gearbox was an improvement but the difference wasn't massive. The only place I really felt it was Anglesey, where there are several corners that sat inconveniently between second and third on the old Supergrad box. 

[Gridgway]

To change tack slightly (not that you can tack slightly), what is it about the 6 speed box that is "wrong" for touring?

Back in the day, I happily did gazillions of road miles with a 6 speed box and never wanted to change it.

Identifying what you want to change will help with finding the right solution.

[John Vine]

#23:  Agree entirely, and I've had a 6-speed for around 20 years.

JV

[DanRo]

My view on the 5 speed Julian:

I have a standard 5 speed and a very revvy K series. 1st is too short, no doubt. I don't do racing starts so it's rarely a problem though. 2nd and 3rd are ok for me, In 3rd it does an indicated 90mph at 8k, probably closer to 80 in reality, but this does allow much of the overtaking to be completed in one gear. 


I would like 4th to be a little shorter. It's often the gear I sit in when I'm waiting, anticipating an overtake; so if I can nip past in 4th, I do. In these cases, the overtake would obviously be quicker if the ratio were a little lower.


I quite like having the over drive 5th. I knock it into this on flowing roads at a constant speed, as well as motorways, but also sometimes on the straights on track days, to give the engine an easier time. This would still be possible with a lower 5th though.


I have driven a 6 speed SLR, which was brilliant, and I don't doubt I would prefer that box on my car. It's likely I would aim to alter my 5 speed ratios though, because it's so much more affordable. A longer first and shorter 4th maybe, but I would definitely take advice from club members and transmission specialists before committing what would still be a decent chunk.