Gearbox 6th Gear

[Numptysnumnuts]

Having never had a 5 GTT and after driving modern cars I found my first trouble free drive in my GTT rather amusing and fun. However I was a bit concerned with revs teetering on 3,000 rpm at just 70mph in 5th. Given that the speedo goes up to 130mph and knowing full well that cars normally never get anywhere close to these speeds straight out the factory, I was just wondering if its worth looking at getting the 6th gear mod from a supplier in Germany or should I not be worrying or are there cheaper alternative safe solutions.

Why a 6th gear?

I know it's only a small engine but seems to have a lot more to give and if done right will provide hours of enjoyment. I am just concerned about high revs on a little engine.

My vehicle is only standard setup at present or so I believe but have in mind a 200BHP setup. After Kris_M looked at it last night it would appear to have a different turbo and when I find out which one of the numerous turbo receipts I have it will give me an idea of what else needs to be done. However there is not much point increasing the BHP if the standard gearbox cannot cope or constantly screams for mercy. All it would do is get me to my legal speed quicker or am I looking at this wrong?

[Matt@CodeRedMotorsports]

Can you link the 6th gear mod from Germany please?

[Matt@CodeRedMotorsports]

The gtt has a torquey engine, so, long stacked gears and it being old are the order of the day.
Modern high revving cars don't have so much torque (in fact I was joking with a chap who has a civic, I told him my torque wrench has a higher rating than his engine makes! Hehe!).
You don't need a 6speed gearbox on a Renault 5 gtt.

[Logg]

130mph comes up at about 6k in 5th. here's a little chart with the revs and speeds. :)

Must admit I'd like a sixth gear too but know it would get me into trouble.

[Matt@CodeRedMotorsports]

You sure that gtt diff ratio is correct?

Sorry edit, ignore me it is correct....

[Logg]

You sure that gtt diff ratio is correct?

Never really checked as it was all ready set up as a spreadsheet on this site somewhere. But it does seem to tally up with my gps speeds once changed to my tyre size.

[Matt@CodeRedMotorsports]

Sorry... I got mixed up with another diff I had floating around in my head:ashamed:....!

[Brigsy]

You don't need a 6th gear on a gtt. I have done loads of long distance runs sitting at between 4-5k rpm for long periods. Its only part throttle when cruising so no need to worry.

As for top speed, the standard box is adequate. Ive seen 150mph a couple of times. I have seen 7200 in 5th before on a slight downhill. I dont believe the van was doing 158mph though? Rev counter probably not very accurate at those rpms lol

[GTphil]

You don't need a 6th gear on a gtt. I have done loads of long distance runs sitting at between 4-5k rpm for long periods. Its only part throttle when cruising so no need to worry.

As for top speed, the standard box is adequate. Ive seen 150mph a couple of times. I have seen 7200 in 5th before on a slight downhill. I dont believe the van was doing 158mph though? Rev counter probably not very accurate at those rpms lol

Still tho, 158mph in an extra van is pretty:smokin:

I once remember scoffs old c1j doing 154mph on the rollers :eek:

Personally like has been mentioned the only benefit of having and extra gear would be the mpg savings on the motorway, the cost probably far out weighs the savings.

[Numptysnumnuts]

It used to be on Reichhard Motorsport page but I can no longer find it. :confused:

This is the link to their gearbox section.

http://reichhard-motorsport.com/catalog/index.php?cPath=25_148_36_72

Mind you it was about €4,000. Even a modified 5 speed is €3,699. I can do a lot for those prices to get where I need to be.

I just got a little concerned from too many years of driving modern cars where 3K constantly in a diesel does harm to your engine (well according to Ford Technicians).

I have read this thread right with regards to those top speed figures quoted are from a standard GTT box and not a modified one?

[Ian S]

If you drop the revs too low you might get LESS to the gallon.

6th would only benefit autobahn cruising? You wouldn't want to drive along way at 6500rpm? Although we did in our Citroen GS (air cooled 1.2 litre flat four) in 1979, South of France and back at that kind or RPM; was only about 80mph or so though!

IIRC, the GTT box has the longest ratios of any of the similar Renault boxes.

[Big Supes]

130mph comes up at about 6k in 5th. here's a little chart with the revs and speeds. :)

Must admit I'd like a sixth gear too but know it would get me into trouble.

Sweet. I may print and stick this to my dash as my speedo doesn't work. :D

[Big Supes]

You don't need a 6th gear on a gtt. I have done loads of long distance runs sitting at between 4-5k rpm for long periods. Its only part throttle when cruising so no need to worry.

As for top speed, the standard box is adequate. Ive seen 150mph a couple of times. I have seen 7200 in 5th before on a slight downhill. I dont believe the van was doing 158mph though? Rev counter probably not very accurate at those rpms lol

7200 on a pushrod engine?! That's bonkers! :D

I would love a 6th gear. The red line in 5th comes around before you know it and I don't fancy driving in the red for too long.

[The new Bill J]

7200 on a pushrod engine?! That's bonkers! :D



Sparkie used to take his to 9k :scared: :D

[Big Supes]

Sparkie used to take his to 9k :scared: :D

I can imagine why he's called Sparkie. :laugh: Maybe I'm too much of a worrier, but holding the throttle open and going well into the red just feels like I'm gambling with my engine.

[Logg]

Sweet. I may print and stick this to my dash as my speedo doesn't work. :D

What size tyres you got mate as I've a couple of different versions?

Also just double check it with GPS as rev counters can be out mines out by 150-200rpm at idle. hate for you to get a ticket due to a silly spreadsheet. :)

195/45/15

[Bigfoot]

http://www.rtoc.org/files/Technical%20Files/Speed%20Calculation/gearbox%20ratio%20speeds.xls

[Big Supes]

what Size Tyres You Got Mate As I've A Couple Of Different Versions?

Also Just Double Check It With Gps As Rev Counters Can Be Out Mines Out By 150-200rpm At Idle. Hate For You To Get A Ticket Due To A Silly Spreadsheet. :)

195/45/15

195/50/15 :)

[Logg]

195/50/15 :)

I don't have that one but will see what I can do once home. Unless anyone else has one for that tyre size.

[Bigfoot]

Now I know how Mart feels when ignored :cry:

[Big Supes]

Now I know how Mart feels when ignored :cry:

Sorry Bigfoot... I have a new laptop and haven't got around to installing MS Office. It's downloading and the awesome BT Infinity is taking ages!

[Logg]

Now I know how Mart feels when ignored :cry:

lol was that the your actual xl file you linked to Dale or as it just comes up as a picture on my phone.

[Big Supes]

http://www.rtoc.org/files/Technical%20Files/Speed%20Calculation/gearbox%20ratio%20speeds.xls

That's awesome mate, cheers. :agree:

[Big Supes]

Regarding the 6th gear mod, does anyone else know if it can be done or anyone who can do it in the UK? I'd love a higher cruising speed if the overall ratio across all the gears isn't interfered with.

[Dave Reed]

The standard box's are fine. I rememebr seeing 8200 in 5th on mine once(private road ofcourse). no Idea how fast I was going, as the seepdo was of the clock lol..

[Brigsy]

The standard box's are fine. I rememebr seeing 8200 in 5th on mine once(private road ofcourse). no Idea how fast I was going, as the seepdo was of the clock lol..

That is the game, i need more power to try this ha

[gttjames]

what about putting a bigger 5th in? Have heard somewhere the 5th gear out of a clio diesel box will go in and give lower revs in 6th???

[Big Supes]

The standard box's are fine. I rememebr seeing 8200 in 5th on mine once(private road ofcourse). no Idea how fast I was going, as the seepdo was of the clock lol..

I would prefer to take your word on that. ;) There's no way in hell I'll be taking mine above 6500. I'd prefer a 6 speed box if one is available (at a sensible price).

[Brigsy]

The c1j will take 7500-8000 all day long, don't panic;)

[Big Supes]

The c1j will take 7500-8000 all day long, don't panic;)

If I make a track day, maybe you or someone else can demonstrate that statement. :D

[Wallace]

The c1j will take 7500-8000 all day long, don't panic;)


:eek:

F**k it, I'm gonna trust your statement and give it some serious beans at the weekend:devil:

Assss long as the fuelings right:agree::wasntme:

[rs250nut]

I would be more concerned about the bowl emptying than adding a six gear...........

[Brigsy]

:eek:

F**k it, I'm gonna trust your statement and give it some serious beans at the weekend:devil:

Assss long as the fuelings right:agree::wasntme:

I take no responsibility for any broken engines:wasntme: the average gtt wont need to rev that high, i only use mega revs due to a big blower and heavily retarded cam

[Miller]

I have always planed to do this conversion on my 20v turbo box for my carrado......

http://www.myturbodiesel.com/1000q/multi/5th-gear-swap-VW.htm

We could do something similar with the jb3 using a 5th gear from a diesel box, never looked into what ratios are available but could be good to save fuel on the motorway.

Could we do this in situation?

Chris

[Matt@CodeRedMotorsports]

Can be done in situ, yes.

[Dave Reed]

That is the game, i need more power to try this ha


Lol.. I guess the Gt is a little more aerodynamic the van is, that's with the efi though, wouldn't dare take it past 7K in 5th with the carb..

[TNT ANDY]

Still tho, 158mph in an extra van is pretty:smokin:

I once remember scoffs old c1j doing 154mph on the rollers :eek:

Personally like has been mentioned the only benefit of having and extra gear would be the mpg savings on the motorway, the cost probably far out weighs the savings.

Not 100% sure about that - I changed the gearbox on my import Scooby waggon as I was revving at 4k on the motorway and getting appalling mpg. Stuck my uk spec box on, got better 3.2k @ 70mph but wrecked the blistering performance and made no gains on mpg. Makes sense really. 4k of easy work or 3.2k of hard work.

[Woznaldo]

I have always planed to do this conversion on my 20v turbo box for my carrado......

http://www.myturbodiesel.com/1000q/multi/5th-gear-swap-VW.htm

We could do something similar with the jb3 using a 5th gear from a diesel box, never looked into what ratios are available but could be good to save fuel on the motorway.

Could we do this in situation?

Chris

Reichhard sell 3 different 5th Gear options.

[Big Supes]

:eek:

F**k it, I'm gonna trust your statement and give it some serious beans at the weekend:devil:

Assss long as the fuelings right:agree::wasntme:

Honestly... don't. :wasntme:

[GTphil]

Not 100% sure about that - I changed the gearbox on my import Scooby waggon as I was revving at 4k on the motorway and getting appalling mpg. Stuck my uk spec box on, got better 3.2k @ 70mph but wrecked the blistering performance and made no gains on mpg. Makes sense really. 4k of easy work or 3.2k of hard work.

Again tho, very dependant on a c1j's spec, turbo/cam. I'm assuming most manufacturers use some kind of calculation to work out the ideal gear ratios for an engines performance. Most 6 speed motors I have driven there isn't a lot of difference between 5th and 6th.

[Big Supes]

I thought modern cars used 6 speed as a way of getting more power up through the range of gears, instead of adding a higher final gear for lower motorway RPM? The final gear is pretty much the same as that of 5th.

[GTphil]

I thought modern cars used 6 speed as a way of getting more power up through the range of gears, instead of adding and higher final gear for lower motorway RPM? The final gear is pretty much the same as that of 5th.

That will be why it feels the same then, I always thought it was to increase mpg at cruising speeds.:laugh:

[Ian S]

Modern cars for Britain or for Germany?

Would be geared different for different cruising speeds wouldn't they?

And then there's gearing for power and for economy.

It's horses for courses, take your pick.

[Woznaldo]

Most modern cars do indeed spread their 6 gears across the same effective range, as in 6th is actually the same as the equivalent 5 speed 5th. There are. of course, exceptions such as the Lotus Carlton (Hero car) that had a massive overdrive 6th purely to get cruising economy. I think it did 80mph @ 2000rpm in 6th, which if the engine had the power would work out as 300mph at its max rpm!

[Big Supes]

That will be why it feels the same then, I always thought it was to increase mpg at cruising speeds.:laugh:

:D

I always look at fuel consumption by how open the throttle is. For examples, to maintain a steady 3000rpm on the motorway you might need to have the throttle open 1/5, but to maintain a steady 4500rpm, it would be less. You could say it's a bit like riding a bike - it consumes less energy to pedal faster, but with less load.


Modern cars for Britain or for Germany?

Would be geared different for different cruising speeds wouldn't they?

And then there's gearing for power and for economy.

It's horses for courses, take your pick.

I'm not sure mate and to be honest, hadn't thought it about it in that way. I thought the majority of cars had a bookmarked top speed which would be governed by the final gear ratio.


Most modern cars do indeed spread their 6 gears across the same effective range, as in 6th is actually the same as the equivalent 5 speed 5th. There are. of course, exceptions such as the Lotus Carlton (Hero car) that had a massive overdrive 6th purely to get cruising economy. I think it did 80mph @ 2000rpm in 6th, which if the engine had the power would work out as 300mph at its max rpm!

Thanks for confirming.

Mmmmmmm..... Lotus Carlton.... :crush: