5-speed gearbox

[petak]

Hello guys!

For some time now I am studying 5-speed gearbox could be installed in R4.

I've read plenty of topics related to this subject, but I have not been able to find precise figures.

I managed to find a transmission ratio for 4-speed gearbox that goes into the R4 and 5-speed gearbox that goes into R5 (old) and I have a theoretical RPMs each gear at certain cruising speed.

The situation is like this

Gearbox from R4 HAO-146


and with this gearbox engin should theoretically run at RPMs


Gearbox from R5 HA1-01-G or HA1-02-D


and with this gearbox engin should theoretically run at RPMs


First three gears are identical, 4th is slightly shorter, and 5th is little longer.
Performance when starting the vehicle and driving up hill would not be changed, but will get lower RPMs at higher speeds.
This is just what I am looking for, to lower RPMs while driving magistral roads at speeds 90-100 km/h.

To me, this gearbox would fit R4 engine perfectlly (maximum torque at 2500o/min, maximum power 4000o/min), but still would like to hear other opinion.
And if someone has their own experience that would be great!

I'm afraid that car could lose "breath" at some point while driving the car when changing gears. All these figures give me conclusion that this case might occur when changing from 4th to 5th gear. 4th would have much RPMs and 5th little RPMs.

Is there someone here on this forum that has fit 5-speed gearbox into normal, standard R4 GTL, can you share your experience with us?

Thank you for reading.
H!

 

[politeperson]

Looking at the whole thing in the round, the 4 speed GTL gearbox will do it all.

At 70mph, the 4 speed is at 2,150 rpm, the 5 speed 2,000rpm. Who cares about the small difference of 150 rpm?

2,150 at 70 mph is fantastic.

What a load of aggro for no benefit. The difference is merely a mechanical curiosity.

How often does a 30 year old Renault 4 do 70mph any way.? Mine does 130 kph on a very good day, a bit down hill, wind behind me if I am holding on with white knuckles. Noisy enough to drown out Deep Purple.

You also have to engineer a new gear change and mess about with the front cross member.

It is not like the Renault engineers did not know what they were doing. I suspect the torque output of a 32bhp 1108cc motor is perfectly matched to the 4 spd box. It feels good to me anyway.

They did have to offer a warranty on millions of them that were sold new in the most hostile environments in all parts of the world, and in my opinion they got it spot on.

On the other hand, if you are just a bit bored and fancy something to do then good luck, it is better than watching football or the X- factor.

 

[montenegro]

I have been considering putting a 5 speed box into a r4 as well, the front cross member would have to be cut out and the r5 one welded in place. Has anyone ever changed the top cover from a r4 box to a r5 ? ie will the long levered cover just drop on in place of the r5 stubby lever ?? unless this is so the amount of work to substitute the r5 gear linkage seems unreasonable in light of the rpm comparison by politeperson. anyone actually having done this please get in touch.

 

[Geoff in the Gully]

Politeperson may have misread the data tables - they're in Km/h not MPH.
Nonetheless, his point about the small difference in rpm remains valid.
However at 100 km/h that difference of 250 rpm drops the revs below 3000. At around this point the engine is getting into it's power range and there's a big increase in fuel consumption. For steady cruising down the motorway it would be nice to have the engine sit just below that boundary.

With my 3-speed box, I dream of even 4 gears

 

[politeperson]

Yes, 70mph at 2,000 rpm does seem a bit optimistic for a 1108cc Renault 4.

 

[petak]

2 politeperson:
I am talking about km/h not mph. It is big difference. But your point is right. Difference is only 200-250RPM if we compare 4th gear on 4speedgearbox, and 5th gear on 5speedgearbox

But i had deferent logic while i was doing comparison:

On normal R4 GTL i am changing from 3rd to 4th gear at 70km/h and RPM are dropping form 3100 to 2150. Sometimes i go up to 80km/h but rarely (if I am taking over someone). And then i am cruising 90-100km/h at 2800-3100RPM.

If i go to 5speed gearbox, situation is like this

On 70km/h i am changing to 4th gear and dropping from 3100 to 2500RPM, then speeding up till 90km/h and changing from 4th to 5th gear and dropping RPM from 3200 to 2600
and after that i am cruising on 90-100km/h at 2600-2850 RPM, quite below 3000 RPM

Also, GTL's engine has highest torque at 2500RPM so it would be better if engine is spinning somewhere around that number.

2 montenegro: It has already been done few times that i know, and technical part of fitting 5seedgearbox is not big issue.

2Geoff in the Gully: you have caught my point of view

Is there anyone here that has normal/standard GTL (1,1 engine; 4 speed gearbox (HAO-146); 135/80/13 tires) and has rev counter installed?
It would be really nice to see exact RPM at some speed in different gears

 

[iMacThere4iAm]

petak, I'm installing a rev counter today so I'll get you some data next time I go for a fast drive.

 

[petak]

petak, I'm installing a rev counter today so I'll get you some data next time I go for a fast drive.

Thank you!

It is not necesery for fast drive.
Just 70-80-90-100km/h in 3rd and 4th gear
Or 45-50-55-60MPH if you have "that" kind speedometer