Swapping 5 speed for 6 speed

[threespires]

I've obtained a 6 speed gearbox which I wish to fit to my NA 1600 BBR turbo which already has a later model LSD and 1800 flywheel & clutch.

Is there anything that might cause problems or is it a straight swap ?

[Cardo]

Pretty much a straight swap...
Reverse light/neutral switch connectors need changing.Swap the electronic speedo drive for the mechanical mk1 unit.
Only two out of the three starter bolts will fit unless you change the engine back plate for a 6 speed one....I just used the two bolts and it's fine.
That all if I remember rightly.
HTH

[threespires]

Cardo said:

Pretty much a straight swap...
Reverse light/neutral switch connectors need changing.Swap the electronic speedo drive for the mechanical mk1 unit.
Only two out of the three starter bolts will fit unless you change the engine back plate for a 6 speed one....I just used the two bolts and it's fine.
That all if I remember rightly.
HTH

Excellent news, I wondered if the electro speedo drive might cause a problem as the mechanical one also powers my Brantz rally computer.

Thanks for your help, the swap will happen next week.

[Cardo]

You're welcome
I'm using mine with a 4.1 diff on my hillclimb car and find the close ratios to be a benefit over the 5 speed.
Cheers
Rich

[threespires]

Cardo said:

You're welcome
I'm using mine with a 4.1 diff on my hillclimb car and find the close ratios to be a benefit over the 5 speed.
Cheers
Rich

Sadly I'm unsure what my LSD rear end ratio actually is, but you saying the close ratios are a benefit is just what I wanted to hear..

[pewe]

If you are DIY'ing the change beg, borrow or steal an engine crane if you don't already have one.
That way you can take engine and box out through the engine bay.
Trade reckon that way it's about three hours each way.
DO NOT try to do it from underneath (no matter how high off the deck it is) big lumps of metal mean big aggro - especially as some of the bolts are v. difficult to access and the clutch pipes can become trapped out of sight between the bell-housing and block on the way back in - ask me how I know!
Presumably you'll be renewing spigot bearing, friction disk, thrust bearing, pressure plate plus the gasket on the first motion shaft housing inside the bell-housing (if that applies to a 6 speed box) and gearbox tail oil seal? Whilst you're at it consider renewing the heater matrix pipes with silicon ones and the water off-take blanking cap just above the clutch slave cylinder. Maybe a new thermostat whilst the water is part drained down?
HTH.
Cheers, Pewe.

[threespires]

pewe said:

If you are DIY'ing the change beg, borrow or steal an engine crane if you don't already have one.
That way you can take engine and box out through the engine bay.
Trade reckon that way it's about three hours each way.
DO NOT try to do it from underneath (no matter how high off the deck it is) big lumps of metal mean big aggro - especially as some of the bolts are v. difficult to access and the clutch pipes can become trapped out of sight between the bell-housing and block on the way back in - ask me how I know!
Presumably you'll be renewing spigot bearing, friction disk, thrust bearing, pressure plate plus the gasket on the first motion shaft housing inside the bell-housing (if that applies to a 6 speed box) and gearbox tail oil seal? Whilst you're at it consider renewing the heater matrix pipes with silicon ones and the water off-take blanking cap just above the clutch slave cylinder. Maybe a new thermostat whilst the water is part drained down?
HTH.
Cheers, Pewe.

That's great advice, I'm not doing it myself, the local garage look after my cars.
I'll replace the parts you've mentioned, the heater hoses are a good idea, this car's heater is tepid at highest temp. There's a heater hose by-pass to the oil filter, part of the BBR conversion, which might cause the lack of heat. My other car, a standard MX, has a heater that toasts me.

Thanks for your input, appreciated..

[skinny]

i'm not sure that heater bypass to oil filter housing was a BBR special. But it's not really needed, i just cut that loop out of my cooling system and went straight from the rear take off through the heater matrix. my heater temps are a bit lower now! However, i did a coolant re-route and ali rad at the same time

[threespires]

skinny said:

i'm not sure that heater bypass to oil filter housing was a BBR special. But it's not really needed, i just cut that loop out of my cooling system and went straight from the rear take off through the heater matrix. my heater temps are a bit lower now! However, i did a coolant re-route and ali rad at the same time

Ok, thanks for this..........

[fatjon]

The six speed is VERY short geared when used with a standard diff. May suit the 1.6 but on my 1.8 it's buzzing its nuts off at 80MPH.

[skinny]

chances are the OP has a taller ratio diff than standard if he's gone torsen LSD, as they are *very* hard to find in a 4.3 - unless you've just got a VLSD, which i think remained at 4.3.

how many revs are you doing at 70mph?

also, are you looking at the close ratio's for hillclimbs - or just day to day?

I went from 4.3 diff to 3.9 Torsen on my BBR just to put longer legs on it for the motorway really. Boost takes care of the rest

Edited by skinny on Thursday 5th June 15:21

[threespires]

skinny said:

chances are the OP has a taller ratio diff than standard if he's gone torsen LSD, as they are *very* hard to find in a 4.3 - unless you've just got a VLSD, which i think remained at 4.3.

how many revs are you doing at 70mph?

also, are you looking at the close ratio's for hillclimbs - or just day to day?

I went from 4.3 diff to 3.9 Torsen on my BBR just to put longer legs on it for the motorway really. Boost takes care of the rest

Edited by skinny on Thursday 5th June 15:21

Sadly I'm unsure what diff I have on my BBR, can anybody ID it ?
[PS - the Daily Mail wasn't mine !]
With this torsen diff, the speedo under-reads by about 15%, ie a 200 mile journey will show about 170 miles on the odometer.
The reason for me going to a six speed is that the car isn't used much in the UK, it's main use is following road rally cars on the back roads of France where the BBR can really stretch it's legs.

[skinny]

probably a 3.6 diff. my 3.9 is around 10% out.

if it's in the air, when you turn one wheel does the other go the same way or the opposite way (or is it locked if you're in gear). either of those would suggest the fuji diff which preloads the gears. fuji was only ever a 3.6 ratio. and yeah you'd probably want a 6-speed with that.

[threespires]

skinny said:

probably a 3.6 diff. my 3.9 is around 10% out.

if it's in the air, when you turn one wheel does the other go the same way or the opposite way (or is it locked if you're in gear). either of those would suggest the fuji diff which preloads the gears. fuji was only ever a 3.6 ratio. and yeah you'd probably want a 6-speed with that.

OK, will check, thanks

[Cardo]

Fuji was also available in 3.9....
Jack the car up,mark the diff flange and count how many rotations of the prop are required to give one full rotation of the wheel....this will tell you the ratio you have.
Cheers

[threespires]

Six speed 'box now fitted without problems. With the few miles I've driven it so far, I'd say it suits my 200ish bhp car very well.

Whilst the car was on the ramp, we found that one turn of the road wheel equaled 1.75 turns of the propshaft. How do I work out the ratio?

Thanks everybody for your input.

[skinny]

I think you did it wrong, was the other wheel turning the other way? Would have been better to turn the propshaft until the wheel does 1 revolution

[threespires]

skinny said:

I think you did it wrong, was the other wheel turning the other way? Would have been better to turn the propshaft until the wheel does 1 revolution

Ahh, thanks for this, I wasn't there when he did it...next time it's on the ramp I'll do it your way....

[J-Tuner]

by the sounds of it then the 6-speed wouldnt be a good swap for better cruising on the motorway? Mine drives now like it needs a longer 6th

[Cardo]

J-Tuner said:

by the sounds of it then the 6-speed wouldnt be a good swap for better cruising on the motorway? Mine drives now like it needs a longer 6th

Other way around Steve,6th is a shorter gear than 5th......you would have to change the final drive to give it longer legs on the motorway.A 3.63 with your 5 speed would do that at the expense of acceleration.Will make 1st gear more useable with the charger though....
Cheers
Rich