Today's Duratec topic - 6 speed gearbox

[Shaun_E]

Thanks for all your replies on my other thread - lots of good stuff.

Today's question is "What do I do with my 6 speed box?"

The plan at the moment is to use the Raceline compact bell housing but this entails shortening the input shaft - has anyone done this?

I need to get various bits of the box up to later spec which is not going to be cheap - any thoughts on this. Already spoken to Phil at R&R.

Alternatively I could swap to some beefy type 9 box. What about a dog box?

Sequential is not allowed.

Engine is expected to be 263bhp/185lbft and I have a 3.92 diff. Usage is sprint and hillclimb.

[Jason Plato]

Ive done the shortened bellhousing and input.

 

Phill took care of matters and I recall the input shaft was circa £230 plus fitting.

 

One chap I know simply took and angle grinder to the input shaft

 

If your starting from scratch you may be better off getting the really small raceline bellhousing and tiny clutch - this removes the nasty step under the car and reduces roatational etc .

 

as for the pros and cons of a 6 vs 5 ...... that is a whole new thread with much personal opionions and very little fact in terms of time saved over a course.

[rgrigsby]

Dave I think Shaun is getting the compact bell housing already.

 

As you say I also know someone that took a grinder to the input shaft and that seemed to work but I wouldn't be in a rush to do that myself.

 

I run with a BGH 5 speed box but my 2.3l has a fair bit more torque than your 2.0l so I'm not convinced changing from a 6 speed is a good plan. It's probably worth a call to BGH to discuss the options on a 5 speed, they'll have a good idea how it would work if you let them know the power/torque and the know the 6 speed box well.

 

Cheers

Rob

[Jason Plato]

There is the std length bellhousing , the short bellhousing and the very small bellhousing suitable only for a 5.25" clutch and flywheel, this also needs a new starter motor.

[Shaun_E]

My plan is to use what Raceline call the "compact bellhousing" which eliminates the step - this is their latest version and I think is the one Dave is referring to. It requires a special flywheel with the ring gear cut in the back of it and also a different starter. The special flywheel allows use of a standard clutch.

Dave - have you had any problems with your gearbox since you upgraded your engine? Phil suggests that the 6 speed might be a bit marginal for 260bhp.

Another question - which clutch master cylinder did you use? Raceline sell a 0.7"

 

Ideally I'd like to stick with the 6 speed so that I'm not changing too much on the car in one go. The switch to Duratec is to get decent reliable power that isn't pushing the limits like my K was.

[Jason Plato]

are you intending a 7.25 " clutch with that smaller flywheel ?

[Shaun_E]

As far as I understand it will be the 8.5" clutch see here - the compact flywheel is labelled 8.5".

[Pendennis]

Raceline compact bellhousing is the shallow type and marries to their shallow inboard dry sump kit. This utilises the compact flywheel, the 7.25" clutch assembly can be used. They do a smaller one now as well Dave?

They do the compact bellhousing in two lengths, one for the long input shaft and one for the short, with engine mounts to suit

[Pendennis]

Shaun, I use the Girling 0.700 cyclinder, but believe the 0.625 would suffice

[Shaun_E]

Pendennis - thank you, that explains things. I will be having the dry sump.

I could then have the longer compact bellhousing and not have to alter the input shaft?

I guess there is an advantage to having the engine further back, especially as I will probably have to have the dry sump tank in front of the engine.

Which master cylinder will give the lightest clutch pedal?

Other than weight, is there any advantage to using a smaller clutch? Anything I need to consider with clutch choice?

[Jason Plato]

I would stick with the wet sump.

 

I suck my dry sump tank in the passenger shortened footwell to reduce front weight.

[Rob Walker]

Have a look at the latest SPC semi helical box that Steve Perks is offering. I recon one of these built into an ali case could be the dogs for the torquey duratec. I have a six speed in mine and the shortened input shaft. Starting from scratch with any duratec over 250bhp I would fit the raceline short & small bellhousing, Ford Slave cylinder,raceline small flywheel, nissan starter motor and 8.5" AP clutch , raceline dry sump kit. Caterham triangular drysump tank that sits in front of the engine. For out and out track work a sequential Sadev gearbox. Oh and caterham exhaust primaries, I have had trouble with the Raceline Primaries fitting various chassis.

 

Rob

[7 wonders of the world]

Rob,

 

So far as I know the Caterham primaires will only fit with the OE long bellhousing, if uesd with the short they foul on the chassis?

 

Be interested to know if you know of any exceptions to this though

 

cheers

[Pendennis]

Shaun, if you use the long input bellhousing the engine sits about 30mm further forward, which may or may not prevent you being able to install the triangular DS tank in front of the crank pulley wheel.

 

The 0.625 will give you the lightest pedal, however I can ssure you the 0.700 is not heavy.

 

Wet sump is great bit of kit

[Pendennis]

I think Neil is right regarding exhaust

Powerspeed have a drawing for their big exhaust system, it's from my 1996 S3 Duratec car, it is in Raceline position about 30mm further back than CC.

 

Cannot see benefit of any bellhousing being shallower than the Raceline DS pan. However again, the first lot of Raceline DS pans required a 20mm (approx) wedge to fill difference in height between that and the compact bellhousing. So if the new bellhousing is flush with the existing early pan, then it gives you another 20mm approx ground clearance.

 

[7 wonders of the world]

Hi Ian,

 

The compact bellhousing sits flush with the bottom of the the Raceline DS thus removing the 20mm step which is present when this DS is used with standard size bellhousing either short or long, CC offered a nylon wedge to reduce the chance of snagging anything on the step.

 

Just surfed the CC site ofr a link to the wedge but no luck

[Pendennis]

Neil, the very early Raceline DS pan was manufactured about 20mm shallower than it is now. So there was a step of about 20mm. They now fabricate the pan so it gradually slopes towards the edge of the bellhousing, thus remove step.

So I presume the new small bellhousing allows them to fabricate their pans shallow again.

[Pat the Plumber]

dry sump guard here

[7 wonders of the world]

 

Arh I see, I hadn't realised they'd changed the design on the pan.

 

 

[Pendennis]

Yer I've had both Like to add they are great, I cannot work the car any harder and it does exactly what a DS system should do.

[Rob Walker]

The Caterham C400 primaries fit. All variants of the Raceline dry sump pan leave a step at the bellhousing joint unless you fit the small flywheel and compact raceline bellhousing. The catertham triaganular dry sump tank will fit infront of the engine with either the raceline or caterham bellhousings, why would it not the raceline bellhousing moves the engine back 18mm increasing clearance obviously caterham made it to suit there bellhousing/engine position.

 

rob

[Jason Plato]

for info the R500 uses the std length input shaft and std length / depth bellhousing.