Sr2 laser gearbox help

[danbowe84]

Hi, is there such a thing as a direct bolt on replacement gearbox that will bolt onto a sr2 fs-de engine, that is a substantial stronger gearbox? Or alternatively does anyone have an idea how much it is to build a tough G15M-R I'm only guessing if someone can confirm what gearbox a 2002 Ford laser sr2 has it would be appreciated greatly cheers

[Ice88]

Guy in the states is researching using the 6speed from the Mazda 6 in a G series bell housing.

How much power are you looking at making? If your going to be making ~300hp then you will need to start considering straight cut third.

[danbowe84]

No way near 300, around 150kw. So your pretty confident a standard one would hold up fairly well?
Obviously not gonna race it or burnouts all day.
Straight cut third? Easy enough to give simple explanation or should I just Google it haha.

[rodhog]

you talking 150kw's at the wheels on dyno or like 130kw's and 150 flywheel.

makes a difference

the G -box can take power.
a LSD and it will hold.

The majority of broken box. Comes from abuse or the wrong parts used.

You will find box's that lasted longest
still had engines making good power.

But had good turbo selection. A laggy turbo works better but not if you have grippe front end. So a smooth transition shocks the box less.

The biggest mistake is Clutch. instead of just waiting to see if a mild setup will do people jump to solid plates, pucks and massive clamp loads.

A soft sprung centre and organic plate with higher clamp will do most jobs up to 400HP. Again tune and turbo selection will effect this as well.

The other side being turbo selection effect driveability. A really driveable quick to spool turbo will put more strain on the box due to more low rpm torque shock.

but with those figures - a KE B6T can make 120KWFW with just the right mods.
G-series held up to that with most ease.

Just fit a LSD and wait to see if you need the 3rd gear. it's insurance but you might not need it right away.

[rodhog]

Originally Posted by Ice88

Guy in the states is researching using the 6speed from the Mazda 6 in a G series bell housing.

Wasting his time IMO.
be quicker bolting up a MPS3 box. - you take same approach as Toyota box.

[danbowe84]

Originally Posted by rodhog

Just fit a LSD and wait to see if you need the 3rd gear. it's insurance but you might not need it right away.

Ok is this a very big job with lots of stuffing around or it is pretty much 'bolt on'
Where would I source an LSD for a me laser, would it be second hand or can you buy em new?

[Ice88]

New from mfactory or mazdaspeed LSD from edwin or such.

Gearbox needs to be dissassembled, diff and pinion gear(?) drilled off and lsd installed.

[danbowe84]

Is installing lsd specialist job or safe enough for me third year mechanic mate, if he's confident and can bribe him to, do it?

[NaughtyGT]

hey Rod, just luv gittin back to the boosted talk haha......

Originally Posted by rodhog

......A soft sprung centre and organic plate with higher clamp will do most jobs up to 400HP. Again tune and turbo selection will effect this as well

the "soft sprung centre" you speak of, do you refer to the pressure plate or clutch disc? When you mention "higher clamp", which do you refer to? I was advised to go with the Exedy hard sprung centred clutch disc on the BPD engine. also, the pressure plate has a very high clamp rate. Here, were looking @ 154fly kw stock not 154wkw. With my particular application though, were talking more like 180-190fly kw though so, I agreed with this advice.

Originally Posted by rodhog

The other side being turbo selection effect driveability. A really driveable quick to spool turbo will put more strain on the box due to more low rpm torque shock....

You could also say that a later spooling turbo, if on the larger side, will kick in 'harder', due to coming on song 'later' (higher in rev range), actually stressing G/Box parts moreso? I remember discussing the pros & cons of which turbine A/R would cause more ferocious wheel spin & @ what revs when contemplating the Merc build.

From memory, concerning the turbine housings on the GT3540R, I had to choose whether to go for the .63 A/R or .82 A/R? if I went the smaller, spooltime would be obviously quicker but, produce 30 odd wkw less on the dyno & apparently give more viscious wheel spin. If I went with the larger A/R, spool would be later, dyno results up 30wkw but power would come on 'harder', essentially with less wheel spin produced though? Question always was, which would stress the driveline more?

This brings me to the FWD torque steer issue! Although all the turbo models with the g series boxes all have the layshaft DS shaft designs, to better handle torque steer. I remember clearly the horrific torque steer I experienced in the BFGT FWD when turning out of the driveway one day in the wet. Slipped the car clean over to the right in a sec! Sh1t was the reaction & with what, a whole 110fly kw?

Imagine the BPD in the wagon man! LSD with the BPD or nothing I decided...........on a side note, had a nice unexpected 4 wheel drift to the left recently (think I mentioned it in earlier thread?). Only changed down to 2nd when entering corner. Turned car to the right (only slowly/normally) began to drift! I put it down to the cheapass Chinese tyres on.....point is. If I was motoring even slightly spirited & did this, woulda hit the truck for sure on the left lane beside me in the left (outer) lane........

All fun in the build ey

[Ice88]

Originally Posted by NaughtyGT

You could also say that a later spooling turbo, if on the larger side, will kick in 'harder', due to coming on song 'later' (higher in rev range), actually stressing G/Box parts moreso? I remember discussing the pros & cons of which turbine A/R would cause more ferocious wheel spin & @ what revs when contemplating the Merc build.

From memory, concerning the turbine housings on the GT3540R, I had to choose whether to go for the .63 A/R or .82 A/R? if I went the smaller, spooltime would be obviously quicker but, produce 30 odd wkw less on the dyno & apparently give more viscious wheel spin. If I went with the larger A/R, spool would be later, dyno results up 30wkw but power would come on 'harder', essentially with less wheel spin produced though? Question always was, which would stress the driveline more?

This brings me to the FWD torque steer issue! Although all the turbo models with the g series boxes all have the layshaft DS shaft designs, to better handle torque steer. I remember clearly the horrific torque steer I experienced in the BFGT FWD when turning out of the driveway one day in the wet. Slipped the car clean over to the right in a sec! Sh1t was the reaction & with what, a whole 110fly kw?

Imagine the BPD in the wagon man! LSD with the BPD or nothing I decided...........on a side note, had a nice unexpected 4 wheel drift to the left recently (think I mentioned it in earlier thread?). Only changed down to 2nd when entering corner. Turned car to the right (only slowly/normally) began to drift! I put it down to the cheapass Chinese tyres on.....point is. If I was motoring even slightly spirited & did this, woulda hit the truck for sure on the left lane beside me in the left (outer) lane........

All fun in the build ey

The answer to your question is that either turbo stresses different parts of the driveline. A turbo that spools really quickly like a GT25 on a FS engine is quite harsh on the diff, as the loosing grip, sudden grip causes the diff to have immense loads and sudden.

A turbo engine that makes alot of power actually forces the two gear shafts in the box apart due to the gears being helical. (this is why third fails in g series that and its a weak gear). This is why going straight cut is advantageous.

The first case also causes stress through out the entire driveline, engine etc. too.

Gearboxes n stuff are my weak point knowledge wise though, so there's no doubt more to it.

[TheMAN]

it is all about the volumetric efficiency and characteristics of the engine also.... the reason why the USDM FS-DE spools quickly with the GT25 is because it has low overlap cams and more restrictive intake manifold which promotes low RPM efficiency... this makes for a big torque surge at low rpm... the FS-DET makes peak torque at 3500rpm if that gives you an idea.... it's like having a diesel engine... it doesn't help that the FS engine is a stroker motor too, so it has a natural tendency to make a lot of torque for given the displacement of the engine

I corrected this ineffiency by improving how the engine breathes at high RPM... because the FS doesn't have VVT, you shift the powerband upwards instead... this is advantageous because a USDM FS-DE runs out of steam past 5500rpm, even with the turbo because it is relatively small... so with JDM cams, JDM intake manifold, oversized throttle body, I have achieved what others couldn't have done on this engine... a smooth linear powerband that has peak power at 6700rpm... no more low RPM torque surge, no more unnecessary shock loads

it is all about how you build your engine and your tune