Launching an impreza - fragile?

[alfa daley]

In one of the posts in GG, I think it was the one about a civic type r mauling an m3, someone mentioned that 4 wheel drive turbo cars are hard to launch and that when you do manage it successfully you can kiss good bye to clutch, diff etc. Any truth in this at all? i am quite partial to the traffic light gp and a trip or two to santa pod would be on the cards. I wouldn't want to buy a car and not be able to use it's full performance now and again.

I'm talking specifically about imprezas but I guess the same would apply to other 4wd turbo cars such as legacy, Evo.

[mark_mcd]

sorry quick reply but basically launching a 4 wheel drive car is going to be harder on the drivetrain of the car than fwd/rwd. in all wheel drive as you generally dial in more revs as more traction is on offer and to stop you 'bogging down'. launching any car all the time wont do it any favours in the long run i.e. expect more wear and tear but generally should be more on clutches and tyres than gearboxes if done right and car was in good health to start with.

Edited by mark_mcd on Tuesday 19th May 23:46

[foggy]

Think it was in Evo magazine I saw something - they said hold the car on the handbrake and just get the clutch biting to load up the transmission ready for a moment or two, then simultaneously release the handbrake and the clutch and away you go, kinda like a hill start.

The process eliminates the inital shock loading caused by the backalsh/slack in the gears, bearings etc. where everything goes from slack to high load and crashes together as per a 'normal' brisk get away.

[scoobydude]

I tend to find I have to use much higher revs to get my impreza off the line without bogging down than I did with any of my 2wd cars. It helps if you have a DCCD and you set it to locked for the launch then roll it back to open for the obligatory corner ( which arrives much quicker than you'd imagine) to begin with.

[liner33]

Launching any powerful car can be hard on the drivetrain , my uprated clutch on my Skyline only lasted 10 1/4 mile runs before starting to slip it had only done 2500miles on the road

[Animal]

The best sympathetic method is prob the same for any car: get it rolling before feeding in the power. The advantage of 4WD is that you're less likely to get wheel slip (although some slip can be beneficial) and can therefore get the power on much faster.

[mrmr96]

Animal said:

The best sympathetic method is prob the same for any car: get it rolling before feeding in the power.

True it is kind, but not very fast.

As mentioned above the best thing to do to extract maximum performance is to dial in plenty of revs and get some boost built up and floor it at the same time as jumping off the clutch.

Car will 'bog down' if the clutch bites and the wheels don't slip as this causes engine revs to drop. I think that because spinning the wheels is unlikely in a 4WD car, you must keep the engine spinning and the 'slip' is done at the clutch. (I.e. engine spins fast with lots of boost and wheels are initially going very slowly.)

This is why launching an Evo on the standard clutch can only usually be done about 5-10 times TOPS before the clutch is dead. I've heard of clutches blowing faster than that too.

If you want to launch, get a decent twin plate clutch. (And then expect to break diffs, shafts and gearboxes, although strain on these items is reduced when following the 'hold against handbrake' method which takes up the slack in the drive train.)

[300bhp/ton]

alfa daley said:

In one of the posts in GG, I think it was the one about a civic type r mauling an m3, someone mentioned that 4 wheel drive turbo cars are hard to launch and that when you do manage it successfully you can kiss good bye to clutch, diff etc. Any truth in this at all? i am quite partial to the traffic light gp and a trip or two to santa pod would be on the cards. I wouldn't want to buy a car and not be able to use it's full performance now and again.

I'm talking specifically about imprezas but I guess the same would apply to other 4wd turbo cars such as legacy, Evo.

Its true, but not the end of the world.

being 4wd is only part of it, only having 2.0 litres with a low CR and a high boosting turbo are the other problems here.

You could go easy off the line and not go to WOT until rolling. But you lose all the benefit of having 4wd on launching. This is very bad from a performance standpoint as the main reason these cars are quick is due to putting the power down, once rolling all of your advantage is lost.

If you do a half measure then chances are you’ll either slip the clutch big time (which you’ll only be able to do so many times) or you’ll bog down.

Only real answer is lots of revs and brutal behaviour, yes using the handbrake can somewhat help, but it won’t solve the issue. Not if you plan to actually drag race at the ¼ mile.

Have a look on some of the US forums and see how the guys over there get on with these cars and drag racing. They are capable but expect something to brake if you abuse it enough.

If you want something less aggressive but just as fast then a n/a V8 with plenty of low down grunt will generally be more gentle on the drivetrain. Although with a manual and sticky tyres you can still break stuff, but usually much lower revs.

Auto’s and big engines work even better and are generally the kindest to the drivetrain. And should be fine for plenty of action time and time again.

[youngsyr]

Launch an Evo at full power on the standard clutch and you'll get a horrible burning clutch smell and quite probably a slipping clutch in less than a handfull of attempts.

I'd imagine Mitsi will justify this by saying that the clutch is designed as the weak link to protect the drivetrain, but that doesn't really explain why they fitted an uprated clutch to the FQ-400!!!

Anyway, the standard remedy if you want to launch it is to fit a twin plate clutch (or triple plate if you have huge power).

Actually launching an Evo isn't particularly difficult; you can flash launch control onto the stock ECU and even without it I don't find it any more difficult than the FWD cars I've driven. The results tend to be a lot more impressive though!!

[mrmr96]

youngsyr said:

the standard remedy if you want to launch it is to fit a twin plate clutch

At what point do things like diffs/shafts/gearboxes tend to break? Surely fitting a twin plate (as I mentioned above) just means that something else will break?

[chuntington101]

mrmr96 said:

youngsyr said:

the standard remedy if you want to launch it is to fit a twin plate clutch

At what point do things like diffs/shafts/gearboxes tend to break? Surely fitting a twin plate (as I mentioned above) just means that something else will break?

I heard Scooby box's are very strong. i thought 400-500lbs ft was about all they could take... Could be VERY wrong though. lol

By the way it Torque not power (yes i know power is calculated fropm torque so the higher the powwer at any RPM the higher the torque ) that makes a mess of drivetrain components. for example F1 gearboxes may beable to take 800bhp, but probalby only 300lbs ft of torque.....ok at 20Krpm! lol

on the other side a BIG lorry may only make 500bhp but well over 1000lbsft of torque.

Cheers

Chris.

[TPB1]

I launched my old V7 Sti once.........5k rpm and side stepped the clutch.

I have too much mechanical sympathy to ever to that again in a car with 4wd.

It did shift off the line like a bat out of hell though!

[bales]

300bhp/ton said:

You could go easy off the line and not go to WOT until rolling. But you lose all the benefit of having 4wd on launching. This is very bad from a performance standpoint as the main reason these cars are quick is due to putting the power down, once rolling all of your advantage is lost.

Not really, most high powered fwd cars can't get the power down in 1st or 2nd so the actual initial launch away from the line is almost negligble.

The advanatge of 4wd on high powered cars is that you can use the power in the lower gears, not just the initial launch.

If your talking about completely standard not particularly high bhp cars then its partially correct e.g say a CTR against a Impreza WRX, if they were both rolling they are very very smilar and its only the initial 0-30mph time that would allow the Scooby to win.

But with any decent powered cars its the ability to put down 400-500bhp at speeds below 60mph which is most useful from a drag racing point of view when talking about road cars.

Note I am talking about road cars here with road tyres so even big power rwd cars tend to struggle in the lower gears.

[youngsyr]

chuntington101 said:

mrmr96 said:

youngsyr said:

the standard remedy if you want to launch it is to fit a twin plate clutch

At what point do things like diffs/shafts/gearboxes tend to break? Surely fitting a twin plate (as I mentioned above) just means that something else will break?

I heard Scooby box's are very strong. i thought 400-500lbs ft was about all they could take... Could be VERY wrong though. lol

By the way it Torque not power (yes i know power is calculated fropm torque so the higher the powwer at any RPM the higher the torque ) that makes a mess of drivetrain components. for example F1 gearboxes may beable to take 800bhp, but probalby only 300lbs ft of torque.....ok at 20Krpm! lol

on the other side a BIG lorry may only make 500bhp but well over 1000lbsft of torque.

Cheers

Chris.

The Evo VIII MR FQ-400 came with the standard VIII MR gearbox, diffs and transmission parts as found on the other VIII MRs and that had a 3 year warranty on parts so Mitsi clearly believe that the driveline on the Evos can take 400 bhp.

Most people in the owners club would say that up to 450 bhp is ok, but some run 500 bhp on the standard parts with no problem whilst others have had gearbox failures at the 400 bhp or below mark.

As with all these things, how you treat them has a lot to do with how long the parts last.

[scoobydude]

I may be wrong, but I'm sure cars like the Mazda 3 MPS have a system which limits the available torque in first and second gear, so as not to mash the transmission and gear box "accidentaly". I think it's a good call from Mazda.

[Marf]

scoobydude said:

I may be wrong, but I'm sure cars like the Mazda 3 MPS have a system which limits the available torque in first and second gear, so as not to mash the transmission and gear box "accidentaly". I think it's a good call from Mazda.

The 3MPS has a helical torsen differential which helps things massively when launching a FWD car.

[chuntington101]

youngsyr said:

chuntington101 said:

mrmr96 said:

youngsyr said:

the standard remedy if you want to launch it is to fit a twin plate clutch

At what point do things like diffs/shafts/gearboxes tend to break? Surely fitting a twin plate (as I mentioned above) just means that something else will break?

I heard Scooby box's are very strong. i thought 400-500lbs ft was about all they could take... Could be VERY wrong though. lol

By the way it Torque not power (yes i know power is calculated fropm torque so the higher the powwer at any RPM the higher the torque ) that makes a mess of drivetrain components. for example F1 gearboxes may beable to take 800bhp, but probalby only 300lbs ft of torque.....ok at 20Krpm! lol

on the other side a BIG lorry may only make 500bhp but well over 1000lbsft of torque.

Cheers

Chris.

The Evo VIII MR FQ-400 came with the standard VIII MR gearbox, diffs and transmission parts as found on the other VIII MRs and that had a 3 year warranty on parts so Mitsi clearly believe that the driveline on the Evos can take 400 bhp.

Most people in the owners club would say that up to 450 bhp is ok, but some run 500 bhp on the standard parts with no problem whilst others have had gearbox failures at the 400 bhp or below mark.

As with all these things, how you treat them has a lot to do with how long the parts last.

i dont think the boxes are the problem in the EVO mate, its the rear diffs!!! if you AYC or SAYC then the rear diff is VERY weak. some people have pushed impresive numbers through them but i wouldn't like to drag race a car with it! lol

The RS diff, and all US cars it seems, are MUCH stronger!

US gusy have pushed modded stock boxes to well over 1000bhp. Not sure what the Ozy guys are doing, but they always run VERY fast.

Cheers

Chris.

[youngsyr]

chuntington101 said:

youngsyr said:

chuntington101 said:

mrmr96 said:

youngsyr said:

the standard remedy if you want to launch it is to fit a twin plate clutch

At what point do things like diffs/shafts/gearboxes tend to break? Surely fitting a twin plate (as I mentioned above) just means that something else will break?

I heard Scooby box's are very strong. i thought 400-500lbs ft was about all they could take... Could be VERY wrong though. lol

By the way it Torque not power (yes i know power is calculated fropm torque so the higher the powwer at any RPM the higher the torque ) that makes a mess of drivetrain components. for example F1 gearboxes may beable to take 800bhp, but probalby only 300lbs ft of torque.....ok at 20Krpm! lol

on the other side a BIG lorry may only make 500bhp but well over 1000lbsft of torque.

Cheers

Chris.

The Evo VIII MR FQ-400 came with the standard VIII MR gearbox, diffs and transmission parts as found on the other VIII MRs and that had a 3 year warranty on parts so Mitsi clearly believe that the driveline on the Evos can take 400 bhp.

Most people in the owners club would say that up to 450 bhp is ok, but some run 500 bhp on the standard parts with no problem whilst others have had gearbox failures at the 400 bhp or below mark.

As with all these things, how you treat them has a lot to do with how long the parts last.

i dont think the boxes are the problem in the EVO mate, its the rear diffs!!! if you AYC or SAYC then the rear diff is VERY weak. some people have pushed impresive numbers through them but i wouldn't like to drag race a car with it! lol

The RS diff, and all US cars it seems, are MUCH stronger!

US gusy have pushed modded stock boxes to well over 1000bhp. Not sure what the Ozy guys are doing, but they always run VERY fast.

Cheers

Chris.

The US and RS cars come with a 5 speed box which is rumoured to be stronger than the 6 speed box found on the UK "FQ" and JDM GSR cars. Makes sense if you think about it - the gearbox casing is the same size for both the six and five speeds, but you've obviously got one more gear in the six speed so each of the gears is smaller.

A lot of people have found that the 6 speed gearbox will tend to give up (particularly the high gear syncros for some reason) before the diff goes.

[madwrx]

just to pick up the point made earlier about the strength of impreza boxes
standard wrx-turbo 2000 5 speed boxes are really only reliable below 300ft/ib above this there on borrowed time(3in3years for me) every time i open one up i cant beleive they last as long as they do,not really built to take anything like the power/torque that even a mildly modded 2 litre can make.

The 6 speed boxes other than normal wear&tear seem to last very well at 500bhp plus although that does reflect in the cost of these.

[RobCrezz]

Best thing to do would be to let the clutch take the abuse by slipping rather that shocking the transmission, as its unlikely to get wheel spin. Much cheaper to change clutch more often than a blown gearbox.