Once you have passed the 400/400 mark, what sort of gearbox upgrades do you guys recommend?

I read a lot about the Lateral Performance strengthened gearset. Telling from the picture in the scoobyshop, that includes the axle and the first 4 gears. Are they simply heat treated (like STI parts I believe?) or are they a different material as well?

Did anybody break one of those LP gearsets already and had to use a dogbox?

I like the speed of a dogbox (shifting), but the noise as if you were going backwards from the straight cut gears would make the car impossible to use on the motorway.

Any thoughts on this?

 

I have used both the lp uprated gearset and the indestructable gearset. Both have their own advantages and disadvantages - dispite popular belief, the only reason why I changed to the lp gearset was that i broke the speed sensor cog in the gearbox, and fancied changing. I was quite happy with the dogset.

I am off to bed now, but I will post what I think are the advantages and disadvantages I had/have with both.

 

The Lateral was the highest claimed torque rating at 400 lbft for a synchro gearkit I could find for an Impreza.

I feel less limited in limiting myself to 450 BHP and 400 lbft (hopefully before 4000 RPM) because on a single turbo Impreza engine with long headers I think you'll struggle to make more than about 200 BHP/ton good for road use.

The point of peak boost under full load in 5th gear might be say 4000 RPM, but to get really good throttle response in 2nd gear I reckon you need to add 1000 RPM to this to get it to really respond the way you want a road car to respond.

On the 2.0 I find that I really don't like driving it so much if the 1 bar boost threshold is over 3000 RPM. This sounds lazy, but a car that makes 1 bar at 3000 RPM is unlikely to be getting really torquey until 4000 RPM, so you need 5000 RPM before it really wakes up. Given that people are struggling for power peaks over 6600 RPM on STi cams on 2.0, and over 6000 RPM on larger capacity engines you end up with quite a narrow and irritating power band.

I'm not bad at stick stirring and like revs, but it has to respond instantly at 5000 RPM to be good on back roads IMHO.

It is quite eye opening to drive a 3.0 V6 overweight French saloon as my daily steed at present. Despite its failings in all respects except the engine and ride quality it makes me very critical of a high power single turbo engine's torque delivery. You still need to rev it to make it go, but you don't end up with that horrid bogged down feeling some big turbo Imprezas have at say 4000 RPM in 2nd gear - there is appreciable and monumental lag, and switching down to 1st is not an option.

 

True; and using ALS makes other people think you're showing off

 

Claudius, I have the LP gearset since October, done a few trackdays with it, but haven't managed to break it yet

First gear is straight cut, 2nd 3rd and 4th are semi-helical with a different tooth profile.

There is obviously a bit of noise in 1st, and some noise in the other gears, but IMHO not annoying at all. 4th is almost unhearable, 5th remains standard.

You can choose between a few different ratios for all 4 gears.

Shifting is the same as with the standard box, synchro noises disappear after a while once bedded in.

Until today, I think they are the best option known to me if you want to use your car as a daily driver. Fitting is crucial and not easy (case has to be worked on to make some room for the first gear). Running in is also important, 100 km with a low grade non synth oil, replace with synth oil and do another 500 or so km, then replace again with the best oil you can find.

Don't skimp on bearings etc when they get fitted.

I've changed gearbox oil a few times since fitting mainly to see how much swarf there is, but there is vertually none, dealer commented actually less than with a standard gearbox on a standard car.

HTH, Mark will correct me if I got something wrong

 

Thanks EvilBevil

Exactly the kind of info I was looking for

What sort of torque and power are you running, though?

Is there any info online on the different gear ratios of the LP gearset?

 

I know they are machined out of a different grade of steel..Im sure mark will comment when he see's this thread..

David

 

Right... so what do you think now that you're amongst the awake?

 

Hi Evil,

What case work was required?

Thanks
Richard (who's just tracked down someone capable of rebuilding my box with Mark's kit...and is a bit concerned about scaring him off )

 

From memory


Here are the "off the shelf" ratio's available for the syncro kit.

They are able to make any ratio you want, but these have been found to be
the best, and strongest tooth profiles.

1st 3.45, 3.18, 2.916
2nd 1.91,
3rd 1.35, 1.45
4th 0.966, 1.16


Richard, I haven't done it myself, my dealer did it, and was not scared by it or did not feel uncomfortable with it in the end. The gears are a bit bigger in diameter, so a bit needs to be "filed" off. (but I don't know where exactly) In fact I think he's buying a set for his tarmac spec competition Impreza.

 

There was no official guidance with the kit on oil. Any specific recommendations as to what to use before the Redline Shockproof I've spent mega cash on?

 

John for the first 100 km and 500 km we used el cheapo mineral oil. Needless to say we took it easy, it's just to "wear in" the gears, synth oil would be too "smooth" to properly do that as I understand it.

 

John... Speak to Barretts Motorsport.

David

 

I'll be running in the engine at the same time, so it will be low loads, lots of varying revs.

 

Now now girls.

Barrett's are just one of the builders that LP have used and are able to offer the warranty with. It doesn't mean that there is cloak and dagger crap.

What's wrong with getting a few opinions on the oil?

Paul

 

Wowowowow!

What the hell are you guys on about?! A fight in a thread of mine, and it wasnt even ME starting it!? Can you believe it!? LOL

Chill out guys, read what gets posted on here and email whomever you want. If the person you are being told to email builds gearboxes, they may have information that completes the one on here, I dont see a problem with that. It doesnt mean David doesnt know just as well, but would confirm what he said. How bad is that?

Not that bad, is it?

The one with the least horsepower here will have to shut up now!

No, wait! That would be me!!! LOL


Come on, back on track

I was told today by a French tuner I should use an STI 6 speed gearbox, that that would hold up to 400/400 and is good for road use, strong etc. Any views on this?

 

Weve sorted it.. not a problem.. just misunderstanding..

6spd. is what I am fitting to mine.. its not a simple as what people tell you though..

The JUN car runs 600ps through the std 6spd box..

Final Drive ratio can be confusing..

Also has a built in oil pump..

Like rocking horse **** to get hold of though...

If you do... get the VSS sensor and the linkage with it.. I didnt

David

 

Sorry about that guys I'll email you both. I was slightly reluctant to ring Barretts since Neil Engineering near Glasgow did mine (built/rebuilt lots of Cossie boxes from years back and since Subarus, including various Prodrive boxes, quite experienced in building boxes for rally cars if that helps). I have every faith the job has been done properly and they replaced quite a bit on it as they needed to and were honest and reasonable throughout showing apparent skill and understanding as to what was required.

 

Right, all the dross removed, back on thread topic please chaps, and thank you for resolving it so quickly and effectively, well done

Steven

ps anymore, and i slap you ok

 

Funny David, my dealer considered fitting a sort of cooling system for his old shape gearbox, LP set or not.

He had noticed that gearbox oil could get quite hot

Claudius, misunderstanding between me & Mr. Wallis. Move along, nothing to see there

To all of you who have posted ****e on here... this outburst between a rather more technical dude (not me) and me (me ) is due to all of the contentious ****e that gets posted on here.

Mods, there's more to a BBS than "guidelines" !

 

EB I know, trust me

 

Steven, that wouldn't have been needed TBH. Not a dig, but actually you seem to not see where I am coming from. Not a big loss mind

****, am I glad I'm not a co-owner of this place !

Oh well, back to gearboxes.

 

What about using an STI 6 speed gearbox?

 

EB, you completely lost me there, no worries though.

Steven

ps i dont co own this, just give up my time for free.

 

Claudius, that is what david will be using in his car IIRC, have a look in the projects forum near the end of his current thread, he shows the pictures of it etc.

Steven

 

Right.. whilst where on with this.. (did this before but not much response..

People quote circa 90bhp transmission losses..

90hp = 67.11Kw.

Surely thats a fair bit of heat to be getting rid of??

So..

Power Steering Cooler
Oil Cooler (Dont even say it christian)
Transmission Cooler

David

 

there is surely a risk of transmission oil being too cool if you are not careful.

Transmission losses dont increase with engine power apparently, or so I heard once from pat.

therefore if you dont cool the standard transmission, why start now?

incidentally, transmission cooling covered!

 

Funny you mention oil coolers. Is it really true that there isnt one?? My tuner told me that today and I couldnt believe it

I'll take a look at the projects, thank you

 

There is a little one where the oil filter goes on?

 

Yes the oil cooler is a small water/oil heat exchanger, but a proper one is a good buy I think.

Paul