2.4 JTD uprated gearbox enquiry - Kev

Sounds like a fun project

RE photos : If you are stuck you can just load them up to www.photobucket.com and post links.

Have you made any changes to the front wishbones, specifically ones that increase negative camber or are you still using the OEM wishbones?

RE the GTA gearbox, I think some of the >400bhp GTAs would be getting close to 550nm, but if you are well over 600nm already then this wouldn't be a proven route for you.

I'll be amazed if the diff isn't worth a couple of seconds a lap to you as it was to me.
At that price I presume its a Q2 diff?

If so, your participation in the AO destruction testing program for Q2 diffs is welcomed!
(no failures reported so far btw)

Cheers,
TB

Originally Posted by kevinw

pics.... I keep getting upload failures - any ideas~?

Hi,

Thanks for the comments -

Yes the Q2 - a few people had told us that it fits the 2.4 and few were adamant that it did not. Then a guy checked my car on chassis number as some have the V6 box which mine does - and then the diff fits so it;s all a bit uncetain. If when they go to fit it there's any issues - it will be packed off to a machine shop and made to fit!

I'm glad the Q2 diff has been working well for you guys, thats good to hear. They sold it as a 'plate lsd' wich it does not appear to be?

The car will certainly gain laptimes - especially out of 30mph corners in 3rd (diesel..) where it will always spin the inside wheel - but hats off to the guys who sorted the suspension - it still puts down huge amounts of power without the diff.

The suspension has stock tca's but the bushes have been modified and the hub top mounts, the top mount etc - all to give endless caster/cammber adjustment - and they just spent a day optimising it after the parts were fitted. They said use the KW's as they are £1000 of bits for £600 and its all down to the set up anwyay. I'm no suspension expert - so left it to them and i'm no racing driver so also left it to them and the results are fantastic. I asked them to do some laptimes before and ater suspension - but they laughed at me and said they didn't want to kill themselves with the std set up! (fair com - i've had some moments)

I like the 'braking later' comment - have you driven a stock 2.4? You really would not joke about brakes!!! I've had tons of cars, all makes and models petrol and deisels - but I honestly thought there was a problem with my brakes from new - it went back 10 times for brakes - or lack thereof - they said 'they are all like that'.... so all 2.4's have no brakes? Odd memories for me, as my mum had a new alfetta 1980 2,0 - that had no brakes, the alfa garage said they were 'all like that' my dads 2,0 cortina at 40mph could pull up (40degree angle..) 40-50 yards faster - but alfa considered that acceptable. Nice to know some things in life can be relied on. Oh - my mun after a year of moaning and given up - went off the M1 on a slip road at 60 - it was a short slip road that the cortina would have stopped in 3 times, she couldn't stop it and hit the roundabout with 2 feet on the middle pedal!

I never thought for a minute that as the car looks so good, and now goes so well - that it could handle and stop too. Being a 'track day man' not race driver - I also never twigged that the extra 150bhp is nothing like as handy as brakes and suspension.... I had the Formula Ford lesson - when we were there last time and the 105bhp FF's were taking 15 seconds off the 4-800 bhp supercars just on brakes and handling - but you only see that with the stop watch - i've always been impressed with noise, smoke, sideways cars - but i'm undergoing therapy from the guys who run the FF's... they think they can help / or may be too late - tba

Kevin

You are right the Q2 is not a plate diff, the Q2 is definitely a torque sensing diff made by Torsen, they are a competitor to Quaife who make a different brand of torque sensing diffs.
See www.torsen.com for more details, apparently the Q2 is a Torsen T-2 diff.

Torsen diffs are a little nicer on the road than plate diffs and also zero maintenance. Plate diffs are a little more hard-core, slightly faster, slightly noisier, and more maintenance but adjustable settings.

I have driven a stock 2.4, and yes the brakes were not great, the problem was at least partially to do with feel as well as stopping power. I found on all the 156 range (except the GTA), you really had to stand on the pedal.
Apparently the T-spark 2.0 stopped from 60-mph in 2.6 seconds which objectively is quite good, but honestly it felt crap on the road..

The 330mm GTA setup is rather good though, pulling > 1.1 negative g with decent pads and type-r tyres, I imagine your tarox 6 pots should be certainly up to the job.


You will have to post an on track vid of one of your trackdays sometime

Cheers,
TB

you need to speak to QUAIFE

http://www.quaife.co.uk/

Quaiffe and the Alfa Q2 Torsen diffs have very similar characteristics.

Originally Posted by jug

you need to speak to QUAIFE

http://www.quaife.co.uk/

Hi, Thanks for the info - it was the supplier who said it was a plate item - but then they don't normally know that much...

It's odd about the brakes - maybe mine just really was bad. You could get it to pull up just fine once but not from much more than 80 in one go - then that was it. It had new discs, pads, fluid etc under warranty more than once - but it never improved. When I took it in for some work a couple of years ago - they lent me an older 156 2,0 and that stopped really well - but they weren't interested in that argument at all! Yes it stops well now - i've got a gmeter i'll try and check the rates - i never thought to measure it.

I'll try and set up some pics soon - and we'll defnately have a vid next time it's at Goodwood - there's a few cars now that we'd like to record being embarrased.

We spoke to quaife about the box - they couldn't do anything for the diesel at all - all odd cogs/ratios/final drive ratios.

The guys next door have been laughing about the diff - they said 'I'd be fine as long as I don't lift off' but then just walk off smiling - I guess thats something i'll have to work on later~?

I have been advised by alfa specialist clovertech the q2 is only good for 300ftlb. So not suitable for the 2.4 in that respect.

For that sort of power you would be stupid not to do things properly and readdress the gearbox, driveshafts and cv assemblies in one go otherwise the next thing will break, the person telling you not to get an LSD knows what he is talking about and I would follow his advice.

Who was the tuner doing the work? And are you and are they going to any of the shows this year, I wouldnt mind a gander if thats alright...

Whats the reason they think 300 lb/ft - have they tested to failure?
Or perhaps more likely just being sensibly conservative based on the engines it has been deployed with.

FYI Its coping with a lot more than that in my car currently, including 7 track days and counting, several of these on type-R tyres.

Cheers,
TB

Originally Posted by Lowtechguy

I have been advised by alfa specialist clovertech the q2 is only good for 300ftlb. So not suitable for the 2.4 in that respect.

You're probably right there Trailbraker, my clutch is rated for 275lbft, currently its coping very well with 325lbft. I think they give a very conservative estimate...

KevinW, what do you reckon your peak torque is at the moment?

Originally Posted by Pud237

You're probably right there Trailbraker, my clutch is rated for 275lbft, currently its coping very well with 325lbft. I think they give a very conservative estimate...

KevinW, what do you reckon your peak torque is at the moment?

I think it depends on mechanical sympthy, if something is fed in slowly it will be ok, but a sudden 300ftlb.... I wouldnt want to pick up the pieces, You have to be conservative with the drivechain...

Hi Guys,

Thanks for the input -

I'm a bit sceptical about 'limits' - as really most of the car should have blown up by now - the engine especially! But having had that apart a few hundred miles ago at 38k - all that was really suffering was the big end shells - they were a bit marked up. I blamed the torque/cylinder pressures - but then remebered that it's been hydauliced twice with water when we were testing the water injection systems (and it went wrong...) and then again when we had some injectors built (thats went wrong...) and filled it up with deisel so 5 hours of cranking with 2 batteries on could well have been the problem with the shells. Sound sdaft, but with the diesels you are always doing your own r&d - and now we have a very high pressure water injection system and a set of injectors when coupled with the ecu mods and some other tricks - can flow enough fuel to smoke still. (so it needs a bigger blower...)

After having 300bhp and more out of a Maestro engine for many happy relaible miles that was designed in the 70's - I have a lot of faith in more modern kit (CAD) and also more with the deisels as they are so low revving and built well.

The vital point there 2 as you picked up on - it all comes donw to how the torque is applied as it's not a grand prix - (650nm max before it all vibrates out of the engine bay...VNT cavitates at high loads) if it were on santa pod each weekend it would be a non runner - but used normally but quickly, it's fine. I'm a sympathetic driver as I have to pay for the bits I break - or worse have it off the road for weeks!

The diff will load up other items - but i'm not going to suddenly change the way I drive - it's purely just to get some traction (at all) in 1st and then in second gears - if the roads dry and warm it's good fun - but when for 80% of the year it's cold, wet and slippery it's a pia to get away cleanly especially with the family in - where I doubt i'll be using half the torque. In the car on my own I never use 1st - you can use 2nd like 1st - but with the family in etc you have to use 1st and thats the only time i wish i had the standard 150bhp engine back and could just floor it all the time.

The race prep guys said depending on the track, it's good enough now that they wouldn't bother with the lsd - the issues are not so much with track/fast driving as just general use. Whilst the accelerator is King - only being outdone by the nut behind the wheel - when it spins up on much more than light throttle - you don't have to be trying to be a boy racer to find some serious pulling going on.

The VNT suddenly becomes the bain of our lives now - as it's especially made for low end torque - despite being larger and modded - it's still hard to set it up to deliver power progressivley - coupled with only having 2,000 to 4500 to work with. Garrett expressed some interest in the project as they admitted they have no diesel tuning/turbo upgrading experience so they are doing some work on the possibilties of going back to a conventional GT2560R or similar - the concern being then - if it doesn't spin up there could be no power below 3000rpm. Despite all their efforts and skills - and everyone elses opinions - the only way to find out is to fit it.

Thats been the way with the deisels - fantastic results, BHP/£ x10 compared to petrol tuning - but 97% of the time once you go past a remap and a KN filter - you are on your own.

The JCB that just did the wheel powered land speed record at 350 ish - 2x 750 bhp (max) 1500nm turbo diesels - twin turbo's and running up to 5.2 Bar (75psi) and achieved 170bhp/ltr after Millions of £££'s worth of work - so my 133bhp/ltr I'll have with the new turbo, half the boost, a stock engine mainly and no ice cooling - i'm happy with. And it's still a road car - does not need towing to start and does 40mpg! And still normally twice as much torque as a petrol.

The Alfa wins for this project as it looks good, has a huge top gear that when we get it running cleanly again will pull 160mph - the cars slippery and now with the suspension mods done stable and stops. We could have used a 3 series but too predictable and the Mrs's car would have been ideal being 3,0 - but she thinks it's scary with 240bhp - so thats off the cards.......

just loving this information just printed off your posts, hope you dont mind

Originally Posted by DGT

just loving this information just printed off your posts, hope you dont mind

Aye, I've got it bookmarked as well

200bhp is fast becoming not enough, I don't know what to do

Kevinw. have you looked into the possibilty of mating it up to a fiat ducato 'box? its bound to be tougher.

also, where did you get your nozzles? fratelli bosio?

Kevinw, could you send me photo of your rolling road ? or do you have one ? other pics of your car also would be interesting .

Hi Guys,

Thanks for the interest!

I've been on holiday so didn't get back earlier.

Just a quick update

The lsd has been fitted - and in itself is handling the torque well, but as we expected the 'next thing broke' ! It worked for about 50 miles, then the lost all drive - on taking out the gearbox again - the clutch splined bub casting had shattered. We had another custom plate made up, and uprated linings and the cover again - for another 100lbft - as the 450lbt item was struggling with the lsd - as now the wheels were connecting with the road much better.

The new clutch just went