Azrael

TF Rallyesport it wouldn't be 100% RWD, it would still have initial torque split of Cossie centre diff (34/66) but any loss of traction on any axle will limit torque transmitted to axle with grip to resistance on the axle that has no grip - so in practise to ~0. To driver it will feel like RWD car in most situation as rear is much lighter nd more prone to loose traction altough in cornrer entry it will behave like 100% FWD -> spinning inside wheel if throttle is applied.

What VC does is that it allows more torque to be tramistted to the axle that has more grip. Grip of the axle that is slipping + VC rate = torque on other axle (taking initial diff split into account of course).


I hope someone got it.



I think there must be something tterribly wrong with SiB's car's drivetrain. If it had failed diff on the track VC would be cooked in an instant anyway. VC's sometimes do lock completly when overheated badly but surely it wouldn't be able to transmit full torque of a Cossie engine and would fall apart.



I know this from experience, my car has done many kilometers with broken driveshaft before I bought it. It had absolutely no LSD action in centre diff whenn I bought, also pig to drive.

Si B

iTrader: (59)

Hi folks,

This post gets better and better now we have peeps with tech knowledge thinking about what my car is doing!!!

Basically to help with diagnosis:

My car has ALWAYS had these diffs in in it for the last 5 years I've had it.

My car is running 4 identical tyres (make and tread depth etc)

My original standard gearbox survived 30,000 plus miles of my ABUSE on track, strip and road. At 320 and later 370 bhp.

I have since had the car mapped by Karl (NMS) and it now runs closer to 450 bhp.

BOX 1:
Since then I have done approx 350 on road miles on my standard box without it breaking. Then I went on track at Ford Fair, did 4 laps and broke it.

BOX 2:
Another standard box, 2nd hand. Again, approx 400 ish miles on road, then on track at National Day, did 4 sessions (approx 75 miles) and broke it.

BOX 3:
Marco's Mullit box. Did approx 275 miles, bedding in. 60 miles thrashing it up to Castle Combe. Did 4 laps, and broke it.

So - all boxes have failed in the same way (cooked VC). All have failed on track. All boxes were filled with Castrol or Silkolene pricey pukka oil!
I am 99% certain each box broke when changing from 3rd to 4th gear in a straight line. Lift clutch pedal after change, no drive. Simple as that.

The clutch is an Alcon 6 paddle, with HD cover and new release bearing new 2000 / 3000 ish miles ago.

I'm not saying my car is not buggered in some way (broken diff or whatever), but I don't THINK my car has turned RWD at any time. It still drives exactly as it always has done - like a 4*4 car - I don't ever go sideways or smoke the tyres, I just plant it and it grips.

Can anyone shed some light on what might be causing this? I'm in the process or ripping my diffs out for Marco to inspect, to eliminate them, or to replace them as needed.

I will do whatever needs to be done to get to the bottom of this!

Si

marco polo

iTrader: (1)

Hi peeps

I have had alot of interest and a good few pepole have asked me a few questions about the Mullit box

i'll tell you what you get for your money once r+d is complete


you will get a fully build box ready to fit in your car

secondly any step of you wish 3.9 /4.1/ 4.4 5.1 extra cost

standard is no extra cost

you will also get an uprated center VC of your choice ranging from 50Nm -to 180Nm and dyno test rating as well not just a questimate extra cost , standard vc no extra cost

Big Tooth gears 2nd /3rd /4th /5th


1st and reverse is standard in "patern only" uprated matrial same Quality/Strenth as the Big tooth gears themselves



The only second hand parts used in the gearbox is the casing/ selector forks/selctor rod thats it everything else is brand spanking new

the gears are "standard ratio but Big Tooth " at the moment


will be doing close ratio version aswell at somepoint and maybe a lower ratio 5th

cheers Marco

marco polo

iTrader: (1)

Hi Tim

I know your not blaming the box i just can't understand why the VC died and why Simon had no drive and the rest of the box apart from the VC was fine in everyway

so i don't really know

I have spoke to a good few people in the rallying/ racing game and they
all said same thing when the vc burns out there is a problem somwhere what i have explained above

now i not blaming Simon at all or his car ,personally i want to find out why the VC died and why the box had no drive when the box is fine in every way

what i don't want to do is ,If Simon has his diffs done and the same thing happens again he would have wasted his money

what do i do ?

marco

Micky The Finn

but he has had problems with three gearboxes all being vc's,that points to a step off problem,i bet he has a 3.6 rear with a 3.9 front and didnt change his original gearbox chains and gears over.

dave cos4x4

iTrader: (5)

got to be something like Tim suggesed,the VC cannot just go for nothing.

hope you do get it sorted though.

Azrael

Even with wrong stop-off and cooked VC it would still go (although constant difference in axle speeds in centre diff will destroy in eventually)! Maybe one of diffs is missing some teeth on CWP?
Weirdest problem I ever heard.

leecavturbo

i know nowt about box's/diffs, but if the diff's are xr4x4 type then surely there not meant for a cossie ????
and if its unusal for these to be fitted to a cossie maybe some clever bugger who had the car previous changed the diff ratio and your just assuming its a std xr4x4 diff just by looking at the casing/part number????

dave cos4x4

iTrader: (5)

as long as they are the same ratio then there should be no problem,only the stength in the units may differ.

Micky The Finn

get the diffs out and get them opened up,

Azrael

Spill their guts and throw them to us




(Sorry I've been reading too much about pirates lately)

marco polo

iTrader: (1)

Hi lads

I have just spoke to Simon on the phone his is taking out the diffs sending them to me so i'll have them apart monday/tues

he also said that he is pretty sure that the front is defo a 3.9 because his mate had counted the amout of turns it takes to make a full revolution

he is not 100% sure if the diff on the rear is a 3.9 so he going to see if theres a little tag(if it's on there) that will tell him what ratio he has got

at the end of the day we have got to find out

we will sort it out one way or other


cheers marco

marco polo

iTrader: (1)

they are expensive

marco polo

iTrader: (1)

on the case now

marco

marco polo

iTrader: (1)

Hi Tim

could well be , would this cause no drive at all even with the VC burnt out ?

marco

Martin-Hadland

iTrader: (2)

Marco,
he does not need to send the diffs to find out the ratio, all he has to do is pop off the covers and count the teeth, then divide the crownwheel by the pinion and bobs your mom ... ratio sorted!

Azrael

Martin - you are right of course but even wrong ratio wouldn't cause this sort of problems.

marco polo

iTrader: (1)

Martin

I know he doesn't have to send the diffs to me too find out what ratios he has got but he wants them looked at checked anyway

Marco

Si B

iTrader: (59)

I AM A TWAT

And as a result want to offer sincere apologies to Marco and the Mullit Crew, for causing people to think there is a problem with the Mullit box.

THERE IS NO PROBLEM WITH THE BOX

I've found out why I've killed 3 boxes now

My useless f@#king car has MISMATCHED diffs on it - I have a 3.92 Front diff (printed on one of the cogs: 13/51)

I also have a 3.62 REAR DIFF.

It has taken me hours of swearing, hitting, beating and levering to get the damn rear diff off the car. EVERY single bolt has either been corroded, or loctited in, or wound up stupid tight by the previous owner.

I'm sending it to Marco to get checked over just for peace of mind - I may also have it upgraded to MULLIT spec as well while I'm there

I also apologise for everyone that has been scratching their heads trying to work out why the failures occured - when the problem was so bloody simple / obvious after all.

The only thing I don't understand is how the original gearbox survived 5 years of hammering round tracks without failure at 320 then 370bhp.

Yet gave up the ghost at 400+ bhp.... surely the VCs I'm frying would have broken at 320bhp if the diffs were mismatched?

Anyway, rear diff will be off to Marco early next week for checks / upgrades.
I'll look for a 3.62 ratio front diff.
Mullit box MK1 will be back on my car
Road and track testing will recommence in earnest - any where and everywhere I can drive I will drive!

If any potential customers want to see or hear the box in action I will be more than happy to take them out in the car for a run, and if I know you, then you're welcome to take the car for a spin and see for yourself what it's like.

Sorry again, humble pie is now being served in my house

Simon

Azrael

I bet your VC's were dead all the time form the begining, you just didn't notice. On tarmac with good lines and good trackin it wasn't that bad.


Some track 4x4 don't have centre LSD.

Micky The Finn

your original gearbox would have had a step off to suit the front diff,and you didnt swap that when you swapped boxes did you?

there's your problem.

Si B

iTrader: (59)

Hi Tim,

POSSIBLY, but I'd say no - In this case why did the original gearbox die? If that had the correct step off, it shouldn't have fried the VC, but it did.

Incidentally, the step off / chain was not swapped on any of the gearboxes because we told Marco the diffs were standard (having no reason what so ever to think they were anything other than that at the time, the car being basically stage 1 when I bought it, and no diff change in the car's history paperwork)

On a side note, can I have some feedback on Ebay? For the Pug GTi6 Starter motor I bought along with the 2wd gearbox? Gearbox seems spot on, nicely wrapped up! Hopefully I won't actually need it!

Starter looked as new, thanks very muchly!!!

250018233630 was the item no

Cheers
Si

Azrael

I'm very curious what else apart form wrong ratios is wrong with that drivetrain. Marco lease post when you have diffs taken apart. I hardly belive it's the ratios alone, unless not only VC's but planet gears in centre diff are destroyed.

Porkie

iTrader: (1)

as I said before Simon

kjc300

iTrader: (1)

Leave the poor boy alone.........


















He's already a cooooooooooooooooooooooont!!!

leecavturbo

its great but not, when you find a problem if you know what i mean

PAUL S

iTrader: (8)

This also seems to prove that the 3.92 Xr4x4 front diff is not as weak as people claim for a road/track car

marco polo

iTrader: (1)

Hi Azreal

you keep saying this , i am telling you that nothing was broken in the box what so ever i mean nothing !!!! do you not belive me ? by the way your talking you seem to think that i am hiding something i am not ?

The VC was totally fooked if something else was broke in the gear fooking box i would honestly post it up here for you lot to see

the gearbox was striped down right in front of my own eyes and i know what i am looking at if anything was broken i would have seen it for myself . I then would have took a pic and posted it on here for everyone to see

I gave a 3k the box to Simon free of charge to test it there is another 2 that are going out free of charge to be tested

i'm not on here to make a fortune i'm here to make a product work

i don't expect it to last a life time either but i do expect it to last along time and alot longer than some of the other gearboxs that are out there

I dont see any of the others out there giving away free boxes to test they just take your money and when it breaks you pay the bill


i will prove how good the box is martin's mondeo is ready soon and thats over 500+ bhp on T04 and 8 greens

watch this space !!!

Marco

Micky The Finn

marco,azrael was not saying something must have broken in the gearbox,he was and quiet rightly saying something must have brok on the transfer side as to lose all drive must be more than just the vc unit.

he isnt trying to show you up at all,he is trying to help you!!

marco polo

iTrader: (1)

Hi Tim

I might have taken it the wrong way for that my apologies

yes but theres nothing broke inside the box at all thats what i am saying


marco

tregmatt

iTrader: (3)

marco if anybody can get it sorted it will be you mate GOOD LUCK

Si B

iTrader: (59)

Lee,

See normally I'd offer up another one of these , but actually I'll just accept one of these

Si B

iTrader: (59)

However Kev can have one:

I thank you

dave cos4x4

iTrader: (5)

got a spare front and rear diff if you need them Simon.

Si B

iTrader: (59)

Incidentally folks, I have bought a new front diff of the correct 3.62 ratio, and am taking it and the rear diff to Marco for him to give the once over.

Rear diff is having the full monty Mullit spec big tooth gears and uprated VC whacked in for good measure

Once that's done, they and the box will be back in the car, and I'll get my self on a Track Day (anyone anywhere) for some hard testing! Hopefully within a week or two.

Si

Si B

iTrader: (59)

Thanks Dave, will bear that in mind - prob will need them as and when the GT30 finds its way on to the car

As above- have now got a new front diff, but always handy to know where to get spares!!!

Si

dave cos4x4

iTrader: (5)

so mine not needed then.

marco polo

iTrader: (1)

well he never had much drive going to the front

marco polo

iTrader: (1)

Hi Si

the diffs should be ready by tuesday/wednesday

we will uprate your 7" diff with 180Nm Vc with uprated gears i'll post a few pics of the gears inside the diff just to show you what they are like compaired to the standard cos diff

and the good thing with a uprated VC it will be like a proper lsd without the noise and will be ok for what you want to do with your car

ill give you a bell to meet up with you i'll drop you off the box and the diffs so you can put everything back in your car

cheers marco

Si B

iTrader: (59)

Cheers Marco,

Will look forward to that job!!

Si