mrviper

I managed to explode my diff in my focus

Dont know why it happend but i thought thease box's are supposed to take 350 bhp and launch at pod over and over.
I only have a 1.8 on bike throttle boddies and mtech v4 that revs to 7300 maybe it didnt like harsh gear changes with the focus rs clutch

This is the 2nd box that has exploded on me the last one was the original ib5 looking one and spat its diff out all over the floor at the traffic lights in the rush hour traffic and i and the traffic couldnt move

It has the early version of the mtx75 not the focus rs type (the cable arrangement is different)

I see lots of diesel box's with the cable brackets at the back like mine and was wondering if the gear ratio's are much different compared to a 2.0 petrol box?

and are (mk3?) mondeo boxes the same?
and if i get a later type box can i put my selector box on it to make my cables fit?

while im at it im going to drop in a st170 lump that i have had in my posession for a few months so roll on 8k rev limiter

cheers

phil_focus

they are strong boxes, only heard of your diff and one others on here in the last couple of days going ever!

i've got a mk1 w reg 2l focus with the mtx75 in, done 105,000 miles now and i bought it at 80 someithing thousand and abused it ever since including VERY hard launches at drag strips and banging it very hard through the gears!!! thats probably what finished off my leaky drive shafts

one thing i will say though is dont believe ford that the oil lasts a life time, no oil does so change it every so often. mine was changed at 74k when the clutch was done and i've done it again very recently and put in fully synthetic and the old red stuff was quite dark even though it had only done 30k. gear change is a little nicer now too 8)

as for using the later type box i'm 99% sure you can just swap the selectors in the boxes over. its on a recent thread somewhere.

mrviper

well i think its the small gears in the diff that has gone because when i had it jacked up and turn one wheel the other wants to turn the same way

and if i drag one wheel on the floor while its in gear in the jack it makes nasty crunching sounds and makes my steering wheel turn to the left

now normaly i presume it would be going the other way round unless it had a lsd

so from what you say about the selectors i could fit a focus rs box without spending £200 in cables and gear stick

i would fit st170 box but the clutch options are shit

phil_focus

yes, i'm sure someone on here in the past coupe of days replaced their mtx75 with the early type and then found out they could swap the selectors on the box and not need to faff about with the cables.

rs box should be a straight swap too pluss its got the quaff atb diff in it so big bonus there!

XRT_si

iTrader: (2)

https://passionford.com/forum/genera...tec-turbo.html

"With the mtx75 the diff explodes at around 275bhp, subject to how often you launch it. Put a lsd in and they can take more power."

It seems diffs are the weak point!

phil_focus

theres no way a 1.8 on throttle bodies is pushing out that kind of power, perhaps there was an oil leak so the diff god hot and exploded?!

anyone going for that sort of power though would be looking at uprated diffs anyway to get the power down, standard open diff would be useless. easiest thing to do would be swap to focus rs box unless you wanted a different diff.

clairendave

High milage and overlooked oil changes. I still have one of the planet gears form my family mondeo 2.0 I had a few years ago. All I did was a spirited start from a junction to beat traffic and BANG.

bookwyse

The MTX75 are prone to spitting the planetary gears from the diff after a while. It is a common problem on the ST200's and a common fix is indeed the LSD as I have fitted in mine.

The turrets are indeed interchangeable between the early and later boxes.

phil_focus

just the confirmation we needed, thanks, and also all these stories seem to confirm a 'weak' diff so good to know 8)

mrviper

thats exactly what i did and if it totaly gave up i would of had 40 tonne of lorry in my face

percybigun

my zetec turbo mondeo used to regularly crunch diffs in its mtx75 at 275-300bhp, i dont know who told you 350bhp. and its doubtful a 1.8 on TB's would be running 350bhp anyway unless its got alot of nitrous.

regular harsh launches at the pod will knack a diff, careful driving on the standard open diff can be done to make it last.

if you didnt launch it you would get away with the standard diff, but the amount of torque steer you will get means you really need a lsd anyway because it will be a bitch to drive and pretty dangerous imo. i know mine was dangerous to drive until i got the lsd and a fairly sorted suspension package.

for some reason the st200 mondeo gearboxes are more prone to diff failure than in lower range mondeo's, presumably because they have slightly different innards and longer final drive

oh and dont use a diesel box, the mondeo 1.8TD gearbox had awful ratios and tops out at around 4500rpm

i *think* the 1.6 zetec gearbox has shorter ratio's (it says they do in the mondeo haynes) so would be better for acceleration than the 2.0 box.

crazycage

[QUOTE=mrviper;5068012]I managed to explode my diff in my focus

Dont know why it happend but i thought thease box's are supposed to take 350 bhp and launch at pod over and over.
I only have a 1.8 on bike throttle boddies and mtech v4 that revs to 7300 maybe it didnt like harsh gear changes with the focus rs clutch

the mtx75 found in the focus rs can and does take 350+hp and launch at the pod over and over ,theres over 40 slips there from the last 18 months running that power in my fezz.

VINNI

I am experiencing problens with my MTX75 gearbox. Mechanic says the diff is on it's way oit so looking for a new one. Is the mk.1 RS box with LSD a straight swap? Are any other boxes suitable or have better ratios? Cheers.

Rsturbo519

[QUOTE=crazycage;5070569]Hi garry how's it going? Can you clear something up for Me. I have fitted a frs box into my s2. I have a frs selector but I have ordered mk1 focus cables. Will these work with the box and selector or does it have to be frs cables.

If they don't can they be made to fit ( make up a bracket ect ect. ) ??

Many thanks
Blair

crazycage

[QUOTE=Rsturbo519;6657323]As long as they are 2.0L focus ones they will work

Rsturbo519

[QUOTE=crazycage;6657483]Cheers for reply. It just says on the eBay add " Ford Focus mk1 mtx75 2001 - 2005 1500223 "