turbodisplay
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| posted on 28/1/08 at 09:45 PM |
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Has anyone got stronger gears made up?
I`m using a MT75 4x4 gearbox in my car, mated to a ford cosworth V6 twin turbo engine. I have a spare gearbox for if or when it goes bang.
I was wondering if it would be possible to get stronger gears made up, I know gearsets exist but they are expensive.
I know of an enginerring company that can make up blank steel to be sent off to a gear cutters, then get heat treated.
Has anyone got gears made up?
Thanks
Darren
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Johnmor
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| posted on 28/1/08 at 10:47 PM |
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Gearbox
Quaife make gearboxes to suit requirements and can rebuild your existing MT75.
But easest option is to find a T5 box from a cosworth Sierra, even a reconditioned one would be cheaper than a Quaife prepared box. Good for around
300hp easy, used by Cobra type kits for large V8 engines so it can take the torque.
Try ebay
http://cgi.ebay
.co.uk/ford-cosworth-T5-gearbox_W0QQitemZ200195715808QQihZ010QQcategoryZ21654QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
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turbodisplay
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 posted on 28/1/08 at 11:03 PM |
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Probem is the 4x4 bit. I have got a skyline box, that is too big to fit, plus has the wrong fitmentadapter plate will take up more space.
Keeping it for another project 
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jono_misfit
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| posted on 29/1/08 at 12:32 AM |
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The escort cosworth guys seem to go for skyline boxes for when they go for big power as MT75's die rappidly (3rd gear?).
Else wise they seem to got for straight cut rally sets, which as you've said arent cheap.
Personally i'd expect a single or few sets of custom gears to be far more expensive than anything thats off the shelf. Even if friendly people
are doing stuff on mates rates.
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RazMan
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| posted on 29/1/08 at 10:56 AM |
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I thought that MT75s were good for around 400bhp or is that just the MTX-75 that Noble use?
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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Jon Ison
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| posted on 29/1/08 at 11:23 AM |
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It will/would be bearings that let go before gears in most cases, your car will be so light wheelspin will protect the gearbox anyway ?
I would continue the build and look to solve the problem if it does show itself rather than solve one that maybe is'nt there ?
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NS Dev
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| posted on 29/1/08 at 01:37 PM |
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depends on a huge number of things.
A friend of mine was in the position of breaking an MT75 at every race meeting. he carried at least 3 spares at all times, all recon and with uprated
bearings but they all stripped third gear, every time.
This was behind a v6 (cosworth BOA 24v 3.7 litre twin turbo admittedly!! )
He fitted an "uprated" MT 75 box and blew that up as well, then (I think) an R&D dog engaged MT75, and broke that.
He ended up using an ex ford motorsport 7 speed box, at £27,000 (twenty-seven thousand) secondhand, and also broke that 
It basically finished the car, as regs meant (IIRC) that he had to keep a gearbox of "ford origins" and there were none with 4x4 that
would take the 700hp and 700lbft of torque appplied through 4 big slicks to tarmac at a standing start.
Back to your lesser issue, mt75 4x4 boxes tend to last ok with 400hp, as long as driven sympathetically, not drag raced, and most of all, with a nice
boost curve that doesn't whack 3rd gear too hard, basically get it mapped progressively not on the cheap and you'll be fine.
I take it you are using a hybrid turbo not T04? Again, avoid the T04 if you want to retain your gearbox in one piece, they are too laggy, and to be
honest, unless you are drag racing, they make a 4x4 drive pretty poorly as well.
[Edited on 29/1/08 by NS Dev]
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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NS Dev
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| posted on 29/1/08 at 01:47 PM |
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PS, in "literal" answer to the question, yes, I have had stronger gears "made up", and its not a five minute job.
First off, you can't just stick them in, ford are no fools and you have to make them physically bigger to get them in, which means getting rid
of something else! We (a friend in autograss) got a two speed, wider geared cluster made up for the Vauxhall F20 FWD gearbox, all other gears removed,
just new input shaft and two layshaft gears, and this was £450, at little profit for those involved (if any) and made locally (coventry) at an
automotive gear manufacturer.
A lot of cost went into designing the gears (and designing and cutting synchro stuff is a skill not posessed by industrial gear cutters) actually
employing a designer on contract to design the gears and do the drawings to the appropriate standards. The costs of this were then split over sales of
future gear kits.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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jono_misfit
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| posted on 29/1/08 at 03:44 PM |
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quote:
Originally posted by RazMan
I thought that MT75s were good for around 400bhp or is that just the MTX-75 that Noble use?
MTX-75 is a 2wd box, but transmission isnt as strained on 2wd as gearbox torque tends to be more traction limited.
If you really fancy splashing out you could buy an Xtrac MT75 replacement that ford used in the Escort WRC cars. Im sure by 1997 / 1998 the torque
would have been up over 400Nm so may be stronger than the slightly older 7 speeds.
If your looking for good advice id go sign up at passionford.com and ask on there. Theres plenty of them use their cars on drag strips.
As NSdev says gear design isnt easy and high strenght gears for small spacial constraints are worse. Ask Xtrac, hewland, or ricardo.
[Edited on 29/1/08 by jono_misfit]
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turbodisplay
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| posted on 29/1/08 at 03:55 PM |
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Thanks for the replies.
I`m using a twin turbo,sequential, first turbo is a skyline, secend is a t3.
Should be quite smooth transision so hopefully not break the box then.
I`m aiming for 350 - 400hp so i may not have a problem
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turbodisplay
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| posted on 30/1/08 at 04:46 PM |
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I used to use the passionford forums but got fed up of legit posts getting deleted, and stopped using it when they were making taseless jokes about
the london bombings, my girlfriend was meters from the bus bomb so it was actually quite personal.
ANYWAY
Looking at uprating the bearings probally would be a good option. I take it the bearings in the gearbox are standard deep grove types?
Probally changing the bearings to tapered will increase the thrust load capability.
Ns DEV: was the gears helical, because I was thinking of straight cut gears for 1,2,3. Or maybee just the week third gear.
Noisy until 4 th but with a twin turbo engine won`t be a problem.
Or i could learn not to use third gear!
Thanks
Darren
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NS Dev
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| posted on 30/1/08 at 06:26 PM |
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quote:
Originally posted by jono_misfit
quote:
Originally posted by RazMan
I thought that MT75s were good for around 400bhp or is that just the MTX-75 that Noble use?
MTX-75 is a 2wd box, but transmission isnt as strained on 2wd as gearbox torque tends to be more traction limited.
If you really fancy splashing out you could buy an Xtrac MT75 replacement that ford used in the Escort WRC cars. Im sure by 1997 / 1998 the torque
would have been up over 400Nm so may be stronger than the slightly older 7 speeds.
If your looking for good advice id go sign up at passionford.com and ask on there. Theres plenty of them use their cars on drag strips.
As NSdev says gear design isnt easy and high strenght gears for small spacial constraints are worse. Ask Xtrac, hewland, or ricardo.
[Edited on 29/1/08 by jono_misfit]
Heh heh that escy WRC box is the one I referred to................splashing out........... 27 grand secondhand is a bit more than that in my book
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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NS Dev
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| posted on 30/1/08 at 06:32 PM |
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quote:
Originally posted by turbodisplay
I used to use the passionford forums but got fed up of legit posts getting deleted, and stopped using it when they were making taseless jokes about
the london bombings, my girlfriend was meters from the bus bomb so it was actually quite personal.
ANYWAY
Looking at uprating the bearings probally would be a good option. I take it the bearings in the gearbox are standard deep grove types?
Probally changing the bearings to tapered will increase the thrust load capability.
Ns DEV: was the gears helical, because I was thinking of straight cut gears for 1,2,3. Or maybee just the week third gear.
Noisy until 4 th but with a twin turbo engine won`t be a problem.
Or i could learn not to use third gear!
Thanks
Darren
we did three versions in the end, one wider gears semi-helical synchro change, one wider gears straight cut synchro change and one straight cut wide
gears dog engaged.
Plus of dog change is its easier to make and stronger, minus is it need a specialist to design one that actually works and quaife etc certainly
won't be about to tell you about the critical face angles etc(though they were very keen to hear what ratios we wanted....can't imagine
why!! ). Plus of synchro is more people can design them but less can cut them!
Helical or not the teeth stilll rip off in an MT75, needs bigger diameter gears but then the whole box gets bigger.............
[Edited on 30/1/08 by NS Dev]
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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Syd Bridge
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| posted on 30/1/08 at 07:53 PM |
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If you're serious about gearboxes for high power 4x4's, then have a look at what they use in the USA behind the V8's off-road.
You'll break your engine before you break the 'box, but they're not light by any means!
Cheers,
Syd.
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turbodisplay
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| posted on 30/1/08 at 09:00 PM |
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I`m thinking that my best bet is to keep this car limited to 400hp, if i want more power build another car with lexus v8 ( 1ufze) twin tubo engine,
with a skyline gearbox. OR modify the chassis to accept the skyline gearbox i have.
Darren
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