Breaker
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| posted on 16/5/09 at 06:06 PM |
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"HD" gearbox ?
I'm planning on building a kitcar with a recent Duratec engine + MT75 gearbox.
Some time ago someone mentioned you should need a "HD" type of gearbox. I tried to find the post with the search, but I can't find
it back. What is this "HD" gearbox or are there more RWD gearboxes that can withstand the power of a throttle bodied Duratec ? (perhaps
Mazda MX-5 gearbox ?)
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cd.thomson
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| posted on 16/5/09 at 06:15 PM |
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where is flak monkey when you need him  .
Try sending him a U2U, he can definitely help.
It is the straight four duratec youre talking about right? I'm not sure youll necessarily definitely have to fit an aftermarket box..
Craig
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fesycresy
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| posted on 16/5/09 at 06:29 PM |
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HD = Heavy Duty
Not all HD boxes are the same mind. Have a look on BGH or Quaife's site.
I'm sure the bolt pattern is wrong for an MT75, you need a Type 9's and a new bellhousing.
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The sooner you fall behind, the more time you'll have to catch up.
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rusty nuts
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| posted on 16/5/09 at 07:24 PM |
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Rally Design amongst others? sell the bell housing to connect to a type 9 box to a Duratech engine . BGH geartech sell uprated type 9 boxes
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flak monkey
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| posted on 16/5/09 at 08:35 PM |
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You'll struggle mating an MT75 to a duratec as the bolt pattern is wrong and the bellhousing is integral on the MT75.
You will need a type 9 box in good condition at the very least. I have decided to go for a heavy duty one as I dont want to be changing the box every
year. Most installs using the std type 9 rarely see a genuine 200bhp. Also bear in mind that you really want a longer first gear ratio as well and
opting for a HD gear kit is the ideal way to do it.
Bellhousings for the type 9 are about £200+vat from rally design, Burton Power, SBDev and Raceline to name but a few.
The MX5 box will fit as well, BUT it needs to be from the new shape MX5 as the old shape is not compatable. Also they are quite a large box, much
bigger than a T9
David
[Edited on 16/5/09 by flak monkey]
Sera
http://www.motosera.com
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ss1turbo
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| posted on 16/5/09 at 09:03 PM |
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There is the "MT75c" gearbox...basically someone's made a non-integrated version of the MT75 so you can have the stronger gear set
of an MT75 with the adaptability of a non-integrated bellhousing. Very nice looking piece of kit, but not cheap...
Long live RWD...
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Breaker
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| posted on 16/5/09 at 09:41 PM |
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quote:
Originally posted by flak monkey
You'll struggle mating an MT75 to a duratec as the bolt pattern is wrong and the bellhousing is integral on the MT75.
You will need a type 9 box in good condition at the very least. I have decided to go for a heavy duty one as I dont want to be changing the box every
year. Most installs using the std type 9 rarely see a genuine 200bhp. Also bear in mind that you really want a longer first gear ratio as well and
opting for a HD gear kit is the ideal way to do it.
Bellhousings for the type 9 are about £200+vat from rally design, Burton Power, SBDev and Raceline to name but a few.
The MX5 box will fit as well, BUT it needs to be from the new shape MX5 as the old shape is not compatable. Also they are quite a large box, much
bigger than a T9
So to avoid replacing the gearbox every year, I should look for a T9, throw out the gears and put in a (fast road) gear kit, stick a new bellhousing
to it and done !
Sorry for my ignorance, but why should you need a longer first gear ?
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ss1turbo
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| posted on 16/5/09 at 09:49 PM |
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If you've ever driven a car with standard type 9 ratios, then you know why....
Long live RWD...
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MikeRJ
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| posted on 16/5/09 at 11:39 PM |
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quote:
Originally posted by Breaker
Sorry for my ignorance, but why should you need a longer first gear ?
1st gear on a standard type 9 is far too short to be of use on a lightweight car.
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bimbleuk
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| posted on 17/5/09 at 04:55 AM |
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I believe the HD just refers to the size of the bearings in the box. I'm sure someone will confirm/correct me on this so a HD box from Ford
would have been fitted to a V6 or diesel?
The BGH gearboxes have uprated bearings and improved oiling. optionally they uprate the selector mechanism and synchro/baulk rings. I don't
think they fit super strong gears when they uprate them as isn't 4th part of the shaft so can't be changed easily/cheaply?
For example the Tran-X uprated box with dog engagement and strengthed gear material is £2650+ VAT !!
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snapper
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| posted on 17/5/09 at 07:21 AM |
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1st gear on an MT75 ( 3.9)is worse than the Type 9 (3.6) Type 9 V6 box is better at 3.3 (3.6 for MT75)
BGH now do a heavy duty box based on the V6 gearset with a choice of 1st gears from 2.8 through to 2.2 ish
I know you will have more revs with a Duratec but the much longer 1st is the way to go with the wheel, tyre, diff ratio, first gear ratio sorted to
give about 45 in first and over 60 in second.
This will transform the driving experience.
Usualy with the type 9/MT75 you are juggling a wide ratio box so if you get the lower gears sorted your 4th gear speed is very high and 5th stupid.
You can also get a lower 5th gear about 0.9
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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flak monkey
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| posted on 17/5/09 at 08:10 AM |
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quote:
Originally posted by bimbleuk
I believe the HD just refers to the size of the bearings in the box. I'm sure someone will confirm/correct me on this so a HD box from Ford
would have been fitted to a V6 or diesel?
The BGH gearboxes have uprated bearings and improved oiling. optionally they uprate the selector mechanism and synchro/baulk rings. I don't
think they fit super strong gears when they uprate them as isn't 4th part of the shaft so can't be changed easily/cheaply?
For example the Tran-X uprated box with dog engagement and strengthed gear material is £2650+ VAT !!
You are correct, the weak point in the std T9 is the laygear needle roller bearings. The HD gearsets do away with this and replace them with a proper
roller bearing, this requires machining of the lay cluster and the layshaft itself. Like you say the BGH boxes als have improved oiling, which is
essentially some slots in the main shaft gears.
David
Sera
http://www.motosera.com
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