What is usually the cause of gearbox breakages. Isn't it usually the week selector forks that are the problem. If the gearbox is treated with a little respect is it good for 400-450bhp.
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Gearbox Failure
- Thread starter stevepudney
- Start date
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Mr Overboooost
Guest
i've had about 15 gearbox's rebuilt and have never had one with buggered gear selector forks.
its usually 1st,2nd or 3rd that seems to go.
as for handling that sort of power you will be better off getting a quaife/nismo or jun gearbox
cheers
gary
its usually 1st,2nd or 3rd that seems to go.
as for handling that sort of power you will be better off getting a quaife/nismo or jun gearbox
cheers
gary
skiddusmarkus
Active Member
My 3/4 slector was snapped in half when the box was opened up.They are cast alloy so I replaced it with one of Ivan's.The other 2 looked fine but I replaced them anyway.
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Toady
Guest
Wat are ivans made of then?
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Odin
Guest
cardboardToady said:Wat are ivans made of then?
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caz
Guest
I heard it was hardened rhino jizz :shock:
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big boy
Guest
ice
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Little Erve
Guest
Chrome Moly.
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Anonymous
Guest
I think SE have a couple of 400bhp cars running the standard box. Give 'um a bell and see what they say.
Dunc
Dunc
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Edd
Guest
I think the main weakness is the selector forks in the gearbox, and the fact the boxes are 10-14 years old and have mist likely suffered long term abuse in Japan and in the UK with launching, dodgy gearchanges and also harsh clutches.
When at hiteq 3 lots of 3rd gear side by side, standard, quaiffe and PAR.
I won't post publically but one of the 3 is by far the superior gear. The std gears the teeth are very thin and i can see that with 400-500bhp you will strip the gears (like Lex did on his standard 5th gear).
You need to either harden the std gears or go for uprated gear set otehrwise the power will destroy them. Like all thing it depends how good condition the gearset is in the first place.
Another thing is that with 400-500bhp you will need a twin plate clutch to hold the power, and this puts a shed load of strain on the gearbox, breaking it.
If your building a 450bhp car it's unfortunately very hard to cut corners without sacrificing reliabilty. To hold that power you need a good clutch, and a good gearbox, if you run a std box you might be lucky, but it won't last long if your going to drag and track the car.
When at hiteq 3 lots of 3rd gear side by side, standard, quaiffe and PAR.
I won't post publically but one of the 3 is by far the superior gear. The std gears the teeth are very thin and i can see that with 400-500bhp you will strip the gears (like Lex did on his standard 5th gear).
You need to either harden the std gears or go for uprated gear set otehrwise the power will destroy them. Like all thing it depends how good condition the gearset is in the first place.
Another thing is that with 400-500bhp you will need a twin plate clutch to hold the power, and this puts a shed load of strain on the gearbox, breaking it.
If your building a 450bhp car it's unfortunately very hard to cut corners without sacrificing reliabilty. To hold that power you need a good clutch, and a good gearbox, if you run a std box you might be lucky, but it won't last long if your going to drag and track the car.
This is what happened to my gearbox when it went
I think one of the selector forks must of broken (2 of them were snapped) and that piece of the selector fork must of gone round the box and chewed everything else up.
All the parts in the blue tray came out the box :shock: there was bits of selector forks, syncro's, and even pieces of gears.
I think one of the selector forks must of broken (2 of them were snapped) and that piece of the selector fork must of gone round the box and chewed everything else up.
All the parts in the blue tray came out the box :shock: there was bits of selector forks, syncro's, and even pieces of gears.
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Anonymous
Guest
Hi Guys,
Gearboxes have weaknesses in different areas, the forks can be a weakness if you shift quickly, the teeth on each gear can be a weakness if it's subjected to more toque than it's designed for (and age of the gear comes into the equation).
So, if you do granny gear shifts you will probably never break a selector fork but if you have increased power or a savage clutch then you could break 1st gear (through launching), second gear (through fast snappy gear shifts with a strong non slip clutch or even through increased power, 3rd gear through increased power, 4th gear through increased power. Don't forget that abuse and fatigue of the gearset can crack a tooth on any gear and then it could break off when you are driving sedately, thinking to yourself 'but i wasn't fanging it and it broke' (but you don't think about the abuse it received before hand.
Then again, you could always break the gearcase. Getting into huge power figures is going to show up some weaknesses of any car which you would need to fix up before or after something breaks.
Personally, i have put together and used a PAR 1/2 dog gearset (fantasitc lighning fast gear changes from 1st to 2nd) and also a PAR uprated synchro gearset (currently in use) and am happy with both of them. I swithced from the 1/2 dog to the uprated synchro as its much easier to drive as a every day car and it can still handle the 360hp at all 4 wheels.
The 3rd/4th selector forks were made of cast chromoly. I am using them in both my 1/2 dog complete gearbox and my uprated synchro gearbox, knowing now that the 3rd/4th selector fork will not break when i shift quickly gives me piece of mind.
Ivan
PS. is carboard or hardened rhino jizz a better material to use? :lol:
Gearboxes have weaknesses in different areas, the forks can be a weakness if you shift quickly, the teeth on each gear can be a weakness if it's subjected to more toque than it's designed for (and age of the gear comes into the equation).
So, if you do granny gear shifts you will probably never break a selector fork but if you have increased power or a savage clutch then you could break 1st gear (through launching), second gear (through fast snappy gear shifts with a strong non slip clutch or even through increased power, 3rd gear through increased power, 4th gear through increased power. Don't forget that abuse and fatigue of the gearset can crack a tooth on any gear and then it could break off when you are driving sedately, thinking to yourself 'but i wasn't fanging it and it broke' (but you don't think about the abuse it received before hand.
Then again, you could always break the gearcase. Getting into huge power figures is going to show up some weaknesses of any car which you would need to fix up before or after something breaks.
Personally, i have put together and used a PAR 1/2 dog gearset (fantasitc lighning fast gear changes from 1st to 2nd) and also a PAR uprated synchro gearset (currently in use) and am happy with both of them. I swithced from the 1/2 dog to the uprated synchro as its much easier to drive as a every day car and it can still handle the 360hp at all 4 wheels.
The 3rd/4th selector forks were made of cast chromoly. I am using them in both my 1/2 dog complete gearbox and my uprated synchro gearbox, knowing now that the 3rd/4th selector fork will not break when i shift quickly gives me piece of mind.
Ivan
PS. is carboard or hardened rhino jizz a better material to use? :lol: