ok, gonna probably take my car to bernie soon for some bits n bobs (he doesnt know it yet tho... lol) and i'm contemplating going for a taller 5th gear whlst i'm there (if the box is apart makes sense to do it. more info here http://www.maddoldbugger.supanet.com/gearbox.html )

now what do we think pros and cons wise...
now obviously ll have a higher POTENTIAL top speed (which the car doesnt have enuf power to pull) but then currently i can bang the car off the limiter in 5th without any hassle, so its hgot more in it, but then that could be becase of the 3.9 diff

now, i can see the benefits being better economy on motorway and less noise on motorway (as lets be honest where else do we really use 5th apart from cruising) but will it have a counteractive effect with needing more load to keep it rolling?

what do we think... good idea or bad idea? i quite likethe idea of being able to do 100mph comfortably wth not much engine nosie and closed loop fuelin still on

 

C'mon guys, i know a lot of ya are clued up about gearing

 

i've got a spare grannada mt75 diesel box if you want it

 

Its not a case of shorter or longer its a case of getting it right for what you want to do.

 

jim i think tony and dojj only did that mod for top speed rns i rember tony saying he cant use 5th doing 70 the ravs drop to low

 

rod, what i want to do well its a road car, and i fancy getting sensible economy at about 100mph ish (as if i'm honest thats the speed i normally drive on motorway )
but then i also fancy a higher top speed. im plannin on bumping up the power a bit more fairly soon and im currently stuck with a 133mph top speed on the limiter

i'm definately moving froma 3.9 diff toa 3.62 for starters, but then this taller gear has always interested me. i just dont want to do somethng without havign all the facts.

here's a graph a found of a standard(ish) 24v cossie RR printout



i know its not all that clear, but you get a general idea of how the power's delivered, ie quite a lot of torque all through the rev range. ps the peak torque on that graph is 217lb/ft if you want a point of reference

 

jim why not fit a T5 box ???? they got taller gears and there very strong too

 

ginge, spot the fatal flaw in your plan

 

worst graph ever

t5 wont fit

 

bernie's working on a conversion plate, but its quite far off completion i think. anyway T5s doing really suite nasp cars so i've heard

 

Right the 5th gear mod was used as you could not get a 3.3 front diff for 4x4. Jim You are 2wd just use some tall cossie diff.

Regarding T5 convertion plates, I can get them now, it comes with plate bolts and spigot extension.

All you need is a Type 9 bell housing and a T5.

 

that still leaves me with a 141mph top speed banging the mofo off the limiter. the 0.75 will give me 156 (providing the car can pull it)

 

or just buy a cossie engine aswell and all problems solved

 

what, one like yours?

 

Jim with the .75 you will make 150mph your engine must be in the 210 to 220 bhp range. So I would got for a .75 diff

 

you mean .75 5th?

johnny, my engine is in that power range at the moment, and im planning on upping that significantly this year.

 

jim my cossie is fine, its just cause i aont spent the money on it the car needs !!!!

needs a basic rebuild but i got other things to purchase first,,,,,,,,,,,,,,,,, food being one of em

 

 

Ginge. Do you see the slight flaw of your statement

 

jim the cossie is fine and runs fine, it needs the alt changing and would benifit from a rebuild but the car works fine


its abit like having rust on the arches and saying it needs sorting, dont make the car have a mot failing rust hole


the total cost of the rebuild ( as the little ends rattle, car still runs though note) is not gonna excess the money spent on your car

also when its done the cars gonna be fine and cost less in total than your car but still worth more


hence why im no stressing as i can break the cossie and get me money back i put into it

 

rich not bothering with a rebuold till i know for sure i wanna keep the car as at the moment i might break it and do somink else


i dont know a cossie out there that dont need any work doin to it, changing the little ends aint the end of the world, just require me to want to do it

 

i know its not related to your car at all jim but having a diesel g-box in my cab means that on a low comp engine that makes power/boosts quite high up the revs 5th gear is absolute shite for anything below about 110Mph

 

shouldnt be a problem with my driving style

 

i guess its gonna be slightly different in your car though as the power is more progressive and you actually have some power below 3.5k