Discussion
After driving my car on the motorway at a steady 70mph my rev counter was reading 2700 ish rpm,do you think this gearbox is more suited to the 2000cc engine it was used for.Im sure at 70mph my engine could cope with the rpm being at least 500rpm lower.Did TVR change the gear ratios for the larger V8 engine..It feels that it eather needs another gear or fith gear being a higher ratio..2700rpm seems to be far to high for the v8 engine..
Edited by SILICONEKID340HP on Wednesday 13th July 21:29
SILICONEKID340HP said:
If you changed the diff would it not change all the gear ratios causing it to accelerate slower.
Yes it would, or faster, depending on the ratio, but that's not what you're after (I think). Actually you make a good point, in terms of economical high speed cruising 
As I said before, I think the T5 ratios are quite good, shame you can't fit a sixth gear, bit like an overdrive 
Ant. said:
The T5 is also known to sap engine power, hence all the later chimpo's and griffs didnt make the power that TVR quoted.
I will give you a tenner to take it off your hands.........
interesting..... not sure what i "chimpo" is?? is it similar to a "griffington"?I will give you a tenner to take it off your hands.........
do you need some wax for your chest wig? :-D
Ant. said:
The T5 is also known to sap engine power, hence all the later chimpo's and griffs didnt make the power that TVR quoted.
I will give you a tenner to take it off your hands.........
No, ant is right - as well as having a much better gearbox, early Griffs were also developed to run on a special fuel formulation which doubled as a pheromone stimulant, which is the root of the legendary performance of early Griffs and their drivers both on road and "landing strip"I will give you a tenner to take it off your hands.........
Here's the proof, captured on secret footage of a griff development mule, cleverly disguised pre-launch as a morgan
http://www.youtube.com/watch?v=Q8kYsiReNik
When up sizing rim sizes there are tyre calculators to get very close to satandard setup so that is total rubbish...The gearbox is not designed for the V8 engine..I wonder how the Tremec gearbox would compare..My mates corvette ls1 sits around 2000rpm at 70mph thats probably why he got 33mpg from Nottingham to Cornwall and back..
Edited by SILICONEKID340HP on Wednesday 13th July 22:49
darkcat said:
someone MUST be up for fitting an overdrive!
Yes me Darkcat!I've been pondering an overdrive for a while now.
Figured a before the diff format rather than a back of the box setup, there seems enough room between the chassis rails to me, just some bracketry & a shorter prop required.
Did a rear mount before the diff OD install on a 1927 Bentley using a "J" type and it worked great.
My thoughts would be to have OD operating on 3rd, 4th & 5th giving two advantages.
1) Using 3rd direct, switching to 3rd + OD, making the Chim an even more rapid A/B road car
2) Motorway 5th plus OD, knocking 500 rpm off with corresponding fuel economy benefits
OD switching from the redundant Vauxhall rear wash wipe keeps everything looking standard and ergonomics spot on for snappy OD engaging & disengaging.
The only issue I see is torque.
I have seen uprated "J" types cope with 250 ft lbs on a fast road Healey 3000, 300 torques from a Tiv may be a twist too far especially in my 3rd gear option above.
However if it could cope, I see an old school overdrive could make the car faster on cross country blasts while delivering better fuel economy on the motorway.
It will also shift a bit of weight rearwards which is no bad thing and has to be a way better path to six forward ratios than the mahoosive heavyweight T56 that would be a nightmare to fit.
SILICONEKID340HP said:
When up sizing rim sizes there are tyre calculators to get very close to satandard setup so that is total rubbish...The gearbox is not designed for the V8 engine..I wonder how the Tremec gearbox would compare..My mates corvette ls1 sits around 2000rpm at 70mph thats probably why he got 33mpg from Nottingham to Cornwall and back..
Tremec build the T5, Borg Warner sold the design and manufacturing rights.The Tremec TKO500 is to all intents and purposes the same box but much beefier and as a result 30kgs heavier also with different ratios, the 600 being rated to 600bhp.
The T-56 with 6 gears is the Corvette box and is too long to fit easily in a TVR.
http://www.ttcautomotive.com/English/products/trem...
SILICONEKID340HP said:
When up sizing rim sizes there are tyre calculators to get very close to satandard setup so that is total rubbish...The gearbox is not designed for the V8 engine..I wonder how the Tremec gearbox would compare..My mates corvette ls1 sits around 2000rpm at 70mph thats probably why he got 33mpg from Nottingham to Cornwall and back..
Daz, the T5 was developed for the mid eighties Mustang.Edited by SILICONEKID340HP on Wednesday 13th July 22:49
Ford used it on the Cossie because it was the only 5 speed that could cope that they has access to.
The T5 is an excellent box & the ratios are fine, if you want to keep it and lower your revs you either need to change your diff and lose acceleration or get another ratio in there somehow.
The only practical way to get another ratio is to fit an overdrive.
Did you have overdrive on your MGB mate?
If you did, you (and anyone else that has driven a car with overdrive) will know it is a forgotten marvel.
SILICONEKID340HP said:
Just can`t see it needs to be doing 2700rpm at 70mpg..If it dropped around 400 to 500 rpm at that speed the fuel economy would be far better..My girl friends 1600cc Volvo C30 Petrol is not doing much more than that.
I see above you say "2700rpm at 70mpg".That MegaSkirt system gives excellent economy Daz
I assume you got your MPH mixed up with your MPG
My two penneth on overdrives, I've owned a number of MG's, and still have a '74 factory BGT V8, which has OD on fourth only. The first few factory V8's had OD on 3rd and 4th, but this went to 4th only very early in production as the massive torque of the V8 (190 ftlb's from the 3.5 RV8 )was consistently breaking the OD on third gear. Many many years ago I drove a Cobra replica demonstrator (under development)which had a 5.7 litre Chevvy engine mated to a toyota 6 speed box, with a much too low final drive ratio. I mention this only because driving it was like trying to conduct an orchestra with the gearstick, and demonstrated that when you have serious torque/power you can have too many gears. IMO a higher 5th or an overdrive 6th is all the Chim/Griff would need in order to maintain awesome performance through the gears (at speeds under 100 leptons). And give better mpg when cruising. Whatever that is. Griff girls will probably throw some light on that one 
)was consistently breaking the OD on third gear. Many many years ago I drove a Cobra replica demonstrator (under development)which had a 5.7 litre Chevvy engine mated to a toyota 6 speed box, with a much too low final drive ratio. I mention this only because driving it was like trying to conduct an orchestra with the gearstick, and demonstrated that when you have serious torque/power you can have too many gears. IMO a higher 5th or an overdrive 6th is all the Chim/Griff would need in order to maintain awesome performance through the gears (at speeds under 100 leptons). And give better mpg when cruising. Whatever that is. Griff girls will probably throw some light on that one Chimpafrolic said:
Daz, the T5 was developed for the mid eighties Mustang.
Ford used it on the Cossie because it was the only 5 speed that could cope that they has access to.
The T5 is an excellent box & the ratios are fine, if you want to keep it and lower your revs you either need to change your diff and lose acceleration or get another ratio in there somehow.
The only practical way to get another ratio is to fit an overdrive.
Did you have overdrive on your MGB mate?
If you did, you (and anyone else that has driven a car with overdrive) will know it is a forgotten marvel.
Yes my MG did have overdrive but remember they only have 4 gears ,overdrive on third and fourth but there is not much difference in third with overdrive and fourth without over drive so third with over drive is a waste of time..The better gearbox for the MGB is Ford Sierra type 9 .Ford used it on the Cossie because it was the only 5 speed that could cope that they has access to.
The T5 is an excellent box & the ratios are fine, if you want to keep it and lower your revs you either need to change your diff and lose acceleration or get another ratio in there somehow.
The only practical way to get another ratio is to fit an overdrive.
Did you have overdrive on your MGB mate?
If you did, you (and anyone else that has driven a car with overdrive) will know it is a forgotten marvel.
All im trying to say is 2700rpm at 70mph is ridiculous for a 340 bhp 5l V8.
Edited by SILICONEKID340HP on Wednesday 13th July 23:37
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