Gearbox Questions - rebuild or c/r box
Discussion
My synchro in my gearbox is starting to wear and I've been quoted around £500 for a rebuild plus fitting/removal.
However, if I were to change instead to the close ratio box what sort of cost would I be looking at? Also what difference does it actually make and would I also need to change the diff ratio at the same time?
However, if I were to change instead to the close ratio box what sort of cost would I be looking at? Also what difference does it actually make and would I also need to change the diff ratio at the same time?
Quinny said:
Not an expert on ratios and all that, but I would imagine that a CR box will give even better acceleration, especially in the midrange....
But it's not like any speed 6 car is lacking in that area in the first place
I do wonder if it would lead to having to make more gear changes, because you're in each gear for less time...
I had a ride in a Sagaris with CR, and a non CR car at Oulton... And the CR driver was definitely using a lot more revs than the non CR car, but the CR car didn't seem to be going any quicker....
Not much help I know..... But I suspect a CR box is much more useful on the track than on the road, so I suppose it depends on driving style, and what the car is used for
Hey ZippieBut it's not like any speed 6 car is lacking in that area in the first place
I do wonder if it would lead to having to make more gear changes, because you're in each gear for less time...
I had a ride in a Sagaris with CR, and a non CR car at Oulton... And the CR driver was definitely using a lot more revs than the non CR car, but the CR car didn't seem to be going any quicker....
Not much help I know..... But I suspect a CR box is much more useful on the track than on the road, so I suppose it depends on driving style, and what the car is used for
I had my Sag gearbox rebuilt very recently and replaced by a C/R + appropriate diff. I'll look up the cost tonight and send you the details via email. It wasn't cheap but definitely worth it.
Alex
Cost aside, I think the CR box and 3.9 diff ratio would be the ideal setup on a Speed 6 engined car. This pic shows std on the left and CR + 3.9 on the right...
The only set back would be higher revs on a motorway etc. But offset against that you have a longer 1st and 2nd which would give more usable power (less wheel spin), then lower and closer top 3 gears which would:-
a) give better acceleration due to the engine having more leverage due to the lower gearing, and
b) the revs would not drop so far between changes, which sould suit the top end nature of the engines delivery.
My std car feels like the gears are too long for road use at least - you'd be doing 30-40mph over any speed limit before you even got out of 3rd gear. My plan is actually to change the diff first to 3.9 and see if the std box feels too low in 1st and 2nd. I'll then make the decision whether to just get my 5th gear syncro done, of wait and change to a CR rebuild when I can afford it.
I'd also be interested to hear what others have paid to have this done?
The only set back would be higher revs on a motorway etc. But offset against that you have a longer 1st and 2nd which would give more usable power (less wheel spin), then lower and closer top 3 gears which would:-
a) give better acceleration due to the engine having more leverage due to the lower gearing, and
b) the revs would not drop so far between changes, which sould suit the top end nature of the engines delivery.
My std car feels like the gears are too long for road use at least - you'd be doing 30-40mph over any speed limit before you even got out of 3rd gear. My plan is actually to change the diff first to 3.9 and see if the std box feels too low in 1st and 2nd. I'll then make the decision whether to just get my 5th gear syncro done, of wait and change to a CR rebuild when I can afford it.
I'd also be interested to hear what others have paid to have this done?
Yeah, I have a similar thing with my gearbox - just on 5th gear. Have been quoted £150-£200 to fix it plus another £200 for removing/refitting. I'm just thinking if I'm paying the labour charge whatever, then can I pay a bit more and change the ratios. But I wouldn't the CR box with my current diff. One thing leads to another...
RM75 said:
Cost aside, I think the CR box and 3.9 diff ratio would be the ideal setup on a Speed 6 engined car. This pic shows std on the left and CR + 3.9 on the right...
The only set back would be higher revs on a motorway etc. But offset against that you have a longer 1st and 2nd which would give more usable power (less wheel spin), then lower and closer top 3 gears which would:-
a) give better acceleration due to the engine having more leverage due to the lower gearing, and
b) the revs would not drop so far between changes, which sould suit the top end nature of the engines delivery.
My std car feels like the gears are too long for road use at least - you'd be doing 30-40mph over any speed limit before you even got out of 3rd gear. My plan is actually to change the diff first to 3.9 and see if the std box feels too low in 1st and 2nd. I'll then make the decision whether to just get my 5th gear syncro done, of wait and change to a CR rebuild when I can afford it.
I'd also be interested to hear what others have paid to have this done?
if you are going to upgrade the engine to a 4.5/4.3 you don't want the CR box/3.9 diff,The only set back would be higher revs on a motorway etc. But offset against that you have a longer 1st and 2nd which would give more usable power (less wheel spin), then lower and closer top 3 gears which would:-
a) give better acceleration due to the engine having more leverage due to the lower gearing, and
b) the revs would not drop so far between changes, which sould suit the top end nature of the engines delivery.
My std car feels like the gears are too long for road use at least - you'd be doing 30-40mph over any speed limit before you even got out of 3rd gear. My plan is actually to change the diff first to 3.9 and see if the std box feels too low in 1st and 2nd. I'll then make the decision whether to just get my 5th gear syncro done, of wait and change to a CR rebuild when I can afford it.
I'd also be interested to hear what others have paid to have this done?
If I keep the S6 engine in my Sag I would go for a 4.5 engine upgrade with standard box and 3.4diff, still each to their own.
all you are doing with changing the diff/box for a 3.9/CRbox is compensating for the lack of power/torque from the engine, I would prefer to get that from the engine.
And if Doms power claims are to be believed for the 4.5 you would be bouncing off the rev limiter half way up the Kemmel straight with the 3.9 option.
Edited by TVRMARK500 on Monday 18th October 18:22
[/quote]
if you are going to upgrade the engine to a 4.5/4.3 you don't want the CR box/3.9 diff,
If I keep the S6 engine in my Sag I would go for a 4.5 engine upgrade with standard box and 3.4diff, still each to their own.
all you are doing with changing the diff/box for a 3.9/CRbox is compensating for the lack of power/torque from the engine, I would prefer to get that from the engine.
Edited by TVRMARK500 on Monday 18th October 18:17
[/quote]
Why wouldn't you want the 3:91 C/R on a Power 4.5? People keep saying this and I took it up with John Reid at Oulton Park at the weekend as I have this box and diff set up and am going to go the 4.5 route in the new year. I would be interested to hear your response as compared to Reidy''s. Thanks.
RM75 said:
Cost aside, I think the CR box and 3.9 diff ratio would be the ideal setup on a Speed 6 engined car. This pic shows std on the left and CR + 3.9 on the right...
The only set back would be higher revs on a motorway etc. But offset against that you have a longer 1st and 2nd which would give more usable power (less wheel spin), then lower and closer top 3 gears which would:-
a) give better acceleration due to the engine having more leverage due to the lower gearing, and
b) the revs would not drop so far between changes, which sould suit the top end nature of the engines delivery.
My std car feels like the gears are too long for road use at least - you'd be doing 30-40mph over any speed limit before you even got out of 3rd gear. My plan is actually to change the diff first to 3.9 and see if the std box feels too low in 1st and 2nd. I'll then make the decision whether to just get my 5th gear syncro done, of wait and change to a CR rebuild when I can afford it.
I'd also be interested to hear what others have paid to have this done?
Paid circa £1,500 for the C/R box (exchange) and 3:91 diff, around March/April of this year, plus a couple of hundred quid to install. IMHO this is by far the biggest value for money, "bang for the buck" mod you can add to your car. The only set back would be higher revs on a motorway etc. But offset against that you have a longer 1st and 2nd which would give more usable power (less wheel spin), then lower and closer top 3 gears which would:-
a) give better acceleration due to the engine having more leverage due to the lower gearing, and
b) the revs would not drop so far between changes, which sould suit the top end nature of the engines delivery.
My std car feels like the gears are too long for road use at least - you'd be doing 30-40mph over any speed limit before you even got out of 3rd gear. My plan is actually to change the diff first to 3.9 and see if the std box feels too low in 1st and 2nd. I'll then make the decision whether to just get my 5th gear syncro done, of wait and change to a CR rebuild when I can afford it.
I'd also be interested to hear what others have paid to have this done?
If that's what you want go for it, for me that combination would be a nightmare, thou what works for me might not work for you,
What does Paul have in his monster Sag, I think it's a 3.08 because of all the power.
Saying that if you were to keep engine standard the Cr box and 3.7 diff is a great option, for me the 3.9 diff means i'm going into 5th even on the smaller UK tracks, which isn't good.
What does Paul have in his monster Sag, I think it's a 3.08 because of all the power.
Saying that if you were to keep engine standard the Cr box and 3.7 diff is a great option, for me the 3.9 diff means i'm going into 5th even on the smaller UK tracks, which isn't good.
Edited by TVRMARK500 on Wednesday 20th October 10:40
The fastest accelerating factory TVR is the Mk1 Tuscan S which on sticky tires did 0-60 in 3.8s (1st gear) and 0-100 in 8.08s (2nd gear) in the Autocar 0-100-0 test back in 2002/3(?).
The factory Mk1. Tuscan S runs the C/R gearbox (1st,2nd,3rd) with a 3.91 diff. The Sags run the same C/R box but with the 3.73 diff which is why they're not "quite" as quick against the clock.
The factory Mk1. Tuscan S runs the C/R gearbox (1st,2nd,3rd) with a 3.91 diff. The Sags run the same C/R box but with the 3.73 diff which is why they're not "quite" as quick against the clock.
dvs_dave said:
The factory Mk1. Tuscan S runs the C/R gearbox (1st,2nd,3rd) with a 3.91 diff. The Sags run the same C/R box but with the 3.73 diff which is why they're not "quite" as quick against the clock.
maybe not as quick from a standstill to 100mph but what about on tracks like Spa, take set up and how a car handles out of the equation.same car/same driver with a 4.5 speed six 450BHP or 600BHP LS7 Sag engine but with different diffs 3.4/3.9, which do you think would be quicker?
also which would be quicker at say V max or on the German autos,
swings and roundabouts,
it's finding the combo which suits you.
Edited by TVRMARK500 on Monday 18th October 20:50
YRRunner said:
Paid circa £1,500 for the C/R box (exchange) and 3:91 diff, around March/April of this year, plus a couple of hundred quid to install. IMHO this is by far the biggest value for money, "bang for the buck" mod you can add to your car.
Thanks - that's actually a bit less than I had thought. TVRMARK500 said:
If that's what you want go for it, for me that combination would be a nightmare, thou what works for me might not work for you,
What does Paul have in his monster Sag, I think it's a 3.08 because of all the power.
I'm pretty sure his has the 3.08 as you say, and he still struggles to contain the wheelspin launching it in 2nd gear! This was actually what got me thinking along the lines of the CR / longer 1st gear etc. I reckon whatever engine you have, ideally you'd want a first gear ratio that can take full throttle once you've got the car rolling, and 5th gear that suits whatever power the engine is putting out.What does Paul have in his monster Sag, I think it's a 3.08 because of all the power.
Changing to a 3.9 would limit my car to 155-170mph in 5th, but I don't know if it has the power to do more than that anyway? But for me, on the road I do my accelerating in 3rd and 4th gear which is where I think the 3.9 diff would help - and certainly make it "feel" faster which is what I'm after I think.
I do agree that a TVR Power 4.3/4.5 and/or track use is probably a different kettle of fish though.
TVRMARK500 said:
dvs_dave said:
The factory Mk1. Tuscan S runs the C/R gearbox (1st,2nd,3rd) with a 3.91 diff. The Sags run the same C/R box but with the 3.73 diff which is why they're not "quite" as quick against the clock.
maybe not as quick from a standstill to 100mph but what about on tracks like Spa, take set up and how a car handles out of the equation.same car/same driver with a 4.5 speed six 450BHP or 600BHP LS7 Sag engine but with different diffs 3.4/3.9, which do you think would be quicker?
also which would be quicker at say V max or on the German autos,
swings and roundabouts,
it's finding the combo which suits you.
Edited by TVRMARK500 on Monday 18th October 20:50
If you want the car for specific purposes, you gear it appropriately.dvs_dave said:
TVRMARK500 said:
dvs_dave said:
The factory Mk1. Tuscan S runs the C/R gearbox (1st,2nd,3rd) with a 3.91 diff. The Sags run the same C/R box but with the 3.73 diff.
maybe not as quick from a standstill to 100mph but what about on tracks like Spa, take set up and how a car handles out of the equation.same car/same driver with a 4.5 speed six 450BHP or 600BHP LS7 Sag engine but with different diffs 3.4/3.9, which do you think would be quicker?
also which would be quicker at say V max or on the German autos,
swings and roundabouts,
it's finding the combo which suits you.
Edited by TVRMARK500 on Monday 18th October 20:50
C'mon guys. How many miles do we actually do on tracks as compared to on real roads? For me, I would sooner have the standing or rolling acceleration than the top end speed (which in truth you are rarely gonna achieve on most tracks anyhow). True to say, it's horses for courses, but I'll take the look of disdain I see in the rear view, from a disgruntled 911 TT, GTR or R8 driver every time!
YRRunner said:
C'mon guys. How many miles do we actually do on tracks as compared to on real roads? For me, I would sooner have the standing or rolling acceleration than the top end speed (which in truth you are rarely gonna achieve on most tracks anyhow). True to say, it's horses for courses, but I'll take the look of disdain I see in the rear view, from a disgruntled 911 TT, GTR or R8 driver every time!
it's not just top speed thou, between 80 and 150mph the 3.9diff car wouldn't be as quick especially with the upgraded engine.Maybe we should hire Brunts for the day then we could test all the options including engines.
TVRMARK500 said:
YRRunner said:
C'mon guys. How many miles do we actually do on tracks as compared to on real roads? For me, I would sooner have the standing or rolling acceleration than the top end speed (which in truth you are rarely gonna achieve on most tracks anyhow). True to say, it's horses for courses, but I'll take the look of disdain I see in the rear view, from a disgruntled 911 TT, GTR or R8 driver every time!
it's not just top speed thou, between 80 and 150mph the 3.9diff car wouldn't be as quick especially with the upgraded engine.Maybe we should hire Brunts for the day then we could test all the options including engines.
Personally, I realise that IF I ever need to rebuild my S6 and go for the obvious 4.3/4.5 option or similar, then I will need to drop the diff ratio back to std 3.54 or whatever it is. This is more due to the increased torque/different torque curve of the larger capacity engine, the 3.6 S6 needs revving to make it move rapidly (which is of course fun).
Edited by Targarama on Tuesday 19th October 10:12
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