Discussion
I am pondering which ratio diff will work best in a number of configurations. I have a 3.31 and 3.54 4HU to hand.
3.54 will be on the track car but consider the 3.31.
I know in the olden days the 3000m came with both ratios. for a road application with a 180hp zetec running a close ratio type 9 from BGH geartech (the long 2.8 ratio'd version) what is the consensus on relative manners on road, performance top end etc
has anyone got a back to back experience of a 3.31 as opposed to 3.54 M and did the ratios in the gearbox change between the cars lessening any differences??
Any thoughts?
N.
3.54 will be on the track car but consider the 3.31.
I know in the olden days the 3000m came with both ratios. for a road application with a 180hp zetec running a close ratio type 9 from BGH geartech (the long 2.8 ratio'd version) what is the consensus on relative manners on road, performance top end etc
has anyone got a back to back experience of a 3.31 as opposed to 3.54 M and did the ratios in the gearbox change between the cars lessening any differences??
Any thoughts?
N.
Neil
Why use such a heavy diff when you only have a lightweight engine? Surely there is lighter more mdern alternative that will giv eyou the ratios that you require?
Most M's came with the 3.31:1 (post chassis 3919 - the Salisbury Diff), the TR6 diff used previously was 3.45:1.
davidy
Why use such a heavy diff when you only have a lightweight engine? Surely there is lighter more mdern alternative that will giv eyou the ratios that you require?
Most M's came with the 3.31:1 (post chassis 3919 - the Salisbury Diff), the TR6 diff used previously was 3.45:1.
davidy
DavidY said:
Neil
Why use such a heavy diff when you only have a lightweight engine? Surely there is lighter more mdern alternative that will giv eyou the ratios that you require?
Most M's came with the 3.31:1 (post chassis 3919 - the Salisbury Diff), the TR6 diff used previously was 3.45:1.
davidy
Call me old fashioned David. We have the Griff replica and I like the bullet proof strength of the rear end. It is also easier for me to replicate the mounting arrangements / bushes / bracketry etc so that all the cars we have are essentially the same platform.Why use such a heavy diff when you only have a lightweight engine? Surely there is lighter more mdern alternative that will giv eyou the ratios that you require?
Most M's came with the 3.31:1 (post chassis 3919 - the Salisbury Diff), the TR6 diff used previously was 3.45:1.
davidy
Obviously the racer will use a 3.54 but was there any difference with the M's gearbox ratios when they were fitted with the 3.31 / 3.54? and how do they both differ in relative terms on the road in the real world.
I was essentially going to use a 3.54 in both cars but life hasn't panned out like that and where I thought I had 2 3.54 ratios, I find I now have 1 of each (Happy new year Herman !!)
Before I put the 3.31 aside for an endurance spare for the Mulsanne straight and buy another 3.54, I wanted to court opinion on real world performance between the two.
I am really just trying to get a feel for what the 3.31 will be like in a road application.
plus a certain North yorks tractor restorer would only vilify me If I moved away to a non original back end
N
Neil
No differences in gearbox, two options on an M standard or overdrive. I know that some M's have been retrofitted with 3.54's but I don't know many that left the factory like that, some of the Turbo's had 3.09's though.
I know what you mean about Daftlad and he is certainly entitled to his own point of view (but we won't talk about the changed parts on the 3000S turbo will we!!!
- I mean I'm sure it never left the factory with Wilton Carpet in the boot
not to mention the changed Turbo, radiator, etc, etc). But however you look at it, its still a great a car and has a lot of TVR DNA.
In my mind, you've already done the engine and gearbox (losing TVR DNA), you might as well go the whole hog and change the diff. The Salisbury gearbox is very heavy lump.
davidy
No differences in gearbox, two options on an M standard or overdrive. I know that some M's have been retrofitted with 3.54's but I don't know many that left the factory like that, some of the Turbo's had 3.09's though.
I know what you mean about Daftlad and he is certainly entitled to his own point of view (but we won't talk about the changed parts on the 3000S turbo will we!!!
- I mean I'm sure it never left the factory with Wilton Carpet in the boot not to mention the changed Turbo, radiator, etc, etc). But however you look at it, its still a great a car and has a lot of TVR DNA.In my mind, you've already done the engine and gearbox (losing TVR DNA), you might as well go the whole hog and change the diff. The Salisbury gearbox is very heavy lump.
davidy
DavidY said:
Neil
No differences in gearbox, two options on an M standard or overdrive. I know that some M's have been retrofitted with 3.54's but I don't know many that left the factory like that, some of the Turbo's had 3.09's though.
I know what you mean about Daftlad and he is certainly entitled to his own point of view (but we won't talk about the changed parts on the 3000S turbo will we!!! - I mean I'm sure it never left the factory with Wilton Carpet in the boot not to mention the changed Turbo, radiator, etc, etc). But however you look at it, its still a great a car and has a lot of TVR DNA.
In my mind, you've already done the engine and gearbox (losing TVR DNA), you might as well go the whole hog and change the diff. The Salisbury gearbox is very heavy lump.
davidy
Too much hassle david.No differences in gearbox, two options on an M standard or overdrive. I know that some M's have been retrofitted with 3.54's but I don't know many that left the factory like that, some of the Turbo's had 3.09's though.
I know what you mean about Daftlad and he is certainly entitled to his own point of view (but we won't talk about the changed parts on the 3000S turbo will we!!!
- I mean I'm sure it never left the factory with Wilton Carpet in the boot not to mention the changed Turbo, radiator, etc, etc). But however you look at it, its still a great a car and has a lot of TVR DNA.In my mind, you've already done the engine and gearbox (losing TVR DNA), you might as well go the whole hog and change the diff. The Salisbury gearbox is very heavy lump.
davidy
the 4HU is heavy but the 10.5 inch CWP compared to the 7.5 of a cosworth Diff means that it is very much a fit and forget install on a 200hp modified car. Plus as soon as the word Cosworth appears in an advert essentially adds £100 to asking prices
as I also said. all of my brackets for mounting etc etc are being replicated in both cars. That way we have a bullet proof rear end in both cars with 100% interchangability between the cars. this means only 1 set of spares required. Plus all of my bracketry is lazer cut and interchangeable that means I can throw a 4HU in any pre-m with my eyes closed
I also think that a vixens only achilies heel is traction due to a light back end. A bit of weight in the middle of the back wheels doesn't harm anything in real terms, not when you consider the featherweight my dad is.
Does anyone have performance data for a 3.31 against a 3.54,
Max speeds in each gear, 0-60 times and top speeds.
Basically can I get away with the 3.31 in the zetec vixen without a loss in performance, or indeed is there a loss in performance.
N.
DavidY said:
I know what you mean about Daftlad and he is certainly entitled to his own point of view (but we won't talk about the changed parts on the 3000S turbo will we!!! - I mean I'm sure it never left the factory with Wilton Carpet in the boot not to mention the changed Turbo, radiator, etc, etc). But however you look at it, its still a great a car and has a lot of TVR DNA.
You cant upset me, I'm unwindable - new years resolution - I mean I'm sure it never left the factory with Wilton Carpet in the boot not to mention the changed Turbo, radiator, etc, etc). But however you look at it, its still a great a car and has a lot of TVR DNA.
..........our car did leave the factory as a 3000S turbo...I will say no more........ other than....it's leather bound wilton in the boot
. Now, back on topic, 3.54 or 3.79 me thinks? would be my choice (it's what I had in my Griffith 400). Magnesium casings can be bought if weight is a worry...also gets that excess wieght out of the wallet.
Daftlad said:
DavidY said:
I know what you mean about Daftlad and he is certainly entitled to his own point of view (but we won't talk about the changed parts on the 3000S turbo will we!!! - I mean I'm sure it never left the factory with Wilton Carpet in the boot not to mention the changed Turbo, radiator, etc, etc). But however you look at it, its still a great a car and has a lot of TVR DNA.
You cant upset me, I'm unwindable - new years resolution - I mean I'm sure it never left the factory with Wilton Carpet in the boot not to mention the changed Turbo, radiator, etc, etc). But however you look at it, its still a great a car and has a lot of TVR DNA...........our car did leave the factory as a 3000S turbo...I will say no more........ other than....it's leather bound wilton in the boot
. Now, back on topic, 3.54 or 3.79 me thinks? would be my choice (it's what I had in my Griffith 400). Magnesium casings can be bought if weight is a worry...also gets that excess wieght out of the wallet.
A 3000m has been fitted with 3.31 , 3.54 and 2500m's fitted with 3.45.
how does a 3.31 diffed car drive against a 3.54.
It's early, Its new years day and phsyco with his GA special diesel block won't be out of bed yet with the definitive answer.
Or should I just throw this 3.31 in the bin now.
N.
heightswitch said:
Daftlad said:
DavidY said:
I know what you mean about Daftlad and he is certainly entitled to his own point of view (but we won't talk about the changed parts on the 3000S turbo will we!!! - I mean I'm sure it never left the factory with Wilton Carpet in the boot not to mention the changed Turbo, radiator, etc, etc). But however you look at it, its still a great a car and has a lot of TVR DNA.
You cant upset me, I'm unwindable - new years resolution - I mean I'm sure it never left the factory with Wilton Carpet in the boot not to mention the changed Turbo, radiator, etc, etc). But however you look at it, its still a great a car and has a lot of TVR DNA...........our car did leave the factory as a 3000S turbo...I will say no more........ other than....it's leather bound wilton in the boot
. Now, back on topic, 3.54 or 3.79 me thinks? would be my choice (it's what I had in my Griffith 400). Magnesium casings can be bought if weight is a worry...also gets that excess wieght out of the wallet.
A 3000m has been fitted with 3.31 , 3.54 and 2500m's fitted with 3.45.
how does a 3.31 diffed car drive against a 3.54.
It's early, Its new years day and phsyco with his GA special diesel block won't be out of bed yet with the definitive answer.
Or should I just throw this 3.31 in the bin now.
N.
Not sure what wheels and tyres you are running, or what engine and how high it will rev. If it were a well tuned tractor engine with standard rolling radius, that revved to mid 6s, a 3,31 would be my choice assuming you're still on 1.00:1.00 final gearbox drive. If it reved in the mid-high 7s, I would look for a shorter diff. My race M will run a 3,31 4HU LSD on 15" wheels with slighltly less rolling radius (1.00:1.00 final gearbox drive - 4 speed).
I think a 3,54 would be a little undergeared unless it had a screamer for an engine.
Neil
From the factory M's were either equipped with a 3.45:1 (TR6) or 3.31:1 (Salisbury). As I said previously some of the Turbos left the factory with a 3.09:1. Yes there was a Salusbury 3.54:1 which I know has been retrofitted by some Sprinters/Hillclimbers. 3.54:1 were fitted to a lot of Jaguars so are fairly widely available, I had one from a Daimler Hearse.
You can work out the performance differences with some simple maths (yes I know it's a bank holiday), but a 3.54:1 is going to have slightly better acceleration for a slight loss of top speed, but there won't be a huge amount of difference (7%). In a road car I would have thought that 3.31:1 will be perfectly adequate, but as John points out maybe you should consider a 3.79 or even a 4.1 as you want acceleration not necessarily top end speed in a V8 racer. Salisbury's could be custom configured to almost any ratio as there are a large number of crown and pinion wheels available.
Unless you want ultimate top end speed then get a 2.88:1 !!
davidy
From the factory M's were either equipped with a 3.45:1 (TR6) or 3.31:1 (Salisbury). As I said previously some of the Turbos left the factory with a 3.09:1. Yes there was a Salusbury 3.54:1 which I know has been retrofitted by some Sprinters/Hillclimbers. 3.54:1 were fitted to a lot of Jaguars so are fairly widely available, I had one from a Daimler Hearse.
You can work out the performance differences with some simple maths (yes I know it's a bank holiday), but a 3.54:1 is going to have slightly better acceleration for a slight loss of top speed, but there won't be a huge amount of difference (7%). In a road car I would have thought that 3.31:1 will be perfectly adequate, but as John points out maybe you should consider a 3.79 or even a 4.1 as you want acceleration not necessarily top end speed in a V8 racer. Salisbury's could be custom configured to almost any ratio as there are a large number of crown and pinion wheels available.
Unless you want ultimate top end speed then get a 2.88:1 !!
davidy
BTW I would agree with John here, in my Taimar (modded 'tractor' engine) with a 3.31 with 15" rims and 225/50's slightly smaller rolling radius than standard car, I reached terminal velocity (at 6,500rpm) comfortably down the straight at Goodwood, with 3.54:1 I would have reached a slower terminal velocity sooner!
So John, I reckon that you are making the right choice too! (as I'm sure you would have entered the straight at a higher speed than me! and Goodwood has a long straight compared with most UK circuits)
But of course GAjon with a higher reving 'tractor' engine has more options.
davidy
So John, I reckon that you are making the right choice too! (as I'm sure you would have entered the straight at a higher speed than me! and Goodwood has a long straight compared with most UK circuits)
But of course GAjon with a higher reving 'tractor' engine has more options.
davidy
Daftlad said:
heightswitch said:
Daftlad said:
DavidY said:
I know what you mean about Daftlad and he is certainly entitled to his own point of view (but we won't talk about the changed parts on the 3000S turbo will we!!! - I mean I'm sure it never left the factory with Wilton Carpet in the boot not to mention the changed Turbo, radiator, etc, etc). But however you look at it, its still a great a car and has a lot of TVR DNA.
You cant upset me, I'm unwindable - new years resolution - I mean I'm sure it never left the factory with Wilton Carpet in the boot not to mention the changed Turbo, radiator, etc, etc). But however you look at it, its still a great a car and has a lot of TVR DNA...........our car did leave the factory as a 3000S turbo...I will say no more........ other than....it's leather bound wilton in the boot
. Now, back on topic, 3.54 or 3.79 me thinks? would be my choice (it's what I had in my Griffith 400). Magnesium casings can be bought if weight is a worry...also gets that excess wieght out of the wallet.
I had bought a 3.54 for dad but my dilemma is that I need that for the racer. dad wants a good performer where top speed not as critical as accelleration (which I know is never the full story without knowing the gearbox ratios.)
my reasoning regards the essex powered cars is that the planned zetec install will have similar power, and gearing but maybe not as much torque.
I want to strike a good balance for dad on road, IE reasonable performance / accelleration and good on road manners with low cruising revs and good economy. plus I have a 3.31 fully built sitting on the garage floor. i just don't want to fit it if i really need the 3.54.
that said a 2.8 capri had a 3.09
I have found a good spreadsheet where gear / wheel / gearbox ratios can give theoretical speeds in each gear.
Neil.
.
Edited by heightswitch on Tuesday 1st January 12:07
heightswitch said:
Daftlad said:
heightswitch said:
Daftlad said:
DavidY said:
I know what you mean about Daftlad and he is certainly entitled to his own point of view (but we won't talk about the changed parts on the 3000S turbo will we!!! - I mean I'm sure it never left the factory with Wilton Carpet in the boot not to mention the changed Turbo, radiator, etc, etc). But however you look at it, its still a great a car and has a lot of TVR DNA.
You cant upset me, I'm unwindable - new years resolution - I mean I'm sure it never left the factory with Wilton Carpet in the boot not to mention the changed Turbo, radiator, etc, etc). But however you look at it, its still a great a car and has a lot of TVR DNA...........our car did leave the factory as a 3000S turbo...I will say no more........ other than....it's leather bound wilton in the boot
. Now, back on topic, 3.54 or 3.79 me thinks? would be my choice (it's what I had in my Griffith 400). Magnesium casings can be bought if weight is a worry...also gets that excess wieght out of the wallet.
I had bought a 3.54 for dad but my dilemma is that I need that for the racer. dad wants a good performer where top speed not as critical as accelleration (which I know is never the full story without knowing the gearbox ratios.)
my reasoning regards the essex powered cars is that the planned zetec install will have similar power, and gearing but maybe not as much torque.
I want to strike a good balance for dad on road, IE reasonable performance / accelleration and good on road manners with low cruising revs and good economy. plus I have a 3.31 fully built sitting on the garage floor. i just don't want to fit it if i really need the 3.54.
that said a 2.8 capri had a 3.09
I have found a good spreadsheet where gear / wheel / gearbox ratios can give theoretical speeds in each gear.
Neil.
.
Edited by heightswitch on Tuesday 1st January 12:07
i am beginning to wonder if my Racer would be better with the 3.31 because of a safe rev limit to be imposed in April??
N.
I'll wait til later to do some maths.
N.
With a 3.54 (non-lsd) it's all too easy to do this... (ok, I admit there's a 302 at the front)
Electron may be along at some stage to confirm whether he went to a 3.08/lsd yet (or something in between) but I think he found first gear pretty redundant with the 3.54, despite the sticky Yoko's
Electron may be along at some stage to confirm whether he went to a 3.08/lsd yet (or something in between) but I think he found first gear pretty redundant with the 3.54, despite the sticky Yoko's
Daftlad said:
heightswitch said:
I am also beginning to think that john is bringing race phsycology into play....
I fall into the gentleman racer mould Neil, one that would only give advice to anyone if I thought it would be of benefit to them.I think it is pretty evident that most of my racing (hopefully) will be with the fast class C boys and very Slow class B boys, obviously with a historic car in B by virtue of its engine size and a rev limit that reflects the 20" over on bore and 10" under on crank I now wonder whether a 3.31 will be a more prudent move in the racer, This may actually preserve the motor a little better through a seasons racing.
Next job is to see what ratio's I have in the box (T10 S)I only have 4 gears though so a taller ratio may be the way to go.
Build is tight for the first race so Ideally I need an informed choice. the diff I don't use will then go into dads car.
Just come in from the garage 40 pieces off to blast and powder coat tomorrow, then I can get the body back on.
Hello all, happy new year.
Neil,
I have a 3.31.1 LSD in mine at present, and it's fine for both my road and track requirements, but you have to consider, I also run the cossie T5 box and smaller overall diameter wheels tyres (225/50/15 on the back).
I have run the TR6 diff, but that was with the old 'mildly' tuned engine, standard ford Capri 4 speed box and 205/60/14 wheels tyres. It gave great acceleration but maxed out at about 125MPH.
When I changed from the TR6 diff to a 4HU LSD from David Gerald I also changed wheel/tyre sizes, then eventually the gearbox.
I'm not sure what ratio this diff was/is as the tag on the back is missing, are there anymore identifying markings on these diffs?
I do still have the diff under a pile of spares so will be able to check.
Anyhow no matter what ratio it is/was I never measured any differences nor could say I really notced any in real life use, but I suppose this may also be attributed to changing to many things at once.
Sorry I cant offer more detail, but the 3.31.1, in my opinion is viable, but if you want to throw it in a bin, throw it in mine.
John.
PS, chassis looks good.
Neil,
I have a 3.31.1 LSD in mine at present, and it's fine for both my road and track requirements, but you have to consider, I also run the cossie T5 box and smaller overall diameter wheels tyres (225/50/15 on the back).
I have run the TR6 diff, but that was with the old 'mildly' tuned engine, standard ford Capri 4 speed box and 205/60/14 wheels tyres. It gave great acceleration but maxed out at about 125MPH.
When I changed from the TR6 diff to a 4HU LSD from David Gerald I also changed wheel/tyre sizes, then eventually the gearbox.
I'm not sure what ratio this diff was/is as the tag on the back is missing, are there anymore identifying markings on these diffs?
I do still have the diff under a pile of spares so will be able to check.
Anyhow no matter what ratio it is/was I never measured any differences nor could say I really notced any in real life use, but I suppose this may also be attributed to changing to many things at once.
Sorry I cant offer more detail, but the 3.31.1, in my opinion is viable, but if you want to throw it in a bin, throw it in mine.
John.
PS, chassis looks good.
Edited by GAjon on Wednesday 2nd January 20:05
GAjon said:
Hello all, happy new year.
Neil,
I have a 3.31.1 LSD in mine at present, and it's fine for both my road and track requirements, but you have to consider, I also run the cossie T5 box and smaller overall diameter wheels tyres (225/50/15 on the back).
I have run the TR6 diff, but that was with the old 'mildly' tuned engine, standard ford Capri 4 speed box and 205/60/14 wheels tyres. It gave great acceleration but maxed out at about 125MPH.
When I changed from the TR6 diff to a 4HU LSD from David Gerald I also changed wheel/tyre sizes, then eventually the gearbox.
I'm not sure what ratio this diff was/is as the tag on the back is missing, are there anymore identifying markings on these diffs?
I do still have the diff under a pile of spares so will be able to check.
Anyhow no matter what ratio it is/was I never measured any differences nor could say I really notced any in real life use, but I suppose this may also be attributed to changing to many things at once.
Sorry I cant offer more detail, but the 3.31.1, in my opinion is viable, but if you want to throw it in a bin, throw it in mine.
John.
PS, chassis looks good.
Hello John.Neil,
I have a 3.31.1 LSD in mine at present, and it's fine for both my road and track requirements, but you have to consider, I also run the cossie T5 box and smaller overall diameter wheels tyres (225/50/15 on the back).
I have run the TR6 diff, but that was with the old 'mildly' tuned engine, standard ford Capri 4 speed box and 205/60/14 wheels tyres. It gave great acceleration but maxed out at about 125MPH.
When I changed from the TR6 diff to a 4HU LSD from David Gerald I also changed wheel/tyre sizes, then eventually the gearbox.
I'm not sure what ratio this diff was/is as the tag on the back is missing, are there anymore identifying markings on these diffs?
I do still have the diff under a pile of spares so will be able to check.
Anyhow no matter what ratio it is/was I never measured any differences nor could say I really notced any in real life use, but I suppose this may also be attributed to changing to many things at once.
Sorry I cant offer more detail, but the 3.31.1, in my opinion is viable, but if you want to throw it in a bin, throw it in mine.
John.
PS, chassis looks good.
Edited by GAjon on Wednesday 2nd January 20:05
Happy new year mate
Is it the 4HU you are looking for a ratio on or the TR6?
The 4hu also sometimes has the ratio stamped on the top of the diff housing at the front where the drive pinion comes out at the front. the other method is 2 tip-ex marks on a drive flange and pinion shaft.
I had a natter with Daftlad this morning and i think i am a lot happier with my plans now.
I am running a 4sp in the racer and will be limiting myself to the 6k rev mark. I think the torque of the 302 plus the limited revs will allow me to run the 3.31 on the track in the griffen. if I feel it is too tall I will change mid season
I will run the 3.54 in my dads car since revs will possibly be slightly higher in the zetec but the lower gearing in the diff will suit the lack of torque, power in the zetec will be around the 180hp mark so the type 9 ratios with longer first gear should suit the car better.
plus I feel a lot happier knowing I have 2 extra cylinders and the same gearing as daftlad
anyhow, isn't it about time you started running round in circles with us!!
Chassis isn't bad considering it turns 40 this year
Neil.
Edited by heightswitch on Wednesday 2nd January 20:21
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