Discussion
At Donnington last week the LSD gave in, every corner i was leaving big smokey No1's, even Craner Curves!!
Digging it out of the Melbourne loop was a joke, its put up with 5 years of abuse so cant complain.
I have spoken to JR of Grantura and he says standard Torque setting on the road diff is 45lbs, and race is 120lbs, i am thinking of going in the middle, JR says would be a good compromise.
Has anyone here had this done, or other option is a proper plated one, but more money.
Digging it out of the Melbourne loop was a joke, its put up with 5 years of abuse so cant complain.
I have spoken to JR of Grantura and he says standard Torque setting on the road diff is 45lbs, and race is 120lbs, i am thinking of going in the middle, JR says would be a good compromise.
Has anyone here had this done, or other option is a proper plated one, but more money.
JR recently rebuilt my BTR cone diff with a Quaife ATB unit. I acquired the ATB cheap from a friend who had it lying on his self for years, but otherwise I would have gone for the plate LSD option. I can’t tell you how good the ATB is since the rest of the car isn’t finished yet.
However, I did keep the old BTR cone clutch unit and recently stripped it down, out of curiosity to see how it works. I have to say that I reckon it is a pretty feeble design. JR will be able to tell you better, but as far as I can tell, each sun gear is connected to the housing by a cone clutch which is under a constant (fixed) pre-load from a spring. This creates a certain amount of torque locking the diff, which will ultimately spin like an open diff once that torque value is overcome. My main objection to this is that the locking torque appears to be fixed under all conditions, whether you be on the power, over-run, free-wheeling, doing 5mph trying to park at Sainsburys, whatever. The diff does not lock up more under power, it’s locked up as far as the fixed torque all the time, until it slips!!
So thinking of your application, if the diff has say 80ft.lb of locking torque, how much torque is your engine putting out and then multiplied by gear and diff ratios????
Thinking also of how much the cost will be just to strip and rebuild your diff, probably with new bearings, seals etc (say £500), then consider how much money you burn each time you go on track.... So I would go the extra £££ for the plate LSD and junk the old cone thing. And if it’s a Hydratrak, definitely junk it.
However, I did keep the old BTR cone clutch unit and recently stripped it down, out of curiosity to see how it works. I have to say that I reckon it is a pretty feeble design. JR will be able to tell you better, but as far as I can tell, each sun gear is connected to the housing by a cone clutch which is under a constant (fixed) pre-load from a spring. This creates a certain amount of torque locking the diff, which will ultimately spin like an open diff once that torque value is overcome. My main objection to this is that the locking torque appears to be fixed under all conditions, whether you be on the power, over-run, free-wheeling, doing 5mph trying to park at Sainsburys, whatever. The diff does not lock up more under power, it’s locked up as far as the fixed torque all the time, until it slips!!
So thinking of your application, if the diff has say 80ft.lb of locking torque, how much torque is your engine putting out and then multiplied by gear and diff ratios????
Thinking also of how much the cost will be just to strip and rebuild your diff, probably with new bearings, seals etc (say £500), then consider how much money you burn each time you go on track.... So I would go the extra £££ for the plate LSD and junk the old cone thing. And if it’s a Hydratrak, definitely junk it.
Well, the cone unit is pretty simple and you could rebuild that yourself if you are so inclined, as long as the cones/housing surfaces are not badly worn/scored. I can't remember exactly, but I think I was quoted a little less than £1k for a new plate unit from JR and it was a similar quote from Elite in Stoke, except that they were unable to free off the seized side screw whereas JR had the proper tools. But presumably JR has already quoted you?
jwoffshore said:
Well, the cone unit is pretty simple and you could rebuild that yourself if you are so inclined, as long as the cones/housing surfaces are not badly worn/scored. I can't remember exactly, but I think I was quoted a little less than £1k for a new plate unit from JR and it was a similar quote from Elite in Stoke, except that they were unable to free off the seized side screw whereas JR had the proper tools. But presumably JR has already quoted you?
Yes, he has to surface grind the faces and set the torque, £150 plus £28 for parts, like i say i will take it apart and re-assemble, it will be the third time apart as i swapped the ratio first to 3.08, i broke that CW & pinion, then i assembled with a motorsport item.Gives me a chance to do the leaky output too i suppose...
7 TVR said:
Topcats put a coned cerb unit in mine and i'm very happy so far although i could not testify to its longevity yet!
Mines a coned unit, like i say its done 5 years, driving it for around 3 miles on one driveshaft, so i could get recovered didnt do it the world of good, if its £200 vs £1000 my choice is made!Just spoken again to JR and he does away with the springs and modifies it.
I asked about doing away with it and putting a plated unit, he said he was at Brands and all the cars that were on the grid were running the modded cone type, good enough for them good enough for me!
Stripped it this morning and it will be back before the end of the week, Hurrah!
I asked about doing away with it and putting a plated unit, he said he was at Brands and all the cars that were on the grid were running the modded cone type, good enough for them good enough for me!
Stripped it this morning and it will be back before the end of the week, Hurrah!
Jr has done me a good used LSD centre, mine was too far gone and turning metal to dust, very pretty sparkly oil.
He has done it with a TVR Motorsport kit, which is 3 centre springs instead of the standard 2.
So far so very good, need to get on track and give it a proper seeing to!
Will it ever stop raining....
He has done it with a TVR Motorsport kit, which is 3 centre springs instead of the standard 2.
So far so very good, need to get on track and give it a proper seeing to!
Will it ever stop raining....
Gassing Station | General TVR Stuff & Gossip | Top of Page | What's New | My Stuff