Speed 6 clutch mod
Discussion
My TVR clutch affair has lasted 14 years. During this time I have been young, middle aged and paranoid about not being middle aged anymore. My desire to fix things hasn’t left me. The speed 6 clutch has sat on the back burner of my mind since the Sag clutch started dragging. I read all the posts and formed an opinion, the tale is long... so to save me hours typing at a snails pace and from boring you all with my ramblings I shall use some slang, sorry.
Sagi version 1 was a 7 1/4 twin plate on a super light flyweel. I was young and it was fun. The T5 changes gear quicker when the driven plates have less mass. These boxes are the best shifting Tremec in my opinion, due to the low inertia of its components, to hang a pair of big plates with springs and things means the syncros have a bit more work to do. So, my mod had no marcel or transmission springs, it changed gear fast. It was a bugger at the lights as the reduced interia meant you gave the game away as you needed some revs to launch. The release bearing was fitted to a hrb meant for the cossie T5 conversion, the bell housing was machined to buggery. Fairly expensive, very if you do the hrb, if you made a carrier like v2 then not so expensive.
Sagi version 2, fitted to the Tuscan, was a triple plate 7 1/4 on a super light, again no marcel or transmission springs, this engine is on its umpteenth rebuild and second billet crank, these are heavier than the ADI standard cranks so have a tad more inertia. Good combo. Bearing is on an extended carrier on the hrb, similar to the Cerb jobbie but to my dims. Less work, better drive. Expensive.
Sagi version 3 is an AP machined to bits in anger after v1 gave up the ghost ( second set of plates ) the hrb is sound, so good bit of kit that. Maybe sell it the fast Ford boys. I used another bellhousing with a RP hrb. So to explain what I did see the pics, to understand why read on.
The sp6 clutch is a bit heavy, bit of a cruiser IMHO. It has 6 butterfly springs, 3 between flywheel and intermediate plate and 3 between interplate and cover, these being stronger than the first 3. They are designed to centre the interplate between the pair of driven plates between the cover and fly when the clutch is released/pedal pressed. The balancing act between strong and weak butterfly springs is controlled by a set of 3 travel limiting devices known infamously as starlok washers, these are on pushed onto 3 hard steel posts that are fixed to the cover and pass through holes in the interplate. A hard steel strap on the interplate snuggles the starlok on the face of the interplate. This controls the travel, and in theory works, these starloks push on and like a bee sting go one way and not the other so as the clutch wears I guess the idea is they shuffle a few thou along the post and limit the travel of the stronger springs and keep the gap as two fairly even gaps. All good. Nope.
Failure of the starlok or snapping of the butterfly or wear in the flywheel face where the butterfly lands unbalances this situation and either a sack load of travel is needed, breaking fingers eventually, or a new clutch is specified. So what have I done. Telly is boring, decorating is boring, taking gearboxes out is cool, machining the granny out of a second hand AP is cool. The result is it works. The theory is based on the fact that lightening the cover plate and interplate means less interia, means they are more likely to move without springs pushing them. Consider that every competition clutch does not have butterfly springs, or at least the hundreds I have seen, so no need for starloks so no chance of these failing and giving the odd bias that results in drag and stiff gear changes. Worthy of note is the fact competition clutches tighten up when hot, there is only so much travel so the more plates the less gap each has, each plate needs a gap either side so a twin needs four gaps, a triple six and all from the same travel of the bearing into the fingers, hence you will notice the lack of marcel springs which in turn makes the clutch sharper and not to everyone’s liking. The twin 7 1/4 needs a strong cover spring so heavy pedal and more wear on the crank thrust bearing if you hold the clutch open a lot, there is less leverage simply put so more grip needed hence more pressure. The triple is the best lively combo I reckon, softer spring and plenty of drive area, if you want to slip it it will cook up and tighten up a bit but only once have I done this and I just allowed a touch more travel and all is well.
Sagi v4 will be a spring less pair of plates in the AP, I shall run it as is for a year or two then out it comes to be ground/machined and put back with no springs, I shall avoid old age and report back in good time, until then comment away but fact is this works.
Special thanks to Darren my engineering friend who dropped everything to do this while I waited. He likes Cars with engines at the back but I forgive him.
J
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Sagi version 1 was a 7 1/4 twin plate on a super light flyweel. I was young and it was fun. The T5 changes gear quicker when the driven plates have less mass. These boxes are the best shifting Tremec in my opinion, due to the low inertia of its components, to hang a pair of big plates with springs and things means the syncros have a bit more work to do. So, my mod had no marcel or transmission springs, it changed gear fast. It was a bugger at the lights as the reduced interia meant you gave the game away as you needed some revs to launch. The release bearing was fitted to a hrb meant for the cossie T5 conversion, the bell housing was machined to buggery. Fairly expensive, very if you do the hrb, if you made a carrier like v2 then not so expensive.
Sagi version 2, fitted to the Tuscan, was a triple plate 7 1/4 on a super light, again no marcel or transmission springs, this engine is on its umpteenth rebuild and second billet crank, these are heavier than the ADI standard cranks so have a tad more inertia. Good combo. Bearing is on an extended carrier on the hrb, similar to the Cerb jobbie but to my dims. Less work, better drive. Expensive.
Sagi version 3 is an AP machined to bits in anger after v1 gave up the ghost ( second set of plates ) the hrb is sound, so good bit of kit that. Maybe sell it the fast Ford boys. I used another bellhousing with a RP hrb. So to explain what I did see the pics, to understand why read on.
The sp6 clutch is a bit heavy, bit of a cruiser IMHO. It has 6 butterfly springs, 3 between flywheel and intermediate plate and 3 between interplate and cover, these being stronger than the first 3. They are designed to centre the interplate between the pair of driven plates between the cover and fly when the clutch is released/pedal pressed. The balancing act between strong and weak butterfly springs is controlled by a set of 3 travel limiting devices known infamously as starlok washers, these are on pushed onto 3 hard steel posts that are fixed to the cover and pass through holes in the interplate. A hard steel strap on the interplate snuggles the starlok on the face of the interplate. This controls the travel, and in theory works, these starloks push on and like a bee sting go one way and not the other so as the clutch wears I guess the idea is they shuffle a few thou along the post and limit the travel of the stronger springs and keep the gap as two fairly even gaps. All good. Nope.
Failure of the starlok or snapping of the butterfly or wear in the flywheel face where the butterfly lands unbalances this situation and either a sack load of travel is needed, breaking fingers eventually, or a new clutch is specified. So what have I done. Telly is boring, decorating is boring, taking gearboxes out is cool, machining the granny out of a second hand AP is cool. The result is it works. The theory is based on the fact that lightening the cover plate and interplate means less interia, means they are more likely to move without springs pushing them. Consider that every competition clutch does not have butterfly springs, or at least the hundreds I have seen, so no need for starloks so no chance of these failing and giving the odd bias that results in drag and stiff gear changes. Worthy of note is the fact competition clutches tighten up when hot, there is only so much travel so the more plates the less gap each has, each plate needs a gap either side so a twin needs four gaps, a triple six and all from the same travel of the bearing into the fingers, hence you will notice the lack of marcel springs which in turn makes the clutch sharper and not to everyone’s liking. The twin 7 1/4 needs a strong cover spring so heavy pedal and more wear on the crank thrust bearing if you hold the clutch open a lot, there is less leverage simply put so more grip needed hence more pressure. The triple is the best lively combo I reckon, softer spring and plenty of drive area, if you want to slip it it will cook up and tighten up a bit but only once have I done this and I just allowed a touch more travel and all is well.
Sagi v4 will be a spring less pair of plates in the AP, I shall run it as is for a year or two then out it comes to be ground/machined and put back with no springs, I shall avoid old age and report back in good time, until then comment away but fact is this works.
Special thanks to Darren my engineering friend who dropped everything to do this while I waited. He likes Cars with engines at the back but I forgive him.
J
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