Modena's progress update

[Modena]

thanks muzza. When I say "heavy" I mean the flywheel/clutch combination physically weighs a lot. The pedal was not too heavy.

The conundrum I now face is that to check clearances I need to pull it all out, and then if I determine that it is correct (or shim it as required) and put it all back together, I risk it still having a problem. The LS1 forums in the US are littered with people complaining about this clutch not releasing at high rpm.

the shift in my case gets harder and harder as the RPM increases. I have experienced crunching as low as under 3000rpm, and over 4000rpm it basically wont go into 3rd or 4th.

[Serpnt]

Ben,

Having suffered for 4 years what you are experiencing and having chaned 4 different clutch's and redone my gearbox twice, suggest you give Howard Reynolds from Race Brakes a call.

I cant tell you the amount of different people I spoke to who gave me all sorts of advise but what eventually worked was I gave Howard my pedal with Master (Tilton), Throwout/Release Bearing (Tilton), Flywheeel and clutch and he set it up in a jig and found my problems. Got a brand new clutch - the right one and at ShelbyFest I was changing at 6000rpm with no problems

Theo

[Tenrocca]

Originally Posted by Modena

Pilot bearing was suggested to me thanks Andrew. However it is the right one, there's only two sizes and it would be very hard to get wrong. I installed the bearing myself so I'm confident it is correct. How did you get it wrong?

Rookie error. One of the few parts not interchangeable between the 5.7 and 6 litre blocks. As a rule, 5.7 blocks use the small pilot bearing. 6l+ blocks the big one.

[SVO 050]

I have been changing the reverse switch in my Tremek and looked at the Mal Wood site for info on the box.
I read in the Tremek installation info that you should not try to shift gears above 6400 rpm??
Anyone seen this detail and can explain why?
Cheers
SVO

[Gav]

Because manual drivers are soft?

[Aussie Mike]

Originally Posted by SVO 050

I have been changing the reverse switch in my Tremek and looked at the Mal Wood site for info on the box.
I read in the Tremek installation info that you should not try to shift gears above 6400 rpm??
Anyone seen this detail and can explain why?
Cheers
SVO

The job of a synchro in the gearbox is to match speeds between gears so that when the next gear is selected it will slot in easily. It means us ham-fisted drivers can easily select a gear without having to double clutch and spin the box up to match gear speeds.

The synchro is a kind of conical clutch between each gear where one cone is forced inside another cone. They were once brass on steel but now they have organic facings like a Kevlar and carbon fiber. The issue is these clutches like any clutch can only transmit so much power. The can only cope up to a point with the loads to spin gears up and down from high RPMs.

6400RPM is probably the manufacturers recommendation for the limit of what the synchros can cope with.

Interesting fact: The cone clutch design was used as the main clutch in many early automobiles. Clutches were faced with leather or cork. Often the clutch pedal had to be pushed down to force the cone into it's socket and transmit engine power to the trans.

Racing gearboxes like in V8 supercars or F1 don't have synchros. They have dog rings on the gears. These are rings with a hard step on them. As the gear is moved across on it's shaft the edges of the steps on the dog rings collide with a bang, the gears speeds are matched instantly and the gear slots in. Very harsh and only works when shifting hard. Gear speeds need to be matched carefully on downshifts (double clutching etc). Not much good for driving down to the shops but they cope with big HP and high RPM shifting.

Cheers

[Jaydee]

And to add to that, they are usually straight cut gears. That's why they whine so much.
JD

[Aussie Mike]

Originally Posted by Jaydee

And to add to that, they are usually straight cut gears. That's why they whine so much.
JD

You are correct. Actually I think they have to be straight cut for the dog rings to work.

Update looks like I was wrong, there are helical cut dog engagements. Found an interesting article about straight cut vs helical cut gears and the reason whey straight cut are used in race boxes. It's down to the side loads a helical cut gear exerts on the case. Straight cut don't exert any side loads so the gear case doesn't need to be as beefy for the same power level.

http://automotivethinker.com/transmi...rs-vs-helical/

Cheers

[Cobrakiller]

What size clutch hose are you running to the slave cly? Is it a T56 or TR6060 trans could be the slave cylinder.

[Modena]

Its a T56, clutch line is -4

I have tried adjusting the pedal with the 1" master but still no good. I have given up on this clutch, and the whole lot will be coming out for an aftermarket unit.

[Modena]

Today was a good day. Some warm clothes, the sunshine streaming in to the shed, and coffee, and the donk is now all disconnected and ready to pull out for a new clutch;







The exhaust headers needed recoating anyway, one of the jobs that is being done while the donk is out. This happened when the engine was originally running in limp mode (lean)




The only casualty was a spark plug lead, which literally came apart in my hands, guess they don't like the heat! I found my excuse to buy some bling ones with heat shields! Hi-Ho, Hi-Ho, its off to Summit we go.....

[LoBelly]

Good Job Ben

Tradition dictates that all jobs must be done three times on a Cobra and you've been skating by just doing things once.

Nice to see you getting into the swing...

LoBelly

[gjkrv8]

Ben I've got a spare lead if the LS1 variety fit the LS3 if you want one. cheers Gregg

[Modena]

Thanks to Phil, Gregg and stiffy, last weekend the donk and trans were removed. While it is out I am tweaking the heat shields to add more shielding over the cats and also getting them coated instead of painted, either HPC coated or anodised, not sure yet.






Picked up the new clutch today. It's an Xtreme twin-plate organic....mmmm....bling

[Modena]

Thats right Ford fans, see that really small thing that makes 430bhp for only 7k? LS goodness #darkside #vader

[Modena]

Look at this thing, it's a shame to hide it under the trans, it's a work of art!

[Tenrocca]

Very pretty clutch Benny, maybe install a perspex window in the box and trans tunnel? Are you sure you got it around the right way though - this looks a bit sus....

[Modena]

nice try buddy. How'd you go with that rash?

[Aussie Mike]

I wonder why they made it so the pressure plate and intermediate steel plate aren't as wide as the actual clutch facing? Probably leaving a good 10% of your surface area unused.

looks well made though

Cheers

[Paintwerks]

Ben, recommend that you forget about Summit for your leads.

Myself, Guy and David March each got a set of custom made (to length and spec), all-black 8mm ignition leads with the woven heat shields for around $200 the set from ICE. They were made the next day and the best part is they are local. They are in Bernard Street, Cheltenham. Great to deal with.

Innovative Ignition Systems & Components - ICE Ignition

Cheers,
Sime