straight cut or helical gears?

[Russ Noble]

Jono,

Lynn posted a gearcalc chart a couple of years ago in this old thread
Porsche G50 Info

I think in any of our cars even with a really tall first and big rubber, if you drop the clutch from a great height you are going to get wheelspin. A slug off the line? I don't think so. However I stand to be corrected in the light of anybody's contrary experience.......

Cheers

[Sandy]

Jono

GearCalc is very good, I spent hours playing with it. Just post the link for the download, that's a better way. I wish I could save a bunch of trans combinations, but you can only save what your working on unless in the list.

Sandy

[Straight 8 Racing]

I found some pictures of a spare first gear from my Holinger box showing the helical cut with dog gears and a 4th or 5th gear set from the Hewland with straight cut and dog gears, its interesting to see how much wider the Holinger gears are even before you add the effect of the helical cut.

Iain

[Sandy]

Originally Posted by jac mac

Sandy----- Have you never watched that TV programme---- ''You are The Weakest Link''--

Jac Mac

I missed this, your humor and input is always valued, you play well too!

Sandy

[Jono]

Was having a look on pistonheads.com last night, saw a thread about clutchless gearchanges so had a bit of a play in my daily driver (4x4 sierra), and it seemed relatively easy, although I did manage one emergency stop while left foot braking and blipping the throttle with my right foot, didn't get the revs right and couldn't drop into 2nd, and forgot my foot was on brake and not clutch . Doh. But in gneral applying the shifting techniques talked about earlier in this thread seemed to work ok.

Are they easier or harder with a synchrobox than dog engagement? I'm assuming the process is easier due the synchros still having some effect in helping the gears to mesh correctly, but as anyone reading the rest of this will gather my knowledge of this is fairly limited.

Kind of hoping that if I can do this I wouldn't have too much problem with a S/C dog box....?

[Russ Noble]

Haha Jono,

That's what I like, I can see you're a good keen man! Let's try it even if we do stuff the Sierra g/box!

You'll be pleased to know that syncro boxes are generally harder to shift clutchless than dog boxes. The syncros baulk the movement into the next gear and make moving the gearlever more difficult and then your revs get all out of kilter and it doesn't happen.

Some syncro boxes are easier to shift clutchless than others. I had a Transit once (for 22 years!) and it was great, the only time I ever used the clutch on that was for taking off. Also an Escort I owned was OK, but I never had much joy with Rootes Group or BLMC/Rover gearboxes.

Hope all that makes you feel better.

Cheers

[Jono]

yes, I thought what the heck, still plenty of MT75's in the scrappers!

That does make me feel better, thanks!