supra 6 speed conversion

[Norbie]

As for this swap...one of those suck it an see jobs i think. Good oil with regular swaps will be essential and i'd look at a tranny cooler as well just to be sure....at the very least monitor gear oil temp for a few meets to see what it's doing.

Sound advice. Heat is the biggest killer of all, and in a race car where the transmission is seeing high load for extended periods you want to keep a close eye on this. The strongest gearbox in the world doesn't mean squat if the oil overheats and loses its lubrication properties.

[Mos]

And therein lies the advantage of a straight cut gear. With less contact patch there's less friction and therefore less drivetrain loss. In a world where 10th's of a sec count this is significant.

The other advantage is that straight cut gears do not induce thrust loads across the gear. Helical gears don't "push" straight but at an angle - these thrust loads are another energy loss that's reduced with straight gears.

the straight cut gear also allows for quicker shifts using the dog engagement rather than syncros.

Isn't dog engagement independent of type of gear set?

Mos.

[MR 1JZ]

I was under the impression that straight cut gears are stronger becuase they are less likely to slip and shear right off?

Am I wrong?

also dont straight cut gear manufacturers such as PPG use stronger steel components when fabricating their gears?

[JustenGT8]

I was under the impression that straight cut gears are stronger becuase they are less likely to slip and shear right off?

Am I wrong?

also dont straight cut gear manufacturers such as PPG use stronger steel components when fabricating their gears?

Yup you're wrong

As Mos says there is a thrust load but that's just a matter of having the right bearing to take it. Use a needle roller instead of a stand BB roller bearing or a 360 thrust washer etc etc and issue sorted.

It's an issue with box construction not the gears themselves. Same could be said for case construction etc etc.

I assume for racwe application the custom gear makers use etter material but that's not a given. A budget staright cut is still budget so there's a range of quality out there like any product.

Yup Mos but most common to see dog and straight cut together eh...gotta go a few years back to find a box with helical gears and dog engagement

[MR 1JZ]

cheers for the clarification then

+rep

[1jzracing]

as for the question of strength comparisons between sq cut and std helical
check out these pictures and make your own mind up
its to do more with the tooth size

the square cut ones are quite strong, i got a whole season from the last set and they break in mid flight ie. under sheer torque they just let go not while im changing gear so its not a shifting issue, i am farly gentle on it wherever possable always use the clutch etc.
the std box will only do a few laps and they tear all the teeth off the input shaft.

The tremec looks strong and might be ok for a street/drag car or the torque of a V8 but i need a 2nd gear of about 1.65 or 1.7 at the absolute max otherwise it becomes usless, if my car falls off boost on the track then i may as well get out and push!

the tremec 2nd is 2.9 far too short and 5th is hoplesssly tall about 0.75:1

[JustenGT8]

So peaky yeah?

Mine won't fall off boost and if it does it's still into 4litres of 10:1 comp n/a V8 and plenty of torque there too.

sometimes there is no replacement for displacement

[JustCallMeOrlando]

the tremec 2nd is 2.9 far too short and 5th is hoplesssly tall about 0.75:1

These are the TKO600 ratios:
TKO-600 2.87 1.89 1.28 1.00 .64
TKO-600 (RR) 2.87 1.89 1.28 1.00 .82

Did you get your ratios wrong or was it a typo? 2.87 is first gear, and I'm yet to see one that has a 0.75 5th.

[1jzracing]

These are the TKO600 ratios:
TKO-600 2.87 1.89 1.28 1.00 .64
TKO-600 (RR) 2.87 1.89 1.28 1.00 .82

Did you get your ratios wrong or was it a typo? 2.87 is first gear, and I'm yet to see one that has a 0.75 5th.

yea I ment 1.9 for 2nd and the RR box fifth would be fine for racing, but its 2nd 3rd and 4th that gets used extensively on the circuit

been a while since i seen the ratios just going from memory and thought 5th was .75 which is pretty standard for many boxes

i must have seen the .64 5th
no one in their right mind would produce a box with such a rediculious overdrive ratio
that would be next to usless in anything with less than a 5 letre eng
and .82 would be a bit close on the street perfect for a small engine

are there any aftermarket gearsets avail for them???

[Norbie]

no one in their right mind would produce a box with such a rediculious overdrive ratio
that would be next to usless in anything with less than a 5 letre eng

Yes well the TKO comes from the USA, a place where a 5 litre engine is considered small.

[JustCallMeOrlando]

What diff and ratio are you running?

[1jzracing]

What diff and ratio are you running?

4.11 with a 650mm diam tyre

[Crazyracer]

I could sell you a Hewland transaxle which would solve all of your ratio problems.

It even comes with a bonus space framed stanza coupe attached

[1jzracing]

I could sell you a Hewland transaxle which would solve all of your ratio problems.

It even comes with a bonus space framed stanza coupe attached

send me pictures!

pm sent

[JustenGT8]

I could sell you a Hewland transaxle which would solve all of your ratio problems.

It even comes with a bonus space framed stanza coupe attached

Now i'm praying for huge tax refund cheque A Hewland backing up a mid engined TTUZ is droolworthy