I'm getting a new gearbox built. Need some input :)

[bug66]

Hi guys!

I'm going to get a gearbox built after I split the last one in two..

The plan is:

- White Rhino housing
- Mendeola MD4E gear carrier housing + nose cone
- Dual Weddle Billet side plates + through bolt
- 3,88 Klingelnberg (heat treated or shot peened)
- Finnish clutch less gear stack or Weddle Race gear stack (see gearing below)
- Weddle 300M input shaft (needed?)


Car+engine:

"Full" weight 67 beetle
2165 turbo 400/400 hp/ft.lbs to the wheels (will increase..)


Gearing:

Today - 3,75-2,14-1,56-1,04
New - 3,20-2,00-1,50-0,95 (suggested from builder)

Spreadsheet:

Untitled (Custom).jpg

I'm thinking maybe a bit longer 3rd gear? 1,45? And 1st gear is a lot heavier than the one I had now. An issue?


Car needs to have gearing to go 9s..



Thanks for all replies

[Casting Timmy]

How do you like the current gears? If your signature is correct with 134mph, are you redlined across the finish line right now or do you have a little more until redline? The new gear stack is spreading out 3-4 more, looks like you have around ~2500rpm drop on 3 and 4 with the current box and then are going to do a 2k and then a 3k drop on the new box.

I might be doing a sand racing gear box soon, so this will be interesting to follow.

The 300M shaft is a good idea as Folts puts those on his drag boxes as well. Watch which input shaft coupler you use as well. I'd also find out about the heavier duty mainshaft bearing option with the MD4E as well. Just for thread future reference the swing thrust washer on the pinion bearing can also be done to the later big nut pinion bearings and is good with drag racing as well. (Machine first, race, and use shorter idler bearing)

Pro shift and slick shift are the old methods for non-synchro boxes, the liberty shift plates are a lot better. The 1-2 slider will probably need the reverse teeth chamfered due to first gear radius on the shaft, so watch out for that. I've also modified a couple of the Weddle reverse gears to get them fighting right (narrow teeth, actually I do a chamfer from the base to the tip to account for gear wobble and make it not rub on 2nd gear)

[Pablo2]

1.45 3rd for sure .. and forget about "treating" the 3.88. Just lightly chamfer the edges of all teeth.

[bug66]

1.45 3rd for sure .. and forget about "treating" the 3.88. Just lightly chamfer the edges of all teeth.

Thanks!

I tried to find a nice setup and looking at 3,44/2,08/1,35/1,00(or 0,93)

I'll post a picture later

[bug66]

Any input on my proposed gearing?

Engine curves:

kurve (Custom).jpg

kurve 2 (Custom).jpg

I have 2 different setups regarding gearing:


Shifting at 7000.


#1 - 3,44/2,17/1,44/0,93

This gives the drop down;
1st to 2nd: 4416
2nd to 3rd: 4645
3rd to 4th: 4521
All in the middle of the steepest torque climb. (with 1,00 4th gear drop is to 4861)



#2 - 3,44/2,08/1,35/1,00

This gives the drop down;
1st to 2nd: 4233
2nd to 3rd: 4543
3rd to 4th: 5185
First shift right at the torque climb, second in the middle of the climb and last right after peak torque..


Should I try to look at gearing for earlier shifts?

Want to pass the 1/4 mile at 140+ mph..