Deeper pinion for a race setup?

[Cranky]

Running about .004" deep on a spooled 8 3/4 and was wondering if there any benefit to leaving it like that for drag racing? This guy is wanting to go at least high 9's and after seeing the shoddy welds on the car (Fox body Mopar power), I wouldn't be comfortable going 14's with it.

 

[Lefty71]

I thought most Fox bodied owners assume those cars car high 9's outta the box lol (til they take 'em to the track).

 

[Cranky]

I thought most Fox bodied owners assume those cars car high 9's outta the box lol (til they take 'em to the track).

He bought it because it was already set up for a Mopar....and was light. Obvious he didn't look at it too good and wanted me to 'redo' all the welds. Never did see the car in person but he sent me pics of it and man....pics usually don't show the flaws very well but this thing was nasty. Very obvious that whoever welded it wasn't experienced at all at welding. One of the worst dirt dauber jobs to ever see!

 

[dvw]

Too deep a pinion and stock lash are a recipe for disaster. I have a pile of Dana parts to show for it. Proper pinion depth and loose lash (.010"-.012") is the ticket. No synthetic fluid either. This comes from Moser, Strange, a local Super Comp guy who does race axles, and the local ring and pinion shop that does race stuff. They all said the same thing.
Doug

 

[Cranky]

Too deep a pinion and stock lash are a recipe for disaster. I have a pile of Dana parts to show for it. Proper pinion depth and loose lash (.010"-.012") is the ticket. No synthetic fluid either. This comes from Moser, Strange, a local Super Comp guy who does race axles, and the local ring and pinion shop that does race stuff. They all said the same thing.
Doug

Yeah, I always set the lash loose for racing and even more for the circle track cars. Was thinking of setting the pinion more forward.....but thinking about the ones that use a trans brake too and thinking a lot of lash might not be the thing to do?

 

[dvw]

Iv'e been told it tries to drive the pinion rearward. That tightens everything up. Every one I broke had no backlash when it was disassembled.
Doug

 

[Cranky]

Iv'e been told it tries to drive the pinion rearward. That tightens everything up. Every one I broke had no backlash when it was disassembled.
Doug

So it's probably better to set the pinion shallow in race conditions....right? Makes since as the pinion tries to push the ring out the back of the housing, right? Never set up gears for someone that was drag racing hard core. Thing is these gears are not drag racing gears (pro gears) as there hasn't been 'soft' gears made for the 8 3/4 in years that I know of.

 

[dvw]

I center the pinion between the root and the top land.
Doug

 

[33 IMP]

I wouldn't be trying to go nines with a transbrake and an 8 3/4.....
Edit: I also had a friend who did race nine inch setups. He also said no synthetic gear oil.

 

[Cranky]

I wouldn't be trying to go nines with a transbrake and an 8 3/4.....

I've tried to talk this guy out of using the 8 3/4 to no avail.....

 

[33 IMP]

I've tried to talk this guy out of using the 8 3/4 to no avail.....

He might get away with it for a while, if that mustang is REAL light. After he breaks it the first time, he may get smart. Better to get smart BEFORE he hurts it......

 

[Ceedawg]

Well crank, back around 68-70 the Chrysler engineers said give a little extra because the gears would suck into each other under power,..I think.. that might be backward..never mind.

 

[dvw]

Well crank, back around 68-70 the Chrysler engineers said give a little extra because the gears would suck into each other under power,..I think.. that might be backward..never mind.

Thats excactly what happens.
Doug

 

[oldkimmer]

The crown wants to pull the pinion back farther into it. Kim

 

[451Mopar]

This seemed to work in the 8-3/4" before I swapped to the Strange S60 axle.
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