Dirt oval rear end question

[gc3]

Hey guys,

I'm trying to figure out what class/race cars use the Winters 8-3/8" Ring gear quick change rear ends to figure out a ball park gear capability.
in the Winters catalog, they mention "max rating 500 hp, 3000 lbs".
I assume this is the based on the rating of the engine at the crank.
After this, most regular cars would have a transmission, so the actual torque the rear end sees would be 3x the crank torque or whatever in 1st gear.

Obviously sprint car rear ends see exactly crank torque (ignoring losses etc).

I just want to figure out if these "V8 quick change" rear ends are used in a direct drive application or if they are run behind a transmission.

thanks!

[freeskier7791]

They are probably run behind a 2 speed transmission, I know dirt late models and modifieds run a similar size rear end with a 2 spd.

[gc3]

They are probably run behind a 2 speed transmission, I know dirt late models and modifieds run a similar size rear end with a 2 spd.

Thanks for the tip, powerglides and borgwarner 72Cs are the 2 spd common trans options?

[Cobranut]

Lots of smaller Winters QC's in road race and oval cars.
Baby Grands use them, as well as Pro-Challenge cars like I just bought.

I see no reason they shouldn't hold up behind a transmission.

[gc3]

Lots of smaller Winters QC's in road race and oval cars.
Baby Grands use them, as well as Pro-Challenge cars like I just bought.

I see no reason they shouldn't hold up behind a transmission.

Thanks, I need more specifics though, as in which ring gear size model for what class?

I'm not concerned whether or not they hold behind a transmission, what I need to figure out is what torque input at the pinion of the rear end can the rear end handle?

[freeskier7791]

8 and 3/8 is probably behind a 500 hp to 600 hp dirt modified geared to hit 100, serious torques.  Most of the high end cars have a custom 2 spd trans basically one speed for the pits and one for the track

[gc3]

8 and 3/8 is probably behind a 500 hp to 600 hp dirt modified geared to hit 100, serious torques.  Most of the high end cars have a custom 2 spd trans basically one speed for the pits and one for the track

That's a good data point. when you say 100, do you mean 100 vehicle speed or contact patch speed? I assume the slip rate is quite high on those cars.... what would you say, like 30% slip? way more?

if they are using 1st gear only for the pits and not throwing gobs of torque through that, maybe I can just assume a 1:1 crank torque to rear end.

in which case 5-600 ft lbs to a rear end is nothing...
I'm trying to find something that packages similarly to hold up to near 1500 ftlbs at the pinion.

[digitalsolo]

Another data point, I would expect that the overall torque handling has to be pretty high on the dirt track rears simply because there is a lot of slide -> traction -> slide transitions in a pretty fast and violent manner, so from a shock standpoint, they'd have to be rather overbuilt.

[gc3]

Another data point, I would expect that the overall torque handling has to be pretty high on the dirt track rears simply because there is a lot of slide -> traction -> slide transitions in a pretty fast and violent manner, so from a shock standpoint, they'd have to be rather overbuilt.

That's a good point too, plus I've been hearing that with syrup these guys are getting more load than cars on asphalt

[freeskier7791]

That is all true, just look at how they set the cars up, the rear end actively steers the thing.  They run lockers so the difference in grip between the inside and outside tires cause some serious twisting.  Contact patch speed is way higher, the tires are slipping as the vehicle is traveling 100 mph

[gadzooks]

Another data point, I would expect that the overall torque handling has to be pretty high on the dirt track rears simply because there is a lot of slide -> traction -> slide transitions in a pretty fast and violent manner, so from a shock standpoint, they'd have to be rather overbuilt.

In a properly set up car there is a lot less sliding than most people think(the rear steer just makes it look extreme), a good driver also avoids violent transitions since they just waste power and break parts. Most of the sliding that happens also does not involve a major loss of forward traction, it's mostly a side load through the corner.

[gadzooks]

Oh, as far as torque output, guys typically run the transmission in a 1:1 gear with a high rear end ratio to minimize power loss through the trans