high pinion????

Nuts · 08-14-2011, 07:47 PM

Always heard not to run a high pinion in the rear but is it really that much weaker? If the gears are designed to run that way how does it matter if its in front or out back?

94Dodge Truggy · 08-14-2011, 08:27 PM

I have heard that it is 20-30% weaker. If you are low HP and mild tire size it may survive.

carwash · 08-14-2011, 10:21 PM

Reverse cut gears are stronger in front application, but at least 20% weaker in the rear. There is a lot of tooth deflection on these due to the type of engagement they have. Most manufacturers suggest no more than a 35" tire and mild horsepower.

But i've seen guys run them and beat the snot out of them and have no issues at all.

blazerbrad · 08-15-2011, 11:21 PM

As mentioned above, a high pinion (or reverse rotation) gears were designed for the front so they were powered on the drive side of the gears = stronger. Put a high pinion in the rear and you are now running on the cost sides = not as strong. Same type of situation but reverse of a low pinion (standard rotation) gears......powered on the drive side when in the rear but cost side if in the front.

I periodically hear about people blowing out the R&P in high pinion rear 60's in rigs like TJ's with 38's, but this is all second hand and I'm sure only a small percentage. A guy in our club has one in his YJ with 37" Boggers with the 4.0L, NV4500, and 4-speed Atlas (manual combined with low gears = more stress). He's been beating on it pretty hard for a couple of years now, including a stint on a set of borrowed 42's, with no issues so far.

Nuts · 08-16-2011, 04:46 PM

I saw one yesterday that was blown apart so I think I'll go with plan B:mad:

flatlander757 · 08-16-2011, 08:44 PM

See how there is a flat side and an angled side of each tooth?

The flat side is the drive side, the angled side is the coast side.

High pinion in the rear = driving forwards on the coast side... so the pinion is basically pushing the ring gear away from itself about as hard as it is trying to turn forward.

If you want a high pinion rear it needs to be BEEFY to handle the abuse... I would consider a HP D70 as minimum... and even then I'd consider pinion bearing replacements as a normal maintenance item every few years.

08-14-2011, 07:47 PM	#1
Nuts Join Date: Feb 2008 Location: middletown,oh Posts: 508	high pinion???? Always heard not to run a high pinion in the rear but is it really that much weaker? If the gears are designed to run that way how does it matter if its in front or out back?

08-14-2011, 08:27 PM	#2
94Dodge Truggy EX-Vice President Join Date: Jan 2007 Location: Fairfield, Ohio Posts: 3,048	I have heard that it is 20-30% weaker. If you are low HP and mild tire size it may survive. __________________

08-14-2011, 10:21 PM	#3
carwash pimpin' IS easy Join Date: Jan 2007 Location: Union, KY Posts: 3,344 Images: 605	Reverse cut gears are stronger in front application, but at least 20% weaker in the rear. There is a lot of tooth deflection on these due to the type of engagement they have. Most manufacturers suggest no more than a 35" tire and mild horsepower. But i've seen guys run them and beat the snot out of them and have no issues at all. __________________

08-15-2011, 11:21 PM	#4
blazerbrad - CORE Member - Join Date: Feb 2007 Posts: 831 Images: 6	As mentioned above, a high pinion (or reverse rotation) gears were designed for the front so they were powered on the drive side of the gears = stronger. Put a high pinion in the rear and you are now running on the cost sides = not as strong. Same type of situation but reverse of a low pinion (standard rotation) gears......powered on the drive side when in the rear but cost side if in the front. I periodically hear about people blowing out the R&P in high pinion rear 60's in rigs like TJ's with 38's, but this is all second hand and I'm sure only a small percentage. A guy in our club has one in his YJ with 37" Boggers with the 4.0L, NV4500, and 4-speed Atlas (manual combined with low gears = more stress). He's been beating on it pretty hard for a couple of years now, including a stint on a set of borrowed 42's, with no issues so far.

08-16-2011, 04:46 PM	#5
Nuts Join Date: Feb 2008 Location: middletown,oh Posts: 508	I saw one yesterday that was blown apart so I think I'll go with plan B:mad:

08-16-2011, 08:44 PM	#6
flatlander757 Fartface extrordinair Join Date: Aug 2010 Location: West Carrollton Posts: 127	See how there is a flat side and an angled side of each tooth? The flat side is the drive side, the angled side is the coast side. High pinion in the rear = driving forwards on the coast side... so the pinion is basically pushing the ring gear away from itself about as hard as it is trying to turn forward. If you want a high pinion rear it needs to be BEEFY to handle the abuse... I would consider a HP D70 as minimum... and even then I'd consider pinion bearing replacements as a normal maintenance item every few years.