Recommendations for axle swap... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

BigAlVB · 07-18-2003, 03:29 PM

Hello all! I'm interested in swapping my 10 bolt 1/2 ton axles for 14 bolt 3/4 ton axles. I have 3.08 gears, I think, and would like 3.73 or 4.10 because I want to start pulling a travel trailer. Also want to use the 'Burb more in the dunes without breaking the axles. I have a 350 and newly rebuilt 700R4.

Any recommendations? I have a 2" suspension lift and 32" BFG's. Also how should I make the 'Burb more bulletproof for pulling? We're thinking 24-27" travel trailer with no slide-outs, no longer than 30' for sure.

This may be in the wrong forum, but I trust all of you implicitly. Please help!

77 Shortbed · 07-18-2003, 10:54 PM

If you are wanting to pull a travel trailer, I would think not less than 4.10s with the 32s. I have 3/4 ton axles with 4.10s and an sm465 in my 77. With 33s the rpms at 55mph are within a hundred or so of my 89 in fourth gear, which has 3.73s, a 5 speed and original tire size.

But then again with the 454 in the 77 I average 8mpg whether I am pulling anything or not.

79Silv4x4 · 07-19-2003, 02:22 AM

with a 700r4 and 32 inch tires there's no question--get at least the 4.10 gears.

77bowtie · 07-19-2003, 07:36 PM

The closest I can get is with a 4.11 ratio, but at 65 MPH & 32" tires you'll rev at about 2805 RPM add a bit more for trany slippage. 2805 puts you near the lower end for a "Daily Driver, Best overall Performance" chart. 4.11 w/33's = 2720 RPM, w/30" tires = 2992 RPM. Jon

Cole's 87 · 07-20-2003, 08:48 AM

32" with 4.10 gears
Drive @ 65mph=2,798rpm
OD@65mph=1,959rpm

Drive@70mph=3,014rpm
OD@70mph=2,109rpm

If you want to play with gear/tire/rpm combos go here and you will find out what you need to know Hope this helps Oh yea when your trying to figure out OD RPM enter .70 instead of 1.00 in the transmission ratio box

http://www.prestage.com/Car+Math/Gea...M/default.aspx

77bowtie · 07-21-2003, 10:11 AM

I do a bit of trailer towing and I've added a remote oil cooler & filter, to help cool down the engine. I've also added a remote cooler & filter to the TH-400. To help keep it cooler when I tow my 25' trailer. But then I live in a fairly hot climate. Good Luck...Jon

07-18-2003, 03:29 PM	#1
BigAlVB Registered User Join Date: Mar 2003 Location: Holland, MI Posts: 74	Recommendations for axle swap... Hello all! I'm interested in swapping my 10 bolt 1/2 ton axles for 14 bolt 3/4 ton axles. I have 3.08 gears, I think, and would like 3.73 or 4.10 because I want to start pulling a travel trailer. Also want to use the 'Burb more in the dunes without breaking the axles. I have a 350 and newly rebuilt 700R4. Any recommendations? I have a 2" suspension lift and 32" BFG's. Also how should I make the 'Burb more bulletproof for pulling? We're thinking 24-27" travel trailer with no slide-outs, no longer than 30' for sure. This may be in the wrong forum, but I trust all of you implicitly. Please help! __________________ "When this car hits 88 miles per hour, you're going to see some serious s*&$!" Back To The Future

07-19-2003, 07:36 PM	#4
77bowtie Registered User Join Date: Apr 2003 Location: New Mexico. Of all places for an Island boy. Posts: 180	RPM @ 65 MPH The closest I can get is with a 4.11 ratio, but at 65 MPH & 32" tires you'll rev at about 2805 RPM add a bit more for trany slippage. 2805 puts you near the lower end for a "Daily Driver, Best overall Performance" chart. 4.11 w/33's = 2720 RPM, w/30" tires = 2992 RPM. Jon

07-20-2003, 08:48 AM	#5
Cole's 87 Registered User Join Date: Nov 2002 Posts: 272	32" with 4.10 gears Drive @ 65mph=2,798rpm OD@65mph=1,959rpm Drive@70mph=3,014rpm OD@70mph=2,109rpm If you want to play with gear/tire/rpm combos go here and you will find out what you need to know Hope this helps Oh yea when your trying to figure out OD RPM enter .70 instead of 1.00 in the transmission ratio box http://www.prestage.com/Car+Math/Gea...M/default.aspx Last edited by Cole's 87; 07-20-2003 at 08:51 AM.

07-18-2003, 10:54 PM	#2
77 Shortbed Registered User Join Date: May 2003 Location: Central Indiana Posts: 16	If you are wanting to pull a travel trailer, I would think not less than 4.10s with the 32s. I have 3/4 ton axles with 4.10s and an sm465 in my 77. With 33s the rpms at 55mph are within a hundred or so of my 89 in fourth gear, which has 3.73s, a 5 speed and original tire size. But then again with the 454 in the 77 I average 8mpg whether I am pulling anything or not.

07-19-2003, 02:22 AM	#3
79Silv4x4 Workaholic Join Date: Oct 2002 Location: Katy, TX Posts: 1,589	with a 700r4 and 32 inch tires there's no question--get at least the 4.10 gears.

07-21-2003, 10:11 AM	#6
77bowtie Registered User Join Date: Apr 2003 Location: New Mexico. Of all places for an Island boy. Posts: 180	I do a bit of trailer towing and I've added a remote oil cooler & filter, to help cool down the engine. I've also added a remote cooler & filter to the TH-400. To help keep it cooler when I tow my 25' trailer. But then I live in a fairly hot climate. Good Luck...Jon



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