5.3 motor. What’s best gear ratio for towing my 21’ boat? Should I go 6 or 8 speed?
5.3 motor. What’s best gear ratio for towing my 21’ boat? Should I go 6 or 8 speed?
Unless you plan to head somewhere mountainous with your boat, it isn’t going to matter much. A bass boat isn’t a huge load.
If you have integrity, nothing else matters. If you don't have integrity,
nothing else matters.
Lower is slightly better, but the standard 3.43 ratio will haul your boat with no issues. Double the weight of your 21' boat and a lower ratio would be nice.
The 6 or 8 speed will work equally as well.
I know you are asking about the 5.3 but I just bought a Sierra 1500 with the 6.2L on Jan 30. I have not pulled the boat yet but it gets better MPG than my 2009 5.3 was getting. There are some great deals going on the GMC's currently. The 6.2L is very strong in my opinion and does not compare to the 5.3. Either one you will be happy though.
5.3L with 3.42 gears will pull your 21 footer without any issues. As far as fuel mileage when towing, I don't look at as I only tow 12 to 13 miles to the ramps I use.
2006 Triton TR-21 XD, Mercury 225 Pro XS, S/N 1B287870
I tow about 3 hours total every weekend. Should I get the 3.08 or 3.42 gears? I guess I would like better gas mileage as long as it pulled my boat ok. I’m in Florida so no hills really. Lol
I was turned away from the 5.3 this time around only because I had oil consumption issues which lead to a lifter collapse on number #1 cylinder at 176,000 miles and GM said it was not enough oil consumption to be a warranty repair way back when so I just dealt with it and it got worse over time. I drove the '99, 211,000 miles without any problems. After I replaced the lifter on the '09 I traded but I can say the deciding factor was the dealer with the 6.2L has powertrain warranty for life to the original owner and I don't buy very often. I have owned a '99, '09, and now an '18 GMC Sierra 1500 4x4. Each one has been better but no real complaints on any of them. The 5.3 is a good motor and I have pulled my boat all over the southeast yearly fishing with no issues and never stranded on the road.
Have 3.42 gears in my ‘14 Silverado with the 5.3 liter. Have pulled boats and trailers all over the country with no issues. It does have the 6 speed transmission.
Aaron Campbell
Barling, AR
2007 Bass Cat Sabre
2011 Merc 175 Pro XS
2016 GMC Sierra 1500 CC, SB 4x4, 5.3, 3:42, 6 speed. I tow a Legend Alpha 199 and a Rockwood 2902WS travel trailer which weighs around 8,000lbs loaded. No problem.
I have a 2013 Silverado with the 5.3 and 3.08 gears. If I had it to do over again I would probably look for one with 3.42 but the 6 speed makes up for it somewhat. I have had no issues whatsoever towing a 21.5’ bass boat. Anything you get 4 speed, 6 speed or 8 speed with any ratio will have zero issues whatsoever with a bass boat.
I pulled a Cougar with a 14 with 3.08’s. It did it, but I’ll never buy another with that gear. Unlike the 4 speed there is no direct drive with the 6 speed. I assume the 8 is the same? Everything is under or overdrives. GM forces you to drive it like you stole it with their transmission programming. They upshift quickly for the mpg. Me and another BBC’r with the 3.42 tracked our mpg and ended up with the same overall, right at 17 at 30K miles. You can expect about the same with either gear. The 3.73 would have been the ticket.
I just got a 2018 Sierra SLT Z71 with the 5.3L, 8 speed and 3.42s. Pulls my TR186 like a dream. I feel very little suspension movement and it has all kinds of power for getting it going. My trailer doesn’t have brakes and stopping is not an issue. I feel it would pull any bassboat with complete ease.
My 2008 with the 5.3 has 3.73s and the new truck pulls it much better. More HP and better suspension. The 08 is an SLE and not a Z71.
Bruce
2019 20 TRX Patriot
Mercury 250 ProXS Fourstroke
HDS 12 Live - Console
HDS 9 Live - Bow
14 GMC with the 3.08 and pull up and down a mountain once or twice a week. 3,000 ft elevation change. No issues at all. If I was going to pull a travel trailer the 3.42 would be better.
2024 Phoenix 818, Mercury 175 (3B414035) Trick Steps, 3 Garmin 106 SV,s, LVS 34. BoatEFX dual bow mount. Ionic 12V 125AH, 2 12V 100 ah LiTime’s for the TM. Minn Kota 345 PCL charger,
Have a 2011 Yukon with 3.08 and 6-speed tranny. Tows wonderfully and plenty of power. Depending on the year you may not like the way the stock setup runs. I had the AFM and stock setup and it drove me crazy. The hunting for a gear and poor performance. I did a BlackBear tune and it drives waaaaay better. I came from a Ford 5.4l and this GMC tows way better with better economy and more power.
2017 Phoenix 819
2016 200ProXS, s/n 2B359849, Mod 1200P73BD
The 3.42 will outshine the 3.08 in almost every category, the 3.08 only beats is in mpgs while unloaded, even that is minimal.
I have a 2017 GMC 5.3 that has 3.42 gears. I feel as though towing with this truck is pretty pathetic. Flat ground up to 55 mph is fair at best. Add hills or 75 mph (speed limit) and this thing is constantly down shifting multiple tranny gears. I’m ready to trade. It averages 11 mpg towing.