Go Back   TeamTalk > General MasterCraft Topics > Tow Vehicles

Reply
 
Thread Tools Display Modes
  #1  
Old 05-23-2006, 11:42 AM
Diesel's Avatar
Diesel Diesel is offline
MC Devotee
 
Join Date: Aug 2004
Boat: 95 Prostar 205
Location: Tulsa
Posts: 1,613
Tow vehicle squating and Fix

At the end of last season I sold my Duarmax due to the inceasing cost of diesel, poor fuel mileage, and an overheating problem GM cannot seem to fix. As a result we used my wife's Yukon to tow the boat at the end of the season. While I was very impressed with the 5.3's power and the running gear I was not impressed with the load handling ability of the factory rear coil springs. Her truck has a factory tow package and the highest CGVW rating of the Yukon trucks yet I did not feel the springs were up to the task. Here is a pic of it last year and you can see the squating rear end with the boat attached.



Here is the after I fixed the problem for comparison. (details to follow)

__________________
05 ProStar 209, Navy Flake, Slate Gray, MCX 1:1
Reply With Quote
  #2  
Old 05-23-2006, 11:44 AM
rodltg2 rodltg2 is offline
MC Addict
 
Join Date: Dec 2004
Boat: SN196
Location: Rocklin, CA
Posts: 6,024
Send a message via AIM to rodltg2
looks like the yukon and boat match well at least..
Reply With Quote
  #3  
Old 05-23-2006, 11:47 AM
DooSPX's Avatar
DooSPX DooSPX is offline
MC Maniac
 
Join Date: May 2005
Boat: 1991 MasterCraft Prostar 190 PowerSlot
Location: Central, FL
Posts: 3,167
Send a message via AIM to DooSPX
details man, details
__________________
1991 PROSTAR 190 Flagship Blue POWERSLOT OJ XMP CNC 13.7x17.5 .110 4B
A.K.A. One of a kind mistake
2011 Best In Show- 1987-2000 class

Trying to keep slalom alive

Need a new prop to fit your needs? Call OJ PROPS 800-359-9730

Quote:
Originally Posted by flipper View Post
"It's better to keep your mouth shut and let people think you are stupid, than to open it and prove it"?
Reply With Quote
  #4  
Old 05-23-2006, 12:08 PM
Diesel's Avatar
Diesel Diesel is offline
MC Devotee
 
Join Date: Aug 2004
Boat: 95 Prostar 205
Location: Tulsa
Posts: 1,613
So over the winter I started looking at my options. First I found a helper air bellows mfg by AirLift called the Air Lift 1000. Basically you place these inside your existing coil springs and they expand as preassure is added to help with the load. Here is a pic....



I have seen these used in the past and was not impressed with thier performance or durability so I passed.

Then I decided to look at completely replacing the coil spring with an air spring assembly. After some research I discovered H2 Hummers have an optional air-ride suspension system. This was perfect since the H2 is based on the Yukon platform and shares almost identical suspension components. After a long search on Ebay I scored a brand new pair of Hummer H2 air springs for $100.

Once I got the coils springs out of the truck and looked at the mounting surfaces, it turns out the Hummer air bags are almost a direct replacement for the Yukon/XL coil springs.

The upper coil bucket has a series of cut outs which were designed to hold the Hummer air bag. Here is a pic of the upper coil bucket and the cut out slots.



The Hummer air bag has tabs which just slide into the cutouts and you turn it clockwise unti it locks in place. Here is the bag mounted in the upper coil bucket.

__________________
05 ProStar 209, Navy Flake, Slate Gray, MCX 1:1
Reply With Quote
  #5  
Old 05-23-2006, 12:16 PM
Diesel's Avatar
Diesel Diesel is offline
MC Devotee
 
Join Date: Aug 2004
Boat: 95 Prostar 205
Location: Tulsa
Posts: 1,613
The factory lower mounting coil bucket (axle side) looks like this.



The Hummer air bags came with a 2.5" centering puck which holds them in place on the lower mount. As a result I had to weld a 14mm nut to axle tube so the centering puck could be bolted over the existing coil bucket. Here is a pic of the welded nut.



Now at this point the bags can be placed over the puck and on to the factory axle coil bucket and you are done with mounting the bags...................unless you want to improve the ride a bit. (details to follow).
__________________
05 ProStar 209, Navy Flake, Slate Gray, MCX 1:1
Reply With Quote
  #6  
Old 05-23-2006, 12:26 PM
bigmac bigmac is offline
MC Platinum
 
Join Date: Jun 2005
Boat: 2004 Maristar 230 VRS
Location: Central Minnesota
Posts: 8,126
My opinion: tow vehicle squat is a function of frame geometry and bad weight distribution, not inadequate springs. IMHO the better (and cheaper/easier) solution is to improve the frame geometry with a weight distributing hitch. Stiffer rear springs make the vehicle look better, but don't fix the probem that's causing that much squat - bad weight distribution.

IMHO, you could have solved the problem better, safer, and easier with a $200 weight distributing hitch.
__________________
'04 MariStar 230VRS/MCX
Reply With Quote
  #7  
Old 05-23-2006, 12:28 PM
Diesel's Avatar
Diesel Diesel is offline
MC Devotee
 
Join Date: Aug 2004
Boat: 95 Prostar 205
Location: Tulsa
Posts: 1,613
With the bags pressured up and mounted to the factory lower coil buckets I was not all that happy with the static height of the bags. Too much piston was showing and I wanted to see a little more extension at ride height. Plus the angle of the factory lower braket put a slight missalignment on the bags wich I also did not like. As a result I built this spacer.





Here it is installed on the truck. It mounts over the factory lower coil bucket and the Hummer locating puck holds everything in place.

__________________
05 ProStar 209, Navy Flake, Slate Gray, MCX 1:1
Reply With Quote
  #8  
Old 05-23-2006, 12:31 PM
Diesel's Avatar
Diesel Diesel is offline
MC Devotee
 
Join Date: Aug 2004
Boat: 95 Prostar 205
Location: Tulsa
Posts: 1,613
Quote:
Originally Posted by bigmac
My opinion: tow vehicle squat is a function of frame geometry and bad weight distribution, not inadequate springs. IMHO the better (and cheaper/easier) solution is to improve the frame geometry with a weight distributing hitch. Stiffer rear springs make the vehicle look better, but don't fix the probem that's causing that much squat - bad weight distribution.

IMHO, you could have solved the problem better, safer, and easier with a $200 weight distributing hitch.
I don't belive there is enough wheel base in the Yukon for the weight distributing hitch to work effectively. I believe the coil springs are just too light. The factory spring rate is around 210 which just cannot handle the extra weight. It was designed to ride well not tow.
__________________
05 ProStar 209, Navy Flake, Slate Gray, MCX 1:1
Reply With Quote
  #9  
Old 05-23-2006, 12:35 PM
G-man's Avatar
G-man G-man is offline
MC Devotee
 
Join Date: Jul 2004
Boat: SN 196 previous 93 stars&stripes 190 red
Location: TX
Posts: 1,529
Nice write up Diesel, If I need anything more done to my jeep you might have the solution. When I had a 97 Tahoe I put the firestone airbags in. The problem in SUV's is the ride is built for a car and not towing.
__________________
06 AWSA Approved Towboat

Last edited by G-man; 05-23-2006 at 12:39 PM.
Reply With Quote
  #10  
Old 05-23-2006, 12:43 PM
Diesel's Avatar
Diesel Diesel is offline
MC Devotee
 
Join Date: Aug 2004
Boat: 95 Prostar 205
Location: Tulsa
Posts: 1,613
So here is a final picture of the bags installed and pressured up at ride height.





At full compression on the bump stops.



Close to full extension.

__________________
05 ProStar 209, Navy Flake, Slate Gray, MCX 1:1
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


All times are GMT -4. The time now is 09:19 AM.