Go Back   Jeep Garage - Jeep Forum > Jeep Platform Discussion > Grand Cherokee SRT - WK2

Join Jeep Garage Today
Reply
 
Thread Tools Display Modes
 
  #1  
Old 05-10-2011, 11:30 AM
andyh's Avatar
Premium Member
My Jeep: 2011 5.7L WK2
 
Join Date: Jan 2011
Location: ILM, NC
Posts: 371
Thanks: 2
Thanked 5 Times in 5 Posts
Rep Power: 2210
andyh has a reputation beyond reputeandyh has a reputation beyond reputeandyh has a reputation beyond reputeandyh has a reputation beyond reputeandyh has a reputation beyond reputeandyh has a reputation beyond reputeandyh has a reputation beyond reputeandyh has a reputation beyond reputeandyh has a reputation beyond reputeandyh has a reputation beyond reputeandyh has a reputation beyond repute
Why is the towing capacity so low?

What is the limiting factor in the 5,000lb max trailer weight?
__________________

__________________
This is my sig
Reply With Quote
  #2  
Old 05-10-2011, 12:29 PM
soontobesrt's Avatar
I drive a modern day Woody
My Jeep: 2005 3.7L WK
 
Join Date: Jan 2010
Location: Philadelphia,PA ----> Trenton, NJ
Posts: 1,602
Thanks: 31
Thanked 14 Times in 14 Posts
Rep Power: 3394
soontobesrt has a reputation beyond reputesoontobesrt has a reputation beyond reputesoontobesrt has a reputation beyond reputesoontobesrt has a reputation beyond repute
Re: Why is the towing capacity so low?

Quote:
Originally Posted by andyh View Post
What is the limiting factor in the 5,000lb max trailer weight?
Well the truck was made mainly to fit the performance sector of the market. That said, it has an independent rear shock/spring suspension setup. Its also a relatively small vehicle when it comes to serious towing, its not F350 haha. Most trucks use leaf spring setups and even better is a nice air setup in the back.

So like I said, I know they "tried" to make it a towing capable truck due to that being the biggest gripe from most owners and other who would have bought if it could respectably tow. BUT, I think they still tried to keep this thing performance oriented and in turn the suspension system and geometry aren't designed for a huge payload. I personally think 5k lbs is a nice load, you can certainly tow a nice size boat around Im just going off the top of my head, dont know the exact reasons here I mean the truck isnt even on the road yet
__________________

__________________

Mods: A Bunch



Reply With Quote
  #3  
Old 05-10-2011, 12:36 PM
cyanideg's Avatar
GO GREEN!
 
Join Date: Jul 2009
Location: MI
Posts: 547
Thanks: 47
Thanked 29 Times in 18 Posts
Rep Power: 5351
cyanideg has a reputation beyond reputecyanideg has a reputation beyond reputecyanideg has a reputation beyond reputecyanideg has a reputation beyond reputecyanideg has a reputation beyond reputecyanideg has a reputation beyond reputecyanideg has a reputation beyond reputecyanideg has a reputation beyond reputecyanideg has a reputation beyond reputecyanideg has a reputation beyond reputecyanideg has a reputation beyond repute
Re: Why is the towing capacity so low?

Your question should be, why is there a towing option at all? Im buying it for power, not to tow a boat.
__________________
Reply With Quote
  #4  
Old 05-10-2011, 12:45 PM
Member
 
Join Date: Apr 2011
Posts: 122
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 1374
ChrisL1976 is on a distinguished road
Re: Why is the towing capacity so low?

I think you pretty much covered it. Its a balance between what the average Jeep owner would be towing and keeping the Jeep suspension geometry off-road capable.

Its on the flip side of owning a big 4x4 truck that will pull 10k and complaining why its not as off-road capable as Jeeps.

From a design cost point....Personal guess, 90% of jeep owners will never need to pull more that 5k, so why waste money designing it for that. I'm sure it could be done, but more than likely the number of estimate sales for the upgrade from suspension and powertrain would price it way to high. Would pay ,say, an extra $5k to be able to pull 10k pounds?
__________________
Chris
2009 Jeep Grand Cherokee Laredo
4.7L V-8
Quad Drive II
Reply With Quote
  #5  
Old 05-10-2011, 12:54 PM
jgc4ever's Avatar
Senior Member
My Jeep: 2012 5.7L WK2
 
Join Date: Mar 2011
Posts: 3,212
Thanks: 0
Thanked 78 Times in 69 Posts
Rep Power: 1160278
jgc4ever has a reputation beyond reputejgc4ever has a reputation beyond reputejgc4ever has a reputation beyond reputejgc4ever has a reputation beyond reputejgc4ever has a reputation beyond reputejgc4ever has a reputation beyond reputejgc4ever has a reputation beyond reputejgc4ever has a reputation beyond reputejgc4ever has a reputation beyond reputejgc4ever has a reputation beyond reputejgc4ever has a reputation beyond repute
Garage
Re: Why is the towing capacity so low?

The 2011 Jeep Grand Cherokee 5.7 L V8 Hemi with trailer tow IV tows more (like 7,500 lbs. I think) than the 2012 Jeep Grand Cherokee 6.4 L Hemi V8 SRT8 (5,000 lbs max). So, does anyone know why the 5.7 L V8 Hemi w/ trailer tow IV on an Overland, Limited or Laredo tows more maximum weight than the 5,000 lbs. the new SRT8 is capable of?
__________________
Reply With Quote
  #6  
Old 05-10-2011, 02:48 PM
andyh's Avatar
Premium Member
My Jeep: 2011 5.7L WK2
 
Join Date: Jan 2011
Location: ILM, NC
Posts: 371
Thanks: 2
Thanked 5 Times in 5 Posts
Rep Power: 2210
andyh has a reputation beyond reputeandyh has a reputation beyond reputeandyh has a reputation beyond reputeandyh has a reputation beyond reputeandyh has a reputation beyond reputeandyh has a reputation beyond reputeandyh has a reputation beyond reputeandyh has a reputation beyond reputeandyh has a reputation beyond reputeandyh has a reputation beyond reputeandyh has a reputation beyond repute
Re: Why is the towing capacity so low?

I understand that towing capability is not a marketing target for this car. I'm just wondering why a car with way more power/torque than the 5.7L tows 2000+ less pounds.

It is the lower towing rating due to the physical design, like the tires for example? Is it marketing? lawyers?
__________________
This is my sig
Reply With Quote
  #7  
Old 05-10-2011, 09:56 PM
soontobesrt's Avatar
I drive a modern day Woody
My Jeep: 2005 3.7L WK
 
Join Date: Jan 2010
Location: Philadelphia,PA ----> Trenton, NJ
Posts: 1,602
Thanks: 31
Thanked 14 Times in 14 Posts
Rep Power: 3394
soontobesrt has a reputation beyond reputesoontobesrt has a reputation beyond reputesoontobesrt has a reputation beyond reputesoontobesrt has a reputation beyond repute
Re: Why is the towing capacity so low?

Quote:
Originally Posted by andyh View Post
I understand that towing capability is not a marketing target for this car. I'm just wondering why a car with way more power/torque than the 5.7L tows 2000+ less pounds.

It is the lower towing rating due to the physical design, like the tires for example? Is it marketing? lawyers?
It would be the psychical design as you put would be the limiting factor. Power is only half the battle with towing so although the SRT8 has a ton of torque etc etc, the suspension isn't setup to handle a ton of weight although it has a tow mode. The suspension setup this rig has is tuned for performance over towing thus the auto/sport/track modes. They do have the tow mode though which as they have mentioned firms up the rear and basically splits torque closer to 50/50 I believe, the point of this being to try and keep the trailer or whatever your towing from swaying and dragging the jeep all over the road. In short, it basically puts a firmer grip on the whatever is behind it

The SRT8 does NOT have the air ride which I'm thinking is the reason why it tows 2500lbs less than the limited/overlands etc. That air ride gives those things a ton more ability to haul, hard to explain how it works but thats a pretty ideal setup, lots of big trucks and other haulers use a similar system. Not sure if the non air rides are capable of the same or not but thats my guess
__________________

Mods: A Bunch



Reply With Quote
  #8  
Old 05-12-2011, 11:30 AM
webspoke's Avatar
Member
My Jeep: 2013 5.7L WK2
 
Join Date: Dec 2010
Location: Dallas
Posts: 179
Thanks: 0
Thanked 3 Times in 3 Posts
Rep Power: 1562
webspoke is on a distinguished road
Re: Why is the towing capacity so low?

It's probably a transmission or differential limitation. The chassis is capable in the 5.7 versions, with and without air suspension, but the transmission is not the 545RFE used in the 5.7's and trucks. Add in the extra torque and power and it probably taxes it, and maybe the colling system too.
__________________
Reply With Quote
  #9  
Old 05-12-2011, 12:16 PM
soontobesrt's Avatar
I drive a modern day Woody
My Jeep: 2005 3.7L WK
 
Join Date: Jan 2010
Location: Philadelphia,PA ----> Trenton, NJ
Posts: 1,602
Thanks: 31
Thanked 14 Times in 14 Posts
Rep Power: 3394
soontobesrt has a reputation beyond reputesoontobesrt has a reputation beyond reputesoontobesrt has a reputation beyond reputesoontobesrt has a reputation beyond repute
Re: Why is the towing capacity so low?

Quote:
Originally Posted by webspoke View Post
It's probably a transmission or differential limitation. The chassis is capable in the 5.7 versions, with and without air suspension, but the transmission is not the 545RFE used in the 5.7's and trucks. Add in the extra torque and power and it probably taxes it, and maybe the colling system too.

hmmm, so even without the air ride the non-SRT is capable of towing 2200-2500lbs mores. Doubt the tranny/diff would limit it as everything the SRT used is the same part or one built for more power than in the 5.7s. The NAG1 is as capable as the 545RFE from everything Ive seen/heard and the rear diff in the SRT8 is a ZF ELSD which is very strong. The regular GC's either have the standard open rear diff I believe or with QuadraTrac II have the same ELSD as in the SRT8. So all in all, I dont see those driveline components being the limiting factors. Im going to bet its part of the suspension tuning system being as they use the same technology but different computer maps for the trucks. Just by ruling things out we can get an idea,

The 6.4 is capable of towing the load, the chassis is as strong or stronger than the regular GC's, the air ride is clearly not a determining factor as shown above. The driveline in the SRT8 is as strong as the normal as the W5A580 has been proven and the diffs that are offered are the same throughout the lineup so they can clearly handle the load. Only thing there could be like you said the added torque/hp of the SRT8 combined with he weight may be the reason but I doubt it, these drivelines are really strong, people have no idea I dont think haha. Seen stock WA580s take 750hp+ consistently with some tuning and some new shift solenoids. Lots of guys have even raced with them successfully for some time.

Don't know much about the specific ELSD used here, not sure if they are ZF's or not but Im going to assume they are pretty strong, safe to say since the SRT8 is already throwing some big power at it and they need to be built to handle all of that with some leeway for more plus last a decent amount of time. Anyone know anything about the ZF ELSD?


The SRT8 suspension is here:

"Short - and long-arm independent (SLA), coil springs, Bilstein Adaptive Damping Suspension (ADS), upper- and lower-control arms (“A” arms), stabilizer bar Rear - Multi-link rear suspension, coil spring, Bilstein Adaptive Damping Suspension (ADS), aluminum lower control arm, independent upper links (tension and camber) plus a separate toe link, stabilizer bar


Some info on the Bilstein ADS, or as they call it - (ACD):

http://www.bilsteinus.com/products/m...c-systems.html


Read from page 40 onward, good info. some info on Daimler-Chryslers Active Suspension in there
http://www.scribd.com/doc/51365510/6...ein-Damptronic


Not to sure if this is what we have or not, but if so seems its a first in the passenger car/SUV sector. This specific system from Bilstein has only been used on motor-homes it appears so should be interesting to see how it works. Unless this isn't the exact system then I dont know. This may just be another Contract between Chrysler and them to make these specifically for the SRT8s so it wouldn't be on the site. Same thing as with the Brembos on the Jeep and many other cars, they make OEM applications but you have to get the parts through Jeep or an aftermarket vendor, cant find get them from Brembo directly.
__________________

Mods: A Bunch



Reply With Quote
  #10  
Old 05-12-2011, 12:57 PM
jgc4ever's Avatar
Senior Member
My Jeep: 2012 5.7L WK2
 
Join Date: Mar 2011
Posts: 3,212
Thanks: 0
Thanked 78 Times in 69 Posts
Rep Power: 1160278
jgc4ever has a reputation beyond reputejgc4ever has a reputation beyond reputejgc4ever has a reputation beyond reputejgc4ever has a reputation beyond reputejgc4ever has a reputation beyond reputejgc4ever has a reputation beyond reputejgc4ever has a reputation beyond reputejgc4ever has a reputation beyond reputejgc4ever has a reputation beyond reputejgc4ever has a reputation beyond reputejgc4ever has a reputation beyond repute
Garage
Re: Why is the towing capacity so low?

I just saw a WK2 hauling a long nice camper trailer headed West on I-80 through Omaha.
__________________
Reply With Quote
  #11  
Old 05-12-2011, 05:11 PM
Marlin's Avatar
"The Aussie"

My Jeep: 1981 5.7L CJ
 
Join Date: May 2009
Location: Licmye Bawlls
Posts: 9,362
Thanks: 65
Thanked 16 Times in 15 Posts
Rep Power: 81004
Marlin has a reputation beyond reputeMarlin has a reputation beyond reputeMarlin has a reputation beyond reputeMarlin has a reputation beyond reputeMarlin has a reputation beyond reputeMarlin has a reputation beyond reputeMarlin has a reputation beyond reputeMarlin has a reputation beyond reputeMarlin has a reputation beyond reputeMarlin has a reputation beyond reputeMarlin has a reputation beyond repute
Re: Why is the towing capacity so low?

I have a theory..... maybe 5000lbs is the maximum the hitch mount and tow ball can take before an SRT launching at full throttle just plain rips it out of the back of the Jeep?

Hey, it's plausable, the things launch hard, and they need to engineer/warranty things for even abusive owners.
__________________
Reply With Quote
  #12  
Old 05-13-2011, 08:56 PM
Premium Member
My Jeep: 2012 6.4L SRT8
 
Join Date: Dec 2010
Location: Ormond Beach FL
Posts: 1,544
Thanks: 0
Thanked 22 Times in 21 Posts
Rep Power: 2942
mjw930 has a reputation beyond reputemjw930 has a reputation beyond repute
Re: Why is the towing capacity so low?

Owning a 2011 Overland and having towed over 5000 lbs more than 2500 miles I'm pretty sure the limiting factor is the same as it was on the old F-150 Lightnings, a combination of the spring rates and the tires, it's certainly not the drive train or the chassis.

The 5000 lbs is probably there because the suspension can only take 500 lbs of tongue weight without causing too much of a rear drop, front rise. The manufacturer can't spec a tongue weight less than 10% of the trailer weight so 500 lbs of tongue weight means a 5000 lb max trailer.

I was hoping they would put the rear helper airbags on the SRT8 when the tow package was ordered like they do on the 2WD WK2's which would add the spring rate needed to support 720 lbs tongue weight my Overland can support. If they are using the self leveling secondary air bags then I have no idea what the issue is.

Honestly, I think with a proper WDH and a well balanced trailer you would have no trouble towing an enclosed car hauler with a track car, just like the Porsche's and VW's do without air suspension. (or my 16' enclosed MC trailer )
__________________

__________________
2012 Grand Cherokee SRT8 Black/Black
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 On
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Roof racks, rails and load capacity?? Overland-North Trouble Shooting/Problems/Service 10 04-23-2012 08:16 PM
RHB Radio Storage Capacity rwshelburne Audio/Visual/Navigation 2 01-14-2011 05:54 PM
Towing capacity Pats2011WK2 Grand Cherokee - WK2 - 2 11-24-2010 01:04 AM
Does anyone know the capacity for Power Steering fluid? lewi3069 Grand Cherokee - WK 5 09-26-2010 07:15 AM
2006 Jeep Grand Cherokee Laredo, towing capacity Jaimie Grand Cherokee - WK 18 07-15-2010 09:43 AM

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 11:41 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Copyright 2012 - JeepGarage.Org
The Jeep Grand Cherokee Owners Community