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Re: [GMCnet] Rear end Ride Height [message #140177] Sat, 20 August 2011 08:16 Go to previous message
Gary Casey is currently offline  Gary Casey   United States
Messages: 448
Registered: September 2009
Karma:
Senior Member
The front wheel castor angle changes 0.4 degrees for every inch change in height difference (lower the rear by 1 inch and the castor will increase  0.4 degrees).

Rob gives a link to a previous discussion on rear ride height.  I won't repost the discussion, but I have some comments on the comments:
1.  Changing front or rear height doesn't change the weight distribution at all (okay, there would be a minute change - and I mean minute)
2.  They wanted to get the fuel to flow to the rear tank?  Why not just lower the rear tank - lots easier.
3.  Reduce the "dive" on braking?  The braking weight transfer depends only on the height of the CG.  The dive depends on the front spring rate and the "anti-dive" geometry built into the suspension (there is none).

I don't like the rear lower than standard because I already tend to drag the rear once in a while.  But there is a real reason to lower the rear - the lower the suspension pivot points the less the rear-to-middle axle weight shift on braking.  That depends on the angle of the line drawn between the pivot and the contact patch.  But why wouldn't they have just lowered the pivot point?  There is ground clearance available to do that.

There is an aerodynamic reason to lower the front compared to the rear - the overall drag goes down and the lateral center of pressure moves rearward.  This does good things for fuel economy and response to gusts and crosswinds.

Gary Casey


Since no one has commented on your question I would suggest you click on the
link below and review what is being posted in response to the thread
entitled "Why was GMC setup to ride low in the rear?"

http://tinyurl.com/42d37gg

Someone calculated the effect on caster for each inch you drop the rear end
but I can't find the email.

Regards,
Rob M.
Sydney, Australia


-----Original Message-----
From: Wayne Lawrence

I have done every thing that I can afford to get max caster and I still
would like a wee bit more.

As you lower the rear end the caster gets better. Please share your thoughts
on running with the rear end lower then stock. The front end is at the stock
height. What are the limiting factors on how low can you go. 
-- 
Wayne
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