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Re: Cut those bump stops..

To: "Daniel Neuman" <dneuman@stars.sfsu.edu>
Subject: Re: Cut those bump stops..
From: Ronnie Day <rday@airmail.net>
Date: Tue, 13 Apr 1999 17:06:04 -0500
>       Okay I am confused...Ron are you talking about the front or rear
>suspension??  I suppose if I remove the bumpstops and take them to 
>work wear I have a bandsaw and belt sander I can shorten them and still
>retain that tapered engage moe gently aspect???
>       sheesh I thought this was going to be easy!!

Actually, now that you mention both ends (I'm pretty sure you installed 
the front NISMO springs with the rear), you'd probably want to cut both 
ends, but not so much as to allow the shocks to bottom out, the coil 
springs to stack solid or to slam the moving parts of the suspension hard 
against the stops.

The purpose of these egg shaped rubber things to prevent the suspension 
bits from getting to this point, in the stock setup. Thinking about it 
I'd guess that the egg shape gives a progressive resistance as you 
compress the bump stop into the fatter part of the egg. If you can 
restore that shape to the shortened bump stop, fine, but remember that 
the whole idea is to prevent hard/sudden contact. When that happens your 
spring rate effectively becomes infinite, but the (kinetic?) energy in 
the moving parts still has to be dissipated, often by something bending 
and/or breaking. At the very least Tom Walters<G> loses another filling!

One of the annoying facts of automotive life is that if you lower a car 
without moving the suspension pickup points upward (not usually 
practical) to compensate for the amount the car is lowered, you reduce 
suspension travel. You can (maybe) get some, but usually not all, of that 
lost travel back by triming these bumpstops. On the front of the 510 
these are actually donut shaped gizmos that you put on the rod coming out 
of the top of the shock/strut assembly, and yes, mine are cut down.

FWIW, Ron


________________
Ronnie Day
rday@airmail.net
Dallas/Ft. Worth
'71 510 2-dr (Prepared class autocrosser)
'73 510 2-dr (Street Toy)


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