strategies to limit dive?

[craigb]

This post stems from having my 113 on the track for a run (see post in general). Hard braking into a corner and then accelerating through it is fine, but where you have a kink followed by a long sweeper in the other direction it was very hard to get that clean with the rear swing axle jumping about as weight transferred front to rear. I think if the car remained flatter (more rebound dampening in the shocks?) it would be a whole lot more predictable.

If you look at the video link in general, you will see the rear end pick up under brakes and with the swing axle the wheels then swing down and become closer together. Back on the power and the wheels move out again which is not such a big deal in a straight line or putting power down in a corner with a bit of wheel spin, but in this long sweeper where you are trying to line it up with some power before putting the boot in hard to pull out of it at the appropriate time, initially the back seems to step out in the wrong direction etc.

Anyway, I reckon if I could limit the dive, the problem would be solved. I don't intend to continue wearing out my low mileage W113 on the track, but I am looking at running a 3.5 W108 I have with a LSD next year and the principles should be the same. Also PC777 is running a W108 and any advice would be appreciated.

[dixy2k]

I am sure that the more mechanically inclined members will suggest plenty good stuff, but in my opinion (since nose dive is a common problem with W113's) stiffer suspension will do the trick. There are lots of pages on the nose dive during braking on this forum which all include stiffer springs and better (maybe even adjustable) shocks.

[Benz Dr.]

The LSD works wonders for these cars. The forward jump you get coming out of a corner is very good. It's like a totally different car.
This ia a VERY rare option in 113's and might be more rare than a 5 speed. I've only ever seen about 2 or 3 over the past 20 years. They come standard in a 6.3 but that axel won't work in our cars. The actual parts might though.

[psmith]

I have heard that progressive springs will help.  Look for the video of Jim Villers at Blacklick, lots of great info on front suspension.

[tel76]

I have just removed the front axle from the 280sl that i am restoring and slotted in between the coils of both springs are about 20 square plastic inserts,was this an attempt to cure this problem many years ago?I asked NAJ about this a few weeks ago and he suggested thats what they were for. Eric.

[Longtooth]

Why won't Olsen publish or provide the spec's for his coil springs?

There's a lot more information on the issue of Olson's Progressive vs just stiffer springs on the thread "Progressive Springs" in the Research & Development Forum.

How many levels of progression are there? Is there only 1, or are there 2? 3?  At what force or displacement does each level occur?  How does each level compare to the standard spring's spring rate?

For those that would like a better description of progressive vs linear springs, this link gives the best non-technical description and comparison I've come across. http://www.fennelfamily.com/gti-vr6/suspension/spring_explanation.html

Olson's charging $1060 for a set of 4 progressive springs http://www.slmarket.com/springs.htm  ... add shipping ($20 minimum) and state sales tax where it applies (say 8%), and you're spending nearly $1150 for 4 springs.  Considering you pay before you know what you're getting that's a bit of a stretch in trust, but mostly because there's no objective measure of what you're buying.  Why no specs?  I've written to request them and have never received a response.  Why no response at all?  I've even asked him just to send pictures of the progressive front and rear springs next to the standard springs shipped with the W113. No dice.

Olson's charging for his reputation (which is authoring books on MB's)... he's not a performance guru fer christ's sake?  Where's his qualifications as a performance specialist?  I think, my opinion only, that he doesn't publish the spec's in order to limit his competition for both linear and progressive springs for MB's... and at a overcharge of at least $500 for a set of 4 springs, imo.  Using his status as an author on classic MB's history, and his position as Director at Large for MBCA, he's charging for his position within the MB enthusiast community. In an affiliated website ["Visit our online store: Mercedes-Benz Market Square, which is brought to you by Greg Magnus and John R. Olson, Inc."] the price for the progresive springs is $799 (set of 4).  Interesting that Olson's site charges $1060, while his affiliated site charges $800...a $260 (25%) price reduction. http://amgmarket.com/marketsquare/store.php?page1-category-id36.html

I challenge anybody to objectively discern a "25% - 30%" firmer condition that he advertises in "hard braking, cornering..." etc.  

A simple corollary is buying an "HD" TV... if there were no spec's defining what "High Definition" meant to each mfg'er, how would one discern that a price of $750 provided more or less "high" definition than a set from another mfg'ers "HD" TV priced at $1500... with no sample TV's to view before hand!  How would you even know it was any better than your standard TV before you bought and paid for it?  What's Olson's return policy, by the way?  He doesn't mention it on his websight, nor the affiliated site that I could find.  Since he specifically specifies "all orders are custom built", it may be reasonably assumed that there is no return policy in fact.

Buyer beware.

[abe280SL]

I remember when I was a kid in the 70s there use to be spacers that you could place between the coil space and twisted to keep it in place.  It use to serve two purposes...raise it a little and stiffen things up.  I don't know if they still exist, but your plastic inserts probably serve a similar purpose.  The only thing I remember it gave the ride a banging feeling when going over bumps...not springy enough.
Now for the positive...when you step on the accelerator and force the first gear...your nose rises.  Now, its not going to change 0-60, but it really feels faster when that nose goes up and you sense a little xtra G force.  
abe

quote:Originally posted by tel76

I have just removed the front axle from the 280sl that i am restoring and slotted in between the coils of both springs are about 20 square plastic inserts,was this an attempt to cure this problem many years ago?I asked NAJ about this a few weeks ago and he suggested thats what they were for. Eric.