Spring Sprong - advise needed.

[merv]

Ok, Techy Question, and has been asked before, but I'm never happy so here we go again.

It relates to spring rates. Now relax, I'm not going to go preaching, but I do want opinions of folk that know what they are on about so I guess this is the forum - huh?

I run a 1993 D90, hard top, 200tdi + heavy bumper (aka Ivor special home made version 1) + Milemarker winch. so up front - pretty heavy. There is NO rollcage, but that just reduces rear weight.

When off roading the back is heavy enough - Tools, recovery gear etc. Spare wheel (35-12.50 on steel) hangs off the back.

I'm running OME springs. 764's up front, 763's on the rear . that's 220 lbs on the front, and 360 on the rear. I'm running Ranch 9000 shocks (5000 miles, 6 months old) and have the front set to 4 and the rear set to 5.

Problem: The back bounces. Going along a reasonable road, it bounces enough to be anoying. I *think* that it's because the spring is too hard for the Rancho 9000 to damp it and it's abotu to bounce allong. I've tested the rancho's (removed them and manually operated them - nearly gave myself a hernia) and they are fine.

so: softer springs are in order I guess, I've chatted with Jamie and might be getting his 764's when he takes 'em off, or should I be looking for something different.

Comments? Advise? Abuse?

Merv.

[Jtisdale]

Merv,

I run the 764's front and rear with 1" spacers in the rear to level it out. I think with substantial gear in the back the 764 may be a bit soft for you. I've got a ST and even with a moderate amount of parts/tools or just one passenger, I can feel it sagging a bit. Take into account that my springs are several years old and may be worn out. Take a look @ rovertym's custom SP-1(I think), it gives ~2.5" of lift(what I seem to get from the 764s with spacer) and is a progressive rate of 260-300lbs. Haven't used em but have heard a few good things regarding them.

Johnathan

[rhills]

Techy answer:

Off road racers run softer springs (relative to the weight) in the back than in the front to keep the front in high and the rear end closer to the ground. On my rig (SW with very little weight in the back), I notice that when I run 220 lb springs front and back, I also get too much bounce from the back. When I go to softer rear springs (say 180 lbs) in the back, the d90 can take high speed bumps off-road with much more control. Unfortunately, the soft rear springs makes rock crawling much more tippy. So I just run my 220 lb rear springs and live with it.

A side note. I recently took off my hard top and the bed. The top weighs 130 lbs, the rear door 57 lbs, and the bed just under 130 lbs. The bed weight does not include the weight of the seats and the seat belt attachments (i.e., the roll bar looking stuff that is under the bed).

Rich Hills

[Old Scout]

what angle are the shocks?

[rhills]

Shock angle - stock

I'm running bilstein which (if I remember right) has more rebound damping than stock or ranchos

[RockRover]

Originally posted by rhills
Techy answer:

A side note. I recently took off my hard top and the bed. The top weighs 130 lbs, the rear door 57 lbs, and the bed just under 130 lbs. The bed weight does not include the weight of the seats and the seat belt attachments (i.e., the roll bar looking stuff that is under the bed).

Rich Hills

Ooooookaayyy Rich. I'll bite. What's goin' on here...I know you like to hold out until "formal" anouncements, but remember...No matter how you slice this pie, we're just a bunch of red-necks that like to wrench. So let's just dispense with all the formalities shall we? That way you can let us know WHAT THE HECK ARE YOU DOING?!!

--D

[Jtisdale]

Rich,

I'm curious to know why you removed the rear half of your D90...are you up to something????

Johnathan

[rhills]

Lets just say I'm thinking about it.

[RockRover]

Fawkin' newbie

[RockRover]

I do have to admit, that a partner in crime (on this side of the world) would sure make my nip and tucks a little less...Uh...Stressfull?

--D

[Jtisdale]

Come awwwn man, tell us!

Johnathan

[rhills]

I'm having trouble with my connection, so if you see this message twice, please ignore it.

I have been experimenting with GRP to make body panels and a top for my d90. I want the highway comfort of the hard top, but don't need all of the space. An extended cab would give me the right amount of space and make it less likely to hit trees and such. I would also like to replace the front wings with GRP versions. If any of you have a US source for these, let me know. I plan to chop these high, put my head lights into hot rod light housing, mount them like Doug's, and chop off much of my front bumper.

The roll cage also needs to be replaced. After taking off the stock cage, I can see why they bend so easily. My goal is to make these changes in a fashion so that I can experiment with different suspensions and WB's over the next few years. My goal for next year's Chile Challenge is just to do the rear body panels and top. The following year will focus on suspension, axle, and WB changes.

Rich

[RockRover]

GRP? Huh...Green Racing Products? Huh? Are you telling me that I didn't have to chop my bed?

[rhills]

GRP - Glass reinforced plastic - fiberglass for short.

I have been playing with home built aircraft techniques for GRP. Woven fiberglass rather than blown fiberglass. Foam cores where flexibility is not required. This results in a much lighter structure than your typical boat construction. I made a 8" square piece 1/8 thick and was able to bend it in a vice around 30 degrees without damage and 90 degrees with internal delamination, but no external separation. In talking to our body shop man in the 4x4 club, he says that reparing fiberglass is much easier than repairing steel panels.

I'll use a white gel coat, and then paint it Alpine White. That way scratches won't show very much.

My main concern is the surface finish. I don't want it to look like plastic. So it will need a bit of uniform texture.

I do not plan to make any cuts to my frame until I know that I can make the final product look good.

If all goes well, then I do not plan to use my old bed. The main reason I am doing this is it will provide a lot of flexibility in vehicle configuration. I can store my old body parts outside for the day I decide to go back to stock.

We should probably start another thread if we discuss this further.

Rich Hills

[merv]

Originally posted by Old Scout
what angle are the shocks?

The shocks are angled forward a helluvalot. There are 3 bolts holding on the shock mounting. If you draw a line through the bottom one and the upper/forward one, the shock mount is about 9" along that line.

This weekend I plan to make them more upright to see does that help give me back some damping. (I'm hoping the holes are drilled such that they are reversable - i.e. that I can swap the mounts from side to side and that way the line will be throught he bottom bolt hole and the upper/rear bolt hole if you follow. If not, a little drilling/modding will be called for. They are home made mounts so that's ok.

Merv.

[Old Scout]

Originally posted by rhills
GRP - Glass reinforced plastic - fiberglass for short.

I have always heard it called FRP (fiberglass reinforced panel) Is GRP the same or different?

Just go Kelvar!

[rhills]

Same stuff.

[dcrover90]

I know it's a bit late but is your rear-end bounce a new problem? Is it violent? Could you have a bent wheel or a tire severly out of balance?

[CT]

Merv

I'm running 764s all round and the 90 handles like a POS on corrugations compared to the softer rear springs I used to run. It just skips over the top of the corrugations and steps out at the back. I'm going to try it with some more weight in the rear (it's a hardtop with 33" spare so quite lightly loaded normally) and see if it helps improve the handling some, otherwise I'll be trying to find a rear spring that's a bit softer than the 764 (but as tall). The 764s are nice and predictable (not tippy) but I do too much driving on logging tracks and prefer to drive with the back wheels following the front ones...

ct

PS check out Rays little mishap - never let the guy in front be too aggressive in a recovery when he's around a corner or... http://www.cortina.org.nz/documents/patrol.html