therieldeal
therieldeal New Reader
2/5/19 12:03 p.m.

In the near future I’ll be picking up an Escort Wagon with a bone-stock Escort GT drivetrain.  I think it’ll make a great part time rallycross car!  I have confirmed that since the wagon body style never came with a BP, I will have to run in Mod FWD class.  Seems a little bit silly, but thems the rules… so much for keeping it stock haha!

I have some ground control coilover sleeves, stock type struts, and even some camber plates kicking around… leftovers from recent upgrades on my autocross car.  I figure I can just add some softer/longer springs and end up with something that’s at least some amount better than stock.

What I’m wondering is… anyone have any spring rate suggestions for a car like this?  How about spring length?  For those unfamiliar with the chassis it has macpherson struts all the way around and will weigh somewhere around 2500 lbs with driver.  I’d be racing with NER at whatever sites they normally use.   Yes, I am a complete rallyx noob.

As an aside I’ll also be doing my first fly & drive to pick up this car… driving it home from CO back to CT.  Any tips?  I have several friends & family who live roughly along the route so I’m only planning to drive about 500-600 miles per day.

_
_ Reader
2/5/19 12:31 p.m.

Don’t forget, you can DIY some home brew coilovers from eBay and the get a spring coupler to give you dual springs. This leads to “half” the spring rate if the top and bottom springs are the same rates. Did this on a rallycross car and it bumped my atrociously hard 450lb spring down to 225, where it felt good. This was also a Mac strut, 2500lb car. 

Edit: don’t forget new shocks, even if they have to be stock. 

¯\_(ツ)_/¯
¯\_(ツ)_/¯ UberDork
2/5/19 12:33 p.m.

How much travel?  Any idea of the corner weights?  Can ballpark something with those numbers pretty easily if we know the suspension design (mcstrut front, beam rear?)

therieldeal
therieldeal New Reader
2/5/19 12:41 p.m.

In reply to _ :

That is a great tip on the spring coupler idea!  Since I’m probably going for stock height or higher anyway I might be able to use pairs of more common, short, high rate springs.  I have short 300# and 200# springs already that came with the sleeve kit.

Shocks can literally be whatever I want since I’m stuck in Mod class due to the engine swap.  I’m aiming for cheap & effective, and to use as much stuff that I already have lying around as I can.

therieldeal
therieldeal New Reader
2/5/19 12:43 p.m.

In reply to ¯\_(ツ)_/¯ :

I don’t have the car yet but my Escort GT, with all its turbo bits & driver is ~2550 pounds and ~65% front weight.  The wagon will probably be about the same total weight but not quite as front heavy.  Macpherson strut x 4, i can check the travel on the struts this evening.

captdownshift
captdownshift PowerDork
2/5/19 12:48 p.m.

280-340lb front and 140-180lb rear

Tim O'Neill and Jen Horsey both ran these many moons ago, I previously had been WAY too stiff in the rear until talking to them. 

¯\_(ツ)_/¯
¯\_(ツ)_/¯ UberDork
2/5/19 12:52 p.m.

My guess is around 275 lbs/in front, 150 lbs/in rear then, assuming a decent amount (like 6" or so) of travel and decent bumpstops and shocks.  Stiffer if you can't let it move that much due to short travel or something.

Looking at Rock Auto, I have no idea what to tell you for shocks, looks like everything is pretty much junk.  Maybe just run it stock with really big cushy bumpstops?

therieldeal
therieldeal New Reader
2/5/19 12:59 p.m.

Yeah there’s not much out there other than stock replacement shocks, too-short Taiwanese tarmac coilovers, and custom/expensive way-too-serious gravel coilovers.

Since this will be a budget build  & also used as a stuff-mover/backup daily driver, I’m going to stick with stock type shocks and 2.5” coil springs, we’ll see how it turns out!  Thank you for the spring rate suggestions.  These are actually stiffer than I was expecting to hear so I’m glad I asked.

 

 

therieldeal
therieldeal New Reader
2/6/19 9:28 a.m.

So I didn’t actually measure the struts, but I realized I can get the travel information from the interweb.  According to KYB:

  • Front: 6.42”
  • Rear: 8.19”

I assume that this is the total stroke of the strut, so I’d have to subtract bump stop (~1”?) and top hat/bearing (~0.5”?) thicknesses from it, leaving ~4.9" of available travel.  So the way I see it my compression travel would look something like:

  • 250#: 1.8”
  • 275#: 2.1”
  • 300#: 2.3”

What’s more important at rallycross, bump or droop travel?  Obviously they are important for different reasons so that’s a tough question … HMM.

Also it looks like my stock spring rates (according to Moog) are approximately:

  • Front: 156
  • Rear: 113
¯\_(ツ)_/¯
¯\_(ツ)_/¯ UberDork
2/6/19 9:39 a.m.

Bump travel is more important as long as you don't have so much preload and so little droop that you're topping out the suspension and lifting wheels off the ground.

I'd include the bumpstop in your travel calculations, use progressive foam ones which can compress down to nearly zero height, and plan to adjust the spring perches to set the thing around stock ride height.  I'm sticking with my original spring rate suggestions based on that travel.

Jay_W
Jay_W Dork
2/6/19 10:30 a.m.

Captdownshift is on the money. That is prettymuch the spring rate my bg protege has and I ain't complaining. 

Oh and remove swaybars or at least disconnect em.

therieldeal
therieldeal New Reader
2/6/19 11:27 a.m.

In reply to Jay_W :

Hey Jay!  How’s the protege holding up these days? Have you been racing much?

FooBag
FooBag Reader
2/6/19 4:16 p.m.

I've got a front and rear corksport strut tower bars for this platform that I'd sell you for $100.  They're not pretty, but there's nothing functionally wrong.  I conveniently live just west of Chicago too, so you could pick them up on your way through...  devil

 

therieldeal
therieldeal New Reader
2/6/19 4:52 p.m.

In reply to FooBag :

That's awesome - yes i will absolutely take them!  Send me a PM/email with your details & I'll add picking these up to my itinerary :). I can either paypal you ahead of time or pay cash when i pick them up.  I have the exact same ones on my Escort GT!

Note: I won't be coming through until April or May so if you need them out of the way sooner, we'll have to figure out shipping.

FooBag
FooBag Reader
2/6/19 5:02 p.m.

Cash when you come by is totally fine.  They're just collecting dust in the garage attic at the moment, so pick up in April/May is all good.  I had forgotten about them until I saw your spring rate post. laugh

captdownshift
captdownshift PowerDork
2/6/19 5:24 p.m.

In reply to Jay_W :

I keep the rear connected for assist with rotation, but the front is long gone from my setup. I know leaving the rear bar connected leaves some articulation on the table, but being so softy sprung I don't worry about it effecting the ability of the front to put power down since the limited slip has gone in.

iceracer
iceracer UltimaDork
2/8/19 4:59 p.m.

In reply to ¯\_(ツ)_/¯ :

FiST spring rates.:  Front 154 lb/in  Rear 131 lb/in     Front bar:   21 mm.

Knurled.
Knurled. MegaDork
2/9/19 8:25 a.m.
captdownshift said:

In reply to Jay_W :

I keep the rear connected for assist with rotation, but the front is long gone from my setup. I know leaving the rear bar connected leaves some articulation on the table, but being so softy sprung I don't worry about it effecting the ability of the front to put power down since the limited slip has gone in.

 

I stopped being convinced that traditional suspension tuning means anything, on a bumpy loose surface, after doing some experimenting.  Granted, this was with an open diff, not a clutch type limited slip or spool.

 

In a nutshell, I firmly believe now that handling (in the sense of getting the car to do what you want) boils down to weight distribution and grip.  A nose heavy car will always handle like a nose heavy car.  Grip, basically boils down to don't let the front suspension bottom out or lift off the ground.  Rear suspension is not critical except in that it must not upset the front.

 

That last part is key.  If you have a stiff rear suspension "for rotation", and you hit a bump with the inside rear, it will unload the inside front, causing it to lose grip.  Furthermore, on a loose surface, getting high weight transfer to the outside on an undriven axle actually increases grip at that end, so under many situations you will be adding cornering grip there, not reducing it, as long as the outside tire is able to maintain contact without stuttering.

 

The best suspension setup I had in a front driver KEPT the front sway bar, doubled the front spring rates, and lowered the rear slightly with stockish spring rates, and adjustable rear shocks on full-soft.  The relatively stiffly sprung front kept body roll down, so the front suspension stayed off the bumpstops without requiring dampers so stiff that it stuttered (the problem with stiff spring/no bar setups).  Lowering the rear, a trick I had been doing since I played with an 80s Golf, also cuts down on body roll without having to screw up the suspension, and the softish settings mostly just kept the rear of the car from dragging on the ground, minimizing how much it upset the front end when it hit something rough.

 

The kicker was when I watched Leon Drake annihilate MF with his Caddy.  Many people paid attention to his tires.  I noted that his car was the only one in MF that didn't have the back end bouncing all over the place, it stayed low and steady and never upset the front, so he was able to keep putting power to the ground pulling through and out of corners.  (Having a well supported drivetrain that didn't flop around causing wheelhop, a nice WIDE powerband - thanks 16v engine - and fast steering helped exploit this too)  He had mentioned offhand that he spent a lot of time getting the rear shocks sorted... everyone looked at the tires though.  It's nice when you don't need to misdirect people smiley

Knurled.
Knurled. MegaDork
2/9/19 8:34 a.m.

This thread makes me want a front driver again.  The key would be to find a chassis that is super easy to swap axles in a hurry, because if you are serious with a front driver you will break axles.  I'm thinking front drive Impreza, if those even exist anywhere anymore.  Replace the F.U. roll pin with a clip and an axle swap should be doable in under five minutes.  If I remember right the axles are the same left to right, which means fewer spares to stock.

 

On the other hand, with many Golfs you don't even need to disassemble any suspension parts to get the axle out.  But rallycrossing a VW means you will also get intimate with transmission replacement and 020s are thin on the ground nowadays...

Jay_W
Jay_W Dork
2/9/19 12:22 p.m.
therieldeal said:

In reply to Jay_W :

Hey Jay!  How’s the protege holding up these days? Have you been racing much?

I am very slowly as finances and time allow, piece by piece putting Humpty together again. Am still hoping to run Olympus but that is starting to look less realistic.

 

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