Ride height question

[kevins2]

Originally Posted by patrickt

...The world will come to an end ....

Well, I certainly wouldn't want to add yet another reason for the world coming to an end. Enough of those out there already

[patrickt]

Now, if you just happen to have 16 bathroom scales sitting around.... Or, more likely, you just order 16 of them off of Amazon, set your corner weights, then return 15 of them for a refund saying you accidentally hit the wrong key on your smart phone when you placed the order.

[Bernica]

I have heard of folks renting the scales from race shops in the past. Also, if you visit a track day event, you will most likely see a few guys with them who may offer some help or a loan. Ask around at your local Cobra Clubs too.
Good luck!

[ERA Chas]

Originally Posted by kevins2

It's supposed to rain hard tonight and tomorrow, so hopefully it will and wash all the salt off the roads so I can get it out for a drive. That would be a great Christmas.

Kevin

Some un-asked for but serious advice about the 'first drive'.
Don't bring anyone in the car with you-that's for when it's debugged and carefree.
Drive around your own block until temps and pressures come up. Until you're bored if you have to. Easier to push home if needed.
Avoid hilly terrain.
Drive in areas where you need to brake as well as accelerate-get the brakes warm.
Have a chase car with a nylon tow strap follow you; even if just around the neighborhood.
Go during full daylight hours.
Avoid desolate areas; in case you need help pushing.
Bring a simple tool box in the chase car. You may need to adjust the idle or move the distributor for example.
Especially have a vice-grips in the car with you-always. I snapped the shifter clean off at 80MPH on a 2-3 shift and used one clamped to the stub to drive home.
Watch in this order; the oil pressure, water temp and amp gauge (or volt meter).
Head back at the slightest sign of abnormal readings.
That's 3 decades of 'first drives' after building, rebuilding and modifications...
Oh and corner weighting the car is fine, especially if driven hard or on track-but don't go nuts.
You're getting hammered by cornering wiz Pattie who's greatest need for corner weighting has been the 15 MPH traffic circle near his fave restaurant...

[patrickt]

Originally Posted by ERA Chas

Some un-asked for but serious advice about the 'first drive'....

I think you should try punching the throttle hard, say, about half way around your very first turn. I think this "the rear end comes out from under you" stuff is just a bunch of malarkey. Or, you could just pull in to your favorite fancy restaurant, throw the kid at the valet station a twenty, along with the keys, and tell him "break it in for me, you'll be doing me a favor."

[Bernica]

All excellent advice from Chas!

I am searching for the YouTube of PatrickT drifting and throwing smoke around that traffic circle!.

[kevins2]

Thanks Chas, good advice and I've already followed most of it - have about 85 miles on the car. My first "drive" was about 12 trips up and down my driveway (172' long, so not as ridiculous as that sounds). The reason was it was late in the day and didn't want to get caught out in the dark if I needed to tow it home for some reason. Driveway was long enough to get some speed to hit the brakes hard enough to make sure they at least work. Also, got a feel for the clutch.

The next day I drove about 40 miles by myself and got the car up to 60 and braked hard a number of times, including some down hill braking. All this within walking distance of my house on some back roads. Didn't take tools or a chase vehicle, but had my cell phone and my wife at the ready to come to my rescue if needed. Have a tow strap. Also have been diligent about watching the instruments. You may recall the defective fuse. Fortunately, I was watching the instruments and noticed the temp creep up a bit and shut it down before it overheated. Still waiting on Patrick to conduct the fuse test he suggested.

So, not too bad for a newbie...

[ERA Chas]

My one regret is that I never installed 500-600 pound springs. I ran the more or less 'standard' 250 / 350 combination and for a 'street spring' car it was very controllable on track with TD's and BB's. In later years, I went tracking less and less so never did.
I think several guys ran stiff springs on the street and I think Ernie was one.
Not living in Manhattan, I could have easily lived with it.

[ERA2076]

Originally Posted by ERA Chas

My one regret is that I never installed 500-600 pound springs.

Damn Chas that's a lot of spring - I think JBL designed around 175lb effective Wheel Rate - Moving the top of the front shocks outboard a few degrees

300 => 173
350 => 201
500 => 287

I'd be afraid it would skip right across the track.

chr

[scottj]

Originally Posted by ERA2076

Damn Chas that's a lot of spring - I think JBL designed around 175lb effective Wheel Rate - Moving the top of the front shocks outboard a few degrees

300 => 173
350 => 201
500 => 287

I'd be afraid it would skip right across the track.

chr

For the track I run 800F/800R and shocks with a lot of nose (C4 Vette susp). No skipping.

[ERA2076]

Originally Posted by scottj

For the track I run 800F/800R and shocks with a lot of nose (C4 Vette susp). No skipping.

Scott - do you by chance know the motion ratio?

x-chr

[scottj]

Originally Posted by ERA2076

Scott - do you by chance know the motion ratio?

x-chr

MR: 0.76 F / 0.71 R
Shock angle: 25° F / 15° rear

Front WR .76² x 800 x .82 = 379 lb/in
Rear WR .71² 800 x .93 = 375 lb/in

I run 236/195 WR on the street with much lighter damping.

[ERA Chas]

Originally Posted by ERA2076

Damn Chas that's a lot of spring - I think JBL designed around 175lb effective Wheel Rate - Moving the top of the front shocks outboard a few degrees

300 => 173
350 => 201
500 => 287

I'd be afraid it would skip right across the track.

chr

Nahh- Joe Rodameister ran 600's on his FIA and was a track terror. Was at reputed 600HP with a Danny Bee Windsor too-iron block IIRC. Never took his granny for a ride though...
Say now Cliff, there's a guy you might like to compare notes with-maybe Peter or Bob can put you in touch with Joe.
Bob did a beautiful design of the 'new' rear. I'd have liked to do the later rear but did not want to hack up the car after I got it all purdy. If only to bleed outboard brakes...
So I improved the Jag with vented rotors, and bullet-proof guts-it never failed. Just heavier than I'd have liked. The no-upper-control arm never caught me out but it did have its limitations compared to the later rear.
Richard made JBL's like rocket sleds with low ride height, engine placement and then - state of art components and layout. Can't compare the two chassis.

[scottj]

The JBL wheel rate of ≈175 is for the street... it also has adjustable roll bars up to 1200 lbs/in.

[kevins2]

My original question in starting this thread was regarding ride height and it somehow morphed into corner weighting, which is fine - lots of good information and debate here. This past Monday I had an opportunity to visit a local race shop. Very impressive - there were 10 - 12 carbon fiber bodied Porsches in there and a couple of street cars - a Ferrari and an Aston Martin. The owner built and owned an ERA a number of years ago. My point is he certainly has a lot of credibility on this topic so I asked about corner weighting. They have scales and a perfectly level floor area for that purpose and routinely corner weight the race cars to within a couple of ounces. He offered to corner weight my car but then added that it isn't worth the effort unless I plan to track the car. I like Patrick's idea of at least knowing how far off it is so I'll get them to put it on the scales this Spring to see where I'm at. As for my original question about ride height, it is now exactly to ERA specs and the alignment is right on.

One thing that suprised me a bit is that the ERA manual indicates rear ride height can be adjusted by changing just one of the double coil-overs on each side. I would have thought it best to keep them exactly the same but apparently that's not a big deal.

Kevin

[patrickt]

Originally Posted by kevins2

One thing that suprised me a bit is that the ERA manual indicates rear ride height can be adjusted by changing just one of the double coil-overs on each side. I would have thought it best to keep them exactly the same but apparently that's not a big deal.

Not on the ERA rear -- it's only got one shock per side, and the spring on that baby is 550lbs.

[kevins2]

Obviously I'm talking about the Jag rear...

[patrickt]

Originally Posted by kevins2

Obviously I'm talking about the Jag rear...

Yes, that was the other great regret for Chas... that he never upgraded to the ERA rear.

[ERA2076]

Originally Posted by patrickt

Yes, that was the other great regret for Chas... that he never upgraded to the ERA rear.

It is a beautiful piece -