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Gremlin Traction Woes

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WesternRed View Drop Down
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    Posted: Oct/15/2020 at 10:50pm
We had our fist run of the new season down here in the southern hemisphere on Wednesday night and I couldn't get the car off the line all night, 60's times were 2.1 or worse. The Gremlin previously hooked up fine off the line with 60' times around 1.70-1.75. MPH is roughly the same (around 112), but ETs were way off due to the poor launches, high 12's vs high 11's previously.

The only thing I have changed on the car over winter is the ignition and I now have timing control via the Holley Sniper ECU and I can't see that making much difference unless something was seriously wrong before.

I'm running 275/60/15 Mickey Thompson ET Pro radial tires, hard to imagine they would go off over the winter?

The most likely scenario is lack of track prep as these are just street meets and the big events don't start for another month or so, then the track will be prepped a bit better, but you are still running on the dregs at the street meets anyway.

So the task at hand is how to improve traction/launch on a poorly prepared track? I even tried launching in 2nd for one run and still had traction issues. In the past I could just load it up on the convertor and release the brake with minimal traction issues. Looking for quick fixes and maybe longer term strategies to make things better.

For reference, the Gremlin is stripped out and runs a 360, 727 and AMC20 rear, no bumpers and weight is around 3000 lbs with driver installed.

Looking at moving weight around, about the only thing I can think of is moving the battery from the engine bay to the rear, but this would only be an incremental change.

Should I consider putting the rear bumper back on, the original is destroyed, but I have the front bumper, which is even heavier with the reinforcement and could be mounted on the back. Trade off between more weight over the rear tires helping traction vs more weight overall slowing it down.

Now that I have a fancy programable ignition system, should I look at retarding the timing at launch RPM? If this is a possible solution, where do I start? I can set it up for timing to be all in by say 5000 rpm, which is what it drops to on the shifts so it would only see lower timing off the line. Convertor stalls around 3000 on the brake and flashes to around 4000 rpm. How much timing would you take out and where would you start feeding it back in?

Suspension is essentially factory with slapper bars on the rear and competition engineering drag shocks all round, set 90:10 on the front and 50:50 on the rear.

I did change out the front springs last season for stock 6 cylinder ones reducing the spring rate from 350 lb/in (Aussie V8 Rebel springs) down to 260 lb/in, but I still feel they are too stiff to really help much with weight transfer. Where can I buy some dedicated drag springs to liven up the front end?

Rear would be tired 6 cylinder factory leaves plus the slapper bars. When it's stalled up on the line, the bump stops on the slapper bars would be hard up on the front spring eye. Not sure what improvements I can make here as I'm not convinced Caltracs would be a big improvement, stiffer or softer springs perhaps?

Technique, any thoughts here or anything else I can work on?


Edited by WesternRed - Oct/15/2020 at 10:53pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 6768rogues Quote  Post ReplyReply Direct Link To This Post Posted: Oct/15/2020 at 10:57pm
I would move the battery because weight you have to haul with you is better in the rear. I would not add weight, it might help the tires grab but you have to move it. You are on the bottom of the world, gravity works backward?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hogman Quote  Post ReplyReply Direct Link To This Post Posted: Oct/16/2020 at 7:32am
W/R, I Didn't Read anywhere in Your Post about the TIRES Going up in Smoke, so, this May be a Mute idea. IF they are Smoking, I Truly Have to rump U ME, You Have been Drag Racing for Some time, & KNOW How to get the Tires Ready to LAUNCH for a Run Down the Strip. IF they are going up in Smoke, OBVIOUSLY That Would be a Good Part of the Problem. YES, I'm SURE You Knew that...... Anywho, IF that's what's going on, COULD You Temporarily BORROW a FRESH SET of Skins for a Day/Night to Try? Tires going off seem to be a Common problem up here.........  JUST TRYING to Help Sir.
GOOD LUCK!!!!  Thumbs Up
Forgot to Mention PRESSURES As Well............





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Post Options Post Options   Thanks (0) Thanks(0)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Posted: Oct/16/2020 at 8:53am
Ah yes, tires going up in smoke, although maybe not literally, basically stepping out big time at the rear and having to get off the gas. I usually try to hold the burnout as long as possible to heat the tires, which may not be that long in the scheme of things, but start the burnout in 2nd and shift into top. Not having somebody outside of the car watching probably doesn't help with the diagnosis, but from my end, not doing anything differently, although I did try a few things to see if it made any difference.

Tires started at 17 psi then dropped to 14 psi, that didn't seem to help.

Was mention of others having similar problems, which adds a bit of support to the lack of track prep theory, but hey, no-prep drags are all the rage these days, so there must be ways to make it work.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote XJ6 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/16/2020 at 9:07am
Try a leaf spring clamp on the front halves which essentially changes them into ladder bars. Do you still have rubber bushings on leafs and control arms? Poly up front will increase quicker transfer aluminum out back in the eyes is better than rubber for racing. Cal Tracs work great with their mono leafs 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Posted: Oct/16/2020 at 9:35am
Rubber bushings everywhere except the spring perches at the moment.

Also think it might be sitting a bit high at the front, I did cut half a coil off the new springs to bring it down a bit so that I now have about 2.5" of available extension at the wheels.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Posted: Oct/17/2020 at 2:27am
So battery relocation would be a US$150 exercise but the time I buy a box, cable and isolation switch, worth it or not?

In the front suspension as a quick fix I could remove the spring isolators and add some spacers to the shocks for a little more extension potential, maybe another inch or I could cut another half a coil off the spring but that is obviously irreversible and would increase the spring rate a little.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Posted: Oct/19/2020 at 9:18am
Since we were talking about getting rid of the rubber bushes in the front suspension, any thoughts on the Opentracker roller bearing conversion for the front control arms? The Control Freak coil over conversion is probably way beyond my budget and I'm not sure if it's more pro touring than drag orientated? 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote XJ6 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/19/2020 at 3:42pm
The opentracker control arm kits look nice but in addition to the price there is precise fabrication/welding involved and seem to be oriented more for road racing/handling. Maybe start with a full poly conversion including the perches and see how that works first if on a budget. Getting a Gremlin to hook is challenging but can be done. Here is a Gremlin that appears to have a Cal Trac setup and soft front springs running some impressive ET

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Post Options Post Options   Thanks (0) Thanks(0)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Posted: Oct/19/2020 at 4:48pm
Originally posted by XJ6 XJ6 wrote:

Here is a Gremlin that appears to have a Cal Trac setup and soft front springs running some impressive ET


Now that's what I'm talking about. I notice the front end actually squats on the line and it has way more suspension movement than mine. Would love to know what the suspension specs are on that thing.

And here they are:

Up front, the suspension is stock AMC with Viking double adjustable shocks. At the rear Caltracs traction bars, split mono-leaf springs, and double adjustable Viking shocks complement the Ford rear.




Edited by WesternRed - Oct/19/2020 at 4:54pm
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