Guys, for those who run leaf springs and Cal-Tracs, have you noticed better reaction times when using the upper holes? I've never tried the upper holes myself, but will on the first test and tune weekend.

One of my chassis tuning books indicates that using the upper holes will 'hit' the slicks harder, but for a shorter period of time.
And using the bottom holes gives a softer, but longer hit.

I'm a foot-brake racer and am desperate to cut my vehicle reaction time, but adding a lot of horsepower is not an option at this time.

Thank you much!
Troy

The top hole will hit harder. Usually a harder hit will improve VRT but you really have to try it because each combination is different.

The biggest opportunity when footbraking is to stage at idle and bring the rpm against the converter after staging.

I'm gonna say no ....... We've tried both upper and lower and really found out the car doesn't know the difference lol We race at one track that's super loose, and we've tried just about everything minus the transbrake and can't get to were we need to be hitting it in his "normal" spot.

Are you deepstaging now ???

In theory you would think so, but I wouldn't expect anything measurable.

I've only ever used the top hole.

quote:

Originally posted by Bad Nusz:
Guys, for those who run leaf springs and Cal-Tracs, have you noticed better reaction times when using the upper holes? I've never tried the upper holes myself, but will on the first test and tune weekend.

One of my chassis tuning books indicates that using the upper holes will 'hit' the slicks harder, but for a shorter period of time.
And using the bottom holes gives a softer, but longer hit.

I'm a foot-brake racer and am desperate to cut my vehicle reaction time, but adding a lot of horsepower is not an option at this time.

Thank you much!
Troy

How hard the tire is planted is relative the setting on the rebound adjuster of the damper/shock, and the capacity of the damper to build force and rearrange the energy of the rear end into heat within oil/gas within the damper, according to the setting on the adjuster.

Whomever wrote this chassis book must have taken the damper completely out of the equation. I'd like see this on the track though, it wouldn't work.

A high bar top hole is a faster reacting suspension setup relative the same variables.

Bad Nusz, Rather than limit the discussion to your Cal-Trac settings, why not widen the scope to include any factors that will improve (shorten) your VRT? (Since that is what you are trying to achieve with the post).
There are some well-known, common tactics to quicken your VRT, (increase tire pressures, raise launch RPM, deep stage if allowed, tighten compression on rear shocks, limit front suspension travel, smaller diameter front tires, etc); and a few lesser-known things as well. See if you can get guys to open up their bag of tricks and share some with you.
If all else fails, and you can't Deep Stage, you can always resort to counting bulbs - I did that for many years, and had more than my fair share of success with it.

quote:

Originally posted by FootbrakeJim:
Bad Nusz, Rather than limit the discussion to your Cal-Trac settings, why not widen the scope to include any factors that will improve (shorten) your VRT? (Since that is what you are trying to achieve with the post).
There are some well-known, common tactics to quicken your VRT, (increase tire pressures, raise launch RPM, deep stage if allowed, tighten compression on rear shocks, limit front suspension travel, smaller diameter front tires, etc); and a few lesser-known things as well. See if you can get guys to open up their bag of tricks and share some with you.
If all else fails, and you can't Deep Stage, you can always resort to counting bulbs - I did that for many years, and had more than my fair share of success with it.

Thank you, Footbrake Jim (and all others). I recall a post where you mentioned successfully counting the tree. That is what I do now, but I don't seem to be as good at it as I was a few years ago. Could be aging. It's tough of course, as one does not have a good, solid reference point on the tree to launch.

I have been looking too at other factors to increase my vehicle reaction time, not the least of which is to switch back to a much higher stall-speed converter that I used to use years ago. I could not launch at any higher RPM that I do now with a lower-stall converter (about 2500 RPM, but my brakes are better these days.

Oddly, it sounds to me, but one of the very top foot-brake racers at my 'home' track launches at only 1,500 RPM with his big-block Scamp, and he admits to having to wait at the bottom bulb.

Lol, I wonder sometimes if I've been launching at too high of an RPM. A tech at Calvert Racing told me that one should launch at about 1,500 RPM less than what his converter stalls at. I'd never heard that before, and always adhered to the wisdom or "wisdom" of launching as high as my brakes would hold.

I've dabbled with deep-staging some and it still seems awkward. The lady who manages my track says that people always red-light when they do that. I may have to revisit that.

So I am sortof looking for a 'magic bullet' that will make a big difference; something that I'd overlooked for years.
I've been reading a lot about racing suspensions lately and have learned a lot. I'd always thought that "shocks don't matter", especially with my lower-horsepower (high 11's) combo.

I've ordered a pair of Calvert 90/10 shocks for the front, otherwise my S10 has stock suspension, save for Caltracs. This may be the time then for adjustable rear shocks anyway.

If my local track test and tune weekend doesn't get rained out/snowed out again this spring, I'll be able to have a lot of time to play around with settings.

As it is, with some adjustments one day last summer I was about run several rounds with my 60-foots varying by an extreme spread of about .005 seconds. Lol, I don't want to mess that up either. If I could only shave off about .05 second off my average RT, I could slaughter 'em.

Thanks again!

quote:

Originally posted by Mike Rietow:
[

How hard the tire is planted is relative the setting on the rebound adjuster of the damper/shock, and the capacity of the damper to build force and rearrange the energy of the rear end into heat within oil/gas within the damper, according to the setting on the adjuster.

Whomever wrote this chassis book must have taken the damper completely out of the equation. I'd like see this on the track though, it wouldn't work.

A high bar top hole is a faster reacting suspension setup relative the same variables.
[/QUOTE]

Thanks, Mike. Cool pic. What book is that from? I thought I had nearly all the drag chassis books. I'm seriously considering new rear shocks now.
Lol, my 'instant center' must be right on the neutral line or something, as observers claim that my S10 neither squats nor separates on launch.

Deep stage it. That's your quickest, easiest, cheapest, and best solution. Been there, done it (still doing it), and teach many students to do it.

quote:

Originally posted by Bad Nusz:

Thanks, Mike. Cool pic. What book is that from? I thought I had nearly all the drag chassis books. I'm seriously considering new rear shocks now.
Lol, my 'instant center' must be right on the neutral line or something, as observers claim that my S10 neither squats nor separates on launch.

The picture may be from a book, I dunno. It is one anyone can easily understand, so I downloaded it to share when these types of questions arise.

The best chassis book by far is the Jerry Bickle book. Read it with the curse of knowledge in mind (look that up if you don't know what it means). If you can read it with the concept of the curse of knowledge in mind, you can learn something new (intricate aspects) just about every time you pick it up, as your experience in drag racing increases.

You have figured out you have chassis problems but have not determined exactly what they are or how to fix them. Once you do the reaction times will come around. For now do not worry or even think about reaction times. Just try to stage shallow and same every time. Get the car to transfer weight, hook rear tires and shocks to control it and then you will be good.

If your car is spinning at the hit or popping front wheels out of beams your reaction times will be all over the map.

Your problem could be wrong converter or carb or some other issue but from what we know I think you have chassis issues you need to resolve first.

I think the OP has most likely already indicated where his traction woes originate. OP you can trace the suspension according to the neutral line using the leafspring forward the axle center-line as the top bar. An IC on the Neutral line works well on a high powered car on radials and a well prepped track progressing power to keep the radial tire from deforming, none of which apply's in your combo. If it were my truck, I'd lower it which will move the IC below the neutral line to get it to pitch rotate at the hit. Or I'd add ballast as high in the bed as I could over/behind the back tires to accomplish the same result. Or a little of both

Strategically placed ballast is always your best friend.

This message has been edited. Last edited by: Mike Rietow,

quote:

Originally posted by Brktracer:

The biggest opportunity when footbraking is to stage at idle and bring the rpm against the converter after staging.

and I also found the RTs to be far more consistent when bringing the RPM up after staging.

quote:

Originally posted by Mike Rietow:
I think the OP has most likely already indicated where his traction woes originate. OP you can trace the suspension according to the neutral line using the leafspring forward the axle center-line as the top bar. An IC on the Neutral line works well on a high powered car on radials and a well prepped track progressing power to keep the radial tire from deforming, none of which apply's in your combo. If it were my truck, I'd lower it which will move the IC below the neutral line to get it to pitch rotate at the hit. Or I'd add ballast as high in the bed as I could over/behind the back tires to accomplish the same result. Or a little of both

Strategically placed ballast is always your best friend.

I can’t run weight that high in the car. We tried it. Pitch rotates too hard. We ended up with 60 in front of the pinion 50/50 crank /cam. 54% front end. Now the car goes out then up. Does not yank the tires out of the beams.

quote:

Originally posted by stk 758 BP!:

quote:

Originally posted by Mike Rietow:
I think the OP has most likely already indicated where his traction woes originate. OP you can trace the suspension according to the neutral line using the leafspring forward the axle center-line as the top bar. An IC on the Neutral line works well on a high powered car on radials and a well prepped track progressing power to keep the radial tire from deforming, none of which apply's in your combo. If it were my truck, I'd lower it which will move the IC below the neutral line to get it to pitch rotate at the hit. Or I'd add ballast as high in the bed as I could over/behind the back tires to accomplish the same result. Or a little of both

Strategically placed ballast is always your best friend.

I can’t run weight that high in the car. We tried it. Pitch rotates too hard. We ended up with 60 in front of the pinion 50/50 crank /cam. 54% front end. Now the car goes out then up. Does not yank the tires out of the beams.

I can dig it.

That's my high gear only 4.10 gear setup I'm gonna do some Super Pro bracket racing, 6.40 dial in. It'll be in low gear for 3 tenths of a second after transmission brake release. 6.40 around 113 mph oughta make it interesting.

I lowered the pickup point as well, so it'll be a slower reacting suspension than previous.

This message has been edited. Last edited by: Mike Rietow,

Bad Nuz if your truck neither squats or separates maybe rear spring is too stiff or is bound up/ Check mounting points to be free.By that I mean bolts should be loose but double nutted to retain.If spring is too stiff it wont have any stored energy to hit tire.

Seems like we went down this road once already with the OP's S-dime....

Here's my take again:
Remove weight from the front of the truck, add horsepower, launch 1500 RPM below converter stall (likely 1000+ rpm higher than where your brakes cant hold any more), add travel limiters to the front, add more power (get a big block), remove unsprung weight from the front (spindles, control arms, brakes, lighter rims, lighter tires, etc), swap in a rack and pinion, 4 wheel RACE disc brakes (wilwood, strange, aerospace etc.). Biggest improvement ive seen is getting the weight off the truck and get 4 wheel, medium duty, race brakes on it.

quote:

Originally posted by TD6297:

quote:

Originally posted by Brktracer:

The biggest opportunity when footbraking is to stage at idle and bring the rpm against the converter after staging.

and I also found the RTs to be far more consistent when bringing the RPM up after staging.

Thanks, guys. What I've always done was to pre-stage, bring up the engine up to launch RPM, then bump into the staged beam.
I'll have to try your method then.

Ironicly, I was thinking of installing a two-step rev limiter (I will need it someday for a transbrake anyway) and using it as an aid to footbraking. I would fully stage, engage the two-step, then floor the throttle with the top bulb lighting.

I imagine I would need to have a brake pressure switch to de-activate the two-step at the launch.

quote:

Originally posted by Mike Rietow:

quote:

Originally posted by Bad Nusz:

Thanks, Mike. Cool pic. What book is that from? I thought I had nearly all the drag chassis books. I'm seriously considering new rear shocks now.

The best chassis book by far is the Jerry Bickle book. Read it with the curse of knowledge in mind (look that up if you don't know what it means). If you can read it with the concept of the curse of knowledge in mind, you can learn something new (intricate aspects) just about every time you pick it up, as your experience in drag racing increases.

Thx again, Mike. Does the Bickle book cover much on leaf spring suspension? I'll probably break down and spend the 60 bucks for the book. Lol, if it gives me just one tip that helps me win just one more money round, it'll pay for itself.

quote:

Originally posted by vetman:
Bad Nuz if your truck neither squats or separates maybe rear spring is too stiff or is bound up/ Check mounting points to be free.By that I mean bolts should be loose but double nutted to retain.If spring is too stiff it wont have any stored energy to hit tire.

Thank you, vetman. One my list this next month is to take a hard look at my rear spring shackles; I know now the theory about why suspensions must move freely.

The rear leaf springs are stock. Old, and stock. I imagine that being truck springs they may be somewhat stiffer than car springs?

Listening to guys I race with, I may have put too much pre-load in my Caltracs.

At any rate too, I'm throwing I bet at best 350 HP at the tires.