optimal shift points .....5sp

[j894]

might take my truck to the strip to make a few passes on Fri.

Just wondering what the optimum shift points would be for the 4.3 with a stick?
If I wind out say, 1st past 5k RPm Im reving out of the power a bit, but when I shift to 2nd will be more in the "meat" of the power.

when Im about to shift to 3rd & dont rev high enough it wont go as good when I do get it into 3rd, but.. I dont wanna spend to much time at the end of 2nd.

It takes longer to spin out of the power the higher the gear you go, so when is it to much?

[Mikz86TA]

In mine 1st seemed really short stock. With the mods I feel its stronger but still dont rev that high. 2nd I can hold longer also but from experience it is deceptive that you can hold it longer and still be pulling. 3rd will ride out. My biggest issue is the 2nd to 3rd shift. Im overcautious bescause of an accidental missed gear shift....throwing it back in 1st.....not good.

[j894]

another thing, Im not sure what the ET will be, but I should be around 80mph maybe a litle more. But I'll be pushing 4600 in 3rd at 80, after which it seems to be slowing. I doubt I would hit 85 in the 1/4., but 85 is about 4800-4900rpm......

at that point Im guessing I should leave it in 3rd around the end of the track? rather than shift to 4th & waste time

[Mikz86TA]

Depends on if its the 1/8th or the 1320. I see now you have a blazer. Im guessing that os what you intend on running. Its a 4x4, 4.3 and manual? Your gearing and weight are going to be much different in its resopnse than my truck. Your gears are most likely 3.42s or higher numerically. I have 3.08s stockers. Extra weight over the tires and steeper gears will definately give you more throttle to lay into it off the start since your traction is going to be better. I would guess you should be able to work out the 60ft times easily first. Basically concentrate on getting off the line quickly with a strong reaction time and getting as much throttle without spinning. Then work on feeling the power band out on how long to hold it in 1st. Then working on your quick 1-2 shift with out breaking the tires loose. Then its working on the 2-3 shift that is easily missed. About shifting......some prefer to keep full throttle and spike the RPM when shifing. But you gotta be shifting with a quickness. Some lay off and let them drop. Which is safest but not best by means of times. Try working on an intermediate way where you slightly lay off the throttle just as you start to move the shifter and lay back on it just before clutch re-engages. Hard to do effectively but IMO its the best way. Ive been working on it from time to time and it seems like the best way from the seat of the pants feeling.

[nomaboy]

usually you can run as many times as you want. just start shifting at different RPM's until you get a best time. every truck is different and it is impossable to give you a cirtain rpm you should shift at. just keep in mind that most people don't run their best time on the first pass, usually takes some time to get the hang of it.

[Mikz86TA]

"most people don't run their best time on the first pass, usually takes some time to get the hang of it." Nor reaction times! Hehehehe My 1st time and my 1st pass was kinda funny. I waited until the green was absolutely lit.....probably others thought I was at a trffic light and had to look both ways B4 moving Hehehe Then I nailed it and spun the tires for a while Oh, burnout B4 staging...now I get it. Hehehe

[j894]

I went yesterday, first pass I missed 3rd lol.
made about 4 passes total, missed 3rd on pass #1 &3. best i got was 17.1... dont know if the track wasn't prepared or what but I spun really bad slipping out the clutch, i don't have that problem on plain asphalt. Might of been because of the damn waterbox, the way they had it setup you could not go around it. other cars prob drug the water on to the track. Although, it spun pretty bad in 2nd also.

The only run I didnt have traction problems was my last one, because I tried taking off in 4HI, But I ended up taking off ****ty & bogging a little. I have a 4th timeslip I have to find, but I think its in my car somewhere, Its similar to the other anyway.

17.832 @ 75.5....11.26 57mph 1/8....2.48 60", first pass, missing 3rd
17.1 @ 79.5 ..10.99 62.5mph 1/8. 2.47 60"
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17.39 @80...11.23 63mph 1/8...2.725 60" ....4Hi

I one of the things that seems to be killing my MPH is the spacing between 2nd to 3rd gear. No matter if I wind out 2nd to 5200rpm or not, When I shift to 3rd it seems to hit a dead spot in power, it doesn't bog but it seems to have to build momentum before it starts going good in 3rd... that & Im a novice driver..

any advice?

[nomaboy]

looks like you get a better launch in 2wd looking at your 60' times. even if you did spin off the line. so i would definatly run in 2wd from now on.

[xtreme canuck]

mine is a bit more flat in third...takes a second to feel the truck really pull. i changed from the 308 to 373 gears and went for one drive and then changed them back . it ruined cruising for me... in 5th gear at 75 mph it was reving over 3000 . if you like highway cruising i would not recommend it .

[Mikz86TA]

This is why Im doing 3.42s one day in place of the 3.08smine is a bit more flat in third...takes a second to feel the truck really pull. i changed from the 308 to 373 gears and went for one drive and then changed them back . it ruined cruising for me... in 5th gear at 75 mph it was reving over 3000 . if you like highway cruising i would not recommend it .

[j894]

My truck has 3.42s with 235/70r15s.... cruises at around 2200 in 5th.

I think the reason the 60" is low with the 4x4 run is I screwed up the takoff. I only used 4x4 for 1st gear. As soon as I switched to 2nd it switched back to 2wd. Push button.

I think i might get some exhaust work don't soon. I hear what sound like my Cat rattling sometimes after startup. Weird that it doesn't always do it? Not sure if its the precat, or the main one.

o2 sensors seem to be original also, they aren't setting a code, but I wonder if it would run better with new ones.

[holsinger17]

The only run I didnt have traction problems was my last one, because I tried taking off in 4HI But I ended up taking off ****ty & bogging a little.


it is not all that good for you 4 wheel drive and drivetrain all together trying to launch your car quickly off the line while 4 wheel drive is engaged.....there are many very expensive parts that can get broken doing such....i'd say find a sweet spot on taking off so you don't spin tires and do not use your 4HI when launching your truck

[j894]

I'll worry about that thanks.

There are plenty of people that do the same thing & beat it much worse that I have, having much more power than I have ...not having any problems. Ask 1fast4by on s10 forum. He runs 14.1 if i remember right, with his stick 4x4 s10. With 3000rpm launches, obviously making a ****load more power than I, and has broken the rear diff., and a few transmissions, not the transfer case, or fwd components.

Likewise, there are typhoons & syclones, making 800hp, running 9seconds with the stock transfer case, front diff, but with a 8.5 rear rather than a 7.5 (doc hover),...also having no problems. Main difference between the 2 is the transfer case.

There are weaker links than the transfer case, on these trucks they are rated for more power than the trans. Its not like I was dumping the clutch at 3000rpm, pulling out while towing would more likely put a bigger load on it.