Getrag Speed range per gear?

[JGrefenstette]

I was just wondering. i saw a video online of a guy with a 92 cummins tearing it up pretty bad. and i looked like he was shifting through the gears increadibly later than i do in my 93. now i dont know if he still has the getrag or not, but it seems so.

my question is:



2nd gear - what speed do you shift at (i shift at 15mph)

3rd gear - " " " (i shift at 30mph)

4th gear - " " " (i shift at 45mph)

5th gear - whats the fastest you would go (i dont think ive got it over 70mph)



i have the 3. 56 rear end the getrag. and 35 inch BFG allterrains. the tires throw of the speedometer a little bit. when my speedo says 52mph im really going 60mph. or at least thats what ive calculated by driving along side my dads car.

thanks

yall

 

[Dieselman359]

I think that last time I checked I could reach ~55mph in 3rd, and 90+mph in direct. I have no idea how fast my truck would go, in 5th over it runs about 2100rpm @ 100mph. Do you have a 3200GSK? If not, you need one!

 

[PToombs]

I don't pay much attention in lower gears. I know 4th is good for 93 -94 mph, and I've been about 110 in 5th, but my off ramp was coming up a little quick.

The key is don't lug it. If there's a cop or I'm trying to low key it, I'll short shift. Otherwise, I wind it up between 2500 and 3000. Try not to run below 1800, especially under load, like a hill, or towing.



By the way, if I'm on it hard, I shift at 33-3500 rpm.

 

[JGrefenstette]

yea this is good to know, see i dont have a tach in it yet. it came in the mail yesterday and i havent wired it up yet. ive been really curious to see if im just really short shifting it or if my truck has some sort of issue. my speedo works half of the time, so im usually just guessing when to shift, and i rarely 'wind' it out. where to these trucks redline at stock? i thought it was like 2800rpms. is it safe to hit 3500rpms with a stock truck?



who knows, i probly have been driving my truck like an old lady, and havnt hit half the potential?

 

[JGrefenstette]

by the way... . how expensive? and how dificult? is the 3200gsk???

 

[JGrefenstette]

ok, i just installed an isspro 4k rpm tach. it futters and dosent work right untill i hit 1500 rpms, but thats a different thread.

i realized though, that ive been shifting at about 1800rpms in every gear!

i was getting it up just past 2000rpms and it felt like if i tryed to get it to 2500 or even 3000 it would explode. how do you possibly get your truck to wind out so much????

 

[dpuckett]

Add more fuel so you dont have to push the pedal down as far to get the same results. :-laf I hardly ever give mine more than 1/3 throttle, and I can still get to 3000rpm pretty fast. My truck is good to the 90mph range in 4th, with some pedal left.



Have you adjusted your valves? If they are loose, it will rattle more, making it seem like its working harder than it is.



Check the slack in your throttle linkages. I know, Pete, Chris, and I all have tight throttle linkages.



For your tach, check your connections, and make sure they are good and tight. For splicing, solder and heat shrink- pass on the butt connectors.



Daniel

 

[JGrefenstette]

good to hear from you daniel.

i hardly press down on the pedal at all. its really responsive. the valves probly do need adjusting. but i just dont see how its possible to get it to 90 in 4th. my truck is totally stock. can it be done with a totaly stock truck???

i would be curious to drive with one of yall and feel one of these 1st gens crank up like that, i just dont know if my truck could handle it, or if its cause im just inexperienced with it. i do know that im not gonna rip it too hard untill i get an egt gauge in it.



good advice about soldering instead of the butt conectors. i like your way much better. ill give it a try.

 

[PToombs]

A 3200 isn't bad to do. Go slow, pay attention, and really pay attention to your shaft/throttle lever marks. Springs from $15-$20. More if you get a gasket kit. I pulled mine, then went to the fuel shop and got just the throttle shaft o-ring, and the cover gasket.

Mine winds cause I have the 3200 gsk, and I lined everything up just right!

I put in 60# valve springs too. If you are going to wind it above 31 or 3200, put them in, all of them!

If the truck doesn't smoke too much, wind it right up! If you lug it and it's smoking like a pig, that's when EGT's will be up.

 

[JGrefenstette]

ok... so what is a safe rpm redline or maximum rpm for my truck?

 

[PToombs]

The way it is now? You can run it til it defuels and you're not gonna hurt it. It should start to defuel from 2600 -2800, but it will wind to 3000 or 3100. This is loaded, ie; driving. If you sit there and hold your foot on it? It'll climb high enough to scare the pants off you! :-laf

 

[JGrefenstette]

hahah, ok then. thats very good to know. thanks, and i dont think ill be sitting there flooring it in nuetral anytime soon

ill put up some pictures of the tach install. i had to get creative when i realized i didnt have a mount for it youll know what i mean when you see the pictures.

 

[glhs]

With 30. 5" tall tire I can run 100+ in 4th.

4100+ rpm is attainable with 60# springs, 366 spring and more timing.

Having my pump set at 1. 65 mm I can feel it trail off at 3400 rpm a bit. If it's set at 2. 25 mm it trails off at ??????.

 

[PToombs]

Mine is set at 1. 65, dyno chart says it starts to drop at 2800, but seat of the pants says 3500! At 35, it just goes away, done!

 

[JGrefenstette]

good gosh. i now understand why i need to get my truck out of the "stock" catigory and do valve springs, gsk, turn up the IP, probly new injectors. then i could probly do what yall are talkin about. but as of now, i have not taken it over 2200rpms. it seriously feels like it would blow up if i did.

in 5th when the speedo says 60mph (acctually going a little over 70mph cause of the tires) im cranking 1800rpms. ive ben shifting between 2000rpms and 2200rpms.

 

[JGrefenstette]

With 30. 5" tall tire I can run 100+ in 4th.

4100+ rpm is attainable with 60# springs, 366 spring and more timing.

Having my pump set at 1. 65 mm I can feel it trail off at 3400 rpm a bit. If it's set at 2. 25 mm it trails off at ??????.

my speedo stops at 100... if you can top out the speedo in 4th gear what in the world do you do with 5th gear!?

 

[rumblefish]

put 'er to the wood... . you have a governor for a reason

 

[JGrefenstette]

so your sayin its perfectly ok to rev it up till it wont go anymore, while in gear???

 

[therabbittree]

yup thats what a governor is for... speed in gear ... i need to finish my dump bed and report back to you speeds with getrag and 3. 07s... its fast. .

 

[dpuckett]

... but as of now, i have not taken it over 2200rpms. it seriously feels like it would blow up if i did.

Check the fuel pressure between the lift pump and injector pump, preferrably after the filter. That is a phenomenon I have noticed- it gets noisy when supply pressure dips below about 3-4psi, esp at higher RPM (2200+). Minimum spec from Cummins is 3psi, with a stock IP. With a modded pump, I dont like to see less than 5.



DP