Jump to content
SAU Community

What Rpm Do You Flat Change At? Double Clutching?

TUF250
 Share

Recommended Posts

TUF250 Proficient

TUF250

Posted
Posted

Hi folks,

My GTSt has the typical notchy, crunchy gearbox particually into second from first.

I have just put soem redline oil in it but I want to reduce the wear on it where possilbe. Now I dont want to flat change without the clutch but I thought if I shift at about those revs it might put less strain on the synchros? is this true or not? If it is then what rpm is best first to second?

Also what is the proper way to double clutch? This is my first manual car and I can drive it well normally but still trying get my head around all the rest of it.

sorry for the newbie type questions but I know I will get the right answer here

Thanks

Duncan Grand Master

Duncan

Posted
Posted

well, the simple answer is the synchros are there to look after the gap in revs between gears.

eg if you shift from 1st to 2nd at about 40klm/h you will have to go from 5000rpm to 2500rpm. The quicker you move the gear shift and release the clutch, the less time the engine has to get from 5000 to 2500.

So the best way to look after your gear box is:

1/ back off the throttle

2/ move the shifter from 1st to neutral

3/ let the revs drop from 5000 to 2500 (depends on gears and road speed of course, this is just an example)

4/ move the shifter from neutral to 2nd.

If you do exactly that you will have basically no wear on the synchros...but you will have slow gear changes which is why all gearboxes have synchros these days. If you get the steps above right you also will not have to use the clutch but you may as well incase you miscalculate.

Downchange is the opposite

1/ back off the throttle

2/ move the shifter from 2nd to neutral

3/ blip the throttle to 5000rpm (depends on gears and road speed of course, this is just an example)

4/ move the shifter from neutral to 1st.

Once again, if you get it spot on the shifter will go straight in, and you won't need to use the clutch.

In practice you should be able to do everything above with some practice, just use the clutch in case you get it wrong. Driving like this minimises the wear on the synchros, but once they are stuffed nothing apart from removing the box and replacing them really fixes it.

bubba Grand Master

bubba

Posted
Posted (edited)

Do you mean "rev matching" as opposed to "flat shifting"??

If you're talking about driving it like a crash box, in trucks it's more about roadspeed than revs in a gear (you will change up or down at particular revs but which gear you grab depends on your roadspeed, which in a truck is hugely affected by road gradient), because we have wide powerbands and fewer gears, it's harder to rev match in petrol cars and is by no means an efficient/economical way to drive.

I have had to shift without a clutch when I snapped my fork pivot, was an absolue ass of a thing to do but it was 3am and I had to get it to the workshop.

Edited by bubba
Harey Veteran

Harey

Posted
Posted
Hi folks,

My GTSt has the typical notchy, crunchy gearbox particually into second from first.

I have just put soem redline oil in it but I want to reduce the wear on it where possilbe. Now I dont want to flat change without the clutch but I thought if I shift at about those revs it might put less strain on the synchros? is this true or not? If it is then what rpm is best first to second?

Also what is the proper way to double clutch? This is my first manual car and I can drive it well normally but still trying get my head around all the rest of it.

sorry for the newbie type questions but I know I will get the right answer here

Thanks

Mine is also very notchy from 1st to 2nd. Doesnt crunch but just takes a bit to get in there. Also downshifting from 3rd to 2nd is a bit hard to get in. All other changes are fine, must be something to do with second gear.

I used to change pretty hard, now I take more care.

bubba Grand Master

bubba

Posted
Posted
Mine is also very notchy from 1st to 2nd. Doesnt crunch but just takes a bit to get in there. Also downshifting from 3rd to 2nd is a bit hard to get in. All other changes are fine, must be something to do with second gear.

I used to change pretty hard, now I take more care.

Double de-clutch with a throttle blip and it should go in real nice like. Also works to get it in to 1st gear while rolling.

Deano 1 Mentor

Deano 1

Posted
Posted

dude just use the clutch... your goin to do more damage crunching gears tryin to learn to rev match than you will just using the clutch.

but if you insist goin from 4th to 5th is the easyest one so start there

Trozzle Grand Master

Trozzle

Posted
Posted

I've taught myself to double clutch on up and downshifts, thanks to the shithouse gearbox in the good ol' VL commy....now I'm getting a bit lazy with the skyline, but I certainly change slowly regardless.

I'll only ever throw it through the gears quickly when I'm driving hard, and then I will ALWAYS double clutch.

my box is a little notchy with 1st-2nd, and 2nd-3rd. Downshifts don't feel notchy, just tight. Strangely though, 2nd-3rd isn't a crunchy kinda feeling, but as it goes from neutral to third without the double-clutch, it feels like 3rd says "naww f*ck off" and gives it a little kick back towards neutral :S

joeyjoejoejuniorshabadoo Grand Master

joeyjoejoejuniorshabadoo

Posted
Posted

i've had my car for 4 years now... the car is still daily'd and makes 300rwkw on the stock gearbox with a c's short shifter to really make it stressed

i have always treated the box like shit.... smash every gear change when i drive hard,(i do heel-toe on down's tho) flatshift when i need to keep them spinning and things like shoving it into first gear from 6k in second to get round cones. oil was never changed.

when i killed clutch this year we looked inside the box and it's still perfect. filled it with motul oil and it crunches 4th a tiny bit now.... but meh... i'll throw some shockproof in there when i get round to it...

moral of the story? gearboxes are replacable and in the scheme of things not that expensive... RB25 boxes are great from the factory and you shouldn't let a cheap, replacable part let you enjoy your car any less....

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • MBS206
      Duncan's V37.......race car?

      By MBS206 · Posted

      Even more fun, leave all the ADAS stuff plugged in, but in different locations, hopefully avoid any codes!   And honestly, all these new cars with their weird electronics. Pull all the electronics out Duncan, and just shove an aftermarket ECU and if needed a trans controller in, along with a PDM. Make it run basic but race car styled!
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      To follow up a question from earlier too since I had the front bar off again (fking!) This is what is between the bumper and the drivers side wheel And this is the navigator side, only one thing but its a biggy! So basically....no putting coolers in the wheel arches without a lot of moving other stuff. Assuming I move to properly race prepping this car I'll take that job on and see how the computers respond to removing a whole bunch of ADAS modules
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      So I prepped the car for another track day on Wednesday (will be interesting to see coolant temps post flushing out and the larger reservoir, with a forecast of 3-14 being 20o cooler than last time I took it out). Couple of things to mention; since I am just driving the car and not taking a support vehicle, I took the rear seats out and just loaded the back up Team Trackday style. Look at all that space! To cover off removing the rear seat....it is weird (note the hybrid is probably different because it wouldn't have folding rear seats) Basically, you remove the lower seat base, very similar to a r series but it is a clip that pulls forward to release the base rather than it being bolted down. Easy Then, you need to remove the side section of the rear seat on each side. There is a 14mm head nut at the bottom of the side piece, the it slides upwards off a hook at the top to release; you also need to unhook the seatbelt from the loop at the top. Then the centre piece is weird. You need to release/fold the seats forward with the tab in the boot on each side From there, there are 2,x12mm headed bolts holding the rear of each seat to the folding bracket, under the trim between the rear seat and the boot (4x christmas tree clips there, they suck). The seat is out but you can see where the bolts attach to the bracket
    • RP1421
      S15 Spec R

      By RP1421 · Posted

      As discussed in the previous post, the bushes in the 110 needed replacing. I took this opportunity to replace the castor bushes, the front lower control arm, lower the car and get the alignment dialled in with new tyres. I took it down to Alignment Motorsports on the GC to get this work done and also get more out of the Shockworks as I felt like I wasn't getting the full use out of them.  To cut a very long story short, it ended up being the case the passenger side castor arm wouldn't accept the brand new bush as the sleeve had worn badly enough to the point you could push the new bush in by hand and completely through. Trying a pair of TRD bushes didn't fix the issue either (I had originally gone with Hardrace bushes). We needed to urgently source another castor arm, and thankfully this was sourced and the guys at the shop worked on my car until 7pm on a Saturday to get everything done. The car rides a lot nicer now with the suspension dialled in properly. Lowered the car a little as well to suit the lower profile front tyres, and just bring the car down generally. Eternally thankful for the guys down at the shop to get the car sorted, we both pulled big favours from our contacts to get it done on the Saturday.  Also plugged in the new Stedi foglights into the S15, and even from a quick test in the garage I'm keen to see how they look out on the road. I had some concerns about the length of the LED body and whether it'd fit in the foglight housing but it's fine.  I've got a small window coming up next month where I'll likely get a little paint work done on the 110 to remove the rear wing, add a boot wing and roof wing, get the side skirt fixed up and colour match the little panel on the tail lights so that I can install some badges that I've kept in storage. I'm also tempted to put in a new pair of headlights on the 110.  Until then, here's some more pictures from Easter this year. 
    • joshuaho96
      R32 GTS (RB20DE) Injectors Replacement

      By joshuaho96 · Posted

      I would put a fuel pressure gauge between the filter and the fuel rail, see if it's maintaining good fuel pressure at idle going up to the point when it stalls. Do you see any strange behavior in commanded fuel leading up to the point when it stalls? You might have to start going through the service manual and doing a long list of sensor tests if it's not the fuel system for whatever reason.
×
×
  • Create New...