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GTwannaB
GTwannaB None
11/19/08 4:40 p.m.

I have a 1997 Nissan 200sx S-ER and I cannot downshift from 2nd to 1st unless I am at almost a complete stop. 5spd manual. No big deal around town, but it kills me when autocrossing. Do people have this issue on other make models? Synchros, general design, I don't know. I just put in a TWM shifter which while very good, had no effect on the downshifting issue. Ideas?

JmfnB
JmfnB SuperDork
11/19/08 4:54 p.m.

Most transmissions don't let you downshift to first to avoid accidentally downshifting.

mtn
mtn Dork
11/19/08 5:07 p.m.

I had a 98 Maxima 5 speed. Couldn't do it, but it was so strong that I could start it in 2nd with no problem and even 3rd could be done without smelling clutch.

Never had the problem with the BMW or the Saab.

dcs
dcs New Reader
11/19/08 5:12 p.m.

I had the same problem but yours sound worse as mine didn't affect me on the rally-x course. Swap in some Royal Purple, that was reccomended to me and it helped.

Worn motor mounts and shifter bushings can apparently exagerate the problem as well, or so say the sr20 boards.

integraguy
integraguy Reader
11/19/08 5:21 p.m.

If I still had an SR20 engined car (used to own a G20) with a manual tranny, I'd AVOID even trying to downshift into 1st unless the car was already stopped. Nissan "says" the manual trannys on late '90s SR20s are not as prone to problems as the earlier cars were....by why invite trouble.

aircooled
aircooled Dork
11/19/08 5:47 p.m.

If these cars can normally do it and it is a wear issue, using synthetic gear lube will likely help.

Otherwise, double clutching and rev matching might be your only option.

iceracer
iceracer Reader
11/19/08 5:59 p.m.

Must be a really tight course if you have to down shift to first.

benzbaron
benzbaron New Reader
11/19/08 6:38 p.m.

Neither my bike or pickup like going into first unless they are almost stopped and if you do force it you hear lots of grinding, then when you release the clutch the engine lugs down. I think if your car isn't going into first, depending on the gearing, it doesn't want to and you shouldn't force it. A good parameter to judge is how fast are you going when you go from 1st to 2nd? 2nd to 1st? If 2nd to 1st exceeds the 1st to second your car is doing you a favor by not going into gear.

Good luck!

Keith
Keith SuperDork
11/19/08 6:57 p.m.

Yup, learn to double-clutch. The gap between 1st and 2nd is usually big enough that synchros have trouble with it.

When you can drop from 2nd to 1st in a non-synchro vintage Land Rover box in low range, you've got it figured. It's even harder in low range.

Autolex
Autolex Reader
11/19/08 7:06 p.m.

my civic and my miata will both let me do it, just rev match (roughly) and it drops right in!

thatsnowinnebago
thatsnowinnebago Reader
11/19/08 7:10 p.m.

You've been granny shifting, not double-clutching like you should.

chknhwk
chknhwk Reader
11/19/08 7:11 p.m.

I second the gear lube additive and worn bushings/motor mounts.

rwdsport
rwdsport New Reader
11/20/08 3:30 a.m.
thatsnowinnebago wrote: You've been granny shifting, not double-clutching like you should.

Thats not the problem, its the damage to the intake manifold you should be worried about. It will cause a piece of the cars floor to break and cause sparks everywhere...

captainzib
captainzib Reader
11/20/08 7:52 a.m.

I have a 91 SE-R and also can't downshift to first unless almost at a complete stop. It bothered me at first, but I generally have enough momentum to get going in second gear unless I am at a complete stop anyway, so I never needed first.

GameboyRMH
GameboyRMH SuperDork
11/20/08 10:04 a.m.

My Samurai has this problem, it's not completely impossible but it needs a perfect double-clutched rev match and it sometimes takes a good bit of force on the gearshift lever. Luckily it puts out plenty of torque at low revs so I can get away with lugging along in 2nd at very low speeds.

My AE92 goes into 1st like butter at any speed reachable in 1st if it's rev-matched properly. If not...well it would still go in I did that once bringing the car home, it nearly did a stoppie...

GTwannaB
GTwannaB New Reader
11/20/08 10:49 a.m.

OK sounds like it is normal then. I drove a miata for 4 years, like Autolex I remember being able to downshift to 1st in that car. The last autocross had a few tight turns, so it was leave it in 1st and bounce off the rev limiter or try to power through in 2nd. I'll check the motor mounts, the shifter bushings are brand new with the short shift kit.

jstein77
jstein77 HalfDork
11/20/08 11:02 a.m.
GTwannaB wrote: OK sounds like it is normal then. I drove a miata for 4 years, like Autolex I remember being able to downshift to 1st in that car. The last autocross had a few tight turns, so it was leave it in 1st and bounce off the rev limiter or try to power through in 2nd. I'll check the motor mounts, the shifter bushings are brand new with the short shift kit.

Ding ding ding - we have a winner (or maybe loser in this case). It's the short shift kit that's causing you this problem. Remember, when you reduce the length of the throw by changing the lever arm length, you are also reducing your mechanical advantage. So now you are exerting less force on the shifter arms, giving less ability to overcome the speed differential of the syncros, thereby making it more difficult to downshift to first.

Tyler H
Tyler H Dork
11/20/08 2:12 p.m.
iceracer wrote: Must be a really tight course if you have to down shift to first.

I have never driven an auto-x course, nor car, where shifting down to first was the fastest way to anything but a new transmission.

benzbaron
benzbaron New Reader
11/20/08 2:35 p.m.

My bike and pickup have such a narrow power range that you have to use the top end of the gears to get power out of the little engines. I've found that when I have to go into first (speed <15mph) it usually is because either I didn't take a decent line into the turn lost my nerves and hit the brakes or took a turn too fast spooked, slowed and had to downshift. Both of those were reflections on me not the tranny.

What do you get out of double-declutching that a smooth shift won't give you? I've had to use the double-declutch on a car with a bad gear synchro, but was curious what it offers over a regular shift. I know I've upset the balance of the pickup in a turn by shifting regularly, but I was just curious. I don't really race cars but do like to drive them hard and was interested in doing some classic car racing until I realized my car was too big, heavy, an automatic and underpowered. I can still race my shadow! Thanks folks!

amg_rx7
amg_rx7 New Reader
11/20/08 2:51 p.m.

I was only ever able to downshift to 1st on 2 cars - 84 VW Scirocco and 95 e36 325is. Both required a perfect heel toe downshift. The trans in VW eventually broke. The e36 got sold.

SupraWes
SupraWes Dork
11/20/08 4:17 p.m.

Cmon guys you know better than that. Its heel-toe not double clutching, That and a good quality lubricant will get you there.

Tyler H
Tyler H Dork
11/20/08 6:47 p.m.

Heel-toe will let you downshift more smoothly when you don't want to upset the car (other than getting to first,) but your syncros are still doing most of the work. Double-clutch works, but going into first isn't the fast way around an autox course. The time spent getting into first gear is longer than just riding out second. If you're off-line, then the run is blown anyway, so don't break the car?

Clutch in, shift to neutral, clutch out, rev to appropriate rpm, clutch in, shift, clutch out, gas....that's a lot of steps, and takes a lot of time.

NickF40
NickF40 New Reader
11/20/08 7:14 p.m.

the last post explained it well, hell toe would be best why double clutch, just rev match......7/10ths 8/10ths?

admc58
admc58 New Reader
11/20/08 8:16 p.m.

I wrote this up for an AutoX class years ago and saved it.

I just match revs by pushing to neutral on brake application and holding revs up and letting the speed reduce to where the shifter goes into the lower gear without any clutch action or crunch. Never broken anyones trans doing this and then the shift is completed prior to apex so I just power out of the corner. There is no lost time for 1st gear downshifts this way.

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Proper method for Double Clutch down shift with Heal & Toe throttle blip....for short “DCHT”.

Example A In this example you are in 3rd gear and downshifting to 2nd.

1) Push in the clutch and at the same time push the shifter into neutral.

2) Release clutch and blip the throttle the correct amount for your speed. (This brings up the clutch/input shaft up to the same speed as the output).

3) Push in the clutch and pull the shifter into 2nd. You should not feel any crunch or kick in the shifter (hot knife through butter).

4) Release clutch. There should not be any “bobble head” feel or change in speed.

In this scenario you get near zero clutch and syncro wear because no parts are slipping.

Note 1: A single clutch push and throttle blip do not match revs properly at the clutch/input shaft/syncro side of the transmission, it just revs up the motor to lesson driveline lash on clutch release. Feels racy but only doing half of the job.

Note 2: Slowing from 5th gear to a stop and pulling the shifter into 1st at 30mph while the engine is at idle is maximum syncro wear…(Honda Crunch).

Note 3: I use the DCHT on the street for comfort and smoothness and to always be in the correct gear for acceleration if needed. It also helps in traffic to be in a gear that will slightly decelerate the car without having to get on the brakes.

Example B To further complicate the issue…On the track & for AutoX I don’t use the clutch for downshifts…that’s right…only to up shift.

Same 3 to 2 downshift… Car is at 7krpm at the brake point

1) Left foot brake hard and at the same time release a little pressure on the throttle and pull the shifter into neutral.

2) Keep RPM at 7000 and continue braking until road speed for 2nd gear matches the RPM. (Instead of bringing engine speed up you are bringing vehicle speed down).

3) Slip shifter into 2nd. Release brake and throttle out of corner.

This works for 5 to 2 downshift at the hairpin on Barber just fine. Only one broken transmission in 30years and that was on an up shift back when I was 16.

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bamalama
bamalama New Reader
11/21/08 12:56 p.m.
NickF40 wrote: the last post explained it well, hell toe would be best why double clutch, just rev match......7/10ths 8/10ths?

Double clutching takes the load off of the synchros and allows the trans to go into gear. All heel-toe does is prevent you from skidding the wheels. There is a big difference when you're tying to drive a car with a crappy transmission. (Which would be pretty much every car I've ever owned)

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