Reverse Lockout

Joined
10 September 2003
Messages
28
I'm trying to find out if most manual cars have reverse lockout like the NSX does. In particular an E36 BMW M3 (1997). It makes sense that most cars would have it.


Thanks.
 
svalleynsx said:
Let's just say "most" is an understatement! I shudder to think if "any" modern day transmission didn't have it.:eek:

It all depends on the shift pattern. My Mini Cooper S did not because you shifted outside the double H pattern to go into reverse (what would be "8th" gear)

I could not figure for the longest time why the NSX had a reverse lockout since the five speed did not, and other six speeds do not. Then someone told me that 6th and reverse are the same position on the pattern, which I think is just stupid, but then I am not an engineer:confused:
 
Most modern transmissions in my experience use a mechanical interference design that requires the user to push or pull the knob that allows guide pins on the lever to allow the shifter to be placed into reverse.

The NSX 6-speed tranny uses a solenoid lockout that uses a pin to prevent the gear shifter to be placed into reverse. When the power is released from the solenoid (due to the speed sensor indicating a speed below X mph), the pin retracts, allowing the transmission to be placed into reverse gear.

I believe the E36 M3 I've driven uses the first method (push down to engage reverse).

Cheers,
-- Chris
 
NSXLNT said:
Could you explain what this reverse lockout is? I never heard this term before.

OK I guess I'm the one most confused here as I am not a mechanical engineer by any means. I always thought "reverse lockout" was the mechanism which prevented someone from accidentally shifting into reverse while in a forward gear? You can imagine the consequences. Say new gearbox?
 
svalleynsx said:
OK I guess I'm the one most confused here as I am not a mechanical engineer by any means. I always thought "reverse lockout" was the mechanism which prevented someone from accidentally shifting into reverse while in a forward gear? You can imagine the consequences. Say new gearbox?

You are correct in your assumptions, but not all gearboxes are so equiped. The five speed NSX for instance.

Actually shifting into reverse will not destroy the gear box because the synchros will not allow it to happen. You will grind quite a bit and everyone in the vicinity will know you just did something that was not supposed to happen (like turning the key to start after the engine is already running:D). One of the reasons I sold my Mini was due to driving a six speed Mini, then switching to the five speed NSX, and occasionally shifting into sixth in the NSX. OUCH:eek:
 
I hesitate to use fifth gear because I am concerned about hitting reverse on the way back down. I've "grinded" a couple of times with the NSX, but have never had a problem with any other manual transmission that I've driven. Any suggestions to practice correctly with the NSX?
 
NSXLNT said:
I hesitate to use fifth gear because I am concerned about hitting reverse on the way back down. I've "grinded" a couple of times with the NSX, but have never had a problem with any other manual transmission that I've driven. Any suggestions to practice correctly with the NSX?

It's funny that you mention this because I have the same problem. On my '91 it always seems difficult downshifting from 5th to 4th. I would always seem to get a gnashing gear sound because 4th was so difficult to find, but I'm almost 100% certain the gear selected was NOT reverse to cause the grinding noise. I would initially just double-clutch and short-shift into third or just idle in neutral and go hard on the brakes coming down from speed to overcome this. Warm or cold makes no difference.

I once owned an Accord that you pushed down on the gear selector to go in reverse, and a Lotus Esprit that you had to push up to do the same. Never had the same problem downshifting from 5th in these vehicles.

Just wondering if any other members here have the same problems with their gear selection? Or is this just a flaw in the design of the gearbox, or does it take a certain technique to do?
 
I don't think it is a design flaw but maybe just something you need to get used to. I've owned and driven a lot of Honda manuals including my 91 5-Speed Integra, my 93 Legend with 6-Speed and electronic reverse lock out like the 97+ NSX, a 91 5-Speed Prelude, 88 5-Speed Accord, and my 92 5-Speed NSX and I never and any problems downshifting from 5th to 4th gear. On a side note, when I made the switch from my 6-Speed Legend to the 5-Speed NSX I caught myself a few times during the first month or two taking it out of 5th gear and ready to insert into 6th. Fortunately I never did and realized what I as doing before grinding anything.
 
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