No Syncros on Reverse

generally Chip and Dip give good mechanic information, but week after week Ray will pull up “your reverse syncro is worn out” for difficulty shifting into reverse on a manual transmission. now given that Ferraris cost an arm and a leg and should have the finest of transmissions, if they are like most other manual transmission, there is no snycro on the reverse gear. almost all other cars certainly do not have a syncro on Reverse.

the reverse gear is almost an after thought in manual transmissions. it resides on a seperate shaft and is the smallest of gears. if a transmission is having trouble only shifting into reverse and not the forward gears, then the problem is the clutch or the clutch adjustment.

Some foreign cars DO have syncros on reverse, but if worn out, try shifting into first gear before reverse, that helped in one of my old cars without synco in 1st gear, no more gear clash.

Very very few cars have a synchronized reverse gear and I’ve never personally seen or worked on one that did.

I totally agree with you this problem is likely related to the clutch. A lesser known cause for this is a worn and dragging pilot bearing.

The synchronizer is the slider that slides on the mainshaft to engage one gear or another. That is to say, in the case of the 1-2 gears it’s the part that slides over the hub to engage the first or second gear to the mainshaft.

The sychronizer BLOCKING RING is the brass ring that helps to eliminate gear clash. No transmission (that I’m aware of) has a blocking ring on reverse, since it’s a pointless addition. But almost all transmissions have a synchronizer on reverse to engage the gear. The only exception that comes to mind are the old three speed transmissions that used a sliding gear to engage either first or reverse, and neither was “synchromesh”.

Another thing that causes difficulty, or even outright binding, when shifting into reverse is worn teeth on the reverse drive gear, the rev. driven gear, and the rev. idler.
Those teeth are all straight cut with sharp bevels to allow the teeth to mesh easily.

Over time and with a worn clutch, abusive and hard shifting into reverse, etc. those sharp bevels start assuming the shape of quonset huts. Once blunt end starts hitting blunt end it may be hard to get in reverse or as the case sometimes, the trans just flat won’t go into reverse until the car is rocked or the shafts are rotated slightly in the transmission.

I wonder how many transmissions get pulled and needlessly replaced because of advice like this.

My Nissan Versa seems to have a synchronized reverse. It is the first stick shift I’ve ever driven with one. Big trucks (think Peterbilt) with un-syncronized trannys have a clutch brake that stops the clutch disk when the clutch pedal is pressed to the floor.

On stick shifts with no syncro on reverse, I always time my shifts into reverse so that the clutch is spinning very slowly when I engage reverse. That eliminates the binding mentioned by ok4450. If the gears do bind, just lifting up on the clutch so that it starts to slip a bit will turn the shaft slightly so that reverse will engage.

Why do you shift while still moving?

I didn’t catch the model or year but heard enough that it’s a stick and manual.

All the answers are applicable and we are not discussing a VW beetle here. Italian hp tranny’s are like swiss watches forward but reverse is like filet mignon to a cheese burger.

I think it’s driver inexperience… (or somebody didn’t tell him). One thing overlooked is having to lift the stick up (reverse lock out which many are equipped with) first gear, lift (usually) then engage. But it also could be that the lock out plate (if equipped) may have been bent giving the impression a smooth reverse “feels” plausible. That or there may be an adjustment screw on the shift lever that has come loose or needs adjusting.

Anyway… I had the high performance fiat 124 spyder… 130mph… reverse was not easy to get into without getting into reverse then lifting upward pressure then into reverse. Completely stopped at idle speed. Sometimes I’d have to engage the clutch a little in first then clutch then shift. Even the manual warned about using reverse too much.

Lets face it regardless… that tranny wasn’t really designed to run backwards and even in my spider I tried to park it to avoid using reverse. But answers here are quite correct and all could apply. Certainly clutch adjustment and it may also be putting into another gear first before applying upward pressure. I do know that italian hp cars require a lot of mechanical attention including clutch adjustments not to mention changing the tranny fluid and checking that… viscosity does break down eventually as transmissions do get hot, too.

thanks for reading.

correction on my post “reverse into reverse”… I meant first then into reverse. sorry the packers are kicking butt and I got distracted.


I don’t. When coming to a stop I take it out of the forward gear just before stopping (perhaps at 1 or 2 MPH), then as the car stops, I put it into reverse. This leaves the clutch spinning just fast enough that reverse will engage without binding, but it will not crunch.