Worn Syncro problem?

[TB Rich]

Hi,

Are these symptoms of worn syncros?

General changing in the lower gears at low speeds is stubbon and when giving the car some beans and changing at high revs it crunches. Downshifting quickly at revs does the same also, clutch dragging??

Its been rebuilt but syncros were swapped for some 'better looking' but still old syncros so i think it could be? Im just trying to rule out clutch as the cause because its a brand new helix organic plate so i assume fine.

Thanks for any input,

Rich.

[GavinPearson]

It's most likely dragging, and you should fix the release system asap before you trash the synchros.

[smhmotorsport]

Does the gearlever feel like there is resistance when trying to change, like its being forced? To check the clutch is clearing, jack the car up (engine not running) and get a mate to sit in the car. select a gear (any) and get your mate to slowly press the clutch down. while he does this you try to turn the rear wheel. Once the clutch is disengaged the wheel will turn freely. Once youve checked its clearing properly make sure the biting point is not at the very top of the movement, as the clutch may be overthrowing. What oil have you put in the gearbox and does it improve/stay the same when warm/hot? Some boxes are very tempermental to viscosity and the box may be dragging due to the wrong oil.

[TB Rich]

Yes there does feel to be resistance against the gearlever. There is even resistance when getting it out of gear and in to neutral which is strange. Oddly I tried moving to neutral without depressing the clutch and it feels too easy to do so?

I know Peugeot MA boxes are poor, but frankly for a rebuilt box it just doesnt feel right and the dragging is cause for concern.

Could the syncros cause the dragging if there all ready worn out??

Thanks

[smhmotorsport]

TB Rich said:

Yes there does feel to be resistance against the gearlever. There is even resistance when getting it out of gear and in to neutral which is strange. Oddly I tried moving to neutral without depressing the clutch and it feels too easy to do so?

I know Peugeot MA boxes are poor, but frankly for a rebuilt box it just doesnt feel right and the dragging is cause for concern.

Could the syncros cause the dragging if there all ready worn out??

Thanks

Im always weary on using old parts when reassembling. Remember, the parts were removed for a reason! Im no expert on 'boxes but it doesnt sound too promising. If the lever is stiff selecting while not running then there may be something bent of not assembled correctly. If all the gears feel tight then maybe the selector mechanism is bent, but i cant see that causing the baulking and grinding while changing.

[TB Rich]

I think im going to have to ring and request it is redone then. It has already been back once because they fitted the reverse saftey latch on to first gear! Unfortunatly Ive spent the money and I cant afford to take it elsewhere however tempting. Would rather make do for a while and save for a Peugeot Sport Cup box and shafts!

I might try some new linkages for now to see if it helps?

Thanks.

[smhmotorsport]

TB Rich said:

I think im going to have to ring and request it is redone then. It has already been back once because they fitted the reverse saftey latch on to first gear! Unfortunatly Ive spent the money and I cant afford to take it elsewhere however tempting. Would rather make do for a while and save for a Peugeot Sport Cup box and shafts!

I might try some new linkages for now to see if it helps?

Thanks.

Dont change the linkage! If youve had it repaired by a garage then ask to go out for a test with the mechanic or failing that the owner of the garage. If they fail to admit its their fault, arm yourself with a copy of the trades description act which normally puts the wind up people....Even if you agreed to use old parts the box shouldnt grind, even when giving it some beans!

[GavinPearson]

smhmotorsport said:

TB Rich said:

Yes there does feel to be resistance against the gearlever. There is even resistance when getting it out of gear and in to neutral which is strange. Oddly I tried moving to neutral without depressing the clutch and it feels too easy to do so?

I know Peugeot MA boxes are poor, but frankly for a rebuilt box it just doesnt feel right and the dragging is cause for concern.

Could the syncros cause the dragging if there all ready worn out??

Thanks

Im always weary on using old parts when reassembling. Remember, the parts were removed for a reason! Im no expert on 'boxes but it doesnt sound too promising. If the lever is stiff selecting while not running then there may be something bent of not assembled correctly. If all the gears feel tight then maybe the selector mechanism is bent, but i cant see that causing the baulking and grinding while changing.

Fortunately, I am an expert.

Without seeing the parts you can never be sure, but there are some very simple reasons why a manual transmission won't synchronise:-
1. The clutch is dragging. Sounds really obvious, but a lot of dealer machanics overlook it.
2. The synchros are worn.
3. The wrong oil is used.

You can tell if a transmission needs the synchros replacing by a simple visual inspection, no disassembly of the shafts is needed (though the box will need to be opened) - just force the synchro cone onto the taper on the gear and look for a gap between the gear engagement teeth and those on the synchro ring. If those are present, the gears will synchronise. AN IMPORTANT LESSON TO LEARN IS THAT A SYNCHRO SYSTEM IS BASICALLY A CONE CLUTCH.

Because a synchro cone does need to evacuate oil from the taper, if you use the wrong grade oil you will never get the cone clutch to work.

This is where point (3) comes in. A lot of people hear that if they use brand X of oil it will be the magic cure all for their problems of longevity and that when they thrash the car round Thruxton or wherever the transmission won't fall apart. This is unfortunately not the case, and brand X may be great on the bearings, may be good in the gear teeth, but if it is incompatible with the synchro system used then brand X is useless. You are best off using the oil that the dealer sells from the manufacturer's parts division, that way you KNOW that you are getting something the manufacturer knows will work with the synchros.

It is also worth mentioning that the synchros have to slow down a clutch disc so obviously the faster that is spinning the synchro load is going to be proportional to the square of the speed and the moment of inertia that the disc has. Bottom line - when you make your engine rev harder, use an uprated (bigger clutch) your synchros may not be man enough for the job and either take longer to synchronise or wear out a lot faster.

I would check the points I have mentioned before assuming the worst.

[steve_d]

My moneys on clutch drag.
I'm not an expert but find it hard to relate a reluctance to come out of gear with anything other than drag.

Steve

[TB Rich]

Thanks. Im going to research what clutch drag exactly is and what can cause it then go back to the garage in a vain attempt of not looking like a gearbox numpty!

Could it be the pressure plate? I have found if I stamp my foot down harder the shift is easier. Its an uprated friction plate but stock pressure plate, possible cause? (The friction plate is a sprung organic helix so not exactly like the beefy paddle i had before - which was fine on the stock pressure plate).

Cheers.

[GavinPearson]

Clutch drag is that the combination of clutch pedal travel, release mechanism operation and clutch finger leverage does not allow the clutch disc to spin freely when you push the clutch pedal to the floor.

In most cars that means there is air in the hydraulic system or the cable needs adjustment, in your case it could be this, or petentially that the clutch cover is not matched with the clutch disc that you have used, for example if the linings are too thick or a 'low lift' cover is fitted, your clutch may barely release even if the clutch is bled or the cable set to the optimum point.

[TB Rich]

Thats very interesting thanks. Incidently its now running a manually adjustable cable in an effort to get it right over the automatic adjusting type that was in there.
Also the cover im running is o/e whereas the friction plate is not (uprated helix item). I'll ring the clutch supplier on monday and quizz them.

Cheers.

[that daddy]

TB rich,not a good idea to mix and match clutch parts of differing construction/manafactuer allways usually ends in tears,sounds like your pressure plate is not totally disengaging the driven plate hence drag/laying up problem,although a few of the posts have suggested this already,i would start with a new performance clutch if your going to remove the box for inspection,i would not use a performance clutch anyways unless neccesary,there always hard to live with on a day to day basis,bigger stock clutch yes,this always worked well with modified fords.i would say steve d,is on the money with what he as suggested(reluctance to come out of gear).