Clutch, Syncro, Gearbox or other?

[Linus27]

Hi all,

Noticed an issue with my 2001 Teg and wondered what people might think it could be. I know it's been discussed lots but it would be good to hear from those who are more mechanical than me

Going into second generally crunches. Third does it occasionally and first can be a bit iffy also. When the car is cold it's all the time. When it's warmed up then it's mostly just second. At higher speeds it's generally ok and rarely does it in any gear. However, when warmed up, if I change gear really slowly, then it doesn't crunch but if I change normally then it crunches. Obviously this can be a pain, for example approaching a roundabout, having to drop into second slowly can lose momentum.

The car was at TGM 2 weeks ago and had all fluids changed.

I have just taken the car for a spin to get a better evaluation. Generally, going into most gears it's very notchy and and the gears mentioned above crunch most times. I tested clutch slip by being stationary in 4th, handbrake on and lifting the clutch and the car stalled immediately. I also tested by driving at 40mph in 5th and flooring it and the car pulled as per normal.

Is my issue pointing towards syncro's or gearbox or do you think clutch is still a possibility?

 

[Dan34]

More than likely the clutch I'd say.

 

[maxvr6]

It probably is the clutch but before you go there its worth checking the adjustment bolt above the clutch pedal, this adjusts the pedal position and some people change it to their preference. If adjusted too much it can have an effect, have a look you'll see what I mean, maybe have a play with it and see if it makes any difference?

 

[Linus27]

Thanks guy, will go and have a look for this bolt and see if it makes any difference.

 

[Rom]

I cant speak to DC5 specifically. But from a general mechanical point of view.

You dont need a clutch to change gear technically. If you can match the speed of the box, to the right gear, you can smoothly change without touching the clutch. But, syncros play a part, they will account for a certain speed mismatch. Getting a perfect speed match isnt something you could do all the time. A clutch allows the input shaft to disengage from the engine, so it can rotate at a different speed and be matched for the next change.

A clutch issue would often make selection of all gears difficult. After all, the clutch doesnt know what gear your selecting. When you say they crunch, how bad, compared to reverse.

Syncros are what match the speed of the gears and shafts. The rings work on friction, matching the speed of the gear to the shaft, once the speed is matched, the syncro hub engages (the gear shift) and locks the gear, and it now becomes the driving gear. 1st and 2nd share a syncro hub, 3rd and 4th etc.
Crunching is usually indicative of worn syncro rings. This is why reverse crunches, as it has no syncro, reverse is a straight cut gear, which is also why it whines.

 

[Linus27]

Thanks Rom. I would say, the other gears crunch more and are far more notchy than reverse.

 

[Rom]

Id certainly look at the adjustment as the others have suggested. Its something you can rule out at home.

Without seeing a syncro, its always an educated guess. So eliminate anything else you can first! Once the clutch is disengaged, the syncro ring is doing all the work to try and match the shaft and gear speed. It has a huge amount of mass to try and slow for such a small ring.

I assume you can select all gears smoothly with engine off?

 

[Linus27]

Id certainly look at the adjustment as the others have suggested. Its something you can rule out at home.

Without seeing a syncro, its always an educated guess. So eliminate anything else you can first! Once the clutch is disengaged, the syncro ring is doing all the work to try and match the shaft and gear speed. It has a huge amount of mass to try and slow for such a small ring.

I assume you can select all gears smoothly with engine off?

Yes, no problem selecting gears with the engine off.

 

[davidpingu]

I think it's probably syncros. I have pretty similar symptoms on a new clutch. Cold changes are always more notchy between 1st and second and sometimes randomly 5th will slightly catch too.

The type of syncros used are more complex than many as I understand it but having seen the way the 1st to 2nd syncro works I can see why they would eventually wear. Lots of moving parts.

Unfortunately as syncros wear, so do the gears. 2nd gear seems to take a battering and often the actual gear needs replacement too.

Considering the cost involved I would say just put up with the cold crunches until it gets to the point where it feels as though it needs to be done but having said that you will get more filings in the box that way. Hopefully the magnets do their job and avoid premature wear of other parts.

 

[Rom]

Second always takes a beating. Its the first synchro to do any work from a standing start, used loads round town, loads of traffic light starts rammed into second etc.

I think from what ive stumbled across, these use a triple cone setup, at least for some gears. Which your right, isnt common place.

Im sure ive seen uprated gear and scynchro sets. But probably cost a small fortune.

 

[darkhawk]

I had similar problem in my ep3


Had the box rebuilt when the LSD went in

MFactory carbon synchros were expensive at all from Tegiwa and TDI north did the work at a reasonable price

Had to chance second gear but other than that was fine. Made the box slick but firm great to drive

 

[darkhawk]

https://www.tegiwaimports.com/index.php/select-car/honda/dc5/drivetrain/mfactory-carbon-lined-synchros-honda-k20a-1st-6th.html

 

[coyote_dc5]

Generally if clutch is wearing or syncros are wearing it would be a gradual degradation and not immediately. Are you saying it's started after a fluid change or did you get that done in response to symptoms, hoping it would sort it? If the cylinders are loosing compression then the slave won't be pressing far or firmly enough to properly disengage

Sent from my Z10 using Tapatalk 2

 

[Linus27]

Generally if clutch is wearing or syncros are wearing it would be a gradual degradation and not immediately. Are you saying it's started after a fluid change or did you get that done in response to symptoms, hoping it would sort it? If the cylinders are loosing compression then the slave won't be pressing far or firmly enough to properly disengage

Sent from my Z10 using Tapatalk 2

It was a combination of feeling the car not changing gear as nicely as my EP3 and other cars and putting it in for a full service and getting everything done to start from a clean sheet. However, the gear changes did not improve and in some ways feel worse.

 

[Linus27]

Just an update from this morning. Drove to work this morning and the car just felt horrible. One new symptom was when I slowed and approached a roundabout, I dropped it into second and as I lift my foot back off the clutch, I was getting juddering through the clutch peddle and I would also say through the engine. It was like I was engine braking from high speed but obviously I wasn't as this was very low speed. It did it again very mildly coming up to the next junction.

 

[coyote_dc5]

First port of call would certainly be a clutch change if your getting that and maybe even flywheel if you don't know it's age and history

Sent from my Z10 using Tapatalk 2

 

[davidpingu]

That does sound more like the clutch from what you've said for it to suddenly feel so much worse. I agree with Coyote.

 

[Linus27]

Thanks again everyone for the help. I'm speak to Tom at TGM and get him to have a look.