Dyna 6

[clayson]

What are symptoms of a worn 3rd/ 4th gear syncro?

 

[Will Blackburn]

Crunching apparently.

 

[clayson]

Sounds like the suspect then. Have a slight crunch on the downshift from 4th to 3rd, will shift ok if I slow right down. I take its dyna box out thru bell housing to do the synchros?

 

[Will Blackburn]

It’s not supposed to be the most expensive job, if it’s not left too long.

 

[clayson]

Ok thanks Will, yea thats what I was dreading, as you say best get her sorted sooner rather than later

 

[clayson]

Anyone on here done the 3rd/4th gear synchro on dyna 6 box before? If so what else to change while in there?

 

[Speedstar]

Anyone on here done the 3rd/4th gear synchro on dyna 6 box before? If so what else to change while in there?

Its a can of worms , put a service exchange box in it !!!! is the only way or you could soon be in a long way

 

[Will Blackburn]

3rd gear synchro is not an uncommon issue on a dyna 6, they recommend having 3A as a set off gear rather than 3C to extend its life. Having said that it means that it is likely that 3rd gear synchro is worn in isolation to the rest of the cogs. So fix that and many years of trouble free service lie ahead. I have had a 3rd gear synchro go in a deutz for the same reason, but not a dyna 6 yet with more hours on the MFs.

 

[clayson]

Yea just trying to work out what’s best long term, ie new exchange box or just replace worn synchro in current box and hope it’s trouble free. It only crunches going down from 4th to 3rd, going up from 3rd to 4 is fine, so sounds like it is just that one side of thesynchro that’s worn?

 

[hilux]

Yea just trying to work out what’s best long term, ie new exchange box or just replace worn synchro in current box and hope it’s trouble free. It only crunches going down from 4th to 3rd, going up from 3rd to 4 is fine, so sounds like it is just that one side of thesynchro that’s worn?

How many hours has it done?

 

[daveydiesel1]

3rd gear synchro is not an uncommon issue on a dyna 6, they recommend having 3A as a set off gear rather than 3C to extend its life. Having said that it means that it is likely that 3rd gear synchro is worn in isolation to the rest of the cogs. So fix that and many years of trouble free service lie ahead. I have had a 3rd gear synchro go in a deutz for the same reason, but not a dyna 6 yet with more hours on the MFs.

How does changing the start off gear help or damage the syncro, its in 3 anyway. Surely its the clutch pack that would suffer in the higher gear

 

[clayson]

How many hours has it done?

Only done 3400hrs, we brought it last year with 2800hrs 2nd hand, only started crunching since calibrating the gearbox. Im the only driver and always take care when down shifting minimising the load on gearbox

 

[avag]

Yes done plenty in claas and mf, the bigger dyna 6 seem more prone to 3rd synchro going, what tractor is yours, any competent man in a van could do it l, only fiddly bit is setting up the rams/rails after rebuilding, done plenty out on farm and no need for the cab to be removed

 

[Will Blackburn]

How does changing the start off gear help or damage the syncro, its in 3 anyway. Surely its the clutch pack that would suffer in the higher gear

Bit less pressure on start off, might be an old wives tail, but I’ll stick to it.

 

[daveydiesel1]

Bit less pressure on start off, might be an old wives tail, but I’ll stick to it.

But a syncro is only working under pressure when the gear is being changed,so in theory if you drove the tractor in 3c its whole life the syncros should be like new after 10k hours. The only bit thats under pressure on start off is the clutch packs

 

[Will Blackburn]

But a syncro is only working under pressure when the gear is being changed,so in theory if you drove the tractor in 3c its whole life the syncros should be like new after 10k hours. The only bit thats under pressure on start off is the clutch packs

I get that, I have had an e/f clutch pack go that was more expensive than a 3rd gear synchro to fix

 

[daveydiesel1]

I get that, I have had an e/f clutch pack go that was more expensive than a 3rd gear synchro to fix

Did it just need new friction discs or had it worn out the steel plates and the whole basket? These things never seemed to be an issue on the old dynashift transmission. Bit of a backward step of a kind

 

[clayson]

Yes done plenty in claas and mf, the bigger dyna 6 seem more prone to 3rd synchro going, what tractor is yours, any competent man in a van could do it l, only fiddly bit is setting up the rams/rails after rebuilding, done plenty out on farm and no need for the cab to be removed

Thanks for that avag. It’s a 7720, is it a split tractor job to replace synchro or any way can it be accessed in situ? Ta

 

[avag]

Yes has to be split and range box removed from tractor

 

[Farmer_Joe]

Get some pic if you do it your self