Gearbox problem,

[Cortooncowboy]

Hi guys ,
Sorry if this is a repost but I cannot find it anywhere, I have a 91 80 series 4.2 12valve manual triple locker,that I have rebuilt and am getting ready to put on the road but have a gearbox problem, it feels like the gearbox is bound up or u der serious pressure like it’s fully locked in pavement, everything just feels wrong, I origally taught I was having drop box problems that it was engaging on its own, as it seems to be coming and going, I can only drive it around the yard at the minute. I opened up the transfer box but can’t find anything wrong that I can see in there only habe found some aluminium shavings but no marks where they came from, I now have the gearbox out on the bench also and the only thing I can tell is if I turn the input shaft with box in neutral and try hold the output shaft I am unable, I tried this with the box still fitted and was unable, (risky enough with an oily rag!) if I gripped gearbox out put shaft with a pipe grips and held on for dear life the shaft was stopped but under pressure and the box became a bit noisier? Has any one came across this or something similar to this? Oh I must add too that the box is plastered in red gasket maker so somebody was in before so unless they done something wrong? I bought her of e bay just before covid hit so have been patiently trying to get it roadworthy!!

 

[Dave2000]

First thought is the centre differential lock is stuck, second the Viscous Coupling is seized. If you did not have it apart I would have said try driving it aluminium shavings on the other hand is not good.

It's not clear if when bench testing by turning the input shaft on the gearbox if the transfer box was fitted? If so, then even if the VC was not seized it would be pretty much impossible to hold the output shaft.

Regards

Dave

 

[Cortooncowboy]

Hi Dave thanks for the reply, I have the transfer box off at this point when turning the shaft and not been able to hold the output. I taught the same the centre diff was sticking but it would happen when driving, one minute it would be sound and next it would come on is there a spring or something to keep it off or just a detention? Maybe it’s gone weak? I don’t think my one has a vc? It’s a 1991?? Would it be possible that the shavings came from the box into the transfer? They are very clean and new looking and I cannot find any marking in casing where it came from?

 

[Dave2000]

A 91 is unlikely to have the VC, but given the age of these vehicles and your comment about the transmission having been apart it is hard to tell what is going on. I have the feeling if you cannot stop the output shaft of the gearbox turning whilst turning the input shaft then I would have to go with a selector issue, careful when taking the gear cluster apart, the selectors have little springs and ball bearings, they are inclined to fall out and get lost.

The shavings is a weird one for sure, is it possible the drain or refill plugs have been drilled out due to being seized in place?

Regards

Dave

 

[Cortooncowboy]

Ya I’m thinking maybe selector too kind of like there is 2 trying to engage at same time or something. I will just have to rip the box but just afraid if I see nothing wrong when I’m in there!!
Good thinking on the drill theory as it looks exactly like the swarf you get from drilling aluminium and you would surely see where it was shaved off I think if it was from a problem because inside of casing is all brown from the oil , bearings and everything look sound in the transfer .
Thanks for your help.