Tranx dog box clicking

[Shaunster]

Hi everybody,

I've recently purchased a tranx sl72 which is recently rebuilt (as I'm told, I know fuck all about gearboxes &#128521

When I turn the input shaft by hand with it in neutral it makes quite a loud clicking. I assume this is just the straight gears meshing, but I wanted to see if this is normal.

The quaife rocket box that came out (which had a few miles on it) didn't make any noise and was actually very quiet for a straight cut box. This is throwing me off a bit.

Any help would be appreciated!

[Graham]

im guessing your tranx is a dog box? which is natuarlly noisier than a syncro

[mexicotait]

Can't help with the dog box but would you be interested in selling your straight cut box

[Forest_rallying]

With a Dog box there'a always an amount of back lash where the drive disc and Dogs mesh on the gears, could it be that where the noise is coming from? There certainly shouldn't be a clicking noise coming from the gears themselves.

As a mater of interest is it a direct or overdrive top gearbox?

You can't always believe the job's been done right when someone says the gearbox has been rebuilt when you buy something. I once bought a Cosworth 4x4 Dog box off a well known Essex Rally car breaker. I paid an extra £250 to have the box rebuilt by an ex Gordon Spooner gearbox Tec. The first event I did, stage 3 and it stripped 3rd gear. I took the box apart myself and enquired about the new gears only to find they were obsolete. So the motto is don't always believe what you are told.

[Shaunster]

Yeah fair shout, sorry to hear about that. Do you think it's worth sending it to a gearbox specialist for a once over then? I've only got the dog box (which has a .87 5th) and a standard type 9 which is on the way out so I don't want to lose it for too long! I'll get a video on tomorrow of it

[Forest_rallying]

I don.t know what the spares situation is like now for the Tran X SL72 since Quaife took over ownership of them. Quaife have a nasty habit of changing the design and number of Dogs on their gears, so if anything needs replacing you often have to renew them all at great expense.

Maybe we are getting in front of ourselves with your problem and it may not be has bad as we think. Good luck on finding the problem.

[Shaunster]

Hopefully this sheds a bit more light on it

[Shaunster]

https://vimeo.com/174341248

[THEDMAN]

Sounds to me like the reverse idler has not disengaged properly and sounding like a ratchet.

P.s. What size of banjo/thread is the breather in the alloy lid???

[Shaunster]

Not sure, it's has some dodgy circling fitting 🤔 I'll have a look at the reverse. I haven't actually been able to get it in reverse yet. I assumed it was tough on the dogs

[Shaunster]

Took the lid off a reckon you might be right. How would I go about sorting it?

https://vimeo.com/174411188

[Forest_rallying]

There's certainly something wrong there with that, it looks like it's trying to ride on the edge of the teeth. You need to find out why the box won't go into reverse gear and that should answer your problem.

Has the gearbox ever been run in your ownership or is it one you have bought second hand?

[Shaunster]

Bought second hand. I think i've sussed out whats wrong with it but it would involve stripping the box down.

So it's now with competition transmission services in markyate. They seemed to know exactly what was wrong with it and will see if it's in need of bearings etc, while it's there.

Thanks for the help

[rhodrievans]

I have a dog box when you out into 1st after just pressing the clutch it clunks as the gear has not had the time to slow down as its constant mesh if you hold your foot on ghe clutch for a few seconds it dosnt make a noise

[wildo105e]

Bought second hand. I think i've sussed out whats wrong with it but it would involve stripping the box down.

So it's now with competition transmission services in markyate. They seemed to know exactly what was wrong with it and will see if it's in need of bearings etc, while it's there.

Thanks for the help

What was the outcome

[Shaunster]

Frustratingly it was a 20p e clip that had come off the reverse selector arm. Very annoying that it's one of the first things you do when the box is going together so it needed a strip down. Not a bad thing though as it was a chance to check everything over, and CTS drilled the offending shaft to take a split pin and washer instead of the e clip. It's obviously happened before as there were two e clips hiding in the bottom of the box! Bernie at CTS made an interesting comment about the position of the shaft the reverse arm rides on, and that when tran x cast their own casting, he thinks the position isn't quite right and the arm has to do a bit of a shimmy, rather than run in the smooth action. It must be one of the areas where the SL72 gets it slightly unreliable reputation from.

Now it's back in, it still doesn't hold reverse very well and you need to push on the gearstick while reversing or it pops out. Having said that 1-5 shifts are like lightning and incredibly smooth and quiet, so all's well that ends well! Not sure i'd buy another SL72, I'd probably save for the G60. But now it's there i'm sure it will do the job and i'm looking forward to breaking the box in at snetterton in a few weeks.

[hawk1903]

Frustratingly it was a 20p e clip that had come off the reverse selector arm. Very annoying that it's one of the first things you do when the box is going together so it needed a strip down. Not a bad thing though as it was a chance to check everything over, and CTS drilled the offending shaft to take a split pin and washer instead of the e clip. It's obviously happened before as there were two e clips hiding in the bottom of the box! Bernie at CTS made an interesting comment about the position of the shaft the reverse arm rides on, and that when tran x cast their own casting, he thinks the position isn't quite right and the arm has to do a bit of a shimmy, rather than run in the smooth action. It must be one of the areas where the SL72 gets it slightly unreliable reputation from.

Now it's back in, it still doesn't hold reverse very well and you need to push on the gearstick while reversing or it pops out. Having said that 1-5 shifts are like lightning and incredibly smooth and quiet, so all's well that ends well! Not sure i'd buy another SL72, I'd probably save for the G60. But now it's there i'm sure it will do the job and i'm looking forward to breaking the box in at snetterton in a few weeks.

Hello,
If you ever like to sell your SL72 ( I assume it is the direct top ratio box ) please let me know. Unfortunately, Quaife does not carry the spares any more. I might have bought the last batch. However, they may always produce spares on custom order basis. I have asked them to produce the complete SL72 but their engineers seem not much keen on the ratios in that casing as far as the reliability goes. The reason I am still interested with the Sl72 is, just because 3 of my customer's still using this box and we always need a good spare box.