Worn Reverse Idler Gear

[sweefu]

Hey everyone,

I am looking for some advice about a worn reverse idler gear. My knowledge about gearboxes is very limited and I'm trying to work out the best course of action.

Firstly, what does the reverse idler gear do? Or idler gears in general. The gearbox is S13 SR20 (same as all small case Nissan boxes)

Secondly, the reverse idler gear in my gearbox is worn, clearly worn down on the teeth/engagement edges. The reverse main gear however looks OK, some wear but not wrecked.
The idler gear would mesh with the drive gear - is that correct?

Lastly, could I get away with not changing this gear? What would the consequences be? Difficult to get into reverse?

I have spare parts gearbox so I could change the gear if need be, but I don't have the tools to do it at home which would mean sending to a shop and more money, I'm trying to use this gearbox as an interim fix until I rebuild my RB25 box so I'm not looking to spend a lot of money on it.

The rest of the gearbox looks very neat to me, the synchros/dog teeth (unsure of correct terminology) all look OK, some wear but probably the best I've seen in a gearbox this old. The rest of the idler and main gears look good too.

Pictures of worn gear and gearbox overall

Wear on the reverse drive gear

Wear on the reverse idler gear

Thanks guys, any input would be appreciated

[89CAL]

Thats some pretty nasty damage. Is the box yours or have you bought it off someone?

The idler gear is exactly what it sounds like, it is just a gear that simply spins on a shaft so instead of one gear driving another (which reverses direction of drive), it runs through an idler to reverse the direction a second time (so it runs forward essentially)

If you can get the other gear stopping the idler from coming off without too much issue, id replace it. The wear pattern on the other gear is not ideal but if its only a short term thing it should be OK. Being that it is reverse and you wont use it too often, you would probably get away with it how it is, but if it were me I'd replace it either with new or good quality second hand. It looks pretty crap and i wouldnt normally suggest to run it, but if its only for a short time and running on a drift car, the worst that can happen is it blows anyway

[sweefu]

Thats some pretty nasty damage. Is the box yours or have you bought it off someone?

The idler gear is exactly what it sounds like, it is just a gear that simply spins on a shaft so instead of one gear driving another (which reverses direction of drive), it runs through an idler to reverse the direction a second time (so it runs forward essentially)

If you can get the other gear stopping the idler from coming off without too much issue, id replace it. The wear pattern on the other gear is not ideal but if its only a short term thing it should be OK. Being that it is reverse and you wont use it too often, you would probably get away with it how it is, but if it were me I'd replace it either with new or good quality second hand. It looks pretty crap and i wouldnt normally suggest to run it, but if its only for a short time and running on a drift car, the worst that can happen is it blows anyway

Thanks for the info and help.

I bought the box off someone in 'great condition' but as with all gearboxes, you don't really know until you open it up. I could just return it to the person I bought it from, but strangely enough the rest of the box is as neat as I've ever seen an old small case box.

I could remove that shaft and replace the idler gear, I've got 2 spares in good condition, I haven't seen an idler gear wear like that before.

The car is my daily driver and I'm getting ready for a Tarmac Rally later in the year, I wouldn't ever put something in my car that was going to blow up!

I'll call some places on Monday and see about labour costs for changing the gear, shouldn't be much in theory for a gearbox shop with a nice press.

[89CAL]

Ah sorry. For some reason i thought you said it was a drift car. Yeah if its a daily and you have a replacement lying around then for sure replace it. Ideally you want to replace the larger gear as well but it will probably be alright short time till you get the 25 box in. The back end of the gear looks pretty nasty, and if you can remove the shift fork and slide it off easy enough it would be good to change it as well especially if you have one of them spare also.

Its been a while since ive played with a manual box. After rebuilding my 25 box, i wasnt really interested in playing with another one lol. Everythings a bit tight in them

[Ben C34]

You have pulled it apart this far. Which is more than most people, go hard and finish it. You can buy a press cheap as.