transmission woes - ring and pinion back lash?

[spiggs]

I assembled a 4 speed gearbox from parts and just got it out today. Shifts fine but makes a loud whine that increases with speed to become really loud by the time it hits the top of 3rd gear. Sounds like a problem with ring and pinion backlash to me. The gearbox is a mix of parts, late case with internals from a Yugo box that was rebuilt with a 4.42 R&P set. The diff uses the ring gear from the Yugo box mated to the diff that is original to the case.

I cleaned and assembled everything following directions from the 5 speed 101 and 4 speed supplement. Preload adjusted using the feeler gauge under the side cover method.

Anything I can do? I did not think the X1/9 gearbox had a way to adjust backlash.

 

[fiatfactory]

There is no backlash adjustment, only the diff preload.

Sounds like a mis-match of internal components... did you say you used the pinion from a 12/53 set and the ring gear from a 13/53 set??? that will be your problem as they are not interchangeable between ratios, you have to use the pair as the tooth pitch is different.

SteveC

 

[TonyK]

Ring and Pinion Sets.

It was my understanding that the ring gear and Pinion are normally a matched set. There could be small variences from one set to another mainly Lash, but how far or how much contact the pinion makes with the ring gear. The two must intersect a right angles, if the pinion does not engage the ring gear fully then you will get tip loading of the teeth and high wear.

Remember that these cars are old and machining back then was done on a Hobb that most likely was not CNC controlled. The gear sets would have been hand selected and matched.

Going way back I rebuilt a 1953 John Deere Crawler which states this very fact, however a shim pack could be purchased and measuring, preloading and finally marking the teeth with bluing to see contact was required. To my knowlege this is not done on the X tranmission.

TonyK.

Grimsby Ontario Canada.

 

[Mark Plaia]

Hmmm....

I have had transaxles that came from the factory and whined a bit. And I have had transaxles that I built that whined. And the one in my '81 X never whined at all in spite of running two different internal gearsets and two final drive ratios in various combinations.

You do not say what oil you are running in the transaxle. I would fill it with old fashioned dino oil (versus synthetic) and run it for a while. The parts may bed in with each other and quiet down. Plus the regular type oil will show any signs of overheating better, either by the hot smell or visible signs that the oil is overheating. Stick your finger in the fill hole periodically and take a look at the oil for visible signs of burning/overheating.

If it is not running hot, and the whine diminishes, you are good to go. If the whine increases or you have signs of overheating, you will have to pull it.

If you do have to take the transaxle apart again, take particular care/notice of the preloads of the shafts.

Ciao,

 

[fastx19]

One other thought.

When you put the cupped washers together, then put the circlip retaining ring on, did you make sure the cupped washers were put back in correct? If not, when you shift gears, it will allow the input shaft to move a bit causing the gears to not line up quite right.

Just another thought.

Eric

 

[spiggs]

There is no backlash adjustment, only the diff preload.

Sounds like a mis-match of internal components... did you say you used the pinion from a 12/53 set and the ring gear from a 13/53 set??? that will be your problem as they are not interchangeable between ratios, you have to use the pair as the tooth pitch is different.

SteveC

Well now that would make some noise! Both had a 12/53 set, the Yugo box had been changed out at some point.

 

[spiggs]

I have had transaxles that came from the factory and whined a bit. And I have had transaxles that I built that whined. And the one in my '81 X never whined at all in spite of running two different internal gearsets and two final drive ratios in various combinations.

You do not say what oil you are running in the transaxle. I would fill it with old fashioned dino oil (versus synthetic) and run it for a while. The parts may bed in with each other and quiet down. Plus the regular type oil will show any signs of overheating better, either by the hot smell or visible signs that the oil is overheating. Stick your finger in the fill hole periodically and take a look at the oil for visible signs of burning/overheating.

If it is not running hot, and the whine diminishes, you are good to go. If the whine increases or you have signs of overheating, you will have to pull it.

If you do have to take the transaxle apart again, take particular care/notice of the preloads of the shafts.

Ciao,

I am using Redline MTL in it. I tried to match the ring and pinion but the parts are unknown to me. My fear is that with the mix and match case + ring and pinion + gearset I just came up with a bad combo. I'll give the dino oil a try. what would you recommend? Will any 80W90 gear oil do? I have heard 20W50 motor oil will work as well. One problem is this is my budget autox car so it does not get many miles, in fact right now just a weekly trip around the neighborhood. I was hoping to get it out to some events this summer after a few more details are taken care of.

 

[spiggs]

When you put the cupped washers together, then put the circlip retaining ring on, did you make sure the cupped washers were put back in correct? If not, when you shift gears, it will allow the input shaft to move a bit causing the gears to not line up quite right.

Just another thought.

Eric

I should have all those together correctly, put in so they are compressed.

 

[spiggs]

It was my understanding that the ring gear and Pinion are normally a matched set. There could be small variences from one set to another mainly Lash, but how far or how much contact the pinion makes with the ring gear. The two must intersect a right angles, if the pinion does not engage the ring gear fully then you will get tip loading of the teeth and high wear.

Remember that these cars are old and machining back then was done on a Hobb that most likely was not CNC controlled. The gear sets would have been hand selected and matched.

Going way back I rebuilt a 1953 John Deere Crawler which states this very fact, however a shim pack could be purchased and measuring, preloading and finally marking the teeth with bluing to see contact was required. To my knowlege this is not done on the X tranmission.

TonyK.

Grimsby Ontario Canada.

Like the 124 ring and pinion. I have done one of those, it uses a crush washer to set lash and was no fun at all to setup. Was hoping the X1/9 setup would just work. Oh well if it wasn't a challenge it wouldn't be fun right?

 

[Jeff Stich]

I am using Redline MTL in it. I tried to match the ring and pinion but the parts are unknown to me. My fear is that with the mix and match case + ring and pinion + gearset I just came up with a bad combo.

Might be. IIRC, all Yugo's had a 17/64 (3.76) final drive ratio, but use the Fiat 5-speed gearset whether it's a 4- or 5-speed Yugo box. You've said the final drive set was later switched-out to a 4-speed 4.42. When you built this trans, did you use a mix of gears from a 4-speed X1/9 trans & from the Yugo trans?

I'll give the dino oil a try. what would you recommend? Will any 80W90 gear oil do? I have heard 20W50 motor oil will work as well.

I've been running straight (non-synthetic) Castrol GTX 20W-50 motor oil in my 128 gearbox for a while now with no issues, though I do change it out once a year. I've been thinking of switching over to 80W90 or Redline next time it's due for a change, just to see if there's any difference.

 

[Mark Plaia]

Any 80/90 non-EP should work for the purpose....

What I am proposing is to put the dino oil in there as a sacrificial and an indicator of condition. And it is cheap. There are sometimes advantages to not having extreme temperature handling capability. The dino oil will tell you if it is overheated.

With the mix of components, it sounds likely that there is a bit of mismatch. That means that there will be some debris generated as you bed things in. Run magnetic plugs at both case locations, and plan on an early transaxle oil change.

Empty the MTL that is in it now, filter it, and save for when you are ready to commit for long haul. It will keep. Run the dino oil in the meantime until you gauge what is needed: Continue on or pull apart.

Ciao,

 

[spiggs]

Might be. IIRC, all Yugo's had a 17/64 (3.76) final drive ratio, but use the Fiat 5-speed gearset whether it's a 4- or 5-speed Yugo box. You've said the final drive set was later switched-out to a 4-speed 4.42. When you built this trans, did you use a mix of gears from a 4-speed X1/9 trans & from the Yugo trans?

I didn't build the Yugo box so I can't really say. It was purportedly built by a very well respected X1/9 trans builder though so I trust that at one time it functioned well. I just took it apart, inspected everything and put it into the X1/9 case using the shifting mechanism and diff that came with the case. I did also assemble it with no gaskets as recommended in the 5-speed/4speed 101 guide. I am just thinking I got unlucky and the Yugo gear set was a little off, the X1/9 diff a little off, then no gaskets and the tolerances added up

 

[spiggs]

What I am proposing is to put the dino oil in there as a sacrificial and an indicator of condition. And it is cheap. There are sometimes advantages to not having extreme temperature handling capability. The dino oil will tell you if it is overheated.

With the mix of components, it sounds likely that there is a bit of mismatch. That means that there will be some debris generated as you bed things in. Run magnetic plugs at both case locations, and plan on an early transaxle oil change.

Empty the MTL that is in it now, filter it, and save for when you are ready to commit for long haul. It will keep. Run the dino oil in the meantime until you gauge what is needed: Continue on or pull apart.

Ciao,

Thanks for the advice. I'll give it a try and see what the oil looks like after running around a bit.