Backlash in the Transaxle?

[Toni]

Is this the slop you are referring to?

[DoctorDex]

Yeah its not much, but I figured every little bit helps.

[Turbo Powered]

Interesting thread. I also have a pretty loud clunk when lifting off the throttle from moderately hard acceleration. I thought it sounded like it was coming from the rear. I have a good tranny, DS, and rear differential from my wrecked TP1, will change the DS first, then tranny (current one has an oil leak plus I think TP1 had an upgraded clutch in it), will also probably install solid mounts when I change the tranny. Last step if still clunking will be to change the differential. Will post outcome later.

Bill

[Toni]

Originally Posted by DoctorDex

Edit: Revisiting an old idea, I found a company that will custom machine dowel pins that fit into the oblong holes and they would be press fit. The material would be 4340 and it would have a Rockwell hardness of between 35 - 40. Would this be hard enough to prevent wearing away of the dowel pins/outer pinion shaft? For just the basic pins, they gave me a ball park figure of ~ $100.00 CDN (cost would be cheaper if anybody else wants some). If I wanted them to have additional hardening it would obviously cost extra. Can anybody tell me if these will work or not? I don't know enough about the engineering/physics/alchemy of metals...

Did you ever find the answers to these questions? What alloy/hardness are the stock pins?

Thanks
Antoni

[DoctorDex]

Originally Posted by Toni

Did you ever find the answers to these questions? What alloy/hardness are the stock pins?

Never did find definite answers to these questions, but according to the machine shop where I had the pins made, the 4340 Heat Treated Stress Reduced (HTSR) steel should be more than enough/overkill when it comes to strength/hardness.

[DoctorDex]

Originally Posted by Turbo Powered

Interesting thread. I also have a pretty loud clunk when lifting off the throttle from moderately hard acceleration. I thought it sounded like it was coming from the rear.

Mine used to sound like it was coming from the rear. I put in some solid rear dif. mounts, double checked my backlash and installed new carrier bearings. As a result, the sound changed (its much quieter; no longer a loud thud, its more of a light clank) and now it sounds like its coming from the front. I think it was the new carrier bearings that made the biggest difference. I have since added F/R solid mounts and the custom planetary dowel pins and the clunking is definitely better than it was, but it is still there.

I'm beginning to wonder if it might be "normal" for AWD mitsus to have a bit of a clunk? I went for a ride in my friends Evo IX and he has a clunk as well, which is especially noticeable between hard shifts. His car has always been babied and it is very low miles so I doubt its a tranny wear issue.

Does anybody have a VR4 or has anyone ridden in a VR4 that doens't clunk between hard shifts? How about when going from decel to hard accel without touching the clutch?

[keithmac]

If you think of all the parts in the driveline/tranny and all the gears that mesh up there`s bound to be some slop. Plus the CV joints will have a some play and there`s 8 of them..

Mines only really noticable when I play with the car to make it do it, normal driving isn`t bad at all and I have to set the rear diff backlash yet.

[venetrex]

Fortunately I was lucky, my transaxle backlase proved to be a combination of a worn output shaft, wasted coupler too (It was a REAL BITCH to get off). And the rear motor mount was slightly torn. I should post a pic of my output shaft. When I had my tranny apart I noticed the sun gear(the one that rides on the output shaft in the VCU Had parts of the output shaft worn on it. Wierd, looked like lack of lubrication. I ground it off. My tranny feels great now. My VCU was okay, amazing considering the abuse I now understand this car endurred. The entire drivetrain feels more positive and engaged!!

[DoctorDex]

There is something wrong with my intermediate shaft that may or may not be linked to this backlash issue.

I recently installed some solid mounts which give the advantage of being able to hear ever little noise the tranny is not supposed to be making. People with healthy tranny's and solid mounts don't complain of hearing these noises, so I know my tranny must be sick.

Here is what happens:

When the car is cold, no noise. Once I put the car through its paces and the tranny is hot, I can hear a metal on metal sound, similar to the sound of a grinding wheel lightly touching metal, which is heard mostly in the lower rpms (<2000 rpm). Above 2000 rpm the sound frequency increases to a point where it is drowned out by engine noise. The sound is most noticeable in 5th gear cruising between 1600 - 2000 rpm. The noise doesn't occur when revving in neutral. The noise is not related to clutch position.

I am not sure what exactly is making the noise, but I have a hunch it might be the fifth gear lightly rubbing on the VCU-planetary case; perhaps because of worn intermediate shaft bearing race on the end cover? Is this possible? When I last had my end cover off, my intermediate shaft bearing race looked as though it had significant wear, but I didn't bother to replace it as it hadn't given me any trouble (to my knowledge).

With regards to the backlash issue, one would think this would cause increased lash because the intermediate shaft would not be pressed up tightly against the input shaft and the gear teeth would not mesh as tightly. Or would this not matter because of the design of the worm gears?

[Bret Brinkmann]

I saw an EXTREMELY worn tappered bearing on the end cover side of the counter shaft once. The only concern the customer had was that the tranny popped out of reverse a lot and 5th gear was starting to get notchy. The counter shaft had about 1/4 in of end play as opposed to having bearing preload. Pretty scarey to me.... And that was a reman from Mitsu with only about 1K miles on it.

The center diff housing never touched any of the gears, but the gears were deffinately not meshing properly from that shaft flopping around. The only gear that needed to be replaced was reverse and that was only because the dogs where hammered.

Bearings usually make a whinning sound when they start to go out. Some times they can make a slight grinding sound as you are describing. Either way, a lot more wear has to occur before they get as bad as the one I mentioned above. If you drain your gear oil look for flakes of metal on the magnet and metal powder through out the fluid. Those are signs of bearing failure.

I do no have a clucking sound in my VR-4. I can get a popping sound from the rear due to my worn trailing arm bushing or the worn rubber in the rear third section of drive shaft, but that is what I get for going RWD and having too much fun. I also noticed that when I first had me RPS II clutch, I had to slightly adjust the way I used the clutch to prevent a slight cluck in the drive train. Not a hugh clutch, but noticable if you paid attention. My SPEC I does not have this problem.

AWD cars should have more backlash than a 2WD car but even an AWD car can develope excessive backlash. Takeing up backlash in other non-worn componants that are with in spec can help reduce the sound but the sound will still be there until the source of the problem is corrected. But first, lets make sure your bearings are good.

That phattlard guy also had a popped VCU. You can tell from the black ring on the VCU around the splined section that the sun gear goes into.