Backlash in the Transaxle?

[DoctorDex]

I just did the conversion to millimeters for the spec values they gave me and they have to be wrong. The spec. they quoted me for the backlash was 0 - 0.0004 inches which would be 0.1 mm. Where as the backlash they measured was 0.38mm. Either my calculations are wrong, or their measurements are way off.

Declan

[keithmac]

That seems to be the internal gear backlash measurement, spec states 0.1 to 0.16mm as acceptable?. Have you trad though the sdjustment part of the manual?

[KORMEX]

Originally Posted by DoctorDex

Just got off the phone with them. Apparently, the units of measurement was in inches, so there was 0.0015 thousands of an inch of backlash, where as spec. is 0 - 0.0004 thousandths. They measured the backlash at the output shaft using a dial indicator and a pair of vice grips to manual turn the output shaft.

I also quizzed them re: my propeller shaft and they said they didn't check to see if I had bad u-joints. Is there a way to check/test the u-joints on a driveshahft with it still on the car?

Thanks.

Declan

P.S. The clunk when going from decel (in gear) to accel seems to be worse in 5th. However, what is worse and what is better is really subjective...

Declan ,
I just can't picture these guys troubleshooting a car for a clunk one guy with vice grips ( ilegal in my shop ) and the other with dial indicators
and they conclude that the shaft has 11 thousands of an inch off.

And they didn't even consider the driveshaft .

If I where you, I would forget everything they told you and start from scratch .

What most mechanics do to check the U-joints on the driveshaft is wiggle it with your hands and listen for a clunk .

[DoctorDex]

I hear what your saying. On the topic of driveshafts, the driveshaft is spinning whenever the car is moving, right? If I'm only getting a clunk when I add a great deal of torque to the shaft, by suddenly accelerating hard, wouldn't this point to U-joints?

Are U-joints replaceable on our shafts, or am I going to have to shell out for a CF shaft?

Declan

[DoctorDex]

Originally Posted by keithmac

That seems to be the internal gear backlash measurement, spec states 0.1 to 0.16mm as acceptable?. Have you trad though the sdjustment part of the manual?

What and where is the output shaft adjustment procedure in the manual?

The specs the dealer quoted me was 0 - 0.004 inches which works out to 0 - 0.1016 mm measured at the output shaft.

They said they measured, with a dial indicator, 0.0015 inches which works out to ~ 0.04 mm. These measurements don't add up because I personally measured ~ 2 mm of backlash, using a pair of calipers, caused by the VCU & Planetary dowel pins. Like Kormex said, I should throw the dealer measurements out the window and start from scratch.

I took my car out for a spin today to see if I could give a better description of the clunk so that I can try and figure out where its coming from. The clunk exists in 1st gear, but I would characterize it as very minimal to non-existent. Once I shift into 2nd, it starts to become more noticeable and it gets worse in 3rd, even worse in 4th and its brutal in 5th. I don't know if this information helps.

Edit: I just got back from another drive and yes it does do it just as bad in 1st. If I get on it hard enough in any gear it will do it, it just seems to do it easier in the higher gears. I find this a bit strange, because wouldn't there be more torque in the lower gears?

I'm hoping to get under the car this weekend and I'll report back with some better measurements.

Declan

[maddog]

more advantage by lower gears mean it takes more time for the slop to occur

.5:1 takes more time to pick up the slack than 1:1

[DoctorDex]

I measured the total backlash at the rear dif. today and I found it to be 7 mm, whereas spec. is 5mm. I measured the 7mm of backlash with the car in neutral, as per manual instructions. Just for kicks, I tried measuring the backlash with the car in gear and I was unable to move the shaft at all.

I was talking with my neighbor, a heavy duty mechanic, about this backlash issue and I took him for a ride to show him how bad it actually is. He pointed out to me that it is actually two clunks in rapid sucession. The first clunk is quieter and it is only a fraction of a second before the second larger clunk. He thought that maybe it could be due to the propeller shaft yoke or lobro joint slamming into its mating part. He reasoned that when you apply a large amount of torque to the rear dif., the rear dif. wants flex upwards and forwards. This upwards and forwards motion is what slams the shaft components into one another. He also said that the dealer probably only adjusted the crown and pinion. However, if the dealer had adjusted my crown and pinion, wouldn't I hear an awful whinning noise from the rear dif.? My neighbor is of the opinion that the majority of the backlash would be between the side gears and the spiders.

Does any of this stuff make sense or are any of these ideas plausible?

Thanks.

Declan

[keithmac]

If you`ve eliminated all play in the driveshaft with the car in gear at the rear diff end, but you get slop in the d/s in neutral then it really does point to the rear diff itself for the play (to be fair 7mm on the shaft doesn`t sound really excessive). Maybe the diff mounting rubbers are past their best? Wit mine I get a small clunk as the slack is taken up, but after that no more noises while accelerating, going to try mine in gear as well, good idea!

[DoctorDex]

IMO, you'd think the best way to test backlash in the rear dif. would be to have the propeller shaft disconnected from the transfer case. With the prop. shaft connected you are limited to measuring the minimum amount of backlash in any one part of your driveline/drivetrain.

Where abouts would I look to find the differential mounting rubbers? I'm curious to look into the idea my neighbor mentioned and I'm wondering if it has any validity? I remember reading awhile back, where someone replaced their rear struts, springs etc. with stiffer aftermarket versions and this cured their clunking on hard accel. Maybe this would help prevent some of the flex in the differential which could be contributing to the clunk?

Declan

[3spride]

I have this same clunking problem...but mine is non-existent under hard acceleration.

I only get this clunking and jerking going on when I am cruising around, trying to stay at a specific MPH. So when I am at say... 6-10% throttle I get the clunking and jerking. It is almost impossible to cruise around a parking lot and it's really bad in 5th (I'd almost say it feels the worst in 5th).

I have replaced the VCU, OS and IS.

I was told by my mechanic (very reliable) that I have a bad carrier bearing, bad right rear bearing, and my rear pinion seal needs to be replaced. So I was kind of figuring that it was being caused by those things.

I am going to replace my DS with a 1pc CF, but that won't be for quite some time.