driveline slop/gear backlash

[terminal5]

Hi all,

I have a 2011 manual GT that is now lovingly referred to as "Clunky".

Clunky is a Brembo car with factory 3.73s, a Spohn UCA w/BMR mount, and most recently a DSS CF driveshaft.

Driveline noise at low speed and light throttle shifting has always been annoying, but since the driveshaft install, it's almost embarrassing. I thought the factory two piece was partially responsible, that's the primary reason I got the 1 piece CF unit. No difference with the new driveshaft until the car is fully warmed up, then it gets really clunky (more than before) and there's the added bonus of some gear whine being transmitted on accel and cruise that wasn't there before.

Reading a lot of complaints with 3.73s and noise. Thinking about swapping in some 4.10s. Maybe I should try a thicker gear oil first? Factory fill is pretty thick already, 75W140. Anybody try the 75W250 or whatever it is that Redline sells?

I did notice what seemed to be a lot of backlash between the ring and pinion when I installed the shaft, maybe even slop in the splined part of the driveshaft itself now that I'm thinking about it. I'll have to get under and have another look when I get the chance. Just in the middle of a several thousand mile road trip at the moment and Clunky's driving me nuts!

 

[grnenvy]

Your problem is being amplified by the DS and any rear suspension mods u have made.
There are countless rants about this. Most guys will get on here and say they don't have extra noise with there aftermarket suspension but there full of shit. U need to choose your parts wisely and figure out what parts u can stand listening to and if they really are worth the added Noise.
U put that factory DS back in and u will be happy again trust me.

 

[bmyles]

I agree with grenvy that's why my suspension is dead stock. I noticed a noise increase with my dynotech after I installed it so I switched to the redline heavy weight shock proof oil, it helped but I still have a very noticeable noise at 85mph. I am still on the fence about putting the stock d/s back in but I hate all the slop in the stock unit. Damed if you do damed if you don't lol

 

[terminal5]

I couldn't wait to get rid of the stock shaft because of all the slop, but the aftermarket one seems worse. I think it's just diff backlash that actually gets masked pretty well by the stock shaft. It's terrible now.

All the driveshaft reviews I've read say there might be more gear whine or some vibration. I have a little whine, but it's bearable, no vibration. Just all this clanking once things are warmed-up. Thought the CF was supposed to help with that. Guys running the aluminum versions must be really hardcore!

I have no complaints from the UCA now that I have the BMR mount.

bmyles, what did the shock proof oil help with, whine or clanking?

 

[Nocturnal'14]

I didnt notice the clunking at all on my '12 and now that I got the 2014 I see what all the fuss is about!

The difference in the two cars is on the '14 I now have the Metco Billet LCAs....to where as when I had the '12 I was using the Eibach adj LCAs. The Relocation brackets/sway bar/struts/shocks are all the same exact ones I used on my other car. Its amazing what a difference in LCAs can make with noise!

Oh, I had Redline Fluid in my other car too!

 

[UnleashedBeast]

Reading a lot of complaints with 3.73s and noise. Thinking about swapping in some 4.10s. Maybe I should try a thicker gear oil first? Factory fill is pretty thick already, 75W140. Anybody try the 75W250 or whatever it is that Redline sells?

I used Red Line Heavy Shockproof with Ford's XL-3 friction modifier (full bottle). Gear noise was reduced quiet a bit after the driveshaft upgrade that allowed for more noise.

The factory shaft is heavy, for good reason. Ford engineered it to kill driveline noise from gears. The 8.8" is known to be noisy.

After using Red Line HSP and Ford XL-3, all gear noise was reduced to near OEM levels, same as the OEM shaft had with BMR upper control arm. Also remember that some of the gear noise is coming through the upper control arm, so unless you swap back to rubber bushings, some of the whine will always be there. This is one of the tradeoffs for poly performance bushings.

End results for my car with full BMR suspension, Red Line HSP + XL-3, and Carbon Fiber drivehshaft = Some decel whine at specific speeds, more than tolerable now (can't hear it with the windows down due to radio/exhaust), and all driveline clunks have been eliminated. Obviously, you can sometimes feel backlash from the gears, but that can't be fixed, only reduced, assuming the gears were improperly setup.

 

[terminal5]

I'll probably try the shockproof gear oil first, if I can find it. But the whine isn't my concern, just the damn clunking.

It's not related to the UCA. When I first installed that by itself I would get a little knocking over bumps, but since I added the mount as well, that went away.

All the clatter I get is from the diff while putzing around at low speed and shifting.

 

[blackbeast12]

I have the same d/s as you no clunk no gear noise at all. Did you measure the distance from the end of your shaft housing and the cv joint bolt surface with the car on the ground? If its less then 3 and 1/4 or more then 3 and 3/4 you shouldnt be using the d/s. double check your uca bolts with the car on the ground! Tell us all your rear suspension mods please, thanks!

 

[UnleashedBeast]

I have the same d/s as you no clunk no gear noise at all. Did you measure the distance from the end of your shaft housing and the cv joint bolt surface with the car on the ground? If its less then 3 and 1/4 or more then 3 and 3/4 you shouldnt be using the d/s. double check your uca bolts with the car on the ground! Tell us all your rear suspension mods please, thanks!

Mine is perfect at 3.5"

 

[terminal5]

Only other suspension mods are the UCA and mount mentioned earlier. Stock Brembo Pack suspension otherwise including springs.

I took the above measurement as close as I could to ride height, on jackstands under the axle. Looked to sit about an inch or so higher than normal probably due to where the other stands were located on the front subframe. At that position, I had 3 1/2" and 2.5 degrees pinion angle. I think we're good there.

UCA and mount were all torqued to BMRs specs. I'm sure this isn't suspension related though.

Clunks existed since the car was new. I got the shaft in hopes of lessening them, but it's either made them worse, or it's coincidental. Pretty sure it's related to ring and pinion backlash. Mine's likely on the higher end of the spec. If I can find some of this shockproof fluid, I'll get in there and measure the backlash with a dial indicator.

Figured this might be part of the issues that many seem to be having with the 3.73 gear sets. I just don't want to swap in 4.10s and find no improvement.

 

[UnleashedBeast]

I see you are overseas, so it may be difficult to locate the fluid you need. Does Jegs or Summit ship international?

 

[terminal5]

I live/work overseas but the car is in Canada. Just gets used a few weeks a year for summer road trips and as something for me to mess with.

On Vancouver Island right now, probably can pick-up some Redline when I'm back on the mainland tomorrow. I see they have a lot of distributors in the Vancouver area according to their website. Hopefully someone stocks it. Probably won't change it until the car gets back to its home in Edmonton where I can check the backlash.

 

[jojobee]

Same boat here.
Since the addition of my aluminum driveshaft the driveline noise became a lot more noticeable.

It got me a mt-82 rebuilt from Ford.

Now that the only nvh i had left was from the 3.73 gears and upgraded suspension i was quite happy with it.

Looking for the ultimate suspension i switched gears to 3.31 and added a Whiteline watts link.
Guess what....the dreaded whine is back.

Soo tired of all this shit, will probably try a Dss driveshaft and replace my Bmr uca for the Roush piece that it supposed to be quieter.

Op, you already have a Dss so in your case i guess its all in the gears..

Good luck, whine is a bitch.

 

[bmyles]

I live/work overseas but the car is in Canada. Just gets used a few weeks a year for summer road trips and as something for me to mess with.

On Vancouver Island right now, probably can pick-up some Redline when I'm back on the mainland tomorrow. I see they have a lot of distributors in the Vancouver area according to their website. Hopefully someone stocks it. Probably won't change it until the car gets back to its home in Edmonton where I can check the backlash.

I got mine at auto value auto parts that's the only place I have seen it(redline 75w250), but their all over ab/bc and it did help with the noise a bit. Check your transmission as well because mine had a lot of slop in it to, more than the rear axle anyway.:beer:

 

[blackbeast12]

I got mine at auto value auto parts that's the only place I have seen it(redline 75w250), but their all over ab/bc and it did help with the noise a bit. Check your transmission as well because mine had a lot of slop in it to, more than the rear axle anyway.:beer:

You don't want thicker oil in a colder climate!

 

[bmyles]

You don't want thicker oil in a colder climate!

thanks for the thought but my car is in hibernation from October/november depending on the weather to may. I would imagine the op's car is to, so it dosent see any cold temps.

 

[terminal5]

Just an update for any interested:

Found the Redline heavy shockproof oil so pulled the diff cover and had a look. Backlash was .013". Ford's spec is .08-.012", which seems a bit high to me already. Looked to be a fair bit of slop in the pinion to side gears too, but I didn't measure that.

Put in the Redline oil without any LSD additive. Been driving a few days now and while I was initially optimistic, I'd realistically say both whine and clunks have only reduced maybe 10%. Some improvement, but not a cure, and still annoying.

I may try to find a shim set and move the ring a little closer to the pinion when I get another chance, but that could just make it whine more too. May just have to get used to it.

Was considering a change to 4.10s, but had the car on the track the other day and was trapping higher than expected. Guess I'll see where the mods take me and how the symptoms progress before moving on gears.

Advice for others: Don't expect a one piece (CF or not) driveshaft to get rid of driveline clunks, it will likely only amplify them. If you can take your car in to the dealer for warranty claims, have them check the ring and pinion backlash.

 

[UnleashedBeast]

Report back if you decide to reduce gear backlash. I'd like to know the results.

Far as clunks, I have minimal clunk noises after the install of the 1 piece. In fact, much less than with the OEM shaft. However, the shaft did amplify decel gear whine. That's why I'm interested in reducing gear backlash.

You don't want thicker oil in a colder climate!

Heavy Shockproof doesn't thicken in cold weather like your average 250 grade gear oil. It has cold flow performance like a cheap 75W-90 gear oil. However, HSP also does thin as much when heated, so it retains a more viscous viscosity. Combined with a formulation that sticks to the gears with minimal sling off, you have a quieting effect and more gear cushion.

 

[MikeLTDLX]

My car has made all kinds of clunks from day one. Even stock, there was a good deal of slow speed clunk in the driveline. I had an aluminum DS, it made no real difference. I sold it. Once I put LCAs in place with poly bushings, I started to hear gear whine around 80-95 mph. Nothing gets rid of that, except turning up the radio. My transmission is a whiner, so I am going to try some Dynamat around the shifter base. Aftermarket shifter, of course, made that worse. Mine also has a rattle/squeak from the rear that I am sure is bent axle flanges. Sounds like a Sherman tank. In all sincerity, the car is a total POS. However, it was cheap and it is fast. Has been reliable as well, despite the abuse. However, every mod away from stock has resulted in the car feeling less and less put together, and more and more like a jalopy. Just the facts of hot-rodding, I guess.

Mike

 

[nosympathy]

I used Red Line Heavy Shockproof with Ford's XL-3 friction modifier (full bottle). Gear noise was reduced quiet a bit after the driveshaft upgrade that allowed for more noise.

The factory shaft is heavy, for good reason. Ford engineered it to kill driveline noise from gears. The 8.8" is known to be noisy.

After using Red Line HSP and Ford XL-3, all gear noise was reduced to near OEM levels, same as the OEM shaft had with BMR upper control arm. Also remember that some of the gear noise is coming through the upper control arm, so unless you swap back to rubber bushings, some of the whine will always be there. This is one of the tradeoffs for poly performance bushings.

End results for my car with full BMR suspension, Red Line HSP + XL-3, and Carbon Fiber drivehshaft = Some decel whine at specific speeds, more than tolerable now (can't hear it with the windows down due to radio/exhaust), and all driveline clunks have been eliminated. Obviously, you can sometimes feel backlash from the gears, but that can't be fixed, only reduced, assuming the gears were improperly setup.

I may not have the one piece driveshaft yet, but the Redline Heavy shockproof fluid is faneffintastic. I am not sure how it will act come winter time when it gets really cold out here, so sub 30 degrees, but so far it has been great.

Also, from reading a lot, though I am not sure how much it will help with a once piece driveshaft car, stiffer motor mounts is supposed to help with the clunking a lot.