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07-21-2026LAST POST
I really shouldn't be attempting this right now but how often are folks changing their differential fluid? Diff Fluid Change DIY
///Mobbin wrote
I really shouldn't be attempting this right now but how often are folks changing their differential fluid? Diff Fluid Change DIY
i'm not 100% sure what the interval is, but it doesn't seem like a big job at all. the only thing i would do differently in that DIY, is the way i jack up the car. to drain it, i would jack up the car on the driver's side to "dump" the oil. when filling, i would jack the car up on the passenger side so i could overfill the diff a little bit.

i do a similar thing with my truck, but when filling the tcase. i jack the side of the truck way up (it has a lot of suspension travel) and i'm able to get almost an extra bottle into the tcase. differentials are one of those things that it doesn't matter if it is overfilled. disclaimer- i'm not an expert on performance differentials, but it probably doesn't matter if it is overfilled.
there are some custom axles for offroading where the diff fill plug is on top of the axle to completely fill the pumpkin with oil and submerge the gears. i wouldn't do this with a car, but it doesn't seem to be a problem.

watch the torque on them plugs, mob. ;)
roastbeef wrote
watch the torque on them plugs, mob. ;)
Lol, this! Unfortunately my shop didn't even resolve my oil drain issue, they just found a plug that fit more snugly as a temporary solution. I'm ordering a time sert kit and plan to fix it myself now so I'm confident in the fix.

Thanks for the info on the diff fluid change, this will be next up! I'm thinking Castrol diff fluid as OE BMW is $$.
Research using non-oem fluids. LSD's may be sensitive to changes, especially if they have been broken in.
roastbeef wrote
Research using non-oem fluids. LSD's may be sensitive to changes, especially if they have been broken in.
True, when I did my diff flush I just used OEM with the FM Booster. I also got a magnetic diff drain plug from ECS.
///Mobbin wrote  
roastbeef wrote
watch the torque on them plugs, mob. ;)
Lol, this! Unfortunately my shop didn't even resolve my oil drain issue, they just found a plug that fit more snugly as a temporary solution. I'm ordering a time sert kit and plan to fix it myself now so I'm confident in the fix.

Thanks for the info on the diff fluid change, this will be next up! I'm thinking Castrol diff fluid as OE BMW is $$.
Just stick with OEM with FM.
It looks like the OEM SAF-XJ fluid with FM booster is what Dinan recommends and looking back on my service records it's what was used by the dealer when my 3.45 Dinan(BMW Motorsport) final drive gear was installed. That was 20k miles and many track days ago, probably a good time for some fresh fluid.

For reference, this looks to be the right BMW Part No. 83 22 2 282 583 and 3 bottles are needed.
Looks like it might rain on me Friday at Laguna. Any rain tips? Smooth inputs, stay off the main driving line?

I'm mounting some new nt01's today, so I'll have decent tread.
Would it be better to run your PSS in the rain vs the NT01?
Depends on how heavy the rain is, but nt01's have some decent depth when new. If it's raining, I won't be pushing it as hard for it to make a difference. It would be a sideways control day.
roastbeef wrote
Looks like it might rain on me Friday at Laguna. Any rain tips? Smooth inputs, stay off the main driving line?
When I was there in the rain there was a bit of a river that formed after turn 4, flowing perpendicular across the track. An e36 with barely any steering input spun out on it and hit the wall hard.

Have fun, be safe. Laguna in the rain was one of my most intense experiences in recent memory.
what is everyones opinion on front control arm bushings. mine are due to be replaced and I was going to just buy new arms all together, but have been looking at the momo ball upgrade. worth it? or just stick with stock
Properstyle wrote  
what is everyones opinion on front control arm bushings. mine are due to be replaced and I was going to just buy new arms all together, but have been looking at the momo ball upgrade. worth it? or just stick with stock
I have monoballs on my tension arms. Love them. Great steering feel and feedback. No noise. No downsides, all pleasure.
NoCarrier wrote  
roastbeef wrote
Looks like it might rain on me Friday at Laguna. Any rain tips? Smooth inputs, stay off the main driving line?
When I was there in the rain there was a bit of a river that formed after turn 4, flowing perpendicular across the track. An e36 with barely any steering input spun out on it and hit the wall hard.

Have fun, be safe. Laguna in the rain was one of my most intense experiences in recent memory.
Yea, it's going to be a slow day if it's wet. I was hoping for clear skies and temps In the 60's. fml.
roastbeef wrote
I have monoballs on my tension arms. Love them. Great steering feel and feedback. No noise. No downsides, all pleasure.
got a link to which you have? did you change out the arm and do them or just use your current arms do the monos
Properstyle wrote  
roastbeef wrote
I have monoballs on my tension arms. Love them. Great steering feel and feedback. No noise. No downsides, all pleasure.
got a link to which you have? did you change out the arm and do them or just use your current arms do the monos
IND had a 15% off sale and I picked up the fall line press-in kit. It's a very tight fitting bolt in kit, so it may as well be press-in.
Attached image
Properstyle wrote
what is everyones opinion on front control arm bushings. mine are due to be replaced and I was going to just buy new arms all together, but have been looking at the momo ball upgrade. worth it? or just stick with stock
I got the non-monoball Rogue Engineering lower control arm bushings and I'm not sure I can tell much of a difference. I would go monoball if I did it again, but would also suggest saving for a BBK, track wheel set, or suspension first. YMMV. Just my new mantra to go for the bigger items before the little after doing it the other way around on most of my cars.
roastbeef wrote
Looks like it might rain on me Friday at Laguna. Any rain tips? Smooth inputs, stay off the main driving line?

I'm mounting some new nt01's today, so I'll have decent tread.
Rain tips? yeah, I've got a few of those. My experience in the rain isn't extensive, but I did drive the A1 ring (now Redbull Ring) in Austria in a downpour. Here are tips for a very wet track:

1) be 1 gear higher than normal (e.g., if you're in 3rd normally, be in 4th)

2) keep the loaded tires off the paint

3) keep off the polished pavement so you'll likely be apexing a few feet off the normal apex. Shiny pavement = bad. Pavement with texture = good.

4) soften your suspension if it is adjustable. If you can, disconnect your sway bars.

5) slow down your inputs (hands and feet) unless things go horribly wrong, then be quick like a bunny (fast hands)

If it isn't too heavy (e.g., no standing water) run the Nittos. If there is standing water run the PSS'.
Thank you Sir.
///Mobbin wrote  
Properstyle wrote
what is everyones opinion on front control arm bushings. mine are due to be replaced and I was going to just buy new arms all together, but have been looking at the momo ball upgrade. worth it? or just stick with stock
I got the non-monoball Rogue Engineering lower control arm bushings and I'm not sure I can tell much of a difference. I would go monoball if I did it again, but would also suggest saving for a BBK, track wheel set, or suspension first. YMMV. Just my new mantra to go for the bigger items before the little after doing it the other way around on most of my cars.
It is very subtle. A bbk is a better option before monoballs. However, I noticed a difference right away. It's a hard feeling to describe, but it's like you get more road feel through the steering wheel.
I love the subtle mods that add up. I also have solid subframe and diff bushings and I feel like each of the mods enhances the other. The car feels very solid, even on oem zcp suspension, and razor sharp steering feel.
Just ordered track tires, time-sert for oil drain, OE drain plugs, more oil, and diff service kit. Will be ready for COTA in no time! :party0030:

I also talked on the phone to a time-sert tech for like 20 minutes, great resource and feel confident about using the kit now.
roastbeef wrote
It is very subtle. A bbk is a better option before monoballs. However, I noticed a difference right away. It's a hard feeling to describe, but it's like you get more road feel through the steering wheel.
I love the subtle mods that add up. I also have solid subframe and diff bushings and I feel like each of the mods enhances the other. The car feels very solid, even on oem zcp suspension, and razor sharp steering feel.
///Mobbin wrote
I got the non-monoball Rogue Engineering lower control arm bushings and I'm not sure I can tell much of a difference. I would go monoball if I did it again, but would also suggest saving for a BBK, track wheel set, or suspension first. YMMV. Just my new mantra to go for the bigger items before the little after doing it the other way around on most of my cars.
My car currently has solid rear sub frame mounts akg track bushings. might as well be solid.

fortuna500 series coil overs with swift springs and camber plates

a st40 front bbk

bimmer world sway bar end links,

be beaings change with arp bolts.

F14 19x10 19x11 PSS 265/30 fronts 295/30 r888s rear. I was doing half mile and drag events before so i know I will need to change to having the same compound all around before getting serious about the track.

Currently looking in to cooling options as I do have a 625kit on my. I may keep it to doing auto x with light tracking until i get a larger oil cooler and misting system.