New mods 3.45 diff 30% loc up uuc stage 2 clutch (1/4 times suck!!) - The Unofficial BMW M5 Messageboard (m5board.com)

GLOSS-IT · 19th June 2004, 18:34

Just had these mods done and am extremely disappointed

My 1/4 times were 14.4 at 100mph(air temp 100 deg elevation 3000 ft above sea level). The big problem was getting the car to hook up

The car would spin in first and second gear. I was dropping the clutch at 2500,2000,1800 and then walking it out. My 60ft times were horrible 2.3 sec. Before I changed the diff and clutch( the factory clutch was burned out bad) I would run 2.0 60ft and 13.8 at 103 mph???? I thought these mods would cut of .5 to 1 sec. Whats going on?? Help????

mottati · 19th June 2004, 18:47

Quote:

Originally Posted by GLOSS-IT

Just had these mods done and am extremely disappointed

My 1/4 times were 14.4 at 100mph(air temp 100 deg elevation 3000 ft above sea level). The big problem was getting the car to hook up

The car would spin in first and second gear. I was dropping the clutch at 2500,2000,1800 and then walking it out. My 60ft times were horrible 2.3 sec. Before I changed the diff and clutch( the factory clutch was burned out bad) I would run 2.0 60ft and 13.8 at 103 mph???? I thought these mods would cut of .5 to 1 sec. Whats going on?? Help????

It sounds like you need some better tires, a better launch technique or both. I don't drag race my m5, but i do think the 345 diff was the best mod for both the street and track use, but i'm not usually trying to accelerate real hard from a stop. Sounds like you could use some slicks!
mike

Teutonaddict · 19th June 2004, 19:22

Quote:

Originally Posted by GLOSS-IT

Just had these mods done and am extremely disappointed

I hope you followed the break-in recommendations on the new clutch. Clutches need to be broken in (bedded just like brake pads) for friction surfaces to hook up optimally...

KSA ///M5 · 19th June 2004, 19:34

I also have the 3.45 diff on my M5 the car is slower in first 2 gears and top speed

if your runing it with the 18in wheels. You maybe fell its faster but its not

the car has alot of power no need for shorter diff. Its better if you use the 3.45 diff with 19in wheels as im doing now but still the M5 with 3.15 diff and 18in wheels is faster

XrayMD · 19th June 2004, 19:54

If you're running in 100degree temps, may I suggest you get the IATS relocation kit. I think you'll notice a big difference. SInce you have the 3.45 diff., you may want to try launching into second and not even using 1st.

GLOSS-IT · 19th June 2004, 20:05

Thanks for the feedback everyone

Quick question what is a IATS and why would it make a difference? Also to answer an earlier post yes the clutch is broken in works great no slipping

Also someone had mentioned in a post that the 3.45 diff would be slower than the stock 3.15? Why?

Gustav · 19th June 2004, 20:08

Maybe beacuse it might require an extra shift to fourth. THowever you can raise the rev limiter to overcome this problem.

gra8fuldd ed · 19th June 2004, 20:46

Quote:

Originally Posted by Teutonaddict

I hope you followed the break-in recommendations on the new clutch. Clutches need to be broken in (bedded just like brake pads) for friction surfaces to hook up optimally...

GLOSS-IT:

Hopefully ... You followed the above recommendation BUT also there is a very similar recommadation from Dinan RE: 3.45 Diff.

The 3.45 Diff from Dinan uses that very heavy "New Car" Break-In Oil and MUST be changed at the same mileage as when that beast was brand new ... i.e. after a 1000 to 1200 miles of use.

After that 1200 mile mark ... Change the Diff Gear Oil and you should be good to go. This will NOT help your times ... BUT it will help you from burning up and replacing your Differential Gears!!

Stage2Pat · 19th June 2004, 21:27

60 ft time is a measure of your chassis.Now with the diff and the clutch you
are hitting the tires harder which is making it harder to launch.Optimum tire
pressure is important at this piont lower and raise pressure untillyou have a FULL contact patch.Look across the tread after a run to see where the scuffing ends.It should be at the outer edge of thetread. Also make sure that
the wear is even across.Too little pressure will show as no scuffing in the center from cupping.You need to shock the tires with out over powering them.

MPH is a measure of horsepower.Tthis will tell you if you are making more power or less.Temp and atmosphere have a big affect on MPH and power.

Its easy to motor full power to the end of the track.
Drags are won and lost in the first 60FT.

XrayMD · 20th June 2004, 05:49

Gloss-It: IATS relocation kit is the Intake Air Temperature Sensor relocation kit. If you're running in hot weather, the stock position of the IATS results in even higher temp readings than true because of heat soak. This results in the ECU ******ing timing and robbing you of power. The false readings can be 30 degrees or more than the true intake air temp (I verified this on two vehicles). The relocation kit disables the stock sensor (located in the driver's side MAF meter area) and installs a new sensor in a more optimal position. DO a search and you will find many threads regarding this inexpensive (about $100) mod. You can get this mod from UFMotorsport or BeastPower. I highly recommend it. It made a definite difference in power in hot weather. My beast runs in 90 degree weather like it did in 60 degree weather.