Mazda Rotary Club

General => General Technical => Anything Engine/Performance/Tuning related => Topic started by: Wav on April 07, 2005, 04:47:00 PM

Title: Uprated Diff, how can you tell?
Post by: Wav on April 07, 2005, 04:47:00 PM
Was running in the other red FD last night after getting it fired up for the first time last Friday :cool and the diff has a wierd rumble at low speed and definitely feels different going into corners. It clunks on take up and knocks a little too.

The car has tein suspension and roll bars, so am thinking it is quite likely to have uprated diff as well, well maybe. So how can I tell what it is? and that it isn\'t just a sha**ed normal diff.

Ta,

Paul:)
Title: Uprated Diff, how can you tell?
Post by: MikeLMR on April 07, 2005, 05:16:16 PM
take it out and look at it is the only sure way ... even then its not clear if you don\'t know what a standard one looks like
Title: Uprated Diff, how can you tell?
Post by: zevans on April 08, 2005, 02:35:37 AM
Practical Perf Car has a REALLY good article on LSDs this month - might provide some clues.
Title: Uprated Diff, how can you tell?
Post by: 20B_boy on April 08, 2005, 10:58:20 AM
Like Mike says, take it apart!

A stock Torsen one looks like this below (but hopefully less broken), uses the worm gears in the middle to send more
torque to the slowest turning wheel. Aftermarket diff often use clutches (have a look at the KAAZ website for some exploded pics from recollection):
Title: Uprated Diff, how can you tell?
Post by: Wav on April 08, 2005, 11:46:48 AM
Cheers guys, I think I\'ll just leave it alone and hope it doesn\'t blow its inards, if it is a std diff, on Jodies (new owner as of tomorrow) way home. Think i\'ll jack it up this eve and just check for play and grinding to make sure it\'s not obviously broken.

Thanks for the replies,

Paul:)
Title: umm
Post by: samfc3s on April 08, 2005, 12:12:16 PM
Sounds as tho u may hv a 2way LSD unless it is knackered;)

Does it clunk when accerate and clunk more on full lock?also does it clunk when u ease off the accelerator?

SAM
Title: Uprated Diff, how can you tell?
Post by: Tintin on April 08, 2005, 10:20:23 PM
I was wondering about uprated LSDs a while back as mine can be quite clunky at low speed ( then again it might just be the bloody clutch ) , anyway I was reading a bit about them and apparently the uprated ones are clunky at low speeds

Are there any other tell tale signs ? and would someone experienced be able to tell either by looking or driving as I don\'t fancy taking it off on the off chance
Title: Uprated Diff, how can you tell?
Post by: J4P RX on April 09, 2005, 05:43:34 PM
Yeah should be able to tell from driving it as theres a fair bit of difference.

It will be clunky, and it will feel like the wheels are skipping too.
Title: Uprated Diff, how can you tell?
Post by: petemillis on April 09, 2005, 06:05:08 PM
Jack up the rear and see how tight it is. The normal LSDs usually allow you to turn one wheel while the other remains still. But one we had jacked up last week - both wheels turned in the same direction and it was very tight. My garagey bloke who does short circuit oval racing reckoned this was an uprated LSD, not just a normal LSD.
Title: Uprated Diff, how can you tell?
Post by: J4P RX on April 09, 2005, 06:20:17 PM
If youve got an LSD doing that then they will both turn in the same direction.  

Wouldnt of thought that would really tell you much since all FD\'s will have diff of some description.
Title: Uprated Diff, how can you tell?
Post by: gsb876 on April 10, 2005, 02:04:12 AM
Brian knows alittle about diff :rollin :rollin :rollin
Title: Uprated Diff, how can you tell?
Post by: Tintin on April 10, 2005, 11:10:48 AM
very true :rollin

guess brian would have noticed if it had an uprated diff