# A VERY Important Note on DynoJet 4WD Dynos! **URL:** \ **Category:** NYSpeed Automotive\ **Created:** [August 31, 2005, 11:04am UTC](https://forums.speedlife.net/t/a-very-important-note-on-dynojet-4wd-dynos/1937 "2005-08-31T11:04:40Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![Inn-Tune](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/inn-tune/32/7588_2.png) [@Inn-Tune](https://forums.speedlife.net/u/Inn-Tune)\ **Post date:** [August 31, 2005, 11:04am UTC](https://forums.speedlife.net/t/a-very-important-note-on-dynojet-4wd-dynos/1937/1 "2005-08-31T11:04:40Z")
DynoJet sells 4WD dynos a few different ways. The most common is the 424 model which has the same front and rear roller diameter and weight. I’ve never heard of any problems with center diff damage on this setup. They have also sold a few shops a 248 model 2WD dyno with a 224x model added onto it. What does this mean? You’ve got a 48" roller and a 24" roller which are not linked. The one roller is twice the size AND about twice the weight (about 3500 vs 7000 lbs) of the other. A 3000 lb weight difference between rollers creates an enormous imbalance in front and rear resistance. What can this do to a center differential? It won’t blow up the diff on every AWD car, but it HAS happened. Cars with non-active OR active diffs can overheat and fail under these conditions. You have been warned. I have far too many local customers with AWD to tell them about this privately, and I’d hate to see any of you blow a diff (which can easily take out a whole tranny) so I’m posting it. -Mike ---
**Author:** ![RuBiCaNT](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/rubicant/32/7622_2.png) [@RuBiCaNT](https://forums.speedlife.net/u/RuBiCaNT)\ **Post date:** [August 31, 2005, 11:07am UTC](https://forums.speedlife.net/t/a-very-important-note-on-dynojet-4wd-dynos/1937/2 "2005-08-31T11:07:27Z")
Does anyone know if Kennedy’s has this type of Dyno? Could save a bunch of people from transmission problems. Good info, Mike!! ---
**Author:** ![Jack](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/jack/32/7613_2.png) [@Jack](https://forums.speedlife.net/u/Jack)\ **Post date:** [August 31, 2005, 11:09am UTC](https://forums.speedlife.net/t/a-very-important-note-on-dynojet-4wd-dynos/1937/3 "2005-08-31T11:09:09Z")
Same with my VCLS? I would think so… I know he has had quite a few DSMs and 3000GTs on his already. ---
**Author:** ![Inn-Tune](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/inn-tune/32/7588_2.png) [@Inn-Tune](https://forums.speedlife.net/u/Inn-Tune)\ **Post date:** [August 31, 2005, 11:10am UTC](https://forums.speedlife.net/t/a-very-important-note-on-dynojet-4wd-dynos/1937/4 "2005-08-31T11:10:18Z")
> [@Jack](#): > > Same with my VCLS? I would think so… I know he has had quite a few DSMs and 3000GTs on his already. Active and non-active diffs such as viscous couplers would both experience extreme differences in front and rear load causing excessive heat. ---
**Author:** ![Locutus](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/locutus/32/7574_2.png) [@Locutus](https://forums.speedlife.net/u/Locutus)\ **Post date:** [August 31, 2005, 11:12am UTC](https://forums.speedlife.net/t/a-very-important-note-on-dynojet-4wd-dynos/1937/5 "2005-08-31T11:12:10Z")
wow… 1800-joes-dad class action nikkuuaaaa ---
**Author:** ![Jack](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/jack/32/7613_2.png) [@Jack](https://forums.speedlife.net/u/Jack)\ **Post date:** [August 31, 2005, 11:14am UTC](https://forums.speedlife.net/t/a-very-important-note-on-dynojet-4wd-dynos/1937/6 "2005-08-31T11:14:43Z")
Unfortunately I can’t get to his site to check on the model number, but I think he bought the AWD as a unit, he did not append another unit to his existing one. (:lol: Too much use of the word unit) But I also heard he got it used… so maybe the previous owner bought 2 different units. BTW - What a stupid fricken idea to even use 2 different rollers… ---
**Author:** ![RuBiCaNT](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/rubicant/32/7622_2.png) [@RuBiCaNT](https://forums.speedlife.net/u/RuBiCaNT)\ **Post date:** [August 31, 2005, 11:15am UTC](https://forums.speedlife.net/t/a-very-important-note-on-dynojet-4wd-dynos/1937/7 "2005-08-31T11:15:08Z")
The viscous coupler is probably the least likely to break considering the design of the differential, but who knows when the fluid is heated up. It could be just as bad. ---
**Author:** ![Inn-Tune](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/inn-tune/32/7588_2.png) [@Inn-Tune](https://forums.speedlife.net/u/Inn-Tune)\ **Post date:** [August 31, 2005, 11:17am UTC](https://forums.speedlife.net/t/a-very-important-note-on-dynojet-4wd-dynos/1937/8 "2005-08-31T11:17:46Z")
> [@RuBiCaNT](#): > > The viscous coupler is probably the least likely to break considering the design of the differential, but who knows when the fluid is heated up. It could be just as bad. They’ve blown from having mildly different front and rear tires. This is FAR more extreme…hence my concern. ---
**Author:** ![system](https://canada1.discourse-cdn.com/flex034/uploads/speedlife/original/2X/b/b7170c8eddc0b95ece6b88172b2f416a08489a45.png) [@system](https://forums.speedlife.net/u/system)\ **Post date:** [August 31, 2005, 11:20am UTC](https://forums.speedlife.net/t/a-very-important-note-on-dynojet-4wd-dynos/1937/9 "2005-08-31T11:20:31Z")
Well the rear roller is the 248 ![http://www.kennedysdynotune.com/images/HPIM0590.JPG](http://www.kennedysdynotune.com/images/HPIM0590.JPG) ---
**Author:** ![Jack](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/jack/32/7613_2.png) [@Jack](https://forums.speedlife.net/u/Jack)\ **Post date:** [August 31, 2005, 11:23am UTC](https://forums.speedlife.net/t/a-very-important-note-on-dynojet-4wd-dynos/1937/10 "2005-08-31T11:23:10Z")
:word: a lot of guys are blowing these things. Most of them won’t even drive around on a spare because they are so fragile. [http://www.kennedysdynotune.com/](http://www.kennedysdynotune.com/) ![http://www.kennedysdynotune.com/images/HPIM0601.JPG](http://www.kennedysdynotune.com/images/HPIM0601.JPG) ![http://www.kennedysdynotune.com/images/HPIM0599.JPG](http://www.kennedysdynotune.com/images/HPIM0599.JPG) ![http://www.kennedysdynotune.com/images/HPIM0590.JPG](http://www.kennedysdynotune.com/images/HPIM0590.JPG) Not sure if you can tell from the pics, or even if the pics work ---
**Author:** ![Nikuk](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/nikuk/32/7254_2.png) [@Nikuk](https://forums.speedlife.net/u/Nikuk)\ **Post date:** [August 31, 2005, 11:41am UTC](https://forums.speedlife.net/t/a-very-important-note-on-dynojet-4wd-dynos/1937/11 "2005-08-31T11:41:58Z")
VC xfer cases are bad news in ANY kind of prolonged load differences. ---
**Author:** ![Inwo](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/inwo/32/7606_2.png) [@Inwo](https://forums.speedlife.net/u/Inwo)\ **Post date:** [September 1, 2005, 5:09pm UTC](https://forums.speedlife.net/t/a-very-important-note-on-dynojet-4wd-dynos/1937/12 "2005-09-01T17:09:25Z")
So is Kennedy’s bad then? ---
**Author:** ![Blue\_Eyed\_Devil](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/blue_eyed_devil/32/7292_2.png) [@Blue\_Eyed\_Devil](https://forums.speedlife.net/u/Blue_Eyed_Devil)\ **Post date:** [September 3, 2005, 5:05pm UTC](https://forums.speedlife.net/t/a-very-important-note-on-dynojet-4wd-dynos/1937/13 "2005-09-03T17:05:55Z")
I read an article a couple years ago that compared many fast cars. The tests included dyno comparisons and the Evolution was fine but the Carrera4 made nasty noises and could not be dynoed. I hope I can dyno at Kennedy’s to see if my car is close to Burchur Racing’s claims. ---
**Author:** ![Inn-Tune](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/inn-tune/32/7588_2.png) [@Inn-Tune](https://forums.speedlife.net/u/Inn-Tune)\ **Post date:** [September 6, 2005, 9:12am UTC](https://forums.speedlife.net/t/a-very-important-note-on-dynojet-4wd-dynos/1937/14 "2005-09-06T09:12:47Z")
> [@AWDrifter](#): > > I read an article a couple years ago that compared many fast cars. > The tests included dyno comparisons and the Evolution was fine but the Carrera4 made nasty noises and could not be dynoed. > I hope I can dyno at Kennedy’s to see if my car is close to Burchur Racing’s claims. The Porsche has issues on dyno that DO have rollers the same size and weight, let alone ones with different size rollers. Dyno Dynamics is one of the only companies who make an AWD dyno that works with Porsche’s setup. -Mike ---
**Author:** ![TrueBlue](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/trueblue/32/7245_2.png) [@TrueBlue](https://forums.speedlife.net/u/TrueBlue)\ **Post date:** [September 7, 2005, 11:02am UTC](https://forums.speedlife.net/t/a-very-important-note-on-dynojet-4wd-dynos/1937/15 "2005-09-07T11:02:46Z")
question - why two different sizes and weights? space constraints? power delivery in an awd car? shits n’ giggles? ---
**Author:** ![Ninja](https://avatars.discourse-cdn.com/v4/letter/n/53a042/32.png) [@Ninja](https://forums.speedlife.net/u/Ninja)\ **Post date:** [September 7, 2005, 1:58pm UTC](https://forums.speedlife.net/t/a-very-important-note-on-dynojet-4wd-dynos/1937/16 "2005-09-07T13:58:15Z")
> [@TrueBlue](#): > > question - why two different sizes and weights? space constraints? power delivery in an awd car? shits n’ giggles? my guess would be cost… I don’t really see any other reason.