Hi

I am working for an engineering design team, building a trailer dynomometer for Prodrive to use when testing various vehicles (WRC included)

We need to urgently source a couple of Differential units for this trailer, which will feed the power from the braking unit from the tyres, hence retarding the vehicle towing the trailer.

From our designs we need a diff with a reduction ratio around 2.1:1.

Coupled to that, we also need to source driveshafts, cv joints and hubs and suspension, so basically a whole axle.

Can anyone help with where we could source these parts? Due to cost constyraints, and lead time, we cant get these parts from Subaru directly through Prodrive, and 2k for a diff from a dealer is a bit too steep for this project.

I have been in contact with API, so we will see if they can help, but any other information/help would be gratefully received.

Thanks

Jamie McWhir

Project Manager
3D Engineering

 

James, i got your email as well as seeing this post here.

There is no final drive ratio on an Impreza [ or most Subaru ] lower than 3.7:1 unless I am reading your question wrongly. Do you not mean final drive [ diff ]

The only cars that would have a final drive of somewhere in the 2's would be yankee monsters and almost certainly not 4 wd.

If i've got it wrong please advise.

David APi Impreza / APi Engines
www.apiengines.com

 

Thanks David

I have got in touch with my designer engineer to check his specs out.

Based on running an 18" rally tyre, we will get around 1400rpm from the wheels at maximum speed. He will verify what speeds our input shafts for the braking system need to be

Thanks, and I will get back to you asap

Jamie

 

Basically, our wheels will be rotating at 500, 900 at 1400 rpm at the speeds they will normally run at.

The braking system we will use, will be inboard, and for the lower speed, e.g. 500rpm, to dissapate the torque figure we need to lose, the brake needs to be running at about 1000 rpm. Unfortunately our brake is limited to 3000rpm maximum, which means we have to build in some kind gearbox on the input of the brake.

Using an impreza diff, (3.7) the wheels would casue the central shaft to rotate at 1850, 3300 and 5180 rpm respectively, hence the gearbox needs to reduce these figures by a factor of 2 for everythin to be hunky dory..

So a standard diff will do it, but then a single step down box of some kind will be needed to deal with the rev band of the brake