Hydraulic propshaft disconnect

Hydraulic propshaft disconnect

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C Lee Farquar

Original Poster:

4,066 posts

215 months

Thursday 8th January 2015
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At Autosport today I saw a rallycross car with a handbrake with two master cylinders. On further enquiry it seems they run a Sadev propshaft disconnect unit on the shaft to the front diff. The reason being that it's 4wd with no centre diff.

First point for discussion is do we agree that the disconnect on the rear diff would be better? It wasn't possible on the car in question as they ran a rear transaxle.

Anyone have any experience of the unit or another variant? I did go to the Sadev stand but there wasn't any body there who was familiar with the unit. I've only found diff mounted units on their website.

For clarity, the stand alone unit puts a permanent 4wd car into two wheel drive when you use the hydraulic handbrake. Permanent 4WD cars with no centre diff and LSDs front and rear do tend to be a handfull in tight corners, especially on dirt.

anonymous-user

53 months

Thursday 8th January 2015
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The front diff disconnect is the lesser of two evils, as it requires "clutch down" when you use the handbrake. Much better to disconnect the rear diff and leave the front wheels connected to the engine (useful if you get a bit keen with the h/b and need to get the show pointing the right way again too......). But, if you have a rear transaxle, that doesn't have a rear "propshaft" to disconnect, then it's still better to completely disconnect the front to enable the rear wheels to underspeed enough.

C Lee Farquar

Original Poster:

4,066 posts

215 months

Thursday 8th January 2015
quotequote all
Thanks, that was my thinking. If the figures stack up it would be much easier for me to fit it on the rear propshaft. My front diff is too close to the transfer box to fit one on the front without major work.


bjd7326

119 posts

146 months

Tuesday 19th January 2016
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if you were to want to disconnect the rear prop what clutch/mechanism would you use on the rear prop?

C Lee Farquar

Original Poster:

4,066 posts

215 months

Tuesday 19th January 2016
quotequote all
If I'm understanding your question Sadev make a self contained inline unit that disconnects the shaft.