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Sierra 7 Diff mouting points
Andrzejsr - 19/11/22 at 08:19 PM

Hi, what are Your experiences and thoughts regarding mounting Sierra 7" differential into the 7-type car chassis?

I am preparing an abandoned MNR kitcar, it is going be for track only.

Currently it has diff mounted (stiff bolted no bushes) on the points marked red on picture below :


https://drive.google.com/file/d/1avsTnJTEh-uYdnGvfKy_ocWOSvUYoxUE/view?usp=share_link


In this chassis I can see it should be quite easy to add mounting points at the Yellow " ? " mark - by welding steel plates to the chasis. Access to the bolt in this place is very easy (diff is quite far to the front in the tunnel, tunnel cover going to make easily detachable.

Just not sure the effort is worth it ? I mean maybe those two (on one side ) mounting points are enough (would like it to be rather more than enough for light car? )

But In other kitcar I know - Westfield to mount the diff, there are used those two Red points and third - at rear of the diff. Here in MNR only those on the side marked red.
have read in Westfield Forum that sometimes occur cracking in the diff cage. Dont know of any in MNR (but have no contact to others MNR users ) .
Maybe while I have car stripped of wort to add some 3mm steel plates tu support this front mount ?
Or might it in some way make a harm to dont know, diff case maybe ? as all mounting is stiff , no bushes. Car is going to be bike engined (CBR 1000rr) so rather not much torque, just vibrations I suppose - engine also stiff mounted to chassis, no bushes.


nick205 - 19/11/22 at 10:38 PM

My MK Indy mounted the Sierra diff as per your image. Road use, no track, 3k miles, sold car next owner did a few k miles. No issues with the diff mounting.


Slater - 20/11/22 at 10:27 AM

As per Nick205 above, my MAC#1 is the same as the MK in terms of diff mounting, all good for last 13 yrs and 15,000 miles. Using the yellow marked mounts would be overkill I think.


bi22le - 20/11/22 at 10:32 AM

My striker users the yellow points as well.

Maybe all JPSC chassis do, unless mine is a modified one.


Andrzejsr - 20/11/22 at 11:47 PM

So rather no harm to attach to front mounts , beside main two "Red".
As I have chassis anyway stripped and going to replace one wishbone bracket (i am not personalny good enough in welding)anyway giving chassis to service specialised in chassis welding and preparing will Ask them to add this front brackets. Just in case. Sicher ist sicher . Thanks for Your feedback!