Rear Diff Mount - Failed!

[greyV8pete]

Just had the fabricated rear diff mount fail on my Hunter. Fortunately at only 5mph when pulling away from the lights, so just a loud bang and not too much of a fright

Anyone had any experience of the billet machined ones as per link below? I would fit the polybush version, not nylon, for road use.

http://www.ebay.co.uk/sch/i.html?_nkw=sierra%20diff%20mount&clk_rvr_id=450683291568&adpos=1t1&MT_ID=10&crlp=15286749040_2113181&geo_id=32251&keyword=sierra+diff+mount&crdt=0

Don't feel like welding up the original as it is a bit flimsy and although £150 quid is a lot of money, it would still give more peace of mind. I wouldn't like to have had the failure at 70mph! Peter.

[CosworthCabrioLee]

Re: Rear Diff Mount - Failed!

Hi Pete, this has been a constant worry also on my car, and I intend to replace mine with one from motor sport developments in Lancashire £120 delivered eBay number 281030650955 this is the one the cossie boys use
Are you going to drop your diff or drop your tank ? I am going to drop the diff and shafts.

[ruby131]

Re: Rear Diff Mount - Failed!

Hi Pete,forgive the pun but you had a lucky "Break" there. I had one go on my XR4I a few years ago ,like you fortunately at low speed but still fast enough to be a bit scary. Cheers Chris.

[Mike]

Re: Rear Diff Mount - Failed!

Just had the fabricated rear diff mount fail on my Hunter. Fortunately at only 5mph when pulling away from the lights, so just a loud bang and not too much of a fright

Anyone had any experience of the billet machined ones as per link below? I would fit the polybush version, not nylon, for road use.


Don't feel like welding up the original as it is a bit flimsy and although £150 quid is a lot of money, it would still give more peace of mind. I wouldn't like to have had the failure at 70mph! Peter.

Hi Peter
Mark Scott kindly lent me his billet machined polyflex mount and it just fits into a Cabrio - the fixing bolt heads are marginal with the fuel tank on mine - in fact I crudely panel beat my tank to increase the clearance:





I took the tank out of mine to install it, but I am still building my car, so maybe it was easier?
Since testing this, which worked fine, I have decided to make my own softer version by using a Scorpio styled two mount fixing using the original style rubber mounts welded to a cross bar, and attached to the normal diff fixing position:





This will stop wind up, whilst hopefully keeping Noise, Vibration and Harshness low. The design has more clearance to the fuel tank than the billet polyflex version.

To answer your question, the billet mount works well in the Cabrio, and as Lee says, the Cossie Sierra boys love it.

[greyV8pete]

Re: Rear Diff Mount - Failed!

Hi Pete,forgive the pun but you had a lucky "Break" there. I had one go on my XR4I a few years ago ,like you fortunately at low speed but still fast enough to be a bit scary. Cheers Chris.

Thanks Chris. Yes it did make quite a bang! Peter.

[greyV8pete]

Re: Rear Diff Mount - Failed!

Many thanks for the pics Mike. The Graham Goode one looks the most stress free with nice CNCd flowing radii and no welds, but is also fiendishly expensive! As there is a full tank of fuel on board I am wondering if it is practical to remove the boot floor as from your pics access would appear to be much easier than trying to fit it underneath and fighting the twin exhausts. I have a horrible feeling that my floor has been put in with Sikaflex as well as bolts?! Peter.

[greyV8pete]

Re: Rear Diff Mount - Failed!

Hi Peter
................ Mark Scott kindly lent me his billet machined polyflex mount and it just fits into a Cabrio .............

Mike. Do you happen to know the supplier for that part? Peter.

[CosworthCabrioLee]

Re: Rear Diff Mount - Failed!

Motor sport developments make them for ggr

[greyV8pete]

Re: Rear Diff Mount - Failed!

Motor sport developments make them for ggr

Thanks Lee. I found this billet machined one on Google / Ebay under their (Motor Sports Development) name. Peter.

[Mike]

Re: Rear Diff Mount - Failed!

Hi Peter

This one looks very similar, but has had less material cut away and has smoother flowing lines, so could prove to be stronger?





Which ever you go for, I think you should not have the issue with tank clearance as they both use counter sunk allan key bolts.

Mike

[greyV8pete]

Re: Rear Diff Mount - Failed!

Hi Peter ..... Which ever you go for, I think you should not have the issue with tank clearance as they both use counter sunk allan key bolts.....

Mike

Hi Mike. Sent my email to you before I read this post! Thanks. Peter.

[cabrioman]

Re: Rear Diff Mount - Failed!

Peter

Was it a standard Ford mount that failed on you?, what hapened to it, the rubber ripped out of the mount or more catastrophic?

John

[greyV8pete]

Re: Rear Diff Mount - Failed!

Peter

Was it a standard Ford mount that failed on you?, what hapened to it, the rubber ripped out of the mount or more catastrophic?

John

No it was a fabricated one with a top hat polyflex bush and was intended to limit movement with the V8 output and was fitted when I first had the car, so it's lasted for several years and about 15k miles. Unfortunately the mounting plate was too thin and the other part of the assembly fatigue cracked all around the weld. See further update post to follow. Peter.

[greyV8pete]

Re: Rear Diff Mount - Failed!

Update from today.

Well this job is going to be interesting! Having done a bit of research and a lot of help via email from Mike I have plucked up courage and ordered a shiny new billet machined rear diff carrier.

Today having finally found which are the correct bolts to clamp in the boot (funny how front becomes rear when you are underneath the car, tired and freezing cold) I have removed the remains of the top fixing plate of the diff carrier. Expecting to now be able to extract the remainder of the bracket I have encountered what is usually referred to as “Catch 22”, namely that the bracket won’t come out with the other half bolted to the diff and the bit bolted to the diff can’t be removed with the carrier in the way. Grrrrrrrr!

Having thought that removing the boot floor would give me plenty of access I realised that the rear of the body mounting would still be in the way and access to the two diff bolts would be even more difficult.

So with the phrase “Mission Creep” niggling at the back of my mind, two options seem to be the most likely way forward.

As both methods require the twin exhausts to be removed (yet again) for access I have already resigned myself to a repeat of that struggle. So after that:

Option 1 – Disconnect the prop shaft to drop the diff, get the new mount bolted on and then offer it all back up into place and hope that it clears the fuel tank.


Option 2 - Drain the fuel tank, yes you guessed it I had just filled up the day before, and then “just” remove the fuel tank. Remove the remains of the old mounting and fit the nice shiny new thing. Offer it all back up and get all the bolts tightened. Then persuade the fuel tank back in. There seems to be about 3mm spare behind the tank for it to move back if I tweak the brackets and there is the option of using countersink head setscrews for bolting to the diff to gain another couple of millimetres. After that the tank may need some local “modification”.

Then I “only” have to refit the exhausts! Oh for a 2 post lift in my garage! Jacking it onto 2 ton axle stands is safe and effective but tiresome after the first half a dozen times


More updates to follow. Meantime I’m off now to crack open a bottle of the red stuff to keep things in proportion! Peter.

[greyV8pete]

Re: Rear Diff Mount - Failed!

My shiny new diff mount has just arrived! Express delivery in 22 hours! Let battle commence! Peter.