Welding up diff mounts... bad idea?

M

MWP

New member
Hi all,

I was thinking about making some poly rear diff mounts, which is a bit of a pain to do.
So then i thought... since poly is quite solid (and other solid mounting solutions exist), why not just weld them up completely?

As in, remove the rubber mounts and weld up:
Untitled_1.jpg


Can anyone foresee any issues with doing so?
 
underscore

underscore

Well-known member
If you weld up those three but leave the 4 mounts that go to the chassis with at least a tiny bit of play I'd imagine it would be fine, it'll be harder on the drivetrain when you're launching it though.
 
M

MWP

New member
I just had a good look through RaceFab's photos... they solidly mount most rear diff's and subframes to the chassis.
So it doesnt look like it'll be a problem.

18414_10153091791824414_7885848271915540874_n_jp.jpg
 
I

Insanity-74

New member
There are a few considerations to make when welding up diff mounts or adding solid mounts to anything, not just diff mounts.

1. Wheres the stress going to go to next?

Allowing parts to move helps eleveate stress to all parts of the car, if you remove that abilty to move the strain has to go somewhere. Usually to the next weakest part. Its figuing out what that part is and can it cope? Its ikely that it will be one of the bolts somewhere as they will be corroded and stressed already, or any of the pressed sheet metal components that may be weakened by corrosion.

2. Diff deisgn.

Do you thing that the diff casing is strong enough to take the extra strain? I would have thought so as its pretty big, but who knows? Cast material does like to go with a bang.

3. How goods your welding?

With the constant strain placed on the diff carrier, will the welds be able to cope?
 
___Scott___

___Scott___

Active member
The place I would be concerned about is the sheet metal the subframe bolts to. The extra loads and vibration may cause fatigue in the thin metal and cause it to crack eventually. Additional reinforcement may be necessary.

The easy way to avoid that problem is to just use a flexible mount, rubber/poly etc...
 
G

GT4times2

Moderator
___Scott___":1zy4o2me said:
The place I would be concerned about is the sheet metal the subframe bolts to. The extra loads and vibration may cause fatigue in the thin metal and cause it to crack eventually. Additional reinforcement may be necessary.

The easy way to avoid that problem is to just use a flexible mount, rubber/poly etc...
Click to expand...



Agreed, plus

There are kits available for our cars. Why complicate things? Stay with what works.
 
M

MWP

New member
Because not complicating things is boring ;)
... and its actually simplifying things. It'll be a tad lighter too.

___Scott___":1wl9fesh said:
The place I would be concerned about is the sheet metal the subframe bolts to. The extra loads and vibration may cause fatigue in the thin metal and cause it to crack eventually.
Click to expand...

Thin metal?
I gather youve never dropped off the subframe and looked at the chassis under there then?
They are built like a brick shit house.
 
M

Mr Alltrac

Member
Interesting idea, should be a fun project! I don't doubt that it would hold, my only concern would be if your not an engineer it would be hard to guess where the stress would be and where to make sure to brace.

Has that other rear subframe been ran in a rally or is it a road race subframe?
 
M

MWP

New member
Its now rather solid :p :D

Just a few progress photos from today.
Should get it finished off tomorrow.

Getting it into the right location was a hardest bit.
The diff is now in millimeter accurate position :)

IMG_20160208_163033.jpg


IMG_20160208_173506.jpg


IMG_20160208_173514.jpg
 
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