Diff mounting brackets

[gtipping]

I was pondering the mounting of the brackets last night and wondered if anyone here had welded them directly to the chassis.

It seemed to me that separate brackets bolted to the chassis would just be another set of fixings that Mr IVA man would be inspecting.

Has anyone got any thoughts on welding the "book" brackets to the chassis or indeed a small redesign to make them more appropriate for welding?

[TalonMotorFabrication]

I can see one problem with doing that and it's called misalignment. If you have to use nuts and bolts to hold the weight of the diff in place while you tack the brackets in place why not just leave them there? If you are planing to just weld the 'B' part of the bracket on when you weld it fully it will pull like a bastard. What are you going to use to straighten it bareing in mind the twist you will exert on the surrounding box section. Try getting a grinder in there to see how much room you've got to cut it off again. For the sake of four bolts, four nylocs and eight washers is it worth it?

I make my mounting plate from 50x5mm flat and set the 'B' part 5'mm in from the edge of the plate to correct the placement, it also gives a better edge to get a nice chunky weld on. I grind a 45deg chamfer down both sides of the 'B' part then tack it both sides every 45-50mm. What ever you do don't run down one side then the other it will pull, weld two sections one side while clamped to a bit of 40x40-50x50 box section then unclamp and do two sections then other side and then repeat.
You should be able to get both brackets within 1-2deg of being plumb using this welding sequence 1+5 4+8 3+7 2+6

1 2
3 4
5 6
7 8

[voucht]

Originally Posted by gtipping

I was pondering the mounting of the brackets last night and wondered if anyone here had welded them directly to the chassis.

It seemed to me that separate brackets bolted to the chassis would just be another set of fixings that Mr IVA man would be inspecting.

Has anyone got any thoughts on welding the "book" brackets to the chassis or indeed a small redesign to make them more appropriate for welding?

Hi,

Welding the diff brackets to the chassis does not work, because if you do so, you will not have enough room to slide the diff in the rear frame, your brackets will always be on the way somehow. The diff can't slide straightly from the stop, neither from the bottom in the rear frame, it has to move sidewards at some point and it will not be able to do so with the brackets attached to the chassis as they will always be in the way. I think it is the reason why they have designed bolt-on diff brackets in the book.

I know that because I had this conversation with a Haynes Roadster builder in Sweden, who wanted to do weld the diff brackets to the chassis. This guy hadn't started his chassis yet, and I was exactly at the point of my build where I was installing my diff in mine. So, to check it by myself, I actually tried to install my diff with the brackets bolted on the chassis. It is just impossible, believe my experience. Unless you modify the diff casing or the rear frame of course. As I said, you have to be able to move the diff in a lot of different directions to find the right position to install it. It is already pretty tight in there, and you don't want, on top of that, big brackets always in the way.

The diff brackets are bolted to the chassis with four 8.8 grade M12 (I even have M14) bolts with nylocks, I don't see how it could be a problem for IVA, I never heard anyone having a problem with that at the inspection (I'm sure other forum members will correct me if I'm wrong)

So bolting the brackets to the diff, and then installing the diff with the brackets on inside the rear frame is, in my opinion, the only way to go.

But it is just my humble opinion and experience of course

Hope this will help and stop you to do something you might regret later

[gtipping]

Thanks Phil and Sylvian for your quick replies - that's why forums are so good. No need to waste my limited brain power on this now - can move on to the next bit.

[flyerncle]

If you look at the top of the diff casing there is a casting line in the center of the diff and this can be used to line up the unit in the center line of the chassis.

Edit : Sierra diff only.

[jps]

Originally Posted by flyerncle

If you look at the top of the diff casing there is a casting line in the center of the diff and this can be used to line up the unit in the center line of the chassis.

Edit : Sierra diff only.

I was recently looking at aligning my drivetrain and it did occur to me that the Book diff mount brackets (for the Ford diff) would, in theory, allow for some shimming to allow the alignment to be tweaked.

Is there any reason why this would not be possible? Not ideal I know, but just wondered if there was a specific reason why it would be a bad idea...?

[alga]

Why do you want to align the diff? There are universal joints on all 3 shafts coming out of it, what's wrong with it being a few mm or out of alignment?

That said, there are 2.5 mm thick washers between the bracket and the diff on one of the sides on my car.

[jps]

Originally Posted by alga

Why do you want to align the diff? There are universal joints on all 3 shafts coming out of it, what's wrong with it being a few mm or out of alignment?

That said, there are 2.5 mm thick washers between the bracket and the diff on one of the sides on my car.

Basically I was thinking in terms of getting the prop to run true - but off-set - and thinking that, if needs be, I could always make adjustments at the diff end rather than the gearbox output end...

Perhaps I am trying to be too precise...?

[K4KEV]

I believe I read somewhere that it is beneficial to have the prop slightly offset
any way to ensure even wear on the uj's

[Badger]

A bit of offset is good - it causes the UJ's to move rather than just stay in one position as they rotate.
Angular misalignment between the gearbox\diff faces is bad, as the UJ's do not fully counter each other. This can lead to vibration and wear from memory.