DIY Gearbox brace how to make

Yes the internal one replaces 5th gears & holds the 2 shafts in place via a figure 8 looking shaft collar brace.
For most people a shot peened well built standard box will do well, next step in cost is PAR followed by Quaife then PPG.
Image below of 5th gear shaft collar brace, one in par kit & 1 for standard >

That brace would be so good if it wasn't so impractical for a street car

So do you shot peen the box casing itself or freeze it? Or both?

Casing is generally cleaned up in terms of casting flash/seems & just cryo treated.
Gears can be cryo & shot peened although just quality job on shot peening is the norm.
Likes of PAR gear kit are shot peened as standard, the current PAR kit straight cut syncro with design revisions & needle bearings is quite a good design & price good too.

I never had my case cryo treated or anything, it just ran a f/g brace at the tail end which was sufficient and kept everything into place even after all these years ive never busted a gear casing

you can get aluminium shotpeened by using a slightly different process but I wouldn't advise that due to thicknesses of casing, if anything I think it could actually weaken it further
shotpeening removes the risk of stress related fractures by around 20%
what it does not do (as someone had been told today by a firm ) is increase the strength by 20-25% that's just not true

What sort of power has been run through that box bob? Is that 570bhp one that was used for drag?

yeah had been used in 2 cars both running in excess of 400hp on the road then finally the drag car which was just over 570hp where it was fitted for a good couple of years

We're the gears in that just shot peened and nothing else? Sorry for all the questions but want to make sure I get this right, would it not be an idea to have it froze as well whilst it's being done and polished?

no they were just shotpeened nothing else, was rebuilt with new bearings, seals ect that's it

Shot peening just produces a skin on the surface of the part that initial cracks have very hard time developing thus greatly improving fatigue strength of components.
Other major thing to be looked at is your shaft end floats when building the box as excessive float is a main player in case failure.

Interesting thread interesting read. Would be interesting which way you ho Pete. How much is shot peening and cryo treating? I guess the box would need to be rebuilt too

I'm getting different prices atm, got to ring some where tomorrow my mate uses for his garage, about £300 to strip and put together, and then send the gear set off and about £200 to have peened, but if the box wants any new bearings that would be extra, had a quote for nearly a grand early for a company that does the whole lot but that seemed a bit steep

Wow £300  to strip and put together?? It  took me couple of hours to replace all bearings on my mates car.... what rates they've got

Wish I could do it my self but never done a box so wouldn't trust myself to take it to piece's

Alot of places are 300-350 to strip and rebuild

Main thing with shot peening is picking someone who specifically into gearbox work as requires good technique/experience to be effective in all the pits & edges of a gears surface, too little peening means no real gains & to much can overstress the surface .

 Years ago when I had mine doneMr B wrote:Shot peening just produces a skin on the surface of the part that initial cracks have very hard time developing thus greatly improving fatigue strength of components.
Other major thing to be looked at is your shaft end floats when building the box as excessive float is a main player in case failure.

That's not entirely correct as it does not produce a skin as such
It was done predominantly to eradicate or reduce stress fractures from cast mouldings of certain materials

Basically the process involves blasting an item such as a gear with ball bearings of various sizes which then adds strength to it by altering the  molecular structure of the item being done as the surface will then be dimpled and stress points spread out rather than in one place
This reduces the risk of a stress fractur

I'm sure someone could google it or something and put a more detailed description but in laymans terms that's pretty much what I was told when I had mine done.

All I can remember is that it was carried out by a company in Northampton which specialised in this kind of work.
I removed the gears and just sent them down to them and at the time they charged around £5 per gear which is bloody cheap considering what the box has been through and how well its lasted

https://youtu.be/AgPsxoZnEa0
.....there you go

GTI-R US wrote:

 Years ago when I had mine doneMr B wrote:Shot peening just produces a skin on the surface of the part that initial cracks have very hard time developing thus greatly improving fatigue strength of components.
Other major thing to be looked at is your shaft end floats when building the box as excessive float is a main player in case failure.

That's not entirely correct as it does not produce a skin as such
It was done predominantly to eradicate or reduce stress fractures from cast mouldings of certain materials

Basically the process involves blasting an item such as a gear with ball bearings of various sizes which then adds strength to it by altering the  molecular structure of the item being done as the surface will then be dimpled and stress points spread out rather than in one place
This reduces the risk of a stress fractur

I'm sure someone could google it or something and put a more detailed description but in laymans terms that's pretty much what I was told when I had mine done.

All I can remember is that it was carried out by a company in Northampton which specialised in this kind of work.
I removed the gears and just sent them down to them and at the time they charged around £5 per gear which is bloody cheap considering what the box has been through and how well its lasted

Skin maybe not the best word but from what I understand of the process the shot peening produces compressed layer of probably around 2thou & this is what I call the skin. The concept is the crack fractures don't start easily in the compressed layer/skin.
Size & speed of peening shot is very critical as is full coverage & overlaping. The dimples deformation left are good for helping retain oil on the parts apparently, some people add protective wear coatings after peening.
That company in Northampton still going ? prices sound reasonable & even if almost doubled would still be good ...

Bob was it called Sandwell by any chance?

yes believe it was Sandwell, was around 10 years ago but that name sure rings a bell

I spoke to a chap there after being given there number by someone I used to race bikes with as he had his gearset done on an R1
at the time I had (like you)never understood what it was all about but was looking for a cheapish option to strengthen the gearset
he advised me not to get the casing done but just the gearset and selectors, in total from memory it cost just under £180 plus the cost of rebuild of the box which I had done locally

then go spend £££££ on quaifes and other boxes which all broke but the little shotpeened shitter lives on after receiving severe abuse throughout the years

This pleases me lol, this is the route I'm going down! I'm very tempted to get a second box and have that done and see just out of interest how much the standard box will actually take?

GTI-R US wrote:yes believe it was Sandwell, was around 10 years ago but that name sure rings a bell

I spoke to a chap there after being given there number by someone I used to race bikes with as he had his gearset done on an R1
at the time I had (like you)never understood what it was all about but was looking for a cheapish option to strengthen the gearset
he advised me not to get the casing done but just the gearset and selectors, in total from memory it cost just under £180 plus the cost of rebuild of the box which I had done locally

then go spend £££££ on quaifes and other boxes which all broke but the little shotpeened shitter lives on after receiving severe abuse throughout the years

Right then, iv spoken to Sandwell, to confirm exactly what it is I will need shot peening,
1. Crown wheel
2. Pinion
3. Gears, how many are there? Is it 11?
4. Selector forks, again how many? Is it 2 or 3?
5. Input shaft.
Is there any thing iv missed guys and are these the correct quantities? So I can get an exact price! It'll be around the £200 mark. They also said they will super finish it (rem process) for £200 for the lot, they say this will further enhance the fatigue life and enhance cooling (apparantly) cheers

Surface finishing is quite good for gearboxes as the reduced friction = reduced surface stresses ...
Main thing to do after investing in the treatment is make top effort on rebuild & keep end floats minimal.
Think a lot of people who had bad gearbox issues had more than one which tends indicate possibly individual usage or way they being built had some role in the failures.

Yeah there was a certain so called forum gearbox builder that loved to build boxes that would fail swiftly after first use
Over shimming was one of his main traits and lack of any knowledge being the other lol