13 replies to this topic

[Oliverbarnes]

Hi all, as some of you may know i am currently building a 1310 supercharged engine which is nearly ready for assembly. The engine is a brand new build with everything replaced however before i assemble everything i want to know if theres anything i should replace in the gearbox whilst i have access to it? The gearbox is bog standard and i have touched nothing in it. i want to know if certain bearings are prone to wear and should be replaced etc. Any help would be greatly appreciated!

 

Engine spec:

 

1310 - 8:5.1

Eaton M45

Stage 4 head

Omega die cast pistons 10cc

ACL bearings 

SW5 camshaft 

1.3 roller rockers

Webber 45

X-pin diff

3.1 final drive

1.1 straight cut transfer gears

Custom Aldon distributor 

Med lightened flywheel/backplate

AP turbo friction disk

Grey diaphragm

 

I think thats all... hopefully should be around 130bhp ATW so i want to make sure the gearbox has a chance. :)

[Swift_General]

Power is not really relevant to the gearbox - it's torque that the gearbox 'feels' and will break it. You really need to strip the gearbox to determine what needs replacing though. Things I would be looking at in particular:

Bearings
Layshaft
Gear teeth
Dog teeth
Baulk rings (measure clearance to hub)
Synchro springs
Selector forks, esp 1st/2nd

Expect to need replacement layshaft thrust.

Also think about speedo drive if you are changing final drive ratio.

If your mini is being used on the road I would ditch the straight cut drops. But that's a personal thing.

Gearbox parts are expensive and expect to have to replace a lot to do the job properly. But mini gearboxes are (reletively) straightforward to overhaul. Good luck!

Edited by Swift_General, 21 May 2018 - 07:59 PM.

[Anthony30]

You also need a Quaife ATB diff. I'm also fitting a straight cut gearset drop gears, centre oil pickup pipe to my turbo.=, with the usual new bearings baulk rings ect.

[Spider]

I agree with what the first two guys have kindly posted up here, however, I'll add a note of caution (and if I remember a couple of photos later).

 

Be very careful when buying the needle roller bearings. One of the suppliers out there (who'll remain nameless) is supplying substandard bearings here. The bearings I've been recently supplied have two or three less needles rollers fitted and are around 1 mm shorter in length - they'll eat through the shafts they run on in little time.

 

I'd suggest obtaining these bearings from an NSK reseller and take your old bearings to compare at the counter.

 

The best Layshafts I've found in recent times are supplied from Swiftune.

 

Selector Forks can be rather hit and miss. I'd suggest taking your hubs down to your friendly Mini Parts supplier's counter and going through a few. The wear limit on these is 0.015", I've been supplied many that are over this right out of the bag,,,,,

 

Not easy to do, but have the Transfer Housing clocked in to the Gearbox and re-doweled, they are all out, some as much as 0.90 mm.

 

There's load more you could do, but that should get you over the line.

[Oliverbarnes]

Thanks for all the help guys, i shall be stripping down the box and going through all the components paying close attention to the things you have mentioned!

[Spider]

Counterfeit Bearings

 

The first ones are the 13H9513 as used on the A+ Layshafts and A+ Mainshaft 'Nose';-

 

 

 

The correct Bearing should have 14 Needle Roller Elements. The counterfeit one here has only 11 and they are shorter.

 

 

Next is the CHM141 as used on the Big End of any All Synchro Layshaft;-

 

 

 

The correct Bearing should have 16 Needle Roller Elements. The counterfeit one here has only 14 and they are shorter.

 

 

Beware.

[Spider]

Some Good News for a change

 

Today, while looking at a damaged but otherwise brand new Outrigger Bearing and comparing that one to one from the 80's, I found that the current RHP types are in fact better.

 

The old bearings have 10 rolling elements, the new ones have 11 and they are bigger;-

 

This is the old type, usually identifiable by a metal cage

 

 

 

This is the two types, showing the newer cage in nylon and the bigger roller

 

 

Yes, the better bearings are the current ones available.

[Rorf]

My 83 box has the original fibre/nylon carrier bearing, first time I have seen that metal cage one.

[Retroman]

The really early ones had a brass cage...was that just 3 synchro boxes...?

 

Stripping 2 tomorrow so will take note

 

Not sure how many rollers, a while since I saw one.

[Spider]

The really early ones had a brass cage...was that just 3 synchro boxes...?

 

 

Ah, so you too are an old bastard like me?  Yes, I recall those too, but I didn't want to post that and show my years,,,,

 

Oooppppss,,,,, too late now,,,,

 

They were fitted to the 3 Synch boxes and I'm not sure when they were phased out.

 

The one with the steel cage that I posted ^ were fitted to the gearboxes we got here (local content??) from somewhere in the 70's (maybe earlier) up to end of production in 81. I was still being supplied them in the mid 80's as a spare part in a Leyland box, though, I have a feeling that the Nylon Caged types were introduced (in the UK at least) around 1980.

 

They weren't often changed here as few people had the right puller to remove the outer ring

[mini13]

Moke,

 

that larger outrigger bearing, is not just a case of youve ended up with a metro turbo one is it? as they were uprated.

 

 

to the OP, looks like youve got it all under control, I would say two things, you dont NEED a quaife ATB, yes they are nice, but there is a fair cost involved, and the (minispares) X pin diff will take what your throwing at it. the SC drops are noisy, a lot of people stay with the helical drops to get a quiet 4th gear, and to be honest the std helicals are pretty strong as long as all the bearings are in good condition. allegedly the latest drops were the best from the MPI's.

[Retroman]

Not sure if I'm an old bastard, but I can be....hahah

 

Anyone asks I'm 38 but have been for a while...started with Minis in 1979...been doing bikes go-karts  tractors and farm tackle a good few years then

 

I would say the brass ones were the hardest to get off, and in the UK we have mirrored what you said...steel cage then plastic....

I usually use the 1st motion nut to push them off and as you say its the outer race thats the problem for most, I hate that bloody circlip

Just put a new RHP one on Petrol's build yesterday and had to put some bearing lock on as it virtually went on with the fingers.

 

Bit of a surprise as its a 1970's Ripspeed SC gearkit...then again the bad luck and problems he has had with that car its no surprise...someone even filed (yes....what the hell) the teeth on his 1st / 2nd centre syncro hub...pure-bred idiot

[Spider]

Moke,

 

that larger outrigger bearing, is not just a case of youve ended up with a metro turbo one is it? as they were uprated.

 

Cheers and yes, I was aware of the Metro Turbo Bearings, but that's a stock one, no question. Same shaft and housing diameters.

[mini13]

Ah, yes I was forgetting the OD is bigger on the turbo one!