41 replies to this topic

[Clubber Lang]

You need to measure the crank tail and the bush diameter. There is a published tollerance but I can't remember what it is just now. You will need some accurate measuring tools, the tollerance is only a couple of thou. Most decent motor engineers could re-bush and ream the primary for you, Yellow Pages is your friend.

Thanks Dan, i have just seen floating bushes on minispares that don't need reaming any ideas or experience of these? regards Steve

[Clubber Lang]

Is there a difference betwen metro and mini 1275 primary gears? regards Steve

[icklemini]

i have just seen floating bushes on minispares that don't need reaming any ideas or experience of these?

Yep work well, sometimes they can block the oil holes in the gear... Note that these are only for the 'front' bush (the one closest to the engine)... you still need to sort the 'top hat' bush.

Is there a difference betwen metro and mini 1275 primary gears?

Nope - but there is a difference between 1275 A and 1275 A+ gears.

[Clubber Lang]

The top hat bush looks to be o.k.?
Meanwhile i have sorted out a primary gear which was on my old A+ 1275 and it looks identical. I have just counted the teath and counted them 3 times one has 29 and the other one has 30? it seems that all 1275 are not the same? One engine is a metro? if that makes any difference? I take it that i can't swap them over then? regards Steve

[Dan]

One is the economy drop gear I think. I'm not sure if they are interchangeable.

Edited by Dan, 20 September 2009 - 11:32 PM.

[Clubber Lang]

One is the economy drop gear I think. I'm not sure if they are interchangeable.

I have tried it in the engine and it turns freely and doesn't seem to mesh so i presume it will be o.k. i also have the idler gear off the same engine but i haven't compared the two idlers yet. regards Steve

[Dan]

It will dramatically affect your gearing if you change to a different ratio drop gear.

[bmcecosse]

Hardly 'dramatically' - 1 in 30, so ~ 3.3% ! IF it meshes ok with the other gear - then just use it.

[Clubber Lang]

Going to find the idler gear off my old engine to see if that matches the primary gear i found. Got new transfer case gasket today from mini spares but looks the same thickness as the one i took off. What is the torque setting for the transfer cover bolts? is it 9lb? regards Steve

[icklemini]

'Standard' Idlers and input gears have 29 teeth, some metros had the 'economy' gear set, these had 30 teeth on the primary, and 28 on the input gear... idlers all had 37 teeth.

Yep you can mix and match and can be benefitial in certain scenarios

[Sprocket]

I seem to remember that the economy primary and input gears are identified by two notches on each tooth, same as the Metro HLE gearset and the oddball close ratio MPi second gear

All A+ idler gears are the same, the 30 tooth and 29 tooth primary gears are interchangeble, as are the 28 tooth and 29 tooth input gears. However, as Icklemini has also said, the 'A' and A+ gears are not interchangeble

[Clubber Lang]

Thanks guys, just done a dry run and found the gears going tight when the casing tightened up? removed the idler and tried it and primary gear fine so i guess its tightening up on the idler, anyone had this before? i've tried it with two idlers i have, they wil turn but stiff. Could it be the transfer asing warped or something? bearings seem ok. regards Steve

[GraemeC]

I have had this once before on an engine & box I rebuilt - the only thing changed was the gasket but it nipped the idler up tight (very tight in my case). I could only put it down to the original (very old) gasket being much thicker than the ones you get now which are pretty much to Rover tolerances.
The soluion is to use thinner thrust washers on the idler gear. MiniSpares sell a set with various sizes in and then it is case of drybuilding until you have the correct clearance.

I actuall ended up using a different transfer case as none of the available shims were thick enough - I believe I had a very extreme case though.

[Clubber Lang]

I take it using two gaskets isa bad idea? regards Steve

[icklemini]

Thanks guys, just done a dry run and found the gears going tight when the casing tightened up? removed the idler and tried it and primary gear fine so i guess its tightening up on the idler, anyone had this before? i've tried it with two idlers i have, they wil turn but stiff. Could it be the transfer asing warped or something? bearings seem ok. regards Steve

Aye you are gonna have to select the right shims for the idler gear - there are a range to choose from.
Also transfer case gaskets seem to come in different sizes :s