Taller M100 diff ratio?

Hi guys.
I’m new here, so be kind please!

I’m looking for a taller diff ratio (longer legs /less revs) for my M100 Sirion. I understand that the L700 used smaller diameter wheels, so I’m assuming that to offset this the diff ratio would be higher. Am I heading in the right direction? I can’t find any specs on the different ratios used in different models, but I’m hoping the “brainy” people on here might know what gearbox I need to steal the final drive ratio out of to achieve what I’m after.



I’ve been doing more searching on line & the L500 Mira has a 3.95:1 ratio vs the Sirion 4.5:1. This is what I’m looking for. Will the L500 gears physically fit into the Sirion box?



Your definitely heading in the right direction numbers wise but I’m not sure if they’ll fit in the Sirion box. @Mr_Gormsby or @FortisD would be the people to ask, they are always playing around with different gearboxes and could probably tell you off the top of their heads what to do.


Welcome Jason.

L500 bits are not interchangeable with M100. It’s not like a rwd where crownwheel and pinion are independent parts. Such a swap would mean layshaft and mainshaft would have to be slipped in also. This won’t fit. And they the L500 and L200 (same) boxes are wide ratio with super low first.

Also I was not aware of a 3.95:1 for the L500. There was a 3.9:1 in some L200s but these are all four speed.

I am going to make you hunt a bit. Here in the wiki I have put the final drive ratios for the 3cly and 4cyl Sirions. You don’t say which yours is. If you have a GTVI then putting in a 3cly box will give you taller gearing.

Why do you even think you need “taller”? Understanding might help us to help you.


Thanks for the reply!.

Yes, I thought that might be the case, different gearbox /non interchange.

I’m heading down turbocharging the EJ-DE & want to “gear it up”, to make better use of the torque increase that I’ll get.

I had a look around the site last night (I’m a newbie) & came across an L700 Post that talked about a 3.9 ratio, so that started me looking…

I’ll spend some time in here today & see a read /explore.

I love my Sirion… I know the Cuore /Mira is the golden child, but I love the size & versatility of the Sirion… & I also love the Mk 1 “face”… So much so that I put the Mk 1 front on my Mk2.

Your build thread on the Mira is providing entertaining “breakfast reading”… Gormsby is a clever man!

Thank you!.

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Sirions would have to be the most underated of all Dai’s :frowning: