LocostUSA.com

Hey guys.. I need some help figuring out what's what with this dedicated racing diff from Elite Racing over in the UK..

Long and short of it: I'm planning a new BEC build, and I'm looking into this IRS diff with integrated reverse- it's spendy, but it solves a lot of problems.. trouble is, I'm having a hard time understanding the available ratios.. They list it all plain as day on their site, but they're called 'drop gears,' which I think are a.k.a. 'quick change gears'..

So I love everything about it, but they haven't answered my email/questions, and I figured someone here could just as easily help me understand their ratio chart.. In the end, all that really matters to me is the final drive ratio, but what the hell are all of those other numbers about?

Here's the link (I can't attach it as a PDF):
http://eliteracingtransmissions.com/wp- ... -List1.pdf

As soon as I find out if I want to go forward with it (or not), I'll have a few qs about the flanges..

Thanks-

ccrunner

_________________
Dean

1972 Honda N600 Restomod "ccrunner's N600 VFR800 repower"

1963 Volvo P1800 Restomod
http://locostusa.com/forums/viewtopic.php?f=36&t=16309

1959 Berkeley SE492 Restomod...
viewtopic.php?f=36&t=19397

"ccrunner's 1960 MGA coupe Restomod" found on MGExp.com

Pretty sure the "drop gears" are the first reduction, to get the high speed out of the bike down to something manageable?

Quick perusal says they're also called "transfer" gears.

So you could do 1:1 drop, with your choice of final drive.

Or spice it up and get your exact final ratio by changing drop gears around.

I think you're onto something... If I'm following, you order the unit with a 'permanent' set of final drive gears, say 2.750..

THEN, you select a set of their 'drop gears' to modify that final drive; perhaps your 'drop set' is 24-20 (0.833), which will result in a final ratio of 2.290..

If you want to be fancy, order a 2nd set of 'drop gears' to install for track days.. say 17-23 (1.353), which would result in a final drive of 3.720..

So the easy-to-swap drop gears can result in a diff that gives a 2.29 'relaxed' highway/low-ish rpm BEC, or use your 2nd set of drop gears for track day and get an aggressive 3.72 ratio that you really would not want to run out on the freeway..

..Have I got the concept down?..

_________________
Dean

1972 Honda N600 Restomod "ccrunner's N600 VFR800 repower"

1963 Volvo P1800 Restomod
http://locostusa.com/forums/viewtopic.php?f=36&t=16309

1959 Berkeley SE492 Restomod...
viewtopic.php?f=36&t=19397

"ccrunner's 1960 MGA coupe Restomod" found on MGExp.com

Pick a final ratio and drop ratio that combined will provide the desired overall final ratio AND a ratio you’d like to try by swapping positions of the drop gears. No need to buy a second set unless you use a 1:1 “drop” set where swapping positions (drive/driven) makes no difference in ratio. A 2.75:1 final and a 20/24 set gives you either 2.29:1 or 3.30:1.

A 2.67 with a 20/22 keeps the ratios closer with either 2.94:1 or 2.43:1 and less parasitic loss than a greater final reduction working against a greater overdrive setup.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

Please keep us up to date. I was thinking of using one. Also looked at the Transworks mini-diff. It got some bad feedback, but that was a while ago.

Based Quickchange looking exterior, I was initially thinking that might be the case too, but needed to know more about how the reversing gear was implemented. From what I'm seeing in the exploded view, it appears that the inclusion of the reversing gear utilizes non-common of gears on each shaft and precludes this useful ability. While I have no real experience with either, it looks to me like it may also be more involved to swap the 'drop gears' on this than a Quickchange too.

http://eliteracingtransmissions.com/wp-content/uploads/2018/11/MX200-Main-Case-Assembly.png

_________________
-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie

You may be right, but I don’t think the drawing is completely accurate.

I spy synchro assy #13-16, to lock reverse gear #8 (always engaged with layshaft #57) to the input shaft. Driven gear #51 looks like the typical quick change but drive gear #17 does not look like the id would engage the same shaft as the synchro, which appears identical in spline size and shape to the layshaft. It would make sense to use existing off the shelf winters gears imho. Maybe deliberately vague to protect their engineering investment?

If I were going to spend that much on something across the pond, I’d verify with the seller. If they don’t respond to get your $$$ I wonder how responsive they will be after they have it.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

Thank you guys for your thoughts on this unit.. I think I've got a handle on the ratios and how to pick what's right for my build, but as stated, I need to learn if the chosen set of drop gears can simply change location to give a 2nd ratio choice (i.e. 20-24 can flip to 24-20).. I also need to settle on axle flange sizes before I would pull the trigger..

--ccrunner

_________________
Dean

1972 Honda N600 Restomod "ccrunner's N600 VFR800 repower"

1963 Volvo P1800 Restomod
http://locostusa.com/forums/viewtopic.php?f=36&t=16309

1959 Berkeley SE492 Restomod...
viewtopic.php?f=36&t=19397

"ccrunner's 1960 MGA coupe Restomod" found on MGExp.com

Email is cheap and some vendors won't invest time (money) in a response. Invest in a phone call: the response you get over the phone should give some indication of the character of the vendor and answer your questions, all being well.

_________________
Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601

https://www.kartek.com/parts-categories/axles.html

If you decide to convert, send them (or Moser, Currie, etc) your bare axle to copy and the overall length needed to have axles made that are the same od as the splines. If the car were heavier with more traction, I'd suggest neck down axles smaller than the spline od or 300m but not likely to be an issue.

Smaller CVs will also be thinner to save some room for a little more travel.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12