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  #1  
Old 27-10-2009, 07:53 PM
gas axe gas axe is offline
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Default wheel size

Hi all

i am trying to find out what wheel and tyre size im going to need for my trike and sometime ago know there was someone on theses here pages that given enough info would be able to work it out for me. Below i have tried to list as much info as possible.

Engine GSX1100G shaft drive
primary reduction ratio 1.681 (74/44)
secondary reduction 1.055 (19/18)
final reduction 2.666 (32/12)
1 st 2.714 (38/14)
2nd 1.809 (38/21)
3rd 1.409 (31/22)
4th 1.181 (26/22)
5th 0.962 (26/27)

measuring the tyre on the floor is 200cm for one complete turn.


diff is granada J reg 2.0 litre ghia
markings on tab is as follows

91GG GA 391
4A 1J02 1228

i would like to see 15 to 17 inch wheels if pos but i dont know whats best and with what size tyres?
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  #2  
Old 28-10-2009, 11:14 AM
Blackjack Blackjack is offline
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The original final drive is 2.666:1.

You're saying the wheel has a rolling circumference of 200cm (what? exactly?)

2.666 turns of the drive shaft moves the bike through 200cms then.

one turn of the shaft moves the bike through (200/2.66) cms, or 75.018.
Since I don't know the ratio of your diff (tried counting it?) and you haven't got any wheels to measure, that's about all I can tell you. But...

It would suprise the crap out of me if the Granada diff wasn't somewhere around 3.8 to one, and most 15" and 17" car tyres (especially the 17" ones) tend to come in at under what you'd expect for a bike tyre as far as the rolling radius is concerned. If you you used 15" wheels with "tall" tyres to get somewhere near the same rolling circumference, that diffs going to give you around 52.6 cm per turn of the shaft IF I'm right about the ratio (which is unlikely, but I don't think I'd be that far out if it's a 2.0 litre one).

What that means is that you'd have roughly 2/3rds of what you had before. So what ever speed it did at 2000 rpm in top gear as a bike, would now need 3000rpm as a trike.

Wheels with a smaller rolling radius would make that worse.

But, that's all speculation and guess work based on an assumption about the diff ratio, so go and get a friend and the diff. Turn the input flange and count that while your friend counts the turns of the output to the wheels. When the turns of the output reaches 10, then you should have counted some where between 30 and 40 turns on the input flange. Say it was 38, well divide that by the 10 turns of the output, you got 3.8:1 and I get a chocolate watch for being a smart ass and guessing right. What you're hoping for is a lower number.

There's no hard and fast about this as different manufacturers tend to arrive a different solutions for shaft drive bikes and the final drives vary quite a lot. Certainly that 3 litre Capri axle we used on the V-Max (which I hasten to add was just what i was given to use!!!!) was taller than I would have liked, but Mark seems to get on with it just fine, admiring the impressive MPG he's achieving apparently. Whatever, Suzukis tend to use taller final drives than Yams (though Ican't claim to have messed with every one ever made so that's "tends" and not "do") but on the whole, that "tall" diff in the V-Max, would be a short diff in yours.

Last edited by Blackjack; 28-10-2009 at 11:22 AM.
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  #3  
Old 28-10-2009, 06:49 PM
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Useful link for diff codes


http://www.locostbuilders.co.uk/view...php?tid=122872
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Old 28-10-2009, 09:14 PM
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So going by Black Jacks reckoning he is bang on the money with that code translating to

3.91 :1

or rather way too tall for the application.
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Old 29-10-2009, 10:59 AM
madtriker madtriker is offline
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so if you had something that was 2.88-1 would that give better speed at less revs?
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Old 30-10-2009, 12:54 PM
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Quote:
Originally Posted by madtriker View Post
so if you had something that was 2.88-1 would that give better speed at less revs?
Yes, higher top speed with that ratio, though you would lose out on your acceleration
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Old 30-10-2009, 07:43 PM
gas axe gas axe is offline
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Default wheel size

ok i have looked at the link (thanks V8) and by doing what blackjack recommended i have counted the turns and can confirm that it looks like 3.9:1

I have also given ford a ring and now know that the original tyre size on the car was 63cm diameter and one turn along the floor comes to 193cm which is pretty close to the bikes 200cm rear tyre. Have i brought a goose of a diff? is there anything i can do with wheel size/tyre size to counteract the ratio.

basically i,m after the trike to pickup speed fairly quickly but would like it to sit at motorway speeds as well.
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Old 30-10-2009, 07:54 PM
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Transit wheels.
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Old 30-10-2009, 07:57 PM
gas axe gas axe is offline
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Default wheel size

transit wheels ????
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Old 30-10-2009, 08:33 PM
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A tall wheel tyre combo will help, though you will have to go really big to effectively reduce the ratio to a happy motorway cruising speed, I am running roughly the same ratio diff and even with rear tyres measuring approx 24", I am still doing 4000rpm @ 70mph





















Though no fooker can catch me away from the lights!
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Old 31-10-2009, 10:17 AM
Blackjack Blackjack is offline
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Thing is, if you got some wheels and tyres that were 36" - 38" tall, have a think what you just did.

Yep, you just spent 300 to 500 on tyres (assuming you used 4x4 tyres and not those redneck low profile thingys) to compensates for having the wrong 30 diff. And everytime you need new tyres, that's going to come back and bite you in the ass.

Banger or stock car racers will often have a diff from a V6 Granny (or better a straight six Carlton, cause the diff is smaller and lighter) which while not "ideal" is almost certainly going to be better than what you got, and not madly exensive...

BMW 3-series came with all knids of engines (so presumably all kinds of diff ratio) and are quite thick on the ground, with some specialist breakers about the place.

Trusting the tag to tell you the ratio is a bit fraught. Occasionally someone's been in the axle, and there just isn't a tag, other times it was the diff internals have been changed but not the tag.
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Old 31-10-2009, 11:58 AM
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Mate of mine used a Freelander Diff in his Max trike, and that seems ok. No real help as yours is different output ratio but heading the right direction.
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  #13  
Old 31-10-2009, 07:14 PM
gas axe gas axe is offline
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Default wheel size

fair point blackjack, i think i will be on the look out for a different diff. just out of interest does anyone no what the ratio for a 1600 mk2 escort axle is??

when you said your doing 4000 rpm at 70mph whats driving it or is that a silly question (v8 trike)
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Old 31-10-2009, 07:36 PM
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Quote:
Originally Posted by gas axe View Post

when you said your doing 4000 rpm at 70mph whats driving it or is that a silly question (v8 trike)


No not a silly question, a V6 3.1 Ford

As for the escort axle, the English axle comes in a 4.1, 3.9 (no change there then ) and a 3.5

Have you thought about a reliant scimitar axle 3.37 ratio (nice and easy to get hold of too)
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Old 31-10-2009, 07:37 PM
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Quote:
Originally Posted by v8_trike View Post
No not a silly question, a V6 3.1 Ford

As for the escort axle, the English axle comes in a 4.1, 3.9 (no change there then ) and a 3.5

Have you thought about a reliant scimitar axle 3.37 ratio (nice and easy to get hold of too)
or a volvo...
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  #16  
Old 01-11-2009, 02:43 PM
gas axe gas axe is offline
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thanks. i am currently talking to a ex banger racer who may be able to help me as he has four difference diffs. i can try em all he says!!

back in 1997 a guy called sid built a trike and was featured in AWOL. it used the same engine as me and was running a ford 1600 ghia axle and 15 inch wheels and the article stated that the ratio was right 4.1 i think (very confusing this) i thought could it be that because its an 1100 bike engine that it may have a largely different ratio to say a 550cc bike ? therefor may not be affected as much. dont know? what do you think
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