GT550 vs GT750 4LS front drum

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Acebars

Re: GT550 vs GT750 4LS front drum

Post by Acebars »

barney01 wrote:Hi I have a 550 J with a 4LS if you want any measurements let me know.
Yes I'd really appreciate it. Can I get a width measurement without the axle. So that's between the axle holes with the plates on the hub. You can actually do this on the bike if you have large calipers or something.
barney01
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Re: GT550 vs GT750 4LS front drum

Post by barney01 »

Hi mate

I have measured it on the bike with digital calipers and it shows 166 mm okay?
NO SMOKE .......NO POKE
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Acebars

Re: GT550 vs GT750 4LS front drum

Post by Acebars »

barney01 wrote:Hi mate

I have measured it on the bike with digital calipers and it shows 166 mm okay?
Many thanks. That sounds right, trouble now is I'm told the GT750 is 6 1/2 inches which makes it around 166mm and that doesn't sound right, the GT750 should be 6mm wider. I think the GT750 measurement I got must have been wrong...

Can I double check that was a GT550 4ls drum?
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Alan H
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Re: GT550 vs GT750 4LS front drum

Post by Alan H »

I can't understand it being wider as the forks are the same distance apart. The 750 and 550J models both have the same triple tree base.
Proof that four strokes are over complicated
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Acebars

Re: GT550 vs GT750 4LS front drum

Post by Acebars »

Alan H wrote:I can't understand it being wider as the forks are the same distance apart. The 750 and 550J models both have the same triple tree base.
"The original center-to-center width of the stock GT750 forks is 185mm (7.28) and 179mm (7.047") for the GT550 drum"

..taken from dotheton.com

The GT750 is 6mm wider and is visibly wider.
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Alan H
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Re: GT550 vs GT750 4LS front drum

Post by Alan H »

This gets even more odd. The GT550J has the same triple tree base as the GT750K, both part number 51410-34000.
The GT750 J has triple tree part number 51410-31001, but doesn't show the top triple tree with handlebar clamps to compare. The front axles are different part numbers as well.
So without a 750J parts book to go through all the details, I can't go any further.
I can't see 6mm being difficult to alter, just get a couple of 3mm spacers if you have a slightly narrower hub. The side panels and brake shoes are the same.
Proof that four strokes are over complicated
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Acebars

Re: GT550 vs GT750 4LS front drum

Post by Acebars »

I can't see 6mm being difficult to alter, just get a couple of 3mm spacers if you have a slightly narrower hub. The side panels and brake shoes are the same.
Yes but the hubs are different, the GT550 is 6mm narrower, I've heard it so many times, and I've seen both visually and yes it is true.
barney01
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Re: GT550 vs GT750 4LS front drum

Post by barney01 »

Acebars wrote:
barney01 wrote:Hi mate

I have measured it on the bike with digital calipers and it shows 166 mm okay?
Many thanks. That sounds right, trouble now is I'm told the GT750 is 6 1/2 inches which makes it around 166mm and that doesn't sound right, the GT750 should be 6mm wider. I think the GT750 measurement I got must have been wrong...

Can I double check that was a GT550 4ls drum?
Yes GT 550 J 1972 good luck
NO SMOKE .......NO POKE
Kettletimes3
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Re: GT550 vs GT750 4LS front drum

Post by Kettletimes3 »

Alan H wrote:This gets even more odd. The GT550J has the same triple tree base as the GT750K, both part number 51410-34000.
The GT750 J has triple tree part number 51410-31001, but doesn't show the top triple tree with handlebar clamps to compare. The front axles are different part numbers as well.
So without a 750J parts book to go through all the details, I can't go any further.
I can't see 6mm being difficult to alter, just get a couple of 3mm spacers if you have a slightly narrower hub. The side panels and brake shoes are the same.
Hi Allan, I have 750j.k.parts book part numbers are.
J top yoke 51311-31700-019.
J bottom 51410-31001.
K top yoke 51311-31000-19.
K bottom 51410-34000.
J Hub complete 54110-31001.
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Acebars

Re: GT550 vs GT750 4LS front drum

Post by Acebars »

That's what I got for the 550 hub.

The 750 hub is 54100 31830
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