GT550 vs GT750 4LS front drum

[teazer]

Thanks.

[Kettletimes3]

Glad to be able of assistance.

[teazer]

OK, I think we got this.....

Based on parts lists reviews and measurements of various wheels:
Early GT750J has the same part numbers for Drum and brake plates as the GT550J 54110-31001 (Hub), 54210-31001 (left plate) and 54250-31001 (Right side plate)
Early GT750J uses spacer, described as 15.1 x 30 x 5 each side of that drum brake -Part #52 09180-15019
That information exists only in early parts lists and vanishes from later lists


GT750J has wider fork legs than all other GT750 disk brake models
GT750 K on fork legs have the same fork spacing as GT550 models - I have asked Alan H to confirm that with his collection of 550's

Later GT750J has different part numbers, 54110-31830 (hub), 54210-31002 (left side plate) and 54250-31002 (right side plate)
Later GT750J does not use spacers but has the same wide fork spacing. The spacers 09180-15019 are still listed now as #20 but are not uses AFAIK.

We can probably summarize from that information that late model GT750J had a wider front wheel than early GT750J and that early GT750J wheel assembly is the same width as GT550 and uses spacers for some reason. It could be that a supplier was late getting the wider brakes to Suzuki so they just used spacers to take up the difference or it could be a design change. I doubt that record still exists, but at least we know which wheels fit which bikes.

It would be really useful if someone with an early or late GT750J could confirm teh width across the drum assembly and whether or not it has spacers and if so, how wide are the spacers.

[barney01]

Excellent research and info Teazer! As you say it would be good if Ian Sandy could include this in his guide, but I have bookmarked this post for the next time the question is asked

[barney01]

Photos added for reference

[oldjapanesebikes]

So Richard (teaser) sent me an email about adding this information to the Field Guide, which I'm happy to do, and my thanks to all who contributed to this thread as it makes it much easier for me to write it up ! I do have one question though - does anyone have a GT750 J or GT550 J that does have the spacers ? And if so, what frame numbers are the bikes ? I have three drum brake'd GT750 J's and the earliest frame number is 161xx. I also have a spare drum that came off a wrecked frame number 144xx. None used spacers - all have the raised centre bosses on the side plate castings and when assembled they measure about 165mm across the width (hub with side plates). Presumably then, the ones with spacers must measure about 155mm and be lower frame numbers and it would be nice to get a handle on that.

Anyone ? Thx !

[oldjapanesebikes]

Not too many replies !

OK then - to make it interesting, I'm running a small contest of sorts and you can read about it at this link on my OJB Facebook page. If you have a GT750 J with a frame number lower than about 12000 then I'd like to hear from you ! 8)