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Post by goandy on May 29, 2016 23:07:00 GMT -5
So I have a pair of rebuilt GT750 front callipers with brand new 'race' pads in them. That's what the PO told me anyway.
With the piston all the way back and both pads as far away from each other as possible, the gap isn't big enough to fit over the discs.
The callipers look almost the same as the RE ones apart from the banjo area being lower. Is there a subtle change in width of the GT750 calliper I'm not spotting?
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rotorious
2nd Gear
Three or more is a Rage of Rotary
Posts: 100
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Post by rotorious on May 29, 2016 23:24:25 GMT -5
So I have a pair of rebuilt GT750 front callipers with brand new 'race' pads in them. That's what the PO told me anyway. With the piston all the way back and both pads as far away from each other as possible, the gap isn't big enough to fit over the discs. The callipers look almost the same as the RE ones apart from the banjo area being lower. Is there a subtle change in width of the GT750 calliper I'm not spotting? I think the difference is in the thickness of the rotor. I vaguely remember back in the day trying to put GT750 pads in an RE caliper and having the same problem. You could probably put GT rotors on and it'll work.
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Post by wayne on May 30, 2016 2:15:59 GMT -5
None of this is making any sense to me. I have both GT's and RE's currently and they all seem interchangeable.
I have just been down to the shed with an RE5 calliper in my hand and put it side by side with my GT calliper and there are no differences, even in the height of the bit that the banjo union bolts down into.
The RE disc is slightly different in part number, 59210-37001 vs the GT at 59210-37000. I'm led to believe that the 1 at the end is generally inconsequential. I don't believe that there are any differences in disc thickness across the LMAB GT range and the RE5MA range.
I'm starting to wonder about this PO Andy.
PS I've used GT pads in an RE calliper several times, no problems.
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ski
1st Gear
"If it ain't broke, you're not trying."
Posts: 53
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Post by ski on May 30, 2016 21:45:29 GMT -5
That is odd. I have ordered pads for mine as well for the GT and had no issues. Sounds to me like you've got rotor or caliper piston issues.
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Post by HGH 770N on May 31, 2016 1:30:29 GMT -5
Andy I have similar issue after re painting callipers and fitting new pads .I didn't remove pistons and pushed all way back before paint. I'm sure its not the pads just I disagreeembly I will let you no what I find, Maybe I should remove pistons and clean or maybe the inner carrier is not free on the pad ?
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Post by goandy on May 31, 2016 1:43:50 GMT -5
Thanks Rog- I'm going to take the calipers apart tonight and see what the go is. I may end up swapping the new pistons, seals etc into my old calipers but I'll measure everything first. There's not much in it- maybe a mm or so... Could even be the new pistons are too long. That'll be a simple fix on the lathe!
Rotors are within spec i.e. not too fat so it's definitely something funky about the calipers.
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Post by HGH 770N on May 31, 2016 1:56:16 GMT -5
New Pistons?? Could be mm out? I used Girling old stock pads and new pipes and master rebuild kit and wondered what I had done wrong, I even swopped the calliper backs over but as soon as I clamped up the allen bolts even with nipples open it would lock up against the disk.
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Post by wayne on May 31, 2016 3:11:50 GMT -5
Andy, I have no doubt that your callipers have the higher mount for the banjo bolt. You cannot say anything absolute about what the bikes had or didn't have when it comes to fine details. As Jess says in another post, they were assembling with what was on hand. Callipers with a slight difference in that part of the casting probably was at the whim of the brake manufacturer(s).
I had two NOS instruments side by side and the colour of the faces is slightly, but noticeably different between the two. However, I'd put money on all the discs being the same thickness even between different models. Likely, as Roger says, the problem is elsewhere.
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Post by goandy on May 31, 2016 8:57:22 GMT -5
Ok so I took the callipers apart tonight and compared them to my originals. Here they are side by side. The "recon" ones are the shiny ones Old RE5: recon GT750: The gt one on the right has a totally different fitting designed for hard lines rather than a flexible one with banjo. That explains the hard lines in the bottom of the box! Pads are even different. Old pad on left, new on right. Must look up the part number... took a couple of mm off the pads on the lathe anyway. Used lots of water in case there was that nasty asbestos in them. Doubt it but you never know with brakes depending where they came from- unknown in this case! Even the bleedin pistons were different. Identical but had a crown in the middle which sits 1.5mm proud. 30 secs on the lathe sorted them! For something supposedly recon, the PO greased everything with rubber grease except for the pistons, both of which were seized in and took a fair bit of effort and heat to remove. So I'm going to rob all the nice new bits and rebuild my old callipers with them. That should fix the problem!
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Post by timpa136 on May 31, 2016 9:14:21 GMT -5
Andy, I saw that stainless steel line which reminds me of the first 73 GT calipers?
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Post by goandy on May 31, 2016 9:17:34 GMT -5
Andy, I saw that stainless steel line which reminds me of the first 73 GT calipers? That's what I think they might be. The pads are still a bit oddball as all the RE/GT pads I've seen have the recess in the piston side pad.
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rotorious
2nd Gear
Three or more is a Rage of Rotary
Posts: 100
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Post by rotorious on May 31, 2016 14:27:53 GMT -5
Now I remember..... that was it, the GT pads I had didn't have the recess on the piston side that the RE pads had. I confused that with a Cavalcade issue where they updated early models with thicker discs to prevent warping and made the pads thinner to accommodate. If you used early pads with later discs you couldn't get the calipers on over the disc.
Come on now, It's been like 30 yrs. Some of these details can get misremembered over time and across so many different Suzuki's.
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Post by wayne on May 31, 2016 18:53:59 GMT -5
Rotorious, I'm hard pushed to describe what I had for breakfast. So there's yer problem, looks like you've got GT750K callipers. They are a different animal. I only made claims for exchange between LMAB GT750 and RE models. This is a K model GT750: Here's an L model GT750 with the pinned brake hose. Note the "leading edge" design where the banjo bolts in to make room for the locating pin. Same as some very early model RE5's. An M model GT750- same as the majority of M/A model RE5's Finally an RE5M calliper, still an early model with steel oil cooler lines but the callipers were now the same as used on the equivalent year GT750. This calliper was also used on the A model RE5.
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Post by goandy on Jun 1, 2016 2:50:24 GMT -5
Rebuilt the first caliper and it now fits beautifully...
Both my bikes have the early pinned style caliper/hoses.
Thanks for all the help fellas!
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Post by wayne on Jun 1, 2016 6:33:51 GMT -5
Thanks gents. I've used this discussion to expand the Brake FAQ (and pinched one of your pics Roger, with credit).
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