Author Topic: V7 850 rear caliper pins maybe incorrectly part numbered and uneven pad wear  (Read 491 times)

Offline gwensp

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Hi All,

its been a long long long time since I last  posted here.

A bit of info first the bike I am talking about is a 2021 V7 850 Stone. I got it in June 2021 and now have over 16000 miles on it and it has been ridden in all weathers that the UK can throw at it. This is just a heads up post for those with V7 850s and possibly also V85TT

I had the back wheel out to get the tyre changed.

 So with the back wheel out I noticed that the rear brake pads are badly in need of changing. So order a set from Gutsibits.
I thought it would be a good idea to pull the caliper and get all the screw and bolts freed off and loosened just in case there was a stroppy one. And yes there was indeed a stroppy one. In this case one of the pins that holds the pads in the caliper.

These are a bit different to the ones you normally see in Brembos on Guzzis, instead of the normal push pin and retaining clip, these are allen headed one with the threads round the allen head (see piccy).  Complete bugger to get out as Brembo (I assume) has used thread retainer. The second one is not budging even with the application of a lot of heat. Its not budging so much that all my efforts have fubared the allen head.  So quick peak at parts list and a and a call to Gutsibits here in the UK(talked to Ed the owner ). But looking at the picture of the bit on Gutsibits website and Ed and I come to the conclusion that the part is not correctly numbered in the Moto Guzzi parts list.

The pin that is stuck is the one that is at the front of the caliper where all the gunge gets thrown. Im thinking that this has contributed to it being stuck very tightly.
The pads where unevenly worn with about 3mm left on one side and 1mm on the other.  (Sorry no piccy) I havent seen a Brembo caliper like this before. It isnt the usual opposed piston type, but a single piston on a sliding carrier like a lot of the Japanese ones. I'm think that like the Japanese ones these will be prone to the sliding mechanism seizing.  So that would be worth checking.

TO put this in to perspective my V7 850 is now over a year old and has over 16000 miles on the clock and has been ridden in all weathers. So I wouldnt expect to see  this on lower mileage bikes or bikes that havent been ridden in winter or bad weather. If you are coming up for first or second service it maybe worth while asking who ever services the bike to check that the caliper pins can be removed and that the pad wear is even.



"It's easier to ask forgiveness than it is to get permission" Rear Admiral Grace Hopper USN
GwenSP
2021 V7 850 Stone
96 Nevada 750
83 Spada NT

Cardiff

Offline sib

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The rear calipers on the V7 850's (as well as V7's going back to at least 2013) are not Brembos.  They are made by an obscure Chinese company (I think it's called Heng Tong).  The pins are listed as part AP8133799 for the 2013 V7(I) and  GU31659181 for the 2016 V7II and 2021 V7 850, but I think they're identical.  The threads are coated with Loctite blue or something similar.  I've changed the pads several times and never had a stuck pin.  If you really can't get the pin out, you may have to buy a new caliper, which is more costly than pins but not extravagantly expensive.  Whenever I come across a screw that won't budge, I use a rattle gun, and that almost always works.  Unevenly worn pads could indicate a stuck piston.  Good luck.
« Last Edit: August 12, 2022, 08:15:35 AM by sib »
Current: 2021 V7 Stone E5
Previous: 2016 V7II Stone
Previous: 2013 V7 Stone
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Offline mechanicsavant

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Another reminder about frequent maintenance . Both my V7’s have that set up ,16 V7II & 21 V7/850 . I’ve got 22k Mi. On the Mk II . I’ve serviced both Ft. & Rr. Brakes at least 4 times . At every tire change , about 6K Mi. & when I put in upgraded pads . Yup the fasteners are loc-tited. As per manual . 17k Mi. On the upgraded pads maybe 50% worn & even.
If my memory serves me , I’m pretty sure there’s somthing in the manual about extreme conditions or racing to 1/2 the service intervals.
When servicing the brakes I’m usually notice the extra crud @ the rear . As it sits @ the bottom of the rotor & crud loves to settle there , the bleeder @ the bottom is another issue.
Best of luck with your issue

Offline gwensp

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The rear calipers on the V7 850's (as well as V7's going back to at least 2013) are not Brembos.  They are made by an obscure Chinese company (I think it's called Heng Tong).  The pins are listed as part AP8133799 for the 2013 V7(I) and  GU31659181 for the 2016 V7II and 2021 V7 850, but I think they're identical.  The threads are coated with Loctite blue or something similar.  I've changed the pads several times and never had a stuck pin.  If you really can't get the pin out, you may have to buy a new caliper, which is more costly than pins but not extravagantly expensive.  Whenever I come across a screw that won't budge, I use a rattle gun, and that almost always works.  Unevenly worn pads could indicate a stuck piston.  Good luck.

The GU31659181  is the number we have but when we took a look at what was in the packetwith that number they were totally different to what was actually in the caliper. The AP8133799 number looks right so I will see if I can track a set down.
"It's easier to ask forgiveness than it is to get permission" Rear Admiral Grace Hopper USN
GwenSP
2021 V7 850 Stone
96 Nevada 750
83 Spada NT

Cardiff

Wildguzzi.com


Online DAMMAG

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If you have rounded out the allen key socket get the appropriate size torx bit socket, hammer it in and use a good size breaker bar to try and undo the pin.

 

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