Help with maintenance for GT Bravado

[retrobiker273891]

I have bought https://www.retrobike.co.uk/threads/18”-gt-bravado.484294/

Everything is nice overall but requires a bit of maintenance for usage and a few issues are with parts I am not familiar with dealing with.

Firstly, there is some sort of damage to the cap/cover of the headset where the stem meets the headtube. The part which covers the ball bearings is not covering it properly and so the ball bearings are exposed in one section to the elements.





Can I replace just the plastic cap to cover the ball bearings again or will I have to get a whole new headset?

I will note that the headset seems perfectly functional otherwise so would like to be able to just replace that little cap if I can.

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Next thing, the crank when riding. I don't know if this is an intended 'feature' or requires some rejigging but I notice when I was pedaling sometimes the crank would not 'take' and take maybe a quarter to a half pedal before the crank would move the drivetrain again. What I mean is it was like freewheeling but in the opposite direction, for a couple of seconds, until it worked as expected again. So no forward momentum until it stopped doing whatever it was doing.

What is that?

Someone has replied on another forum that it means the hub is 'shagged' but they are really discouraging of any retro bike stuff and don't know if that is just their usual prejudice. Can it be fixed myself with some tlc?

I noticed it seemed related to my speed. I haven't ridden enough yet to get a clear idea of the pattern but it seemed that the faster I was going the larger the 'reverse freewheel' effect was and the slower then the less to almost indistinguishable it was.

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Another thing, the brakes.

As per the description it says parallel push V-brakes but, having experience maintaining them in the past, they do something I have not experienced before.

I had to tune the brakes but how things are is that the brake blocks are almost touching the rims already and yet the brake levers are almost fully depressed to get them to brake. This means I am unsure how to tune them more because pulling the wire further out will not help and since they are so close, and even rubbing a teensy bit still, I am unable to make the wire more taught.

In my past experience with brakes when there is little clearance at the brake blocks then there would be barely any lever tension on the brake levers and they would be taught. So it seems there is excess slack somewhere along the line for both front and back so not sure how to diagnose that as it isn't something I have experienced before. So advice on that please.

EDIT: Doing some more reading are my issues likely related to the 'parallel push' function?

Just found an article from sheldon brown which details some of their unique issues with these types and some possible remedies. I know the front one is squeaking a lot currently which they note in the post as a sign of them requiring some attention.

Parallel-Push Linkage
v-type brake
Older Shimano's XTR and XT V-Brakes feature a special parallelogram linkage. This serves two purposes:

It causes the brake shoes to remain at the same angle to the rim throughout the stroke, and throughout the service life of the pad.
It causes the direction of motion of the brake shoes to be close to horizontal, rather than the usual slanted arc centered on the pivot boss. This is a major advantage for those who use very fat tires on narrow rims, because it prevents the shoe from rising up and damaging the sidewall of the tire on release, and also prevents having the brake shoes dive under the rim as they wear down.

Unfortunately, the extra pivots considerably complicate the mechanism, and this has caused maintenance problems and excessive squeal in practice.

Reader Paul Rintoule has sent in some advice on maintenance of parallel-push brakes:

Shimano parallel-push V-brake tune-up kits have all but dried up so I fixed my squealing XT parallel-push V-brakes by adding disc brake rotor washers to tighten up the parallel-push pivot cage. This works the same as the tune-up kit did.

Firstly, buy some disk brake rotor spacer/washers from a bike shop and super glue from the local supermarket, hardware store etc..
Remove the brake arms from the bike using a 5mm Allen key.
On your workbench, remove the brake pads.
Using a utility knife, peel off the silver stickers from the ends of the parallel-push cage pivot.
Take a photo of a parallel-push cage to remember the order of existing spacer and spring.
Remove the 2mm Allen set screw from each brake arm. You now can push out the parallel-push cage pivot.
Give the parts a wipe clean.
Now reassemble the brake arms and parallel-push cages including adding one or more rotor spacers between the brake arm and the parallel-push pivot cage to take up most of the slack. You want each pivot cage still to turn freely on its pivot without binding.
Replace the 2mm Allen set screw in each brake arm using blue threadlock compound.
Degrease the silver main pivot stickers and the ends of the main pivot using solvent and a cotton swab (Q-Tip).
Clean the brake pads with using solvent and sandpaper and then reattach.
Clean the wheel rims using solvent and sandpaper/fine steel wool.
Reattach the silver main pivot stickers using a small amount of super glue around their perimeter. When glue has set (10 or 20 seconds) reattach the brake arms to your bike, remembering to use blue threadlock compound on the main pivot bolts.

You have now removed the slack that causes severe squealing.

Looks like a case of stripping them down and figuring out what makes them tick.

 

[Takingabreak]

As Brucey has said on the other site that you are posting almost identical questions, the plastic cover on the headset could probably be glued. Regarding the hub being shagged, that's not quite what the poster said. He said the freehub body might be shagged which is a different thing. The body is the part that the cassette slides onto and is usually removeable from the hub so it can be replaced when it wears out. I am surprised you think the posters on the other site are discouraging, I've read the thread and they are giving you a fair assessment of what needs to be done to get the bike up to scratch

 

[retrobiker273891]

As Brucey has said on the other site that you are posting almost identical questions, the plastic cover on the headset could probably be glued. Regarding the hub being shagged, that's not quite what the poster said. He said the freehub body might be shagged which is a different thing. The body is the part that the cassette slides onto and is usually removeable from the hub so it can be replaced when it wears out. I am surprised you think the posters on the other site are discouraging, I've read the thread and they are giving you a fair assessment of what needs to be done to get the bike up to scratch

They are yes after the first few discouraging comments, which is what prompted the initial comment. The next few were encouraging and have yet to see what else has been written

I retract my statement. It is just frustrating when people jump to criticizing an old bike before even getting an idea of its state.

 

[kingoffootball]

What model is the rear hub? That could helpfomeone advise whether it's easiest to replace the freehub or whether it could be the pawls sticking and methods for freeing them up.

[edit] I followed the link and saw it's a Deore hub. Too new for me to know, but generally for Shimano hubs it's not difficult to replace the freehub.

 

[Takingabreak]

and it may not even be the freehub because it looks as if there are 9 speed deore shifters with an 8 speed cassette, so the chain may be skipping rather than the freehub slipping. I would suggest confirming the shifters are 9 speed first, then if they are, fitting a nine speed cassette.

 

[retrobiker273891]

and it may not even be the freehub because it looks as if there are 9 speed deore shifters with an 8 speed cassette, so the chain may be skipping rather than the freehub slipping. I would suggest confirming the shifters are 9 speed first, then if they are, fitting a nine speed cassette.

It is 8 speed though I think I ascertained now since there are only 7 clicks unless you are able to set 9 speeds to do less clicks somehow.

 

[Gtpulse]

Your headset cap I’d take it off, degrease it and superglue the ends together.

The slack in the drivetrain engagement as others have said is likely to be sticky pawls in the hub. I’ve had success with these squirting in some wd40 with the straw in the very small gap between the cassette body and the hub its self at the large cog end. Leave it to soak for a while cassette side down then work the cassette back and forth, you’ll get a feel and a noise for when the pawls are engaging smoothly.

 

[PhillB]

So, just to say 'Nice wheels'... I have a 98 Bravado and love mine.

I can only agree that it sounds like a gummed up pawls or a slippy chain... On the brakes, have you tried the barrel adjusters on the levers, wind those out a bit and see if they make a difference to the brake pull feel? Some photos of the brakes an levers might help folks diagnose.

 

[ishaw]

Everything said above is where I'd go with headset and freehub, though headsets aren't expensive, you could even just buy the top half. What headset is it! I've a bag of spare headset parts and may have something.

Sticky freehub pawls sound like the culprit. When you stop pedalling does it take a bit for the freehub to frewgeel, causing the chain to initially go slack. The opposite when pedalling would be it doesn't engage initially causing a jump sensation at the cranks.

Brakes in my mind could be 1 of 2, or even both things I have in mind. Sounds like there is not a lot of spring tension in the callipers. This could be caused by the pin being located in the slickest position on the frame and forks. There are usually 3 holes to locate the pin into, all affect the spring tension and ultimately the position of the pad relative to the rim. It could also be the spring tension screws being screwed out and not putting enough tension in the spring. This results in the callipers not springing back very far and the brake feeling sloppy and loose cables, meaning you pull the lever and not a lot happens. Try screwing in the spring tension screws. One on each brake. This will spring the brakes back and keep tension in the cable. Remember, when you do this you'll want to adjust each side so that each brake springs back and equal amount or one side might spring back a lot and away from the rim while the other side doesn't, leaving it close to or still against the rim. Each side will pull the other unless you tension them evenly.

The locating pins and holes they locate in action as a pre-tensioner or starting point for the tension so you might need to move the pins to a hole that starts with more tension to begin with if adjusting the screws has little effect.

Hope this helps

 

[retrobiker273891]

So, just to say 'Nice wheels'... I have a 98 Bravado and love mine.

I can only agree that it sounds like a gummed up pawls or a slippy chain... On the brakes, have you tried the barrel adjusters on the levers, wind those out a bit and see if they make a difference to the brake pull feel? Some photos of the brakes an levers might help folks diagnose.

I am unable to take credit.

Is this one a 98? I have been told by seller 97 though not sure and someone else has said 96. I don't mind really though perhaps useful to know if I want to look up specific parts to find what a specific year came with.

If the chain was slipping that would be very noticeable no and have not noticed that? For instance if in the granny gear up front and going into a too small gear in the back then the chain slips then due to the slack and that is very easy to notice.

This other issue is not that. Whereas with a chainslip there is initial torsion then slippage, in this case, it is like just air peddaling, as if the chain were off and only then it kicks back in.

Yes I tried unscrewing and screwing back in with the brakes. I think screwing back in made the front work better however didn't make a noticeable difference on the back. The spring seems fine for both except the metal casing that attaches the wire to the levers seems to be producing too much force on the left side lever (if you were on the bike facing forward) such that it is unable to spring back since as soon as it is released the lever jumps back again.