Rear End Wallow?

For all your handling questions

Rear End Wallow?

Postby Stereordinary » 08 Feb 2021, 23:47

This might just be a n00b question, because I’m still a pretty new rider, but why do I feel like the rear end is a little wallow-y on bumps? It’s a sort of sideways shifty feeling like what I would expect a flat tire feels like, only I’ve been checking my tire pressure and it’s up where it should be. The tire is less than five years old, and I haven’t put a lot of miles on it. Maybe I need to change the preload on my suspension? I’m a pretty light rider (about 160 lbs. last I checked), so maybe it should be stiffer? I’m a little confused and this feeling makes me less confident while riding. Any help would is appreciated.
Stereordinary
 
Posts: 44
Joined: 05 Aug 2020, 16:21

Re: Rear End Wallow?

Postby hugojose » 09 Feb 2021, 09:55

Have you checked the play on rear swing arm? From time to time, the bolts are supposed to be retorqued.
hugojose
 
Posts: 130
Joined: 05 Sep 2017, 00:43

Re: Rear End Wallow?

Postby Freddy » 09 Feb 2021, 10:45

Stereordinary wrote:This might just be a n00b question, because I’m still a pretty new rider, but why do I feel like the rear end is a little wallow-y on bumps? It’s a sort of sideways shifty feeling like what I would expect a flat tire feels like, only I’ve been checking my tire pressure and it’s up where it should be. The tire is less than five years old, and I haven’t put a lot of miles on it. Maybe I need to change the preload on my suspension? I’m a pretty light rider (about 160 lbs. last I checked), so maybe it should be stiffer? I’m a little confused and this feeling makes me less confident while riding. Any help would is appreciated.


Like any problem, start with the most likely and work progressively down the list of possibilities. ... So in that order

Rider sag .... every motorcycle needs to have both front and rear rider sag set correctly for the riders weight. If not the geometry of the motorcycle won't be correct. It'll be nose up/down, or sitting too high/low in its suspension. Unlike a car, the weight of the rider (and any load they may be carrying) is a significant percentage of the total load on the suspension and how much it compresses. The suspension (preload) needs to be adjusted to set the suspension in its correct at rest position. I won't describe how to correctly set rider sag as there are a zillion YouTube videos on the internet. The rear is easy to adjust, the front is also adjustable, but being an internal adjustment (easy to do) is just a bit more difficult.

Shock absorbers ...... how olds your bike?? Obviously as a Zephy something like 25 years old. Shock absorbers should be recondition or replaced about every 5 years as the oil in them losses its viscosity through use. The oil 'molecules' suffer a torturous life and literally get torn apart reducing the effectiveness of the shockabsorber. A bike with poorly performing rear shocks will handle like a pig.

Front forks ...... Same oil problem as the rear shocks. The oil in the front forks should be changed about every 12 months. Your bike probably has the original oil in it, if in fact there is fork oil in it.

So what to do ....
Set a correct front and rear rider sag.
Get someone to hold the bike upright while you push down quickly and firmly on the back of the seat releasing it and watch how it returns. If it just instantly bounces back with some minor up/downs before settling, the shock absorbers are shot. The genuine shocks can be rebuilt, don't let anyone tell you they can't. Whether or not that the best decision is another question.
Replace the oil in the front forks. Use 10W fork oil, I'm reluctant to say 15W which is about what's needed for the most important fork action (rebound) as it does have a downside. 10W isn't ideal but a safer bet. They are routinely genuine workshop manuals on ebay, these will show you how to do routine maintenance like changing the fork oil.

Get those three thing squared away and you should have a bike with correct operating but basis suspension set to its correct geometry. Only them if it still doesn't give the confidence go to the next step.
Freddy
 
Posts: 593
Joined: 06 Sep 2017, 11:06
Location: Sydney Australia

Re: Rear End Wallow?

Postby Stereordinary » 09 Feb 2021, 18:02

hugojose wrote:Have you checked the play on rear swing arm? From time to time, the bolts are supposed to be retorqued.

That I can do fairly easily, so I will be sure to ASAP.

Freddy wrote:Like any problem, start with the most likely and work progressively down the list of possibilities.

Thank you Freddy, for your thorough answer. It sounds like you’re suggesting full and complete rebuilding of both front and rear suspension. That’s a big intimidating job for me, but something I’d be interested in doing. Do you have the link for the rear suspension rebuild? I know I’ve seen one before, but I guess I forgot to bookmark it.
Stereordinary
 
Posts: 44
Joined: 05 Aug 2020, 16:21

Re: Rear End Wallow?

Postby ZoneAdmin » 10 Feb 2021, 09:49

Please see links for method produced by Gazzz Garage to rebuild shocks for a Zephyr.

https://www.gazzz-garage.com/2016/06/30 ... ck-part-1/

https://www.gazzz-garage.com/2016/07/12 ... ck-part-2/

Good luck.
Regards
Dennis

Current bikes: Zephyr 750 C4, Zephyr 750 C3
-------------------------------------------------------
Previous bikes: Kawasaki Z1000 A2, Kawasaki KH400 A4, Kawasaki KH250 B1
ZoneAdmin
Site Admin
 
Posts: 73
Joined: 09 Aug 2017, 13:52
Location: Cwmbran, Wales

Re: Rear End Wallow?

Postby Freddy » 10 Feb 2021, 11:01

Stereordinary wrote:
hugojose wrote:Have you checked the play on rear swing arm? From time to time, the bolts are supposed to be retorqued.

That I can do fairly easily, so I will be sure to ASAP.

Freddy wrote:Like any problem, start with the most likely and work progressively down the list of possibilities.

Thank you Freddy, for your thorough answer. It sounds like you’re suggesting full and complete rebuilding of both front and rear suspension. That’s a big intimidating job for me, but something I’d be interested in doing. Do you have the link for the rear suspension rebuild? I know I’ve seen one before, but I guess I forgot to bookmark it.


Don't be intimidated by my comments, there is nothing in there that's all that difficult. Changing the front fork oik is actually VERY easy, as long as you have some basic tools including a jack. It is I believe pretty well described in the genuine workshop manual. It's actually a good first project to 'sink your teeth into'. You have an old bike. While the Zephyr's are simple and solid, it still will require maintenance, so its actually nearly essential to be able to do much of this yourself. Otherwise it probably isn't an economical proposition to be paying someone to do everything. A person who doesn't want maintenance is probably best off with a new or near new bike.

Setting the rear and front sag is also very easy, as long as you understand what your are trying to achieve. A pretty good video of the process https://www.youtube.com/watch?v=ZtzTyCKh5fY&ab_channel=MotorcyclistMagazine In the case of a Zephy you don't have screw type adjusters in the front. What you have is an internal spacer and some washers. When you change the fork oil you'll see these components. It's the length of these you change if adjustment is needed (adding more washers to lengthen or cutting a new tube to shorten). The front suspension on a Zephy is a pretty basic thing.

With the rear shocks, probably the safest bet is to take one off (bike on center stand, two fasterners one top one bottom) and take it to a motorcycle suspension specialist to test for you. Be wary a lot of them are nothing more than snake oil salesmen, so don't let them talk you into a set of cheap replacements. You can test them yourself pretty well if you can get the spring off. A suitable size ratchet strap works well as a spring compressor. You'll never get the original linear spring off without a spring compressor.

P.S. Don't take any notice of what the guy in the video says about how to determine if you have the correct rate springs. It's actually not correct. It's important to know how, but there is a much better method. But that as Thomas would say "is a story for another day".
Freddy
 
Posts: 593
Joined: 06 Sep 2017, 11:06
Location: Sydney Australia


Return to Tyres, suspension, etc

Who is online

Users browsing this forum: No registered users and 1 guest

cron