Bump stop on rear shock

**manwithav8** · 12th October 2007, 19:26

How important is it?

Took the other half out for a quick ride tonight and checked over a few things at a stop. I have noticed the bump stop ( if thats what they are called) has persihed to a point where it is now flaking off in chunks.

Also while down there I noticed the spring preload is wound up to it's maximum ( not by myself ) so if I were to wind it up a little more for two up riding I can't. Any suggestions?

**chanceyy** · 12th October 2007, 19:36

Betsy bump stop is perishing as well but others who know way more than I do said its nuffin to worry about ..

**Robert Taylor** · 14th October 2007, 08:01

Originally Posted by manwithav8

How important is it?

Took the other half out for a quick ride tonight and checked over a few things at a stop. I have noticed the bump stop ( if thats what they are called) has persihed to a point where it is now flaking off in chunks.

Also while down there I noticed the spring preload is wound up to it's maximum ( not by myself ) so if I were to wind it up a little more for two up riding I can't. Any suggestions?

Well, there are 2 types of advice in this world, bad advice and good advice. My advice is to not listen to bad advice, even if it feels more comfortable on your pocket.

There is a very good reason why a servicable bump stop should be there, to prevent mechanical bottoming out / to provide a final progressive cushion should there be an event that uses most of the travel of the shock. There will be occassions when you dont have time to avoid nasty / abrupt bumps / potholes etc, and the end result will be doubly bad if you are carrying a passenger.

The fact that the available spring preload is maxed out is a serious clue that the spring is too soft for you, so that poor bump rubber has in its life been doing more work than it should. Also, because of all this your rear tyre life is suffering.

**chanceyy** · 14th October 2007, 08:04

hmmm so perhaps its back to the drawing board for betsy then ? do you need to replace the whole shock or can you just replace the bump stop ?

being that she is an old bike 83 RZ350 have trouble sourcing parts for her at the best of times .. or will she fit aftermarket ?

**manwithav8** · 14th October 2007, 10:16

Originally Posted by Robert Taylor

Well, there are 2 types of advice in this world, bad advice and good advice. My advice is to not listen to bad advice, even if it feels more comfortable on your pocket.

There is a very good reason why a servicable bump stop should be there, to prevent mechanical bottoming out / to provide a final progressive cushion should there be an event that uses most of the travel of the shock. There will be occassions when you dont have time to avoid nasty / abrupt bumps / potholes etc, and the end result will be doubly bad if you are carrying a passenger.

The fact that the available spring preload is maxed out is a serious clue that the spring is too soft for you, so that poor bump rubber has in its life been doing more work than it should. Also, because of all this your rear tyre life is suffering.

I was hoping you would eventually answer this post. Have been keeping an eye on your suspension posts and enjoy reading them.

So Robert, answer time. Same question as Chancey, can the stop be replaced or am I looking at a whole shock/spring rebuild???

I haven't looked into the sag and have only been riding the bike for 3 weeks now so the damage was already done. The preload may well be over done for me, I am 66kg without riding gear so that would have to be one soft spring..

What would you suggest Robert.

**Robert Taylor** · 14th October 2007, 11:27

Originally Posted by chanceyy

hmmm so perhaps its back to the drawing board for betsy then ? do you need to replace the whole shock or can you just replace the bump stop ?

being that she is an old bike 83 RZ350 have trouble sourcing parts for her at the best of times .. or will she fit aftermarket ?

Either or, we have Ohlins bump stops in stock in many sizes that fit a whole plethora of Japanese shocks, and they are cheaper than the Japanese ones, which also arent readily available.

**Robert Taylor** · 14th October 2007, 11:34

Originally Posted by manwithav8

I was hoping you would eventually answer this post. Have been keeping an eye on your suspension posts and enjoy reading them.

So Robert, answer time. Same question as Chancey, can the stop be replaced or am I looking at a whole shock/spring rebuild???

I haven't looked into the sag and have only been riding the bike for 3 weeks now so the damage was already done. The preload may well be over done for me, I am 66kg without riding gear so that would have to be one soft spring..

What would you suggest Robert.

See my most immediate previous post. Also set the spring preload so that the bike sinks under its own weight by 5 - 8mm. Then sit on it fully kitted in normal riding position, feet on the pegs. Have a helper hold the front of the bike facing you and clamping the front wheel with his / her legs. Have another helper take a ACCURATE reading using the same reference points. Your rider sag should for that bike be between 30 -35mm solo. If it is less the spring is too firm in rate, if it is more the spring is too soft. ( Note that all readings are expressed from a measurement taken fully topped out, wheel off ground)
Overpreloading a soft spring means it will end up being topped out with no static sag ( bike weight only )
I am guessing that it is a Sachs shock? If so spare setting parts such as springs are hard to come by, but with a very small modification we have successfully fitted a number of Ohlins springs to these.

**manwithav8** · 14th October 2007, 11:42

I will get a few mates to help out.. Will get the sag all set and contact you if I find that the spring is too soft. Now on the bump stop, can I just fit a new one or is there something else that needs to be done here?
The bike has not long clicked over 11000k so I am assuming the the shock hasn't been touched since new. Is there a time/kilometer base where shocks and forks require servicing?

**manwithav8** · 14th October 2007, 11:51

If I set the sag correctly, can I raise the rear ride height without it affecting the spring preload or should I adjust the height then set the sag? Or will it not matter which way I do it?

**geoffm** · 14th October 2007, 12:27

Originally Posted by chanceyy

hmmm so perhaps its back to the drawing board for betsy then ? do you need to replace the whole shock or can you just replace the bump stop ?

being that she is an old bike 83 RZ350 have trouble sourcing parts for her at the best of times .. or will she fit aftermarket ?

Plenty of RZ (RD350 YPVS in Europe) aftermarket shocks out there, for varying dollars. Some suspension people will rebuild the OEM one if it is not to stuffed. Given they were pretty budget when they came out...
A number of people on the RD forum have done shock swaps with success using Yamaha R6 and R1 and Honda CBR600 shocks. Some others:
http://eastcoastrzs.tripod.com/id2.html
http://eastcoastrzsr1shock.tripod.com/R1Mod/

There are cheap aftermarket shocks (http://shop.wemoto.com/index.dyn?oid=2147829)
http://www.lm-spares.co.uk/acatalog/...onoshocks.html
but I suspect the quality will be no better than getting your original one rebuilt and the cost will be the same.
You can also buy new ones from Norbo at RDLC Crazy
http://homepage.ntlworld.com/ultimatelccrazy/
I bought some LC stuff from him with no problems.

Best option, ignoring money, is a nice yellow Ohlins...

**manwithav8** · 14th October 2007, 13:06

WHy is it that when I sit on my bike the rear end squeaks... If I bounce up and down it squeaks. I s damn anoying. Is it trying to tell me something?

**TDC** · 14th October 2007, 19:39

Originally Posted by manwithav8

WHy is it that when I sit on my bike the rear end squeaks... If I bounce up and down it squeaks. I s damn anoying. Is it trying to tell me something?

Look at your suspension linkages! These items are often very overlooked and often are the source of poor handling. When installed at the factory they have a small amount of a mid to poor quality grease lubricating them. And the spend the rest of their life working under significant loads with no further maintenance. Cleaning out the old grease and replacing it with a good quantity of a good waterproof grease before they fail is a good thing to do. Also check the bearings at the ends of the shocks.

**Robert Taylor** · 15th October 2007, 08:32

Originally Posted by geoffm

Plenty of RZ (RD350 YPVS in Europe) aftermarket shocks out there, for varying dollars. Some suspension people will rebuild the OEM one if it is not to stuffed. Given they were pretty budget when they came out...
A number of people on the RD forum have done shock swaps with success using Yamaha R6 and R1 and Honda CBR600 shocks. Some others:
http://eastcoastrzs.tripod.com/id2.html
http://eastcoastrzsr1shock.tripod.com/R1Mod/

There are cheap aftermarket shocks (http://shop.wemoto.com/index.dyn?oid=2147829)
http://www.lm-spares.co.uk/acatalog/...onoshocks.html
but I suspect the quality will be no better than getting your original one rebuilt and the cost will be the same.
You can also buy new ones from Norbo at RDLC Crazy
http://homepage.ntlworld.com/ultimatelccrazy/
I bought some LC stuff from him with no problems.

Best option, ignoring money, is a nice yellow Ohlins...

PM me for pricing, I dont make a habit of pricing over this forum as I beleive in full and proper service rather than dutch auctions. There is a lot of seemingly deliberate misconception about Ohlins pricing so you may be surprised.

Although in the end event it is a choice between budget price and budget performance against a higher price and something that actually works properly.

The oem shock is indeed rebuildable but it does start to add up if it needs a shaft. Again there is a choice between budget rebuilds and actually doing the job properly......I make no apologies in saying that, there is a LOT of shonky work going on by people I wouldnt even trust to fix my lawnmower.

**Robert Taylor** · 15th October 2007, 08:34

Originally Posted by manwithav8

I will get a few mates to help out.. Will get the sag all set and contact you if I find that the spring is too soft. Now on the bump stop, can I just fit a new one or is there something else that needs to be done here?
The bike has not long clicked over 11000k so I am assuming the the shock hasn't been touched since new. Is there a time/kilometer base where shocks and forks require servicing?

The forks should have had their oil changed at least twice in that period and one full strip. Shock can go to 20ks.

**Robert Taylor** · 15th October 2007, 08:35

Originally Posted by manwithav8

If I set the sag correctly, can I raise the rear ride height without it affecting the spring preload or should I adjust the height then set the sag? Or will it not matter which way I do it?

Set your desired ride height / geometry first.