Author Topic: What are bump stops designed for (Read 712 times)

Beno · « **on:** October 23, 2019, 07:55:14 PM »

Hi everyone,

I know this subject has come up before and I have read through several other threads but I have a couple of questions and hoping you can help me out.

My bump stops from front suspension of 1980 Cali are a lot bigger than their “new” replacements. I can no longer purchase the longer ones anywhere (first photo).

What are they actually designed to do?
Would it make a difference to install the shorter ones?

Also based on other threads the last two images seem to be alternatives but does this affect anything else overall and what are your opinions about how I should move forward on this?

yellaterra · « **Reply #1 on:** October 23, 2019, 09:01:54 PM »

Hi Beno, Your bump stops are there to protect the integrity of the mokes suspension system from severe failure or fatigue from misuse, a safety item of last resort when you hit a hole or bump in the road, especially at speed. Common thing in some moke owners by experience. Also, the vehicle being over loaded may cause the bump stops to come into play whilst you are driving. Ie, just one more item I need to move? No bump stops is a bigger issue in your moke then a slightly smaller one in length. Hope this helps you to understand why you need bump stops on your moke. They are necessary for your safety while driving and enjoying your moke. As to which type you use choose one that is as close to your original one. Cheers

Beno · « **Reply #2 on:** October 23, 2019, 09:58:49 PM »

Thanks Yellaterra,

That helps put things into perspective. What would the difference be if I swapped.
As in, if instead of having the shorter replacements go in the same spot as the originals what would happen if I switch and put the other type on the upper control arm instead of attaching direct to the subframe?

mellowyellow · « **Reply #3 on:** October 23, 2019, 10:32:43 PM »

Hi Beno,
A while ago I upgraded the front suspension to hilo's and replaced the bump stops and L-pads. There are some pics in my garage thread that may help you.
https://www.mokeforum.com.au/index.php?topic=9942.30

Halfpint · « **Reply #4 on:** October 23, 2019, 11:43:18 PM »

Hey Beno, Ive been waiting for this question

If the longer bump stops are no longer available ( They are a pain to fit, not impossible though), Its simple, go the hydro type.
The last ones in your pics. So easy to fit, easy to replace, and just like the original bump stops, will prevent your suspension from over traveling.

After all, thats their primary function, to stop over travel.

There are some front sub frame mods that can be made to strengthen them, but if you keep good rubber donuts, maintain good height via adjustable cones, and dont travel many ks on dirt or corrugated surfaces, I doubt the subframe will cop too much.
I agree with Yellaterra, it's a last protection .
Its unlikely the bump stop will even come into play if your donuts and shockies are in good condition

Quote from: Beno on October 23, 2019, 09:58:49 PM

Thanks Yellaterra,

That helps put things into perspective. What would the difference be if I swapped.
As in, if instead of having the shorter replacements go in the same spot as the originals what would happen if I switch and put the other type on the upper control arm instead of attaching direct to the subframe?

On some models where the shorter bump stops were fitted, the factory welded some plates onto the control arms. Over travel is our enemy here Beno. You can try and find the original long bump stop rubbers, or fit the shorter bump stops along with the control arms with the plate welded on them, or fit the hydro bump stops.
All will give you the protection from over travel. Its up to you how much effort you want to give to achieve the same result.

Any questions happily answered or discussed, its a very good topic youve chosen to talk about

Halfpint

moemoke · « **Reply #5 on:** October 23, 2019, 11:54:28 PM »

The ones in the second photo are hydro bump stops which bolt onto the top arm, usually need a bit of filing to make the fit though.
The advantage is that they are easier to replace as you don't need a double jointed wrist to reach the usually rusted nuts inside the tower, I'm not even sure you can reach the nuts with the donuts in place. the other advantage is that if the donuts have sagged and the moke is almost riding on the original bump stops they will bend the subframe where they are mounted but with the hydro arm mounted ones you can add a thicker plate to this area 6 or 8 mm is usually the go, needs to be welded in though.

Halfpint · « **Reply #6 on:** October 24, 2019, 12:11:26 AM »

Front hydrolastic Bump stop kits
http://www.minispares.com/product/Classic/Suspension/Front/Hydro/C-AJJ4007.aspx?190202&ReturnUrl=/search/classic/%20bump%20stop.aspx|Back%20to%20search
These are the ones Im talking about.
Yep, original bump stops are so much of a pain to get at Moemoke.
HP

Beno · « **Reply #7 on:** October 24, 2019, 12:53:33 AM »

Awesome thanks everyone for the info!

So I’ve had a look at what mellow yellow did on her minibeast and it looks as though I should be doing the same then.

And I’m glad someone was waiting this question Halfpint 😃 I have new doughnuts and HiLo’s so that should assist and I’m not planning on any cross country dirt road expeditions unless I’m running from the police after robbing a bank to get the Moke back up and running 😜

I have hunted hi and low for the original length bump stops but nobody seems to make them anymore. My question in this regard is given I would be switching the bump stop from “hitting” the upper control arm to now “hitting” the subframe is there anything extra I have to do to the subframe to account for this change? Is this what you were talking about moemoke?

And in saying that would it be necessary for any extra reinforcement if I used the stops shown in my third picture given the difference in surface area? Or are these for something completely different?

Terry · « **Reply #8 on:** October 24, 2019, 08:43:04 AM »

Hi,

if you are going to switch to the hydrlastic style bump stop you can cut the rubber, which looks like it is half off anyway, from your old bump stop and then bolt just the metal part back onto the subframe and that will help spread the load from the new bump stop.

If you want a bit more reinforcement you can weld the cut out bump stop to a piece of wider/thicker metal and then bolt that up in place and further spread the load.

Most people wouldn't realise how often they hit the bump stops just in normal driving(speed bumps, driveways) and a even more are driving around with flat donuts and the bump stop being really their only form of suspension and they just put it down to the hard ride of a Moke.

And before you fit anything, make sure the subframe area where the bump stop mounts is flat as you have been riding on the bump stops for a awhile so it is probably starting to deform. The lip or edge of the sub frame just below the where the bump stop mounts should be straight/horizontal and not slightly curved or bent. A picture would be nice.

Terry

Halfpint · « **Reply #9 on:** October 24, 2019, 09:24:24 AM »

Quote from: Terry on October 24, 2019, 08:43:04 AM

If you want a bit more reinforcement you can weld the cut out bump stop to a piece of wider/thicker metal and then bolt that up in place and further spread the load.

Thats a good option to do it Terry. Still need the donuts out or at least a couple 7/16 spanners with bends in them.

The reason I like the bigger bump stops is the surface area is bigger, unlike the point contact. But either will work fine for normal road use.

This is how I reinforced the subframes, its pretty easy when the subframe is out and stripped though.

I have both my Mokes converted over now.

With the new Hydro bump stops(either type), the brackets will sit a bit high and the bolt holes wont line up spot on, so like what Moemoke said, you will need to file a bit. But before you take any metal from the bolt holes, check where the bracket comes into contact with the control arm isnt raised a bit and file it down flat first. Even a light file on the control arm to take any slight high spots off will help a fair bit.

Let us know how you go with it.

Cheers
Halfpint

Beno · « **Reply #10 on:** October 24, 2019, 10:47:13 PM »

Halfpint your photos are awesome and I have shown them to my brother to get him to weld it up like yours.... makes complete sense.

And after reading your reply Terry, I went back and had a look and sure enough..... big dent, here’s some photos. You can clearly see the passengers side where there was major damage to the bump stop there is damage to the subframe whereas the other side not as bad.

Terry · « **Reply #11 on:** October 24, 2019, 10:58:33 PM »

Hi,

normally it is the drivers side that is worse, but really what you have is not bad and is about what you'd be happy with after trying to straighten it out.

After years of a bump stop providing the only form or suspension besides low tyre pressure you can get towers that are deformed enough that the donut can't be removed and the normally straight edge gets close to a 45 degree bend.

And I think HP is just showing off his welding skills.

Terry

Beno · « **Reply #12 on:** October 24, 2019, 11:06:59 PM »

Haha well they are pretty impressive welding skills!

And my apologies, the bad one is the drivers side... got them messed up with all my attempts to copy and paste photos in gallery from iPad.

At least I now know exactly what to do to fix the problem so once it’s all welded and in place I will make sure I add some photos.

Beno · « **Reply #13 on:** November 17, 2019, 09:35:43 PM »

So I have my subframe back from my brother who did the welding for me.

Now it’s time to put everything back on there.

Halfpint · « **Reply #14 on:** November 17, 2019, 09:43:46 PM »

Nice work

Now the fun bit, assembling it all.
Are you putting it together after the subframe is fitted to the body or before?
Just don’t forget to fit the steering rack before the subframe, you don’t have to tighten it up, just have it in place with all 4 nuts on the U bolts.
HP