I'll start by saying maybe its been a big Christmas and the pudding was especially nice.. but when I took the kids + wife for a ride in my 69 Mini K - the rear drivers side wheel scuffed up into the wheel arch flares.

I took a look more closely, and evidently the bump stops that are part of the suspension setup (ie these ones https://minisport.com.au/mini-hydrolast ... -flat-type) were completely perished.

Question is - can these flat type bump stops be replaced without needing to depressurise the hydro system?

The other bump stops that sit ontop of the rear arm, are also a bit of a mystery.... one is designed for a an early English hydro car (21A1520) and the other has a VW part number on it... needless to say these will be replaced with the correct Aussie hydro ones

It is possible to replace the hydrolastic rear flat trailing bump stops by raising and supporting the car body and also supporting the rear subframe with a jack or jacks. You can then loosen the rear subframe mounting hardware. I left the rear mounts intact but had to disconnect the front mounts. Removing the front mounts should be done with great care as you don't want to damage the threads of the captive nuts fitted to the body. By lowering the subframe you can get enough clearance between the body and the subframe to remove the bolts holding the bump stops to the subframe. New stops can then be fitted. I had to do this as I had forgotten to install the flat bump stops during a rebuild a few years ago. The hydrolastic system had NOT been pressurized but the hydro pipes were fitted and connected. You should always be careful working with a pressurized suspension system, I bought a pump years ago for this very reason.

Fixing these bump stops will not improve your car's ride height. I imagine you've checked the Minisport website for suspension hardware, e.g., the donut style rear hydro trailing bump stops, packing washers for the suspension ball. Maybe a hydro pump up may be needed. There are many experts here who can provide good advice.

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Clive G
1969 Mk II Cooper S
1970 MK II Cooper S
1963 Triumph Spitfire
1982 RX-7 Series 2

The flat bump stops you refer to (21A1517) are a 'rebound' stop; these only come into contact with the trailing arm when the car body is up in the air and the wheel and suspension are hanging down - not being pushed up into the wheel arch. They usually look a bit the worse for wear but they aren't your bottoming-out problem.
I've never tried to change one with the subframe on the car, however, if the original rebound stop has been installed correctly with the bolt inserted from the front of the subframe and you can see its nut/washer as in the MiniSport catalogue photo you refer to, you can see the bolt head between the front edge of the subframe and the car body. It can be reached with an ordinary 1/2"AF open-ended spanner while you replace the nut and old stop.

With due respect to cgo's comments, I don't think it's necessary to separate the subframe. He had to get enough clearance here to insert the needed bolt, but your setup already has the bolt. The trailing arm will need to be raised slightly to give clearance but I think the suspension won't need depressurising.

It could be that your system is a little low. I can remember my K scraping rear tyres with a 'full' load of passengers. Minis today rarely travel with more than 2 up.

Your are correct Bill, I didn’t have the bolt in situ and couldn’t fit the bolt from the front.

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Clive G
1969 Mk II Cooper S
1970 MK II Cooper S
1963 Triumph Spitfire
1982 RX-7 Series 2

Thanks so much for the replies Colin and Bill.

I just looked at the bolt that holds it in.. and it would appear both the nut and bolt head are accessible.

I'll add it to the list of stuff to do

Great to know there's a community that's willing to help keep our Minis on the road.

I think the rear competition bump stops may be what you are after (if you haven’t already) - i believe they are taller and would stop as much travel on the trailing arm. https://minisport.com.au/mini-hydrolast ... ition-pair

Recently my front was very low and was just touching the bump stops, i had no issue with rear scrubbing. I was sad to pump it up actually because the stance looked cool, 1 knuckle clearance under front guard. Just that the ride was loosening my teeth. I will be adding front shocks though, as now it is at the correct height I’ve noticed it is diving under brakes.

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1966 Mini Deluxe - “Gabby” 34 years under restoration and counting...
1970 MGBGT
1959 MGA

The original style rear bump stops are available.
$50 a pair from Minicraft...... $90 for exactly the same thing from somewhere else.

https://www.minicraftmotorsport.com/sho ... rq=AYA7069
https://www.minicraftmotorsport.com/sho ... rq=AYA7069

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Caught up with John Sneddon today (he's conveniently around the corner from me) - I'll get a set of competition bump stops.

Thanks for all the replies. Appreciate the help and advice

I have found competition bump stops good on the rear. A benefit if running wider wheels than stock is the tyres won't hit the wheel arches if you blow a hydro bag.... as I found out.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Just thought I'd follow up on this post. I installed the new bump stops today.

The mounting the rubber onto the bracket for the progressive / competition bump stops was a challenge. I found using hydraslip (silicone based lube for pool pump seals) worked well, and also using a Black and Decker Workmate to squeeze the rubber onto the bracket. I previously tried coil compressor, F and G clamps and a vice.. none of which worked great.

The flat bump stops needed the swing arm raised (pretty much all the way) and took some persuasion but weren't took bad.

Looking forward to taking it for a drive... just have to wait for the rain to clear up!

Nice. From memory I forced something through the rubber a little bigger the bracket to stretch the rubber a little, then started one side and corkscrewed the rubber on.

MGB also use the same rubbers on the rear, but the mounting is part of the chassis so you don't have the benefit of doing it in a vice...

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1966 Mini Deluxe - “Gabby” 34 years under restoration and counting...
1970 MGBGT
1959 MGA

I use dishwashing detergent, they fit on pretty easily. But I've had lots of practice!

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Well done.
It's good to finish a job that works as intended. They don't always.
I have tried to fit these to the front as well but they set the ride height too high for normal road use.

I also found them too high for the front unless it's a rally car?
Maybe could be trimmed but I stuck with the conical ones.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Good to know re front bump stops.

Took the Mini for a spirited 80km drive... the ride is much better. I'll have to try a run with the wife and kids, but I'm sure it will be good.

Thanks for everyone's help and ideas