Using front hydro for dry set up.

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java gt
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Using front hydro for dry set up.

Post by java gt »

Seeing as someone cut the rear stub axles off my latest MKII project while it lay in a field with the previous owner so going the hydro route is gone.I will use the front hydro frame which is a good rust free example,my question is apart from knocking back the tabs in the towers to get the cones to fit with Hilos and using dry top arms,is there else I need to do to use the hydro frame.
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Re: Using front hydro for dry set up.

Post by mab01uk »

If you did want to go the hydro route.....

Hydrolastic Stub Axle 21A1486 and 21A1490
These are new stub axels (supplied by Minispares) that have been modified to accept the hydrolastic helper spring. Supplied with the C clip(13H2193)
21A1486 is RH (RH thread)
21A1490 is LH (LH thread)
https://shop.catmint.biz/product/hydrol ... d-21a1490/

Extract below is from Keith Calver's website.

Suspension - Converting from wet to dry.
"Now, it’s entirely possible to modify the hydro front subframe to accept the rubber springs and other necessary bits and pieces. The displacer unit is seated in the tower in the same way as the cone, the difference being the locating ring's size/shape. The displacer sits inside it’s seating ring, the cone outside. The diameters of these differ too, the hydro being bigger, and has lugs pressed into it. To get the rubber spring to fit the hydro ‘frame, these lugs need to be bent outwards. The rubber spring then locates inside the ring. Sounds easy, eh? Achieving this is accompanied by all kinds of 'blue' air and skinned knuckles. More often than not, eventual submission and fitment of a dry ‘frame!! It’s all down to access - or lack of it (as in ‘severe’). There are ways round it, but we’re supposed to be doing this the easy way, remember? Then you need to drill holes in the tower outer ‘elbows’ to take bump stops. Use the later single stud fixing as this eases the whole drilling/fitting thing."
The full article here:-
https://www.calverst.com/technical-info ... et-to-dry/
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Peter Laidler
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Re: Using front hydro for dry set up.

Post by Peter Laidler »

You didn't explain where the axles had been cut off. Was it the actual AXLE part or the inboard support pin part ?

If it was the rear/inboard support pin, that is simplicity itself to repair without stripping the swinging arm - although you've got to take it off the car of course. The repair has been fully detailed on the forum in the past so I won't go into it again.

But it does save the aggro of pressing the old ones in a bit further, removing the large circlip thinggy and then pressing them out..... and the new ones in. Better still, you can repair/rebuild to whatever wet or dry spec you want/need. Especially good if you ain't got access to a press.

Mind you, converting a wet front sub frame to dry doesn't look as simple as fixing what you've got!
java gt
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Re: Using front hydro for dry set up.

Post by java gt »

Apologies for the lack of detail,I meant the rear trailing arms were cut halfway along their length and the whole hub assembly removed via consaw and the rear hydro units are gone as well and as hydro cars are rare over here in Ireland I was going to convert it to dry and use the front subframe with a new dry rear subframe. I’ll have the front stripped this week so I’ll look at towers and see about getting the cones to fit. Better wear gloves given the advise above 😀
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Re: Using front hydro for dry set up.

Post by abs »

No need to modify the hydro front subframe just make the round steel ring on the rubber doughnuts square, easy enough with a big hammer and that way you you haven`t ruined a hydro subframe.
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Re: Using front hydro for dry set up.

Post by 360gts »

I assume you are also going to change the front upper arms.....these are quite different to the dry version.....different ratio.
You can use the wet arm but it will make the ride a lot harder.
java gt
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Re: Using front hydro for dry set up.

Post by java gt »

360gts wrote: Thu May 23, 2024 3:32 pm I assume you are also going to change the front upper arms.....these are quite different to the dry version.....different ratio.
You can use the wet arm but it will make the ride a lot harder.
Yes,I will be changing the top arms to dry ones
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Re: Using front hydro for dry set up.

Post by CooperTune »

I'm about to put a wet front sub frame into dry service. I have never had an issue reshaping the locating ring. I use a large pair of vise-grips. The bump stop platform is not drilled for a dry bump stop. I drill the wet upper arms to accept 3/8 shock hardware. It seems I have seen special hardware to mount shocks without drilling. I have used the higher spring rate arms on race cars and auto cross cars. I continue to collect wet sub frame parts in the event someone will require them. Steve (CTR)
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Re: Using front hydro for dry set up.

Post by Costafortune »

Unless you use HiLos, the car will sit quite low on the front. Not a problem but you will need the shorter front dampers otherwise it will bottom out.

A dry front subframe isn't rare or valuable, so......
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