treb
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| posted on 2/4/15 at 11:00 AM |
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Fitting HiSpec rear brakes to a J15
Just got my SVA compliant rear brakes from HiSpec but the mounting lugs are way off and it looks like serious re-engineering is needed to make them
work.
I know these calipers have been fitted to other J15's so it can be done
Is there anyone out there who has successfully done the modification and can give me some ideas of what needs to be done.
treb
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daniel mason
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| posted on 2/4/15 at 11:58 AM |
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What rear uprights are on the j15?
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Paul AS
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| posted on 2/4/15 at 01:10 PM |
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The rear uprights are Sylva's own steel fabricated items. The caliper they are drilled to take is from the Sierra XR4x4 V6
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Kdempsie
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| posted on 2/4/15 at 02:19 PM |
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Now this might not be entirely helpful but if you read these posts it explains what I did to fit Wilwood brakes to mine. I think the Hispec brakes
have similarities.
Hope this helps a bit.
https://jpsc.org.uk/forum/viewtopic.php?f=4&t=1209&start=10
Keith.
[Edited on 2/4/15 by Kdempsie]
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Jenko
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| posted on 2/4/15 at 04:11 PM |
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Ahhhh.... a subject VERY close to my heart!.
Reality is, the hispec's DONT fit.......and the only way to get them to fit is to re align the mount. The hispec rears are designed for a
westfield that reversed the mount. Hi spec were selling them as replacements for the VW Hydra caliper, but they got that wrong.
Read this page of my blog, and all will become clear:
Click
Up shot was hispec altered my upright by changing the mount position, and we also had to use different pads.
[Edited on 2/4/15 by Jenko]
MY BLOG - http://westfieldv8.blogspot.co.uk/
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theprisioner
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| posted on 2/4/15 at 04:23 PM |
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What is the advantage of hispec on rear vs hydra?
http://sylvabuild.blogspot.com/
http://austin7special.blogspot.co.uk/
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Jenko
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| posted on 2/4/15 at 04:38 PM |
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The hispec are smaller and lighter than the hydra, and also give far more clearance around the drive shaft gator and under a 13 inch wheel. The exit
line of the handbrake cable is also more forgiving.
That said, unless they have now changed their design so they bolt straight on, I would be tempted with the wildwood offering as it really was a pain
getting the uprights modified.
MY BLOG - http://westfieldv8.blogspot.co.uk/
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theprisioner
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| posted on 2/4/15 at 05:27 PM |
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With a milling machine, lathe and a welder I am convinced you can make almost any setup work. Sounds like a worth while mod for 13" wheels.
http://sylvabuild.blogspot.com/
http://austin7special.blogspot.co.uk/
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Jenko
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| posted on 2/4/15 at 06:36 PM |
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Agree...with mine all they did was move the mount...it's just could not have done that myself.....I can't weld :-(
MY BLOG - http://westfieldv8.blogspot.co.uk/
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theprisioner
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| posted on 2/4/15 at 07:49 PM |
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It is fairly heavy metal 6 thick from memory and your life could be dependant on it. Nae bother!
http://sylvabuild.blogspot.com/
http://austin7special.blogspot.co.uk/
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treb
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| posted on 2/4/15 at 10:27 PM |
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Firstly , thank you very much Jenko and theprisoner for your replies and useful insight.
Just spent half an hour with a cup of tea staring at the problem.
As I see it my basic choices are:
a) ditch the HiSPec offering and go with radial mounting Willwood and a bracket (nice job you did there!) or go with the Rally Design RD3637 branded
offering of a VW Hydra calliper that Jeremy suggests.
Has anyone used these Rally Design callipers?
Are they a straight bolt on?
b) Try to modify the uprights to accept the HiSpec callipers, now I have them - if it does not work I will have to replace the rear uprights.
Jenko - From your website pictures it appears that HiSpec machined off the original caliper mounting lugs and made up some new mounting lugs that
welded in behind behind the original ones - am I right as the site images were not that clear? Your welding has to be good !
Living down under means sending the uprights back to HiSpec is out the question
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theprisioner
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| posted on 2/4/15 at 11:53 PM |
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I used the Hydra RD product. Issues are:
1) Larger wheel size 15" instead of 13"
2) handbrake cable routing
3) Hydralic union size selection issue and clearance with rubber drive shaft boot
It is basically a copy of the VW Passat rear calliper.
There is an issue with brake balance. Rear engine cars need a larger rear calliper (than a front engine rear wheel drive car) to get the right brake
balance for competitive driving. I am not sure this issue has been explored here.
I wish I could help on the fabrication issues!
http://sylvabuild.blogspot.co.uk/2012/11/rear-suspension-and-brakes.html
http://sylvabuild.blogspot.com/
http://austin7special.blogspot.co.uk/
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Jenko
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| posted on 3/4/15 at 09:03 AM |
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Treb.....You are correct, the fix is simple if you have the equipment and ability.....there is plenty of meat around the old mount to weld the new one
too...if you already have the calipers and uprights, then this may be the way to go. I'm a bit dissapointed with hispec that they did not learn
thier lesson and re-word thier website!. I'm sure if you thought you would have to reweld your upright you would not have bought them.
MY BLOG - http://westfieldv8.blogspot.co.uk/
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nickm
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| posted on 3/4/15 at 07:13 PM |
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Hi
I have the VW calipers same as the prisoner and concur with all the issues. Jenko got Hi Spec to remake them to fit, i was hoping for a future upgrade
that Hi Spec would start to sell/make Jenkos spec caliper. but obviously not !
Nick M
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treb
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| posted on 3/4/15 at 09:51 PM |
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Thanks everyone for your contributions.
I have tried to summarise what I have learnt below. Please feel free to add/delete comments as it may be of help for someone else
No easy bolt on solution but the bottom line for me seems to be
a) If you are going for an all out track car and want 13"rims , don't mind quite a bit of machining / welding then go HiSpec or
Willwood
b) If you do not mind 15" rims and want a perfectly good system and cheaper system, go Rally Design or Sierra
Sylva J15 Rear Brake Caliper Choice
1 Sierra XR4x4 V6 Will fit According to Jeremy upright needs wittling
and pads need shaping
2 Rally design Will fit. Can only be used with 15"rims
(Hydra RD3637) Only needs two washers to centralize. Issues with hand brake cable routing
Cheap Issues with Hydraulic connection and drive shaft
Heavy boot clearance
Single piston design
3 HiSpec Light Expensive
Can use 13" or 15" rims Will not fit - calliper lug offset is way
out
Two piston design Will not fit - radial position of the lugs will not clear
No issues with handbrake or hydraulic a 238mm diameter disk
connection Will not fit without cutting off existing
mounting
lugs and welding in appropriately positioned lugs
Sufficient room for a good weld
Sufficient material to minimise weld
distortion
4 Willwood Will fit with "dog bone"adaptor Expensive
(Radial mounting lugs) Light
Appears easier to fit than HiSpec
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Jenko
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| posted on 3/4/15 at 10:26 PM |
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I think that's a good summary. Only thing worth adding is the clearance with the boot using the hydras is a little more involved than two
washers. You need a thinner banjo and banjo bolt....but, it can be done. They are good calipers and actually quite light.
MY BLOG - http://westfieldv8.blogspot.co.uk/
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Kdempsie
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| posted on 3/4/15 at 10:47 PM |
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Treb,
Without wanting to complicate it further I will be modifying the out board hand brake lever a bit on the Wilwood calipers.
I want to use 13" Compomotive wheels with 24mm offset and 6" wide, so that they fit within the body plan. That means the transition
chamfer on the inside of the wheel touches the lever. I am remaking the outer lever to give the clearance required. I'll post a picture when I
get a bit further.
Keith.
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rdodger
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| posted on 4/4/15 at 09:01 AM |
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If you fancy the Hispec isn't it just easier to chop off the caliper mount and weld it back in the right place?
If you don't have the tools to do it a small engineering shop could do it very easily.
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treb
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| posted on 13/5/15 at 05:49 AM |
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Hi everyone
Just to let you know I managed to fit the HiSpec rear brake calipers to the J15 upright.
It was not such a big job and no real problems - more angst about cutting the upright
I have pictures but do not know how to post them here
Thanks once again for the encouragement
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