motoTrooper
True Classic
Thanks! I kinda did think about it, but I don't think I could've kept it mid-engined. And $$$$. I'm very interested in throttle oversteer at the moment... Should be an "involving" car to drive.
Recent lurker, new Scorpion owner #1553 restomod
- Thread starter motoTrooper
- Start date
darwoodious
Darin Nelson
To do AWD you need to drop the Subaru drivetrain and go find a totaled Audi R8 4.2 (the V8 version). No longer the "low cost" project motoTrooper was talking about. It'd be interesting tho
motoTrooper
True Classic
Episode 2 is out!
kmead
Old enough to know better
Oh man, you ended it with a cliff hanger! Get to the juicy part and just leave us hanging!
I want my 41 minutes back!
Kidding. Very cool. Really looking forward to seeing the next (thrilling) installment. Sergio Leone would be proud...
You neglected to mention the actual diameter of the pistons in the front and rear calipers. Could you please measure them and include that info in the next video and offer it up here on the forum so there is a record?
Many thanks and great progress.
Karl
Dr.Jeff
True Classic
Thank you Christopher for not only the development of the brake application, but also for putting together the video. Lots of great info.
Interestingly the rear caliper adaptor brackets you made are almost identical to some I put together to test the fit of a set of VW calipers.
I can post the piston sizes for the 500 calipers when I get back from my trip in a couple days.
One additional piece of information that would be nice is if you could measure the weight of the calipers and rotors for both sets to compare.
We should include the results of your progress on the brake upgrade thread under the X1/9 section.
Well done, thanks.
Interestingly the rear caliper adaptor brackets you made are almost identical to some I put together to test the fit of a set of VW calipers.
I can post the piston sizes for the 500 calipers when I get back from my trip in a couple days.
One additional piece of information that would be nice is if you could measure the weight of the calipers and rotors for both sets to compare.
We should include the results of your progress on the brake upgrade thread under the X1/9 section.
Well done, thanks.
motoTrooper
True Classic
Karl, thank you for the comment. Yes I was remiss in stating the sizes of the pistons. I was also incorrect in my observations.
The piston sizes of the Abarth calipers is front 54mm, rear 34mm! The rears are the same size as the X1/9s!
Stock fronts X1/9 and Scorpion are 48mm
X1/9 rears 34mm Scorpion 38mm....
BUT Episode 3 is now out so there's that...
The piston sizes of the Abarth calipers is front 54mm, rear 34mm! The rears are the same size as the X1/9s!
Stock fronts X1/9 and Scorpion are 48mm
X1/9 rears 34mm Scorpion 38mm....
BUT Episode 3 is now out so there's that...
kmead
Old enough to know better
That was great, fun intro
Nicely done with the flipping of the actuating mechanism.
Bummer about the size of the calipers. You may want to investigate the possibility of not using the Fiat rear caliper and move to the VW Girling type caliper to get to a better balance of the front to rear brakes. Especially as the front calipers are so much larger than the existing X or Scorpion. There don't seem to be a lot of rear calipers much larger than the 38mm but I will continue to look.
Great news for X owners who might want new rear calipers e brakes that work much better (which I am a huge fan of) the ones on my X have never been that effective. The ones on my Golf are damn good.
The Girling pattern brakes I believe would work in the same manner in regards to the ebrake brackets but don't know that for sure.
Nicely done with the flipping of the actuating mechanism.
Bummer about the size of the calipers. You may want to investigate the possibility of not using the Fiat rear caliper and move to the VW Girling type caliper to get to a better balance of the front to rear brakes. Especially as the front calipers are so much larger than the existing X or Scorpion. There don't seem to be a lot of rear calipers much larger than the 38mm but I will continue to look.
Great news for X owners who might want new rear calipers e brakes that work much better (which I am a huge fan of) the ones on my X have never been that effective. The ones on my Golf are damn good.
The Girling pattern brakes I believe would work in the same manner in regards to the ebrake brackets but don't know that for sure.
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motoTrooper
True Classic
Very interesting, are these Girling ones 38mm? What is the mounting bolt spacing on your VW? Answers Karl, dammit!
motoTrooper
True Classic
Hopefully for owners of X1/9's the video at the very least could help them upgrade their 34mm systems to modern components for a reasonable outlay. The Fiat 500 rear calipers have to be a big leap in performance especially with the jump in rotor size if they have 14" wheels already...
kmead
Old enough to know better
Very interesting, are these Girling ones 38mm? What is the mounting bolt spacing on your VW? Answers Karl, dammit!
I do have a used one at my other house. I will be over there tomorrow night, I will grab it and do some measuring.
As you said measuring a caliper on a car is a frustrating exercise
Sorry to mention a problem without offering the solution.
FYI Autocorrect on an IOS device is your enema
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kmead
Old enough to know better
I picked up the grungy old caliper and its carrier. Consider that it was 15 years of Michigan winter and so on on and hadn't frozen up (115k miles) so nasty as it is, its not bad considering the life it led.
The caliper itself is aluminum with steel ebrake brackets and the carrier is cast iron as most of these are. As an FYI the front caliper for these is cast iron so it is much heavier and more prone to seizing. Mine had not.
The unit shown is used on the left rear of a Golf.
They use a 38mm piston. The caliper casting actually has it in the face of the casting.
The e brake mechanism should be able to be reclocked in much the same way as they ones you just did. In this case the area it screws into has the same margin all the way around the ebrake drive.
The bolt center on the caliper carrrier is 90mm and use M10 fasteners. The carrier is threaded. It could of course be drilled out or it might work to your favor to have a plate fastened to the bearing carrier and then having a through hole in the bracket to thread into the carrier or if you through drilled the carrier and threaded the plate it should work as the faces of the carrier are both flat.
The rear VW rotor is 232mm diameter but others were available, one might need to grab a different carrier intended for that rotor diameter. In this case with a notably larger rotor you would be able to just use your transition bracket to be the inbetween element.
You should be able to go into any Pickapart and grab a set to test for cheap from any 1999-2005 Golf or Jetta TDI or 2.0 the six cylinder and 1.8T used a larger caliper carrier with the larger rotor.
Let me know if there are some other dimensions you would like or any other info I can glean for you.
New ones as a pair with all hardware can be had for 190-229 depending on who you buy them from. The images shown are from ECS: https://www.ecstuning.com/b-ecs-par...8fTjcP6199BdhflP61IE57B48l80kje4aAmpREALw_wcB
The caliper itself is aluminum with steel ebrake brackets and the carrier is cast iron as most of these are. As an FYI the front caliper for these is cast iron so it is much heavier and more prone to seizing. Mine had not.
The unit shown is used on the left rear of a Golf.
They use a 38mm piston. The caliper casting actually has it in the face of the casting.
The e brake mechanism should be able to be reclocked in much the same way as they ones you just did. In this case the area it screws into has the same margin all the way around the ebrake drive.
The bolt center on the caliper carrrier is 90mm and use M10 fasteners. The carrier is threaded. It could of course be drilled out or it might work to your favor to have a plate fastened to the bearing carrier and then having a through hole in the bracket to thread into the carrier or if you through drilled the carrier and threaded the plate it should work as the faces of the carrier are both flat.
The rear VW rotor is 232mm diameter but others were available, one might need to grab a different carrier intended for that rotor diameter. In this case with a notably larger rotor you would be able to just use your transition bracket to be the inbetween element.
You should be able to go into any Pickapart and grab a set to test for cheap from any 1999-2005 Golf or Jetta TDI or 2.0 the six cylinder and 1.8T used a larger caliper carrier with the larger rotor.
Let me know if there are some other dimensions you would like or any other info I can glean for you.
New ones as a pair with all hardware can be had for 190-229 depending on who you buy them from. The images shown are from ECS: https://www.ecstuning.com/b-ecs-par...8fTjcP6199BdhflP61IE57B48l80kje4aAmpREALw_wcB
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motoTrooper
True Classic
Nice work Karl, bocce balls those caliper mounting bolt sections are beefy! Thanks for the link as well, it is interesting that in the photos there is no machining of mating faces where the caliper bolts to the hub. You're right about the clocking or swapping of the e-brake mechanisms. Looks totally doable. Thanks for the detective work Karl!
kmead
Old enough to know better
Unfortunately I don't have both calipers so I can't do the switch of the hardware. My only concern is that the reclocking will interfere with the bleeder.
This is the base kit which doesn't include the hoses which may not work on an X anyway.
https://www.ecstuning.com/b-assembl...rake-caliper-replacement-kit/1j0615423424kt2/
I think the OE ones are spot faced on both the inner and outer faces but It has been a long time since I saw a newish OE carrier
This is the base kit which doesn't include the hoses which may not work on an X anyway.
https://www.ecstuning.com/b-assembl...rake-caliper-replacement-kit/1j0615423424kt2/
I think the OE ones are spot faced on both the inner and outer faces but It has been a long time since I saw a newish OE carrier
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Pete Whitstone
True Classic
Karl, what era and model of VW parts are being discussed here? I have some in my shop from when I considered this swap, pretty sure they are MK1 Rabbit stuff.
Pete
Dr.Jeff
True Classic
Thank you again Christopher for the excellent work.
Keep in mind that the size of the piston is not the only factor effecting braking performance. As you stated, the difference in rotor diameter and improved design of the caliper will offer an increase over the stock Fiat X1/9 - Scorpion units.
Here is a little representation of the 500 rear calipers for reference:
Pete, there are a few options for rear VW calipers. Depending on the year model they might be alloy (as with the Mk4's in Karl's example) or the earlier versions are a heavier cast iron (as in the Mk1's you reference). However they have the exact same fitment/mounting, so can be used. But some people feel the earlier versions are a more 'difficult' design internally to rebuild (has to do with how the e-brake mechanism works), although I don't find that to be the case if you realize the procedure. There are also some choices in mounting brackets; certain models had larger rotors and therefore the brackets position the caliper further out (radially) accordingly. As if that wasn't confusing enough, not all models came with disk brakes on the rear (especially for the earlier series). And if I recall correctly there are also other styles of rear calipers (non-Girling) on some VW's in this era that use a completely different mount bracket/e-brake/etc. But it is generally agreed by the water-cooled VW crowd the Mk4 (roughly 1997 to 2007, depending on the model) Girling rears are the better choice (for older applications...new stuff is completely different) in terms of design, operation, price, etc. That crowd uses them on the earlier models as something of a upgrade (either converting non-disk to disk, or non-alloy to alloy). Although that desire for Mk4 units seems to have driven the price up somewhat, they are available (new) from a number of manufacturers and countless suppliers so prices vary widely....roughly $80 each (and up) including the bracket. Rebuilt units are readily available as well.
I was looking at the earlier (non-alloy) versions of these VW rear calipers when I did a quick fitment check here (bottom of page 2): https://xwebforums.com/forum/index.php?threads/front-brake-option.32608/page-2
Keep in mind the width-spacing of the mounting bolts is only one of the criteria in adapting these; the offset of the caliper relative to the rotor and the radial location relative to the rotor diameter are a bit more difficult with the VW rear calipers. Therefore the adapter bracket for them is a bit more complex; it needs to be more "3-dimensional" than the flat plate used for the 500 units, so machining is required. Also a different diameter rotor will be needed.
Keep in mind that the size of the piston is not the only factor effecting braking performance. As you stated, the difference in rotor diameter and improved design of the caliper will offer an increase over the stock Fiat X1/9 - Scorpion units.
Here is a little representation of the 500 rear calipers for reference:
Pete, there are a few options for rear VW calipers. Depending on the year model they might be alloy (as with the Mk4's in Karl's example) or the earlier versions are a heavier cast iron (as in the Mk1's you reference). However they have the exact same fitment/mounting, so can be used. But some people feel the earlier versions are a more 'difficult' design internally to rebuild (has to do with how the e-brake mechanism works), although I don't find that to be the case if you realize the procedure. There are also some choices in mounting brackets; certain models had larger rotors and therefore the brackets position the caliper further out (radially) accordingly. As if that wasn't confusing enough, not all models came with disk brakes on the rear (especially for the earlier series). And if I recall correctly there are also other styles of rear calipers (non-Girling) on some VW's in this era that use a completely different mount bracket/e-brake/etc. But it is generally agreed by the water-cooled VW crowd the Mk4 (roughly 1997 to 2007, depending on the model) Girling rears are the better choice (for older applications...new stuff is completely different) in terms of design, operation, price, etc. That crowd uses them on the earlier models as something of a upgrade (either converting non-disk to disk, or non-alloy to alloy). Although that desire for Mk4 units seems to have driven the price up somewhat, they are available (new) from a number of manufacturers and countless suppliers so prices vary widely....roughly $80 each (and up) including the bracket. Rebuilt units are readily available as well.
I was looking at the earlier (non-alloy) versions of these VW rear calipers when I did a quick fitment check here (bottom of page 2): https://xwebforums.com/forum/index.php?threads/front-brake-option.32608/page-2
Keep in mind the width-spacing of the mounting bolts is only one of the criteria in adapting these; the offset of the caliper relative to the rotor and the radial location relative to the rotor diameter are a bit more difficult with the VW rear calipers. Therefore the adapter bracket for them is a bit more complex; it needs to be more "3-dimensional" than the flat plate used for the 500 units, so machining is required. Also a different diameter rotor will be needed.
kmead
Old enough to know better
I recall a spreadsheet on one of the 'Locost' web sites for figuring the desired components and balance of a braking system. I will look around. It's actual capabilities may be different from my recollection...
Start here:
http://www.stoptech.com/technical-support/technical-white-papers/proportioning-valves
The zip file is a spreadsheet which has multiple sheets. You will need to gather some info about your car which is likely something you already know or can find in Road and Track or similar.
It is from a the Locost forum prepared by Mike Polan and based on a book about brakes by Herb Adams. It should give you a starting point which will need to be verified with testing of course.
Start here:
http://www.stoptech.com/technical-support/technical-white-papers/proportioning-valves
The zip file is a spreadsheet which has multiple sheets. You will need to gather some info about your car which is likely something you already know or can find in Road and Track or similar.
It is from a the Locost forum prepared by Mike Polan and based on a book about brakes by Herb Adams. It should give you a starting point which will need to be verified with testing of course.
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kmead
Old enough to know better
As an aside, the Miata has correctly clocked floating calipers which are 36mm diameter (on the early 1990-1992 cars) so that might be another alternative caliper choice for others going down this path. I am not sure what the later Miata rear calipers are (likely the same but with larger disks).
Dr.Jeff
True Classic
Nice summary of the topic. One thing to keep in mind regarding "bias valves"; while the "kneepoint" (as they describe it) can be adjusted via the knob, the "slope" could also be adjusted by modifying the internal spring within the valve (add shims / shave the spring shorter, or replace with a different value spring). So the system can be tailored more than they lead to. They also have some other interesting articles:
http://www.stoptech.com/technical-support/technical-white-papers
I recall seeing a good technical article on another brake company's site (Wilwood?) discussing master cylinder size selection.
I hope we are not straying too far away from Christopher's intent with this discussion...should we move it elsewhere?