Changing 944 to 951 Calipers Possible ???
02-24-2005, 06:53 PM
#16
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Originally Posted by Matt Marks
Not sure if you can do it with standard Turbo brakes, But I have Big Reds on stock NA spindles/hubs, etc. using some adapter brackets and a little fab time to build the correct spacers to match the calipers to your rotors. The same process works (as I understand it) for M030 brakes as well.
Kokeln and some others out there make the brackets, but there's a lot of fussing and fiddling with a lathe or grinder to buld the spacers (basically really thick washers) to get the caliper to sit right on the rotor.
You'll also need the turbo rotors, or in the case of the big reds, I have 928 GTS rotors on the car. Stopping power is UNBELIEVABLE on the track - I can carry my braking 100-200 feet further than your typical NA or even Turbo S's which equals lots and lots of passes at the end of the straights
For what it's worth, when I did this a year ago or so, new Big Red calipers were actually a couple of bucks cheaper then new M030's - ?!?
I'm running a 968 motor, so I needed the extra brakes
Kokeln and some others out there make the brackets, but there's a lot of fussing and fiddling with a lathe or grinder to buld the spacers (basically really thick washers) to get the caliper to sit right on the rotor.
You'll also need the turbo rotors, or in the case of the big reds, I have 928 GTS rotors on the car. Stopping power is UNBELIEVABLE on the track - I can carry my braking 100-200 feet further than your typical NA or even Turbo S's which equals lots and lots of passes at the end of the straights
For what it's worth, when I did this a year ago or so, new Big Red calipers were actually a couple of bucks cheaper then new M030's - ?!?
I'm running a 968 motor, so I needed the extra brakes
02-24-2005, 07:00 PM
#18
Hitsquad Ninja
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it's a VERY good idea to use turbo spindles...the n/a spindles are whimpy compared to them...i have all the parts for my conversion acquired...and when i have my n/a spindle next to my 951 spindle i will take a pic and post it so everyone here can see. there IS a reason why the factory used different spindles you know....
02-24-2005, 07:34 PM
#19
Burning Brakes
Joseph,
Try http://www.kokeln.com/products/951_8...iper_kit.shtml - I think this is what I have on my car. Then my mechanic machined the custom spacers to locate the caliper left/right so it sat correctly on the rotor.
For the rears, I mounted a set of 87 Turbo fronts as I had a spare set lying around. Some more spacer maching was required. The rears work great, but I can't let the pads wear down more than about 50% as the calipers were designed for the thicker front rotors. If I have more wear, then the pistons end up being too far out, and get mis-aligned and won't retract.
My typical pad combination is Pagid Orange or PF 97's up front, with some cheap metalmasters in the rear. This solves two problems...with the current setup and the 33bar bias valve (standard on the 944S), I was getting too much rear brake bite with pagids, which would kick in ABS at the rear resulting in very unstable braking. Switching to the metal masters reduced the amount of rear bite so the car is now very stable under braking. Plus, paying $40 for a rear set beats the heck out of paying $250 for a set of pagids - as I have to buy "front" pads...
If you do this swap, and don't have ABS, be very very careful with how you drive the car until you're sure you won't get rear lock-up. I've seen two different cars in the last year make a poor choice on rear pads and rear brake bias, and end up going off the track backwards into the tires.
Try http://www.kokeln.com/products/951_8...iper_kit.shtml - I think this is what I have on my car. Then my mechanic machined the custom spacers to locate the caliper left/right so it sat correctly on the rotor.
For the rears, I mounted a set of 87 Turbo fronts as I had a spare set lying around. Some more spacer maching was required. The rears work great, but I can't let the pads wear down more than about 50% as the calipers were designed for the thicker front rotors. If I have more wear, then the pistons end up being too far out, and get mis-aligned and won't retract.
My typical pad combination is Pagid Orange or PF 97's up front, with some cheap metalmasters in the rear. This solves two problems...with the current setup and the 33bar bias valve (standard on the 944S), I was getting too much rear brake bite with pagids, which would kick in ABS at the rear resulting in very unstable braking. Switching to the metal masters reduced the amount of rear bite so the car is now very stable under braking. Plus, paying $40 for a rear set beats the heck out of paying $250 for a set of pagids - as I have to buy "front" pads...
If you do this swap, and don't have ABS, be very very careful with how you drive the car until you're sure you won't get rear lock-up. I've seen two different cars in the last year make a poor choice on rear pads and rear brake bias, and end up going off the track backwards into the tires.
02-24-2005, 09:00 PM
#20
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hubs and spindles on 86 951's are competely different than 87 up. smaller wheel bearings, different rotor mounting. You can put 87 up spindles/hubs/rotors on an 86, but you will have limited negative camber. brake calipers are interchangable, but 86 pistons are slightly smaller.
02-24-2005, 10:19 PM
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Thanks again for the info, Matt -- definitely worth investigating that route further. In the ideal universe, I'd go with the 951S spindles too, but that's been like looking for the Holy Grail. Have you seen it?
02-25-2005, 12:04 AM
#23
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86 turbo and 86 n/a's have different hubs and spindles than each other, and different than later years. 87 and later turbos and n/a's all have the same hubs, but the spindles are different for the brake caliper mounting/bolt pattern.
The bolt pattern of a standard turbo caliper is only about a 1/4" different hole spacing than an n/a caliper. So there is no adaptor bracket that will mount a turbo caliper to an n/a front spindle that I am aware of. The adaptor brackets available are for mounting the 928S4/M030/TS and larger calipers to either standard turbo or n/a spindles.
For these 87 and later cars, I am not aware of any difference in size or strength of the spindle itself between the turbo and n/a version, so I would like to see a picture that shows something different. Since the wheel bearings are the same parts for an 87 n/a through an 89 TS, that tells me that the spindle diameters are the same. And having repacked and replaced wheel bearings on all of my cars over the years, I dont recall ever noticing a size or apparent strength difference between an S (which has the same spindles as an n/a), an 87 turbo, and an 89 TS (just slightly longer, but not a larger diameter).
Use a 5/18 or 5/33 bar brake proportioning valve with the standard turbo brakes on all 4 corners. Factory valve is the 5/18 for the turbos and TS. Many upgrade to the 5/33 to use more rear brake, which is definitely fine on a TS, but Ive been having some rear end instability using it on my 87T and I am questioning going back to the 5/18 valve (this is for a race application, Im sure the 5/33 is fine for street use).
The bolt pattern of a standard turbo caliper is only about a 1/4" different hole spacing than an n/a caliper. So there is no adaptor bracket that will mount a turbo caliper to an n/a front spindle that I am aware of. The adaptor brackets available are for mounting the 928S4/M030/TS and larger calipers to either standard turbo or n/a spindles.
For these 87 and later cars, I am not aware of any difference in size or strength of the spindle itself between the turbo and n/a version, so I would like to see a picture that shows something different. Since the wheel bearings are the same parts for an 87 n/a through an 89 TS, that tells me that the spindle diameters are the same. And having repacked and replaced wheel bearings on all of my cars over the years, I dont recall ever noticing a size or apparent strength difference between an S (which has the same spindles as an n/a), an 87 turbo, and an 89 TS (just slightly longer, but not a larger diameter).
Use a 5/18 or 5/33 bar brake proportioning valve with the standard turbo brakes on all 4 corners. Factory valve is the 5/18 for the turbos and TS. Many upgrade to the 5/33 to use more rear brake, which is definitely fine on a TS, but Ive been having some rear end instability using it on my 87T and I am questioning going back to the 5/18 valve (this is for a race application, Im sure the 5/33 is fine for street use).
02-25-2005, 12:53 AM
#24
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Originally Posted by Matt Marks
For the rears, I mounted a set of 87 Turbo fronts as I had a spare set lying around.... with the current setup and the 33bar bias valve (standard on the 944S), I was getting too much rear brake bite with pagids, which would kick in ABS at the rear resulting in very unstable braking. Switching to the metal masters reduced the amount of rear bite so the car is now very stable under braking.
If you do this swap, and don't have ABS, be very very careful with how you drive the car until you're sure you won't get rear lock-up. I've seen two different cars in the last year make a poor choice on rear pads and rear brake bias, and end up going off the track backwards into the tires.
If you do this swap, and don't have ABS, be very very careful with how you drive the car until you're sure you won't get rear lock-up. I've seen two different cars in the last year make a poor choice on rear pads and rear brake bias, and end up going off the track backwards into the tires.
Part of your rear bias problem is because of using front calipers on the rear of the car. Because the piston sizes for the fronts are 40/36mm versus the rear 30/28mm, your rear end now has 1.7 times more clamping force than with standard turbo rear calipers (this is a ratio of the piston area and Force = Pressure x Area). If using a different/less grippy pad in the rear solves the problem, then great. But otherwise you may want to try a 5/18 bias valve (to reduce the pressure), or find a set of rear calipers (reduce the piston area).
02-25-2005, 02:17 AM
#25
Burning Brakes
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This is possible, there is a great article on this very change in the November 2002 excellence magazine. No I don't memorize every article but I was rereading old issues the other day and rembered the article entitled "Project 944: Short Stop". They upgraded the 944 NA car with the following parts:
On the rear they used Brembo calipers from a 944 turbo, 968 or 944 S2. two small spacers and a set of 11.77 inch rotors from a 944 turbo or 968.
On the front they used calipers from a 928 S4. These acording to the article will at least double the braking power and fit inside 16" wheels. They used 12" rotors up front.
for the front calipers they used a spacer from Powerhaus and I believe they used a kit from powerhaus for the rear install as well.
Sounds like a less troublesome swap vs. the all 951 swap with spindles and all....
Hope that helps!
On the rear they used Brembo calipers from a 944 turbo, 968 or 944 S2. two small spacers and a set of 11.77 inch rotors from a 944 turbo or 968.
On the front they used calipers from a 928 S4. These acording to the article will at least double the braking power and fit inside 16" wheels. They used 12" rotors up front.
for the front calipers they used a spacer from Powerhaus and I believe they used a kit from powerhaus for the rear install as well.
Sounds like a less troublesome swap vs. the all 951 swap with spindles and all....
Hope that helps!
02-25-2005, 02:28 AM
#26
Burning Brakes
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Yeah I have the Excellence article. They went with adapters on the front using the wimpy NA spindles. As Jake mentioned the turbo spindles are worth the extra effort. I also called Power Haus and they sell the adapters in their kit for big dollars, $1995 IIRC that was for a complete Big Red kit. So I don't know that you can buy just the adapters. I am choosing to go with turbo spindles.
02-25-2005, 09:42 AM
#27
In my case I found someone that was selling parts off of an 86 turbo. The front includes struts, spindels, lower arms & calipers. Rear has: calipers and aluminum trailing arms. +Hubs. I am going with Crossdrilled rotors.
Basically everything to upgrade a NA to turbo specs.
Basically everything to upgrade a NA to turbo specs.
02-25-2005, 10:53 AM
#28
Burning Brakes
Oddjob,
I agree on your analysis. Once one of my buddies upgrades his brakes, i"ll be swapping the proportioning valve with him. But for the time being, the metalmaster solution works well enough and keeps my costs down.
Does anyone have a side by side picture of an late NA hub/spindle vs. an 87 turbo or TS spindle side by side? That should solve the riddle...
Or, if anyone has the PET handy (it's not on my work machine), can they look to see if their are different part numbers for the combinations mentioned above?
I agree on your analysis. Once one of my buddies upgrades his brakes, i"ll be swapping the proportioning valve with him. But for the time being, the metalmaster solution works well enough and keeps my costs down.
Does anyone have a side by side picture of an late NA hub/spindle vs. an 87 turbo or TS spindle side by side? That should solve the riddle...
Or, if anyone has the PET handy (it's not on my work machine), can they look to see if their are different part numbers for the combinations mentioned above?
02-25-2005, 11:44 AM
#29
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Originally Posted by Matt Marks
Does anyone have a side by side picture of an late NA hub/spindle vs. an 87 turbo or TS spindle side by side? That should solve the riddle...
Or, if anyone has the PET handy (it's not on my work machine), can they look to see if their are different part numbers for the combinations mentioned above?
Or, if anyone has the PET handy (it's not on my work machine), can they look to see if their are different part numbers for the combinations mentioned above?
Hubs are the same for an n/a, S, S2, and Turbo (probably a 968 too but I didnt check that). The only difference will be for the ABS ring, but now all hubs superceed to the same part number, so they will all have the ABS ring if you buy one from the dealer.
The TS/M030 has a different hub, which I believe are only slightly longer.
The wheel bearings are the same for all of the 87 and later cars, including the TS. So the spindle diameter is the same for all the 87+ cars. As far as I know (Im about 97.6% sure) the only difference between an n/a and a turbo spindle is the bolt pattern for the brake caliper. But if someone has some pics that show something different, please share....
02-25-2005, 12:12 PM
#30
Hitsquad Ninja
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ok it is NOT hard to find spindles at all. within one week of setting out to look for them i found a person about 20 minutes away from me selling a set for cheap....