Tom's 40mm brakes

[MCG]

The fact that these can no longer be obtained makes me sad...

Yeah, me too. I could probably use a set for my '97 GTS

[AZTVR]

I've looked around partsrack and found nothing of the sort, although I have not called or inquired.

Jon does not have a staff of folks to put everything onto his web site and keep it up to date. Don't count on the website to reflect all of what he can provide. If you need something, ask him.

[GTS Dean]

I spoke to Tom recently about rebuilding a set I've had for a number of years. He was not inclined to do so due to his current employment status. He said the brake thing was a labor of love and a service to the Viper community that he was happy to do when he had time and there was an acute shortage of effective alternatives. Not so now.

I too, am sad.

[MacGyvers Mullet]

Would anyone know what it would take to have someone else do this for us? For instance, a local expert machinist in any given city that we live in?

Is the most difficult part being boring the caliper out from 36mm to 40mm? From there just a correct sized piston and seals? Or is much more involved than that?

[JonB ~ PartsRack]

Jon does not have a staff of folks to put everything onto his web site and keep it up to date. Don't count on the website to reflect all of what he can provide. If you need something, ask him.

I think we have 2 sets remaining. Email me JonB@PartsRack.com $895/pair core exchanged.

[GTS Dean]

Would anyone know what it would take to have someone else do this for us?

Or is much more involved than that?

The machine work is pretty straightforward. It's the disassembly and reassembly of the self-adjuster that takes practice and some talent.

[Rosie]

Anyone needing a set of the 40 mm rear calipers for gen 1+2,Chuck Tator has two sets in stock as of today 8/12/16,I think they cost 850. and you must send the old cores back to Chuck or pay 300. to keep them,a great up-grade for the non-ABS cars,makes the braking much more balanced you`ll definetly notice the difference,also the SS brake lines is a good option too,these cars are getting to be 20 years old ;Tator`s Garage#914 763-9507.Rusty.

[Rosie]

Correct phone #914-763-3136 Tator`s Garage,good luck.

[MrCreosote]

What do you use for maintenance parts? Seals, boots, pistons?

[Fatboy 18]

It's all available.

This is just one company in the UK that supplies parts
http://www.biggred.co.uk/

https://wiki.seloc.org/a/How_to_Rebu...Brembo_Caliper

https://wiki.seloc.org/a/Brembo_Caliper

https://www.elise-shop.com/rear-cali...qmpdidrqofgan3

[FlashFyre]

What do you use for maintenance parts? Seals, boots, pistons?

A fellow named Rick is still doing the 40mm mod. He took over from Tom. Lives near Toronto, Canada.

[MrCreosote]

Thanks, looks good.

Didn't know about these until about 12 hours ago - have a used set coming w/fronts all red. Car is 96 GTS black w/red stripes and black chrome wheels. Frankly part of the purchase is that they are red, LOL

Read interesting bit about these: great on street, but the rears fade first on track implying this is a bad thing - I would think the opposite: Stock: If fronts gone, you stand on brakes hard, rear locks up, ass may come around, bad. Rear fade first, ass stays planted, should be just what you want on track, right?

[GTS Dean]

I experimented a lot with incremental fluid, pad compound, brake bias and rear piston diameter before coming up with what I've run for 20 years with a lot of track time and road miles under my belt. I pulled the nut off the rear proportioning section of the combination valve and removed the proportioning spring, then screwed the cap back on and did a full bleed. Braking improved noticeably. I then went to the 40mm kit and found that I could get them to actually make enough temperature to experiment with pads again.

If most of your driving is street, a matched set of pads is not a bad thing because you will likely never experience the dynamics and temperatures of track driving.

What I like is a rear pad that has really good initial bite, medium torque and not too much increase with temperature. I like fronts that modulate really well with progressive temp increase and good release properties to combat front lockup. Having the rears less sensitive to pressure and a slower release helps the back end be more predictable with trail braking. When weight transfers to the front, you don't want too grippy a back pad or you may loop it. If you have adjustable shocks, adding a little more rear rebound and front bump stiffness will give you better initial weight transfer control under braking to use the rear performance improvement.

[MrCreosote]

Thanks Dean for the info.

I doubt that I will ever track the car but I do confess I am a lunatic trail braker. I had a 93 Formula Firebird at Nelson Ledges and it understeered beyond words (98 Z28 Camaro DID NOT!). It just kept killing the front tires at the sharp right hand before the straightaway. So I kept diving deeper and more trail braking. It was getting ridiculous. I finally got up to enough speed that it was going to work and I got LATERAL WHEEL HOP. I never knew such a thing existed - felt like I was going to break the car into pieces. So I just chilled and drove the way the car liked it.

[TTSnake]

Who should we contact to get a set of these?

[AviP]

Who should we contact to get a set of these?

Try Rick Shaefer. His email is ricks40mm at hotmail dot com. I'm not sure he is still doing this. The upgrade is a definite positive. It reduces that front dive as well as the stopping distance by 20-30 ft.

[40mm]

Try Rick Shaefer. His email is ricks40mm at hotmail dot com. I'm not sure he is still doing this. The upgrade is a definite positive. It reduces that front dive as well as the stopping distance by 20-30 ft.

Yes I am still doing these.
Email above is correct. Thanks!

[MrCreosote]

Hum, more thoughts on this:

I have a 96 GTS w/18's. I want to get Gen 5's (being a hard head, I want the 1/2" wider fronts) which means 19" rears.

I believe the 19" are 1.5 " larger in diameter, 3/4" on the radius.

For a given pedal effort w/18's, the rear calipers are going to be applying the same braking torque but the force at the pavement will be less because the 19's are taller.

This reduced force is 12/12.75 = 0.94 or a 6% reduction in braking.

So the 23% increase from the 40mm's will be reduced: 1.23 * 0.94 = 1.16 to a 16% increase.

So for a given pedal force with the 40's and 18's, the change to 19's will result in less vehicle braking.

To get the same vehicle braking, additional pedal force will be required which will put more load on the 40's which will make them run hotter and fade sooner.

On the positive side, stock rears AND 19's will really put the car out of balance - even worse than stock. So the 40's will help with the balance. Would Porsche air deflectors work in the rear? that would be a cheap cooling solution.

One thing is for certain, the 19's will produce more braking force at lockup, so that is in the good direction.

Are my calculations good? does this make sense?

[TTSnake]

Would I be able to do this for just the fronts? Or will that throw off the balance? I kinda don't want to grind off the rear ear tabs.

[Fatboy 18]

I will throw this into the mix which is what I have done on my Gen II

https://www.flickr.com/photos/905823...57632214538274

[goggles Pizano]

What do you mean by just doing the front? What do you want to the fronts?

[MrCreosote]

I think he is wondering if he can do bigger fronts and NOT cut up the rear spindle.

[MrCreosote]

It occurred to me that brake balance calculators are likely online already.

And YES they are:

https://brakepower.com/

https://www.tceperformanceproducts.com/bias-calculator/

...now I'm off to find a tire friction calculator: effect of diameter, width, sidewall on coef of friction. This will be a lot trickier but one might argue that the contact patch is proportional to diameter but I suspect it is some power rule since a 48" tractor tire has more than twice the pull of a 24" one. EDIT: Good Grief, the tire calculators are Sick - like Slip Angle is an input! LOL

[TTSnake]

I think he is wondering if he can do bigger fronts and NOT cut up the rear spindle.

Yes, that's right. I just want to upgrade the front brakes and not change the rears.

[goggles Pizano]

Yes, that's right. I just want to upgrade the front brakes and not change the rears.

Not a good idea. You will basically just have front brakes