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View Full Version : VT Calipers & Rotors on VS Commodore



Micka
25-04-03, 11:30 PM
Since I fitted VT calipers & rotors on my VS I have greater brake pedal travel. Reason being because the twin piston VT calipers require more brake fluid to be displaced by the master cylinder than the single piston VS calipers.
The VS 7/8" master cylinder is much smaller than the VT 1" master cylinder and can't keep up with the demands of the VT calipers.
I can't fit the VT master cylinder onto the VS brake booster because there is a shallower hole in the rear of the primary piston of the master cylinder than the VS has and the booster pushrod will constantly push against the piston.
Can anyone assist with suitable 1" master cylinder to fit or other suitable fix.:worship:

Trevor@BDA
27-04-03, 08:35 PM
I am pretty sure that the VS has a 1 inch master cylinder to suit as the Pursuit vehicles etc had 1 inch if I remember correctly.
I will need to check out my listings tomorrow to see what can be done here.
It is a pretty common conversion and we have sold a few of these VT type kits here in Qld so there must be a fix - just a case of finding it
Regards
Tervor @ BDA

dattoman1000
27-04-03, 10:13 PM
VS master should have enough displacement to drive the system no worries.
You can fit the VT master if you shorten the front rod coming out of the booster. This would be best done by a professional as to do it properly the booster needs to come apart.

dbasteve
30-04-03, 06:48 PM
How much travel are we talking about?
How long since the conversion was done?

It's not unusual to have a softer pedal with this conversion for the reason you stated but not excessive travel.

A few guys have made an adaptor to use the VT M/Cyl.
Try doing a search on the Commodore club forum for the latest M/Cyl conversion method too.

CptVipeR
30-04-03, 07:06 PM
I have had a VT calliper and rotor conversion on my 95 VS, and I too would say it has a slightly longer pedal travel than other standard VS/VR I have driven.

I hadn't actually thought the master cylinders were a different size, so it hadn't occured to me that this was the reason for extra pedal travel.

Might have to investgate some upgrade options when I get some new rotors (as the current ones are starting to look a bit sad) :(

dbasteve
30-04-03, 07:08 PM
http://www.commodoreclub.net/cgi-bin/yabb/YaBB.cgi?board=GENTECH;action=display;num=10360076 76;start=2

Have a look at this discussion on the M/Cyl issue.

Bugger! The link wont work.

The topic to search for is "VL VN to VT brake conversion" from Oct 2002

http://www.commodoreclub.net

Jimbo123
30-04-03, 09:30 PM
I put the VT booster and master combo into my VN. Travel is excellent at the moment, but I have single finned calipers on there now.

http://home.iprimus.com.au/jimk00/VN/brakes-booster-and-master.htm

I have a bit of firewall flex which I'll address with a better bracket.

Hope to be putting in Nissan 4pots and 330x28mm slotted dbas shortly.

There's GMVPSS on the CCC forums that self-manufactured an adaptor to fit a VT master onto his VP. But I can't see how he matched up the holes, maybe it was a VS booster - dunno. Not sure how the bolts were long enough also??

There's also another, (Lostit), that took his VS booster and VT master to RaceBrakes that mated them up properly - he put them into his VB.


Try the link below,...

http://www.commodoreclub.net/cgi-bin/yabb/YaBB.cgi?board=GENTECH;action=display;num=10360076 76;

The thread Steve's referring to above was around the same time that I was doing the leg work on gathering information on what I decided to do above - dattoman was a wealth of information!!

Jim.....

Micka
01-05-03, 02:49 PM
Thanks for all the replies.

DBA Steve.
it is a combination of both extra travel and a softer brake pedal. I have become use to it although it would feel better to have a firm pedal. I especially notice it when I drive a standard VS or VT and then get back into mine.
I must say though, putting the pedal issue asside, the brakes definetly pull up a lot better. They will be even better once I fit some DBA slotted disc rotors and Bendix Ultimate disc pads all round.

Jimbo
I like the the link that you supplied -http://home.iprimus.com.au/jimk00/VN/brakes-booster-and-master.htm
Very informative and answered what I have wanted to know about fitting a VT booster.

Let me know how you go with fitting the Nissan 4 pots.

Jimbo123
01-05-03, 06:11 PM
Hopefully be picking up the rotors later this week/early next.

I already have the callipers.

I have a complete spare strut, so will be playing 'fabricating the bracket' once I have everything :-)

Micka
01-05-03, 08:28 PM
I would have thought that a company such as Hoppers stoppers down your way would carry the brackets in stock. Anyway, have a look here, these guys may be able to supply them if needed.

http://www.commsport.com.au/prod227.htm

dattoman1000
01-05-03, 09:31 PM
Hoppers don't do those.
But comsport do if your using the Z32 300zx caliper.

Jimbo123
02-05-03, 11:19 AM
Yeah, Commpsport do, but look at the $$ they want for just a chunk of metal with some holes in it :-(

dattoman1000
02-05-03, 10:48 PM
I didn't contact them for a price.

However would the avaerage Joe rather buy something and bolt it on or spend 3 or 4 weekends pissing around trying to make something they have no real idea about. Such as thicknesses,steel type,welding,etc. And then still possibly get it wrong and have to make them at least twice.

I'm talking about Joe Average here not yourself Jimbo.

Jimbo123
02-05-03, 11:54 PM
Guess it'll give me something to do instead of messing with the PC over a few weekends.

There's no rush on my part. I've had the callipers for a few months now and should get my hands on a pair of DBA019S shortly.

What you described there sort of looks like how I might go :-)

Bah,... I'll just give it all to a fitter+turner mate to make it all up properly once I get the dimensions of things sorted out.

spirit123
03-05-03, 05:06 AM
Just a quick question; what are the three little threaded holes which are around the stud holes on VT rotors? Do they serve any use on a previous commodore conversion?

Cheers!!

dattoman1000
03-05-03, 02:36 PM
Those little threaded holes serve a special purpose.

They are sanity holes.

They save your sanity when your trying to extract the disc off the hub and its rusted/stick on. Rather than bashing the shit out of the disc with the largest hammer you can find - albeit fun and your ready for this after all the pushing pulling and grunting and straining.
You thread some 8mm (I think) long bolts into the holes and do them up. They go thru the disc and contact on the hub flange. As you do them up the disc pops off the hub with much les stress.

Alot of genuine discs don't have these holes. Causing alot of pain and swearing and tool throwing in workshops all over the world.

dbasteve
05-05-03, 06:46 AM
LOL!

M8 x 1.25mm

SLE355
10-05-03, 10:21 PM
Will the 4 piston R32 calipers with 296 or 330mm discs fit a 16" rim remembering that VN GPA twin piston with 330mm disc's won't fit behind my 16" Simmons?

dattoman1000
10-05-03, 11:42 PM
You must have bought yourself some crappy offset simmons.
I have fitted 330mm discs and Lotus Brembo 4 spots under 16" simmons on a Torana before.

I'd say you might get the Nissan caliper on the 296mm VT rotor but if you can't fit a claw type under your wheels you certainly won't fit a 4 spot on a 330mm.
2 weeks ago we fitted AP 4 spots on 296mm VT discs to a Mustang under 15" wheels.

I couldn't get 330's under 16" HDT wheels on a VK Brock once so we had to settle for VT discs and calipers. They have a crappy inner on them too.

If you were trying to fit Nissan calipers on a 330 rotor you'd have to make sure you have the right ones. They all suit different disc sizes and if you try to fit the wrong one the pad will sit above the outer edge of the disc or low on the disc depending which one you fit.
Just thought you'd like to know that.
If your going for 296 rotors the idea one would be R32 GTR non V spec as they had 296mm discs too.

Jimbo123
11-05-03, 12:27 AM
Hey dattoman,

I think the callipers I have were off of an R33,.. they initially were rapped around the 296x32 mm rotors so I was told.

I was planning on trying to get them on my VN with some 330x28mm DBA019s,.. but now you have me a bit worried,.. might be too strong a word,.. maybe thinking again,.. anyhow,..

Was setting up a deal for some 019s but it now looks like maybe falling through, dunno yet.

Anyway, my Qs then,..

1. How would I know what sort of calipers I have,.. can't recall any markings on them other than the word "NISSAN". Reckon you could tell if I post up a pic?

2. Assuming they are the R33. With the right bracket setup, will I be able to get them over the 019s with appropriate pad cover?

3. No point in asking about my rim, don't think you can see it in your crystal ball :-)

Any info appreciated.

Jim.....

dattoman1000
11-05-03, 02:59 AM
Show us a pic Jimbo. The thing I need to see is the length of the mount leg and the radius of the curve in the centre where the disc runs.

You'll find the R33 ones should be O.K as they suited a 296mm disc. They should go O.K on the 330......I can check this at work as I have a R32 GTR non V spec which are the same radius.
If you had R32 GTS or Z32 calipers which only fit a 280mm disc then I'd be rethinking it.

If they suit a 32mm thick rotor why wouldn't you go for a pair of flash new 4048's. 330mm x 32mm. You'd need a VT conversion hub for it also. The new 4000 series look the goods and are cheaper than I thought they were going to be.

SLE355
11-05-03, 08:54 AM
I bought my rims brand new there 16x8 to suit a VH Commodore. The bolts just hit the outer edge of the caliper :(


dattoman1000 can you supply a kit using the nissan 4 spots? I was looking at the ones from commsport what do you think of these kits?

I was also looking at just using a set of VL Turbo front brakes. How much better would the nissan conversion be over this?

Jimbo123
11-05-03, 11:22 AM
Originally posted by dattoman1000
Show us a pic Jimbo. The thing I need to see is the length of the mount leg and the radius of the curve in the centre where the disc runs.
Will do later today,.. after we do the mother's day rounds.

[Edit,... pics taken url follows]
http://home.iprimus.com.au/jimk00/VN/nissan-4pots.htm


If they suit a 32mm thick rotor why wouldn't you go for a pair of flash new 4048's. 330mm x 32mm. You'd need a VT conversion hub for it also. The new 4000 series look the goods and are cheaper than I thought they were going to be.
One sign,.. the $$s. The 019s I was looking at picking up for $300 a pair new. My preference was hubs and hats, as more options would exist but the $$ just keep adding up.

Hubs,.. $200-250 and no idea what the hats would be worth. I was thinking the 046BS,.. but I guess the 4048's could do as well. Any idea on the $$ for either the 046BS or 4048's? PM me if you like - just rough ball park.

Jim.....

dattoman1000
11-05-03, 07:24 PM
$300 for a pair of 019's. ??
Must be a private sale of left overs or something nasty from Asia.
Discpads.com sell their DBA slotted ones for $366 each.
For what your doing I'd go with DBA branded product only.....imports won't cut it when your beating up on it.
Actually I'd go 4000 series DBA's if your going to drive it like I think you are.
Jimbo those calipers are the same as I have at work. I'll check them against the discs with some pads in them and see how the pad radius sits.
I'll get you some prices on the 4019,4046B and 4048 all in slotted tomorrow.

SLE355 I'd be going for VT calipers and discs before I fitted VL turbo ones. Theres not much difference between VLT and your stock brakes but there a big difference between VT and VLT.

I don't have brackets for the Nissan conversion. There are so many different setups available for Commodores I had to draw the line somewhere. I sell AP and Brembo kits as well as the C4,C5 and VT seups. I think thats enough stock for me.

I know its a terrible pain but could you fit shorter bolts ?
Thinking about it thats what we did with the Torry.The owner sat for hours removing 1 bolt at a time and replacing it with a shorter one. Retorquing each one at a time. He only had to do the fronts but since he had 2 sets of wheels - 1 for street and one for track - he still had to do 4 wheels....what a pain. Then when he stepped up to 17" simmons he wanted bigger brakes again.......I told him NO !!!

SLE355
11-05-03, 10:13 PM
All the kits i've seen for VT brakes are around $2100 because they come with a changeover master/booster so that you dont end up with a long pedal. They also use at Cebco anyway the HSV twin spot's which i think are C5? calipers as the stock calipers flex to much?

I have replaced a set of bolt's on a previous set of simmons but would rather leave them if i can although it could be a last resort.

Jimbo123
11-05-03, 10:22 PM
Originally posted by dattoman1000
$300 for a pair of 019's. ??
Must be a private sale of left overs or something nasty from Asia.
Discpads.com sell their DBA slotted ones for $366 each.
For what your doing I'd go with DBA branded product only.....imports won't cut it when your beating up on it.
Genuine dba they were,.. yes for the pair. I thought it was for one initially. Anyhow, that's why I said it was a deal that now looks like falling through - only because the guy is in NSW and I can't get him and someone I have up there teed up for an exchange. DBA is what I'll get,.. its the finer details I'm still trying to sort/think through.


Actually I'd go 4000 series DBA's if your going to drive it like I think you are.
Looked at their web site earlier today,.. they do look rather tidy the 4000 series.


Jimbo those calipers are the same as I have at work. I'll check them against the discs with some pads in them and see how the pad radius sits.
I'll get you some prices on the 4019,4046B and 4048 all in slotted tomorrow.
Much appreciated - it may help me decide on one way or the other.

Oh, if they're the same, what sort are they,.. just so that I know for future reference and all that sort of stuff.

Thanks,

Jim.....

SLE355
13-05-03, 05:17 PM
Can you use the VN GPA calipers on VL turbo or VT disc's?

dattoman1000
13-05-03, 08:44 PM
Youd have to use the VT disc as that caliper is designed for a 28mm thick disc. The VLT is only 23mm.

You'd also have to make a custom adaptor bracket to use this caliper on a VT disc. I've never tried to do it but I guess its possible.