Lotus Elan Central

by **nitroman** » Sat 19.04.2008, 21:25

What is the bore of the BMC (ie, 1-1/8" bore?)? Also what is the distance between the two bolt-holes? In other words, is it a GM standard "mounting-pattern" like this one? http://www.ssbrakes.com/products/detail ... (0%20-%200) Seems if we knew some of these figures we could go up in bore size yet still find a bolt-in BMC. Comparing bore & stroke of various units (ie, Bore = 0.7”, stroke = 41 mm movement) makes it easy to compute total fluid movement VS pedal travel.

If the OE rod isn't adjustible we could make it so with a kit like this: http://www.ssbrakes.com/products/detail ... (0%20-%200)

Perhaps a place like this http://www.pastparts.co.uk/ might even be able to "re-bore" the OE unit to a larger internal-size & find a suitable new cylinder to match. It's certainly worth a call isn't it, UKers with a telly?

Decreasing the pedal-travel would perfect the Wilwood installation. There is no safety issue, but the BMC is used to its maximum ability in the Wilwood application. It would be nice to just tap on the pedal.
==============================================

About the 1990-1993 Pontiac Lemans:
It was a piece of crap car but there are similarities to the M100.
Designed by Opel in Germany (where it was sold as the Opel Kadett), the upmarket 2.0L engine (base engine was 1.6) came from Holden in Australia, transmissions, both automatic & manual, came from Isuzu in Japan. Car was dubbed a "world car" and was assembled by Daewoo in Korea. Depending on the market it was also rebadged as an Opel or Vauxhall.

by **ailwyn** » Sat 19.04.2008, 22:36

Candles wrote:I cannot get to the pipes to undo them, nor can I undo the nearside mounting nut! I've got the arch liner out so the offside nut was a piece of old wee, but I'm stumped with the rest! I'm almost tempted to just cut through the pipes and make new ones for the reinstall!

Candles,

I managed this (so anyone can) I use a crows foot to get the n/s nut of the master cylinder mounting, took a while, a lot of patience (which I don't have in any abundance), and just blood sweat and tears to finish it off.

I removed the PAS reservoir mounting and pushed the reservoir out of the way as best I could (it would have been easier if I'd removed it completely but wasn't that brave). Removed any pipes I could get at, I think it was 2, and bent them back out of the way as best I could. It then required the crows foot to be attached to an extension bar (I think it was 6") and then on to the breaker bar. I had to coax the crowsfoot and extension underneath the remaining brake pipes and back up in order for it to reach the nut. It didn't take much effort to remove the nut, it just took a long time as I could only manage a quarter turn on the nut each go, then the extension bar would detach or the crows foot would come off and I'd have to slide the whole thing under the brake pipes again.

Hope that helps.

Ailwyn

by **Candles** » Sun 20.04.2008, 10:28

I feared there wouldn't be any magic! Has anyone considered removing the wiper motor for better access?

Thanks for your help Ailwyn.

Candles

by **ailwyn** » Sun 20.04.2008, 10:41

Candles,

It probably would have been easier if I'd removed the PAS reservoir completely.

Just keep at it, you (must) have more patience than me so once it's had about 3 full turns you may be able to take it off with your finger tips.

IIRC it would have needed the whole wiper assembly to be removed to have access from the side (and enough room to turn the nut).

It was a PITA to have the plenum attached and work with the pipe connectors for the rear, but it was doable, lying on top of the engine with one arm each side of the plenum.

Ailwyn

by **Candles** » Sun 20.04.2008, 17:48

Well thanks very much for the encouraging words, I got it off with surprisingly little swearing in the end. For anyone trying this here is my advice:

WD40 & clean everything a few days before. The O/S mounting nut has to come off from the wheel arch (liner removed). Then drain as much brake fluid as possible (I let it pour from the calipers, do the rears as well). Having eased the PAS reservoir forward, the top 2 brake lines are just accessible. You need a 13mm and an 11mm spanner. I removed the MAP sender connection to create some more spanner room. Once you've got them turning a flat at a time, you simply need patience until loose enough to turn with your fingers. Tie the top rear line (11mm nut) towards to wiper motor to allow better access to the mounting nut.

Using a 13mm crow's foot spanner, attack the N/S mounting nut. This will turn about 2 flats at a time, and again, patience is the key. Eventually the assembly will be free apart from the two lower brake lines. At this point you are thinking: "No way am I getting to those."

You are correct, you aren't. Lean on the cam cover and reach around the right hand side of the intake plenum with your right hand, armed with a 13mm spanner. Now ask your glamorous assistant to shine a torch from the O/S wing, down the back of the plenum. You should see two brake unions. Undo both and hey presto! The master cylinder is loose. Now you need to carefully thread the lines around the others and ease the body out past the PAS reservoir. I reckon you could do it in 2 hrs.

Wiki to follow when I have pics.

Candles.

by **ailwyn** » Sun 20.04.2008, 20:45

Glad you got it undone. Like I said, if I can do it.... :-D

by **Monty** » Sun 20.04.2008, 21:10

Well done Candles, let us know what you intend to do with the New BMC and if it solves the issue with locking up the front N/S brake. It`s a shame we can`t find a BMC with a slightly bigger bore

by **Candles** » Sun 20.04.2008, 21:16

I'm going to try and get the large fittings for the lower holes and flare up the pipes to the rears. I'll keep the old pipes in case I want to revert to the Lotus part. I'll let you know how I get on. I don't want to gut the new cylinder just to use the internals on the old bore. If the whole thing works out nicely, I may buy another Pontiac BMC as that should see me good until 2038 :shock:

for another $20 or whatever I paid!

I'm not so sure about this 'larger piston' idea. There's a lot of chat in the other threads about it but I'm not converted. As someone said, just sort the rears out and it'll be fine!

Candles.

by **Monty** » Sun 20.04.2008, 22:12

nitroman wrote:What is the bore of the BMC (ie, 1-1/8" bore?)? Also what is the distance between the two bolt-holes? In other words, is it a GM standard "mounting-pattern" like this one? http://www.ssbrakes.com/products/detail ... (0%20-%200) Seems if we knew some of these figures we could go up in bore size yet still find a bolt-in BMC. Comparing bore & stroke of various units (ie, Bore = 0.7”, stroke = 41 mm movement) makes it easy to compute total fluid movement VS pedal travel.

Nitro`s,

The stock bore is 22.2mm (7/8")

Found one on RockAuto`s with a bigger bore 25.4mm (1") but don`t know if it`ll fit

1998 PONTIAC TRANS SPORT MONTANA 3.4L

http://www.rockauto.com/catalog/raframe ... 163k309450

by **Candles** » Mon 21.04.2008, 19:18

Here are the pics of the Pontiac BMC. I've just had a somewhat fruitless experience tracing fittings for the large lower holes. I went to an industrial pipe fittings place which seemed to have everything (admittedly not much imperial) and they couldn't even guess what it was. Anyone got any ideas?

Currently it is looking like I'll be doing the Unipart thing above anyway!

Candles.

by **GeoffSmith** » Mon 21.04.2008, 19:32

Try Pirtek. They're nationwide and rebuilt my PAS pipe for me.

by **Candles** » Mon 21.04.2008, 19:53

Hmmm good one Geoff: They seem to list some of the imperial stuff as well which may be the reason I was unsuccessful earlier.

Candles.

Edit: I have a feeling they might be a 9/16" UNF.

I also want to plumb in my new oil pressure sender to the return line from the oil cooler. That is another thread/union! The sender is 1/8" NPT according to AutoMeter and I have a handful of adapters for it.

Edit again: These guys look promising but charge £8 postage!

Speedflow

by **GeoffSmith** » Mon 21.04.2008, 20:22

The two old boys who did mine knew the threads as soon as they looked at them. They did a couple of urgent HGV repairs while I was there and they're pretty well stocked up. They probably weren't the cheapest I could have got but they used a bit of ingenuity to use only one standard coupling to repair both ends and re-brazed the pipe to banjo fitting.

by **Monty** » Mon 21.04.2008, 20:25

Candles,

Demon tweeks do different types of adaptors for sender units

http://www.demon-tweeks.co.uk/products/ ... e=LMA090/B

http://www.demon-tweeks.co.uk/products/ ... de=GLOHA25

by **Candles** » Mon 21.04.2008, 20:30

Thanks for the quick responses Gents, I think I'll try Pirtek in Lincoln as I can't afford to use trial and error with Speedflow although they look pretty good.

Candles.

by **nitroman** » Tue 22.04.2008, 04:05

Thexton universal thread gauges #432
These come in quite handy for me. http://www.toolsource.com/universal-thr ... id=froogle

by **Candles** » Thu 24.04.2008, 19:35

Well, I tried Pirtek, and the guys there were really excellent. He sorted out the oil pressure sender connection issue with a bit of ingenuity.

The Pontiac master cylinder foxed him though: They didn't stock anything that large in such a fine thread, however, they did say they could machine up two union nuts, but this seems a little extreme for something that must be available somewhere. He did measure the thread though: 16mm aperture x1mm pitch.

I've tried searching the internet for this size but I'm not turning up anything.

So, before I cut my losses and get the unipart one, any suggestions?

Candles.

by **GeoffSmith** » Thu 24.04.2008, 22:20

Don't know if this helps, but I think they may be M15 x 1. Check out the two Raybestos ones listed on Rockauto. The first design lists M12 and M15 outlets but the second design lists M12 and M10.

It looks like ESM's identification of the Pontiac LeMans might have been correct, just that there are two versions fitted.

by **GeoffSmith** » Thu 24.04.2008, 22:31

More evidence:

1988-90 LeMans WRONG
1989-93 LeMans RIGHT!

You wanted an 072-8250 not 072-8251 I'm afraid.

by **Monty** » Thu 24.04.2008, 22:37

GeoffSmith wrote:Don't know if this helps, but I think they may be M15 x 1. Check out the two Raybestos ones listed on Rockauto. The first design lists M12 and M15 outlets but the second design lists M12 and M10.

It looks like ESM's identification of the Pontiac LeMans might have been correct, just that there are two versions fitted.

Well spotted Geoff

Looks like this is the one

RAYBESTOS Part # MC39869 {Professional Grade Bore Size=7/8" Number of Ports=4 Primary Outlet Size=M12x1 Secondary Outlet Size=M10x1}
2nd Design $128.79

and would think this Doorman one is the same too

and is a little cheaper

DORMAN Part # M39869 {First Stop}
w/Power Brakes; Bore = 7/8"; Stamped 2631 on Booster $107.99

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