6 replies to this topic

[bob]

Hi Guys,

Long-long-long shot here but chasing some info on the early pre-92 twin-pot calipers with the 41mm pistons, - found in Galant, E38a, vr4 89-92
not the 43mm pistons used by every other twin pot system RVR through to EVOX.

the early caliper is MB699450, runs pistons MB618229 which are 41mm - found in Galant, E38a, vr4 89-92
the rvr/evo 1-3 is MB950176, runs pistons MB857837 which are 43mm
both use the same frame bracket.

every caliper onwards runs the same piston (43mm) right through to the evoX

Has anyone ever noticed this variance - seen impacts of swapping to later model calipers?
Does anyone have an old pair of early 41mm bore calipers lying around?

back story:
I have a pajero io (small 4g94 powered hairdressers 4x4), brakes have always been Meh, I've gone and upgraded the fronts to twin pot calipers from an RVR, this is a very common mod for all single-pot front mitsi's like fto etc all before i knew about the piston size difference on the io. it should be a straight swap no master cylinder changes needed (like every other mitsi)

pajero io front piston is 57mm, unlike every other single pot front (lancer, fto, outlander single pot, airtrek) that have a piston of 60mm, 
pajero io rear disks which have a piston of 35mm, unlike every other rear disk end that has a 38mm piston.
The smaller pistons in the io have much to do with it's ultra-short master cylinder (strut tower in the road) i.e. less stroke on master cylinder needs smaller volume pistons etc etc. no other mitsi has a stupid short master cylinder and there is 3/4" between end of master cylinder and the front coil spring so no joy there.

symptoms are softer pedal and more travel required to get brakes clamping hard, and the rears come on early. i.e. front calipers need too much fluid to actuate aka bores too big.

When you ratio the standard single-to-twin caliper piston sizes of evo's / rvr's, fto's etc back against the io i really need a twin pot with 40.8mm bores, the early 41mm caliper is the closest i will get.

Help!

[BMGTZ]

can you have the existing master cylinder bores out and sleeved to create a large bore...thus displace more fluid.

 

This was a common practice with some early toyotas when fitting twin cam engines. The brake place that does it will need to be able to supply a larger piston and seals. It will mean you will need to run a restrictor/biase valve in the rear line tho.

[Taz]

BHSS in capalaba will be able to sort the issue, best place in QLD to do brakes used to work there myself.

[Starion VR4 Derek]

Hi Guys,

Long-long-long shot here but chasing some info on the early pre-92 twin-pot calipers with the 41mm pistons, - found in Galant, E38a, vr4 89-92
not the 43mm pistons used by every other twin pot system RVR through to EVOX.

the early caliper is MB699450, runs pistons MB618229 which are 41mm - found in Galant, E38a, vr4 89-92
the rvr/evo 1-3 is MB950176, runs pistons MB857837 which are 43mm
both use the same frame bracket.

every caliper onwards runs the same piston (43mm) right through to the evoX

Has anyone ever noticed this variance - seen impacts of swapping to later model calipers?
Does anyone have an old pair of early 41mm bore calipers lying around?

back story:
I have a pajero io (small 4g94 powered hairdressers 4x4), brakes have always been Meh, I've gone and upgraded the fronts to twin pot calipers from an RVR, this is a very common mod for all single-pot front mitsi's like fto etc all before i knew about the piston size difference on the io. it should be a straight swap no master cylinder changes needed (like every other mitsi)

pajero io front piston is 57mm, unlike every other single pot front (lancer, fto, outlander single pot, airtrek) that have a piston of 60mm, 
pajero io rear disks which have a piston of 35mm, unlike every other rear disk end that has a 38mm piston.
The smaller pistons in the io have much to do with it's ultra-short master cylinder (strut tower in the road) i.e. less stroke on master cylinder needs smaller volume pistons etc etc. no other mitsi has a stupid short master cylinder and there is 3/4" between end of master cylinder and the front coil spring so no joy there.

symptoms are softer pedal and more travel required to get brakes clamping hard, and the rears come on early. i.e. front calipers need too much fluid to actuate aka bores too big.

When you ratio the standard single-to-twin caliper piston sizes of evo's / rvr's, fto's etc back against the io i really need a twin pot with 40.8mm bores, the early 41mm caliper is the closest i will get.

Help!

You Might be in luck... I maye have a spare set out of my VR-4... 1993. Let me check

[bob]

You Might be in luck... I maye have a spare set out of my VR-4... 1993. Let me check

cool, let me know how you go

 

[bob]

can you have the existing master cylinder bores out and sleeved to create a large bore...thus displace more fluid.

 

This was a common practice with some early toyotas when fitting twin cam engines. The brake place that does it will need to be able to supply a larger piston and seals. It will mean you will need to run a restrictor/biase valve in the rear line tho.

it's a really weird stupid internal design - slacks creek said they've not seen anything like it before.
I'm going to try and get the front/rear volumes same ratio as the FTO / Evo / Outlander and see how it goes - would have been awesome if i'd known prior to fully refurbishing the front pair of RVR HSG EVO3 calipers i'm running

[bob]

so - 
airtreck single piston 28.3cm2
airtreck twin piston 28.7cm2

io single piston 25.5cm2
vr4 twin piston 27.7cm2

not great but 27.7cm2 is better than 28.7cm2 when you are valved for 25.5cm2