I'm starting to think about making my propshaft, to mate an MT75 to a sierra diff. I seem to remember seeing photos where the big rubber donut jobbie on the output end of the MT75 has gone.

What have others done, have you all bolted up to the big rubber thingy, or does it somehow come off to reveal a different (simpler?) connection option??

JohnN

dont use the rubber bit

its usually too wide for the tunnel and isnt able to cope with the angle of the prop shaft - its used as a dampener on the donor car

get a prop custom made - its safer and easier than trying to get bits cobbled up.

will cost about 125 quid

atb

steve

[Edited on 17/2/04 by stephen_gusterson]

The 'doughnut' is actually a small flywheel and is used as a damper. It is not made of rubber and will not, (in itself) compensate for any offset in the driveshaft. It will however fit into a standard book transmission tunnel should you wish to do so.
Personally I intend to ditch it and get a prop shaft made to fit the three spoked adaptor that it fits to.

Mick

Steve - My tunnel is wide enough! I just hope there's room left for a cobra roadster seat. (my chassis is 4" wider)

Just wondered about the total fixedness of it all without the rubber whatsit, the prop would have to be a pretty accurate length - unlike a type 9 gearbox install.

I guess that means that the MT75 would be no good in a solid rear axle situation as it has no slined output?

JohnN (mine is bigger!)

Mick,

I remember now, it was one of your pictures that showed the rubbery steel whatsit removed.

Looks like I need to find a local propshaft guru to tell me what's possible. (what he can supply and fabricate)

I was hoping to do a cut & shut on my sierra prop, as recently described by others, but the MT75 end of the sierra shaft is much smaller than the diff end.

JohnN

As Stephan G said,Don't use the 'doughnut part of the.........mmmmm..Doughuts.Sorry,side tracked.With it fitted,the prop runs out,as stated due to the angle and gives triffic vibes at 1500rpm in 1st plus.Very scary.Mine did.I remade it,retaining the "star" parts of the doughnut bolted together,2 ujs & the length of tube worked out as per book re axle travel.Hasn't been a problem.

my dono had a '9' fitted - which has the rubber donut. The pics I have seen in manuals of the 'balancer' look like a wheel thingy. I cant speak for that.

If the rubber joint fits - great. Be aware that its not meant to flex too much - like a UJ would - so unless its running pretty much in-line, you risk it failing and possibly severly maiming / killing yourself.

Props can spin at 7,000 rpm................

atb

steve

If you have one made you will be supplied with an adaptor which bolts onto the 3 finger output casting which the damper flywheel bolts to, This then allows a normal u/j joint to be fitted to the new propshaft. Mine was also fitted with a slider section to allow for slight movement for and aft as the egine moves and means there there is no stretch stress placed on the joints if the prop is a few mm too short/long. It is the easy option having one made, better safe than dead.

i seriously suggest you use the rubber "donut" on the output triangle flange on the gearbox - you can throw the metal plate away tho that covers it - if you dont use it you'll end up like my mate - shearing output flanges off the gearbox - the donut is there to take the initial strain and dampen out heavy gearchanges so that there is a lot less pressure on the gearbox internals and the outputshaft bearings.

use the rubber bit, then immediately after that, a univeral joint and then another universal joint as close to the diff flange as you can (bit like standard sierra prop rear end)

above - NOT the way to do it!!!!!!!!!!!!!!!!!!!!




place donut here and use it - for your own safety and the longitivity of the gearbox.

I may have missed something here !

My MT75 has the same tripoid adaptor as that shown in Graceland's photo. However the bit I removed to reveal the adaptor was certainly not rubber. It was a fairly heavy metal ? flyweel type of thing. Are there two different types of coupling available as if so then my previous comments may not apply to installations differing from my own.

Mick

Almost every prop I've seen the rubber doughnut has been ditched. I've heard several stories of them shearing and props freeing as a consequence!

All models have the rubber donut however some XR4x4 boxes have a heavy flywheel bolted to the flange on the back of the box.

In answer to the original question on the thread why dont you fit the flange from a Transit MT75 box and do away with the pronged flange

you got a picture of the transit mt75 output flange?

My gearbox was out of a DOHC Sierra, no donut there, unless one of the kids ate it while I wasn't looking! The bit I took off was a metal flywheel. Be interesting to see how Westfield do it as they use the box all the time. I have never seen anyone retain it.

Litlle POLL for MT 75 users:

Used the litlle flywheel: Yes No
Used the rubber Donut: Yes No
Balanced: Yes No

Surely it depends on what sort of back axle you've got - if you have a live axle then you don't want the rubber thingy as it was not designed for significant angles of flex. However, if you have a fixed Sierra type of diff rigidly mounted then the rubber donut is optional - you can choose whether or not to have the vibration/shock damping, as long as the gearbox and diff are in the proper alignment.

David

I'm building a Westfield and the prop supplied by them uses the rubber donut. However, i got mine made by Bailey and Morris and they don't use the rubber donut.

Bailey and Morris are specialist prop manufacturers and if they say it doesn't need the donut then i'm happy with that.

Bailey and Morris

Cheers
Simon

quote:

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Originally posted by AvonBelgium
Litlle POLL for MT 75 users:

Used the litlle flywheel: Yes No
Used the rubber Donut: Yes No
Balanced: Yes No

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Further investigations getting quotes for props gave me what will be my solution.

Remove the metal flywheel and the ribbuer thingy it connects to the prop by. Unbolt the tripod which should pull off a splined shaft and replace it with the transit flange.

This then allows a simple propshaft, flanged at both ends, with a splined telescope section near the front, to take up minor movement.

Photo attached showing existing metal flywheel/tripod thingy and the transit flange below
Rescued attachment propflange.jpg

Maybe this could this be a sticky?

I've ordered a new one.

FORD-Numbers on the bill:
- nut: 1373345
- flange: 6171398

- On the package:
Flange-drive:
6171398
Y 52219 002
88VT 4K177 AB
K6(DP) 0030

Will let you now if it fits!

quote:

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Originally posted by t.j.
Maybe this could this be a sticky?

I've ordered a new one.

FORD-Numbers on the bill:
- nut: 1373345
- flange: 6171398

- On the package:
Flange-drive:
6171398
Y 52219 002
88VT 4K177 AB
K6(DP) 0030

Will let you now if it fits!

---

The combination of the metal thingy and the rubber donut which is missing in the photo was fitted to the DoHC to smooth out the take up of the so called "executive models" of the sierra. All well and good in a 1.5 tonne tin top but not required in a kit car weighing less than half that

quote:

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Originally posted by ss1turbo

quote:

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Originally posted by t.j.
Maybe this could this be a sticky?

I've ordered a new one.

FORD-Numbers on the bill:
- nut: 1373345
- flange: 6171398

- On the package:
Flange-drive:
6171398
Y 52219 002
88VT 4K177 AB
K6(DP) 0030

Will let you now if it fits!

---

Was that for the transit solid flange? And if so, how much did they charge?

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