ok i have just completed a five spd conversion from this forum i was told would fit in no mods but i had to change the gbox mounts for some reason my mk had only the single bolt holes for the 4spd box so i used a piece of angle iron and drilled 2 holes in the angle and then bolted 1 end to the original mount and then fitted the gbox (rubber) mount to the other end /hole in the angle there for movint the mounting point by around 50 mm ( now my question)> will thias be strong enuff and by the way i was using 5mm angle and high tensile bolts
Cheers Bourkey
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5 spd
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Bourkey, a bit of punctuation would help us understand your question but I think I understand the gist of it.
I think that most forum members when talking about 4sp/5sp conversions think only of the actual mating of the new box to the engine as this is the tricky part. I know I do. We take for granted that other mods will also be required because of the extra length of the 5 speed. These include
* Repositioned engine mounts
* Shortened rear driveshaft
* Lengthened front shaft
* Longer handbrake cable for a shaft mounted brake
* Longer speedo cable depending on where the take-off drive is
and probably a few other things I have forgotten such as repositioning or redesigning bash plates, extending wiring for the brake and 4wd indicator lights and possibly modifying the transfer lever position/mechanism.
As for your specific question re mounts, don't underestimate the loads involved. Think of your truck becoming airborne and hitting the ground at speed. Transmissions are awful heavy. I find it helpful to actually think how the force from the gearbox in such circumstances would be transmitted to the chassis by visualising or actually sketching the path the force has to travel. If there are any abrupt changes of direction you will likely have problems. So try to avoid cantilevered mounts as I think you describe. The setback on an MQ is nearer 100mm than 50mm.
On my conversion on an MQ I made a completely new bracket for the RH side which I bolted through the rail with 4 HT bolts, using a backing plate under the bolt heads for the full height of the rail to prevent crushing. Engineers do not like chassis rails being welded because of possible distortion. I also connected it to the existing bracket with a plate to improve fore and aft rigidity - probably overkill.
On the other side I fabricated a full depth bracket which I bolted to the side of the existing bracket, with HT bolts. Because of the depth of the bracket on this side there is a smooth path for the force to travel on its way to the chassis. With HT bolts it is important that they be torqued correctly as the joint relies on friction grip between the surfaces as a result of the clamping action of the bolts.
I have had no problems with this in the six years or so since the conversion. From your description it seems to me that your proposal is a bit light.
David
I think that most forum members when talking about 4sp/5sp conversions think only of the actual mating of the new box to the engine as this is the tricky part. I know I do. We take for granted that other mods will also be required because of the extra length of the 5 speed. These include
* Repositioned engine mounts
* Shortened rear driveshaft
* Lengthened front shaft
* Longer handbrake cable for a shaft mounted brake
* Longer speedo cable depending on where the take-off drive is
and probably a few other things I have forgotten such as repositioning or redesigning bash plates, extending wiring for the brake and 4wd indicator lights and possibly modifying the transfer lever position/mechanism.
As for your specific question re mounts, don't underestimate the loads involved. Think of your truck becoming airborne and hitting the ground at speed. Transmissions are awful heavy. I find it helpful to actually think how the force from the gearbox in such circumstances would be transmitted to the chassis by visualising or actually sketching the path the force has to travel. If there are any abrupt changes of direction you will likely have problems. So try to avoid cantilevered mounts as I think you describe. The setback on an MQ is nearer 100mm than 50mm.
On my conversion on an MQ I made a completely new bracket for the RH side which I bolted through the rail with 4 HT bolts, using a backing plate under the bolt heads for the full height of the rail to prevent crushing. Engineers do not like chassis rails being welded because of possible distortion. I also connected it to the existing bracket with a plate to improve fore and aft rigidity - probably overkill.
On the other side I fabricated a full depth bracket which I bolted to the side of the existing bracket, with HT bolts. Because of the depth of the bracket on this side there is a smooth path for the force to travel on its way to the chassis. With HT bolts it is important that they be torqued correctly as the joint relies on friction grip between the surfaces as a result of the clamping action of the bolts.
I have had no problems with this in the six years or so since the conversion. From your description it seems to me that your proposal is a bit light.
David
1982 Patrol K160 SWB (MQ) 4L P40 Petrol with Megasquirt fuel injection and EDIS ignition. Warn 8274 winch with Gigglepin head
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