I wanna build an Astra 4x4, and although the cav/cally system would be the easiest route to go down its far from ideal.
Having had a look around there isnt really any options that wont prove too expensive to make the project worthwhile as its something to be done 'relatively' cheap as and when suitable cheapish parts are available.
So the sierra 4x4 system looks favourite, it offers considerable benefits over the VX system, both in strength and the way itll drive. Central transfer box torque split of 34fr/66rr with viscous diff lock, and a rear LSD too. Sounds nice. Also the MT75 can i believe be mated to an XE or LET with abell housing adapter from SBD.
Looking to buy a complete car, mechanically sound, shell as rusty as poss (suitable only for breaking, keeps cost down). Rusty sierra shouldnt be hard to find.
Now, wanting advice from anyone slightly familiar with this car.
-Is the rear susp on the sierra fully independent?
-Do we think the front diff will be able to clear the bottom of the sump without too many issues? Or gonna be a custom sump jobbie?
Id like to retain the front hubs and struts from the astra, gona be able to get shafts made up to fit ford box to VX hub/cv assembly?
All advice appreaciated, and opinions welcome too (although some may be ignored ).
The front diff on the Sierra is bolted to the sump and one shaft passes through it. The rear end is similar to the Cav/Cally/Senator/Carlton. The bellhousing available are for the Type 9 which is the more common box. Plenty of gear kits available too. The rear end has an LSD as standard too. There are 2 sets of diff ratios, 3.62 in the XR4x4 and 4.1 or 4.2 in the later 2.0 litre version. The shaft problem is easily solved with plenty of cash.
I think you may have problems fitting it in - the Sierra engine layout is longitudinal which is OK in that car, but you may not have enough room in the nose of an Astra to fit the engine in with the front wheels in the right place.
Thanks fellas, length was not an issue i had really considered i spose as these were just general thoughts at the minute.
Locating the front wheels in the right place shouldnt be too much of an issue would it as the front diff is driven by a separate output shaft from the transfer box, the length of this could be adjusted if neccessary to get the front diff in line with the hubs.
Spose the main issue (with length) is getting the box positioned properly so the gear lever is in the right place ie not too far back. Thats what will dictate whether the setup will fit in the car or not.
Does anyone know how the selector works in these? Is it cable or rod displaced from the box or does the lever disappear directly into the top of the box?
If cable or rod then again that allows some degree of adjustment in lever position so as to get the box positioned better, if direct link into box then it doesnt.
Oh bugga and ar se, spoke to SBD today and 2 probs.
1 - the sarah i was looking at buying has the MT75 box in it. Well they only do a bell housing to mate the type 9 sierra box upto the VX lump, so thats a no go.
2 - if i do find a 2.8 (which had the type 9 box) going cheap enough its still no good. The box wont take the torque of a LET for long.
Back to the drawing board.
Im disappointed really, it was the only possible solution next to utilising the std VX 4x4 system and seemed far superior to it. Any other type of 4wd system presents real problems in mating up to the LET engine and this is a DIY budget car not a chequebook job so couldnt afford the expense of getting parts made up to mate other boxes to the LET.
This is where you need to find yourself an engineer who's into cars. Making the Type 9 bellhousing fit onto an MT75 isn't difficult. The cheaper option is to get a 1.8/2.0 carlton or 1.8 manta box, cut the main casing down and weld a plate on. Don't knock the abilities of the type 9 box. Remember that turbo technics made twin turbo XR4x4's which probably had as much, if not more, torque as a tuned LET.
hmm interesting post
i have heard of a company doing that conversion but can't remember which one- iwill check
can you not use a calibra or cav sys? i know that they are not the best in the world but i'm sure you could get the floor pan off one or the other to fit!
i have considered the same for a nova or at least rear wheel drive poss rear engined
if it turns out you cant get any gen on this try it then that way you are the first=cash make cash then sell your blue print to people/companys
everyone wants 4wd its fun as is rear wheel drive that astra is screaming out for a transformation. GOOD LUCK AND LET ME KNOW AND VISA VERSA
kris
You mean weld the casing to the ford box casing so as to fit it that way? You seen that done before?
16vmanta said:
Don't knock the abilities of the type 9 box. Remember that turbo technics made twin turbo XR4x4's which probably had as much, if not more, torque as a tuned LET
Right then, ill be on the lookout for another one then, either 2.8 with the T9 box and see how it holds up, or the 2.9 with the MT75 which is stronger and try making that fit instead.
Didnt really want to, the cav/cally system is really only part time 4WD as std which is not what i want. Until you lock it that is.
When locked its then full time AWD but without a proper central diff, only the viscous coupling to act as a diff, which wont do it much good.
Most importantly, the VX system will always be primarily front biased, whereas a system like that on the XR's is 64% rr and 34% front, would be a better drive.
The bellhousing on the carlton/manta boxes is cast into the main casing. What you do is throw everything away apart from the casing. Cut it down until it's slightly longer than it needs to be. Square it off with a mill. Then weld a plate on. Make the holes in this plate match those in the frod bellhousing. If you get it right, and it takes a bit of messing measuring everything, drawing it, checking, measuring again to be sure, allowing for the plate not being square and needing machining afterwards, finding the right positions for the holes, etc, then your laughing. I've been through this process, making a bellhousing to fit the 265 Getrag from the Monza fit onto an XE. As i said, find yourself a good general engineer who doesn't mind you asking dumb questions and appreciates what you're trying to achieve. This is only a small part of the overall conversion. There were a few conversions mentioned in CCC through the 90's which mainly used the 4x4 floorpanel in another shell.
Thanks mate, defo sounds like a task for an engineer to help me with, wouldnt be too confident about the strength of it all if i did that meself.
Ill see what comes available, think that i would rather go to the effort of getting the MT75 to fit as its stronger and with slightly higher gearing too IIRC.
why not look into other 4x4's with engine mounted transversaly(?) such as lancia delta, mitsu evo's, mazda gtr's, nissan gti-r's, corolla wrc's, +++
with an adapter between the gearbox and engine it should work.
offcourse, the sierra parts are easier to come by, probably a lot cheaper,
easier to get upgrated parts and so on.
but as for construction, in an astra, the other choises seem easier.
I've looked at mating a LET with a MT75 4x4 my self, although in an Ascona B.
Manta 1.8 with 4-speed box has separate bellhousing, so no cutting's needed.
only 5-speed box's has bellhousing casted into box.
I've planned to use Carlton 24v diffs with lsd both in the front and at the back.
ps.: my plans excist only in my head sofar...
good luck on your project.
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