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GS450h Transmission. What engine mounts.
Posted: Sun Jun 11, 2023 6:34 pm
by acollins22
Hi Everyone,
I have the old IC engine out of my car now and I'm contemplating how to mount the GS transmission in its place.
I don't imagine anyone hard mounts the trans to the chassis so what do you do for engine mounts.
This is for a Scimitar so it's a ladder chassis.
Thanks,
Andy.
Re: GS450h Transmission. What engine mounts.
Posted: Mon Jun 12, 2023 10:30 am
by celeron55
Look at the relevant project topics by using the forum search function:
search.php?keywords=gs450h&terms=all&au ... mit=Search
Re: GS450h Transmission. What engine mounts.
Posted: Mon Jun 12, 2023 11:54 am
by Uppertown
Try and get the output as close to where the original was as possible and try and match it's angle too. You'll then hopefully be able to make a hybrid of the original Lexus mount and the bolt on Scimitar crossmember. At the front you've got more of an issue if you are trying to avoid modifying the chassis, have a look at what is nearby you may have to get imaginative but I'm guessing you'll need some sort of extension running forward from your transmission locking plate. For actual rubber mounts look at things like older V8 Landrover. The more in shear you mount them the softer they are; 45°is a good starting point for an engine but with a motor you may get away with having them in pure compression - at least from an NVH point of view.
https://www.ebay.co.uk/itm/274829859836 ... R-CMmveVYg
Re: GS450h Transmission. What engine mounts.
Posted: Mon Jun 12, 2023 5:38 pm
by acollins22
Thanks both for your answers. I've got a good idea where to go now.
Thanks,
Andy.
Re: GS450h Transmission. What engine mounts.
Posted: Mon Jun 12, 2023 7:06 pm
by Pete9008
Also worth bearing in mind that the engine mounts aren't just there to support the engine, they also have to cope with the full torque reaction from the drive/prop shaft and with a GS450h box in low gear that could be substantial.
In particular one mount will be in tension under acceleration and without the normal 100kg or so of engine weight on it to help compensate may not be too happy.
Re: GS450h Transmission. What engine mounts.
Posted: Tue Jun 13, 2023 1:57 pm
by PatrcioEV-ATX
Someone better at metal fab could have done this much more elegantly, but I used generic engine mounts bolted to my frame rails and then a cross member bolted to the 450h bell housing.
For the output end, I created a custom crossmember that bolts into my cars original transmission mount points.

Re: GS450h Transmission. What engine mounts.
Posted: Tue Jun 13, 2023 2:13 pm
by acollins22
That's very helpful. It's what I had in mind and it's great to have it confirmed.
Cheers,
Andy.
Re: GS450h Transmission. What engine mounts.
Posted: Tue Jun 13, 2023 2:18 pm
by PatrcioEV-ATX
acollins22 wrote: ↑Tue Jun 13, 2023 2:13 pm
That's very helpful. It's what I had in mind and it's great to have it confirmed.
Cheers,
Andy.
You might also like what artuk did:
https://www.youtube.com/watch?v=Jj3IG3Gnd-o&t=204s
Re: GS450h Transmission. What engine mounts.
Posted: Tue Jun 13, 2023 3:29 pm
by Uppertown
acollins22 wrote: ↑Tue Jun 13, 2023 2:13 pm
That's very helpful. It's what I had in mind and it's great to have it confirmed.
Cheers,
Andy.
Just be careful about drilling holes in your chassis - the UK DVLA can get very difficult about it. Having said that Scimitar chassis look a bit like Colanders and I've never seen two alike apart from at the Middlebridge sell off.?
Re: GS450h Transmission. What engine mounts.
Posted: Fri Jun 16, 2023 5:41 am
by xp677
land rover defender engine mounts, super cheap on ebay.
Re: GS450h Transmission. What engine mounts.
Posted: Fri Jun 16, 2023 8:17 pm
by acollins22
I've been standing in the engine bay today, taking measurements and getting my head around the task ahead.
I _think_ the Land Rover mounts will fit straight into the existing engine mounts so no chassis mods needed
I'll let you all know when they arrive.
Cheers,
Andy.
Re: GS450h Transmission. What engine mounts.
Posted: Sat Jun 17, 2023 8:24 pm
by xp677
There's also generic ones like this:
https://www.ebay.co.uk/itm/353534023512
Not sure if they're strong enough, though. They are a bit squishy. Maybe the biggest ones would be good.
Re: GS450h Transmission. What engine mounts.
Posted: Sun Jun 25, 2023 6:19 am
by evMacGyver
Have you experienced noise from the transmission on slightly higher revs? Is it normal to get increasing noise from about MG2 4000-4500rpm and up? In my case its about 80km/h and MG1 is locked. Somehow disruptive noise starts from none to "full" at quite exact rpm and keep up all the way as revs gets higher. Torque being positive, negative or neutral makes no difference
I did not put great also sound insulating mountings, however clutch side have square metal pipe and some soft rubber between it and subframe, no direct bolts to subframe. Rear mounting is GS450h original.
Could be drive shaft too. Did lift rear of the car and another person listened from the below and could not locate the source to be drive shaft. So noise could be from transmission front mounting. But is that noise normal?
Re: GS450h Transmission. What engine mounts.
Posted: Mon Jun 26, 2023 2:37 pm
by PatrcioEV-ATX
evMacGyver wrote: ↑Sun Jun 25, 2023 6:19 am
Have you experienced noise from the transmission on slightly higher revs? Is it normal to get increasing noise from about MG2 4000-4500rpm and up? In my case its about 80km/h and MG1 is locked. Somehow disruptive noise starts from none to "full" at quite exact rpm and keep up all the way as revs gets higher. Torque being positive, negative or neutral makes no difference
I did not put great also sound insulating mountings, however clutch side have square metal pipe and some soft rubber between it and subframe, no direct bolts to subframe. Rear mounting is GS450h original.
Could be drive shaft too. Did lift rear of the car and another person listened from the below and could not locate the source to be drive shaft. So noise could be from transmission front mounting. But is that noise normal?
I can say I've had mine up to 90+ and not noticed any added noise (but wind!)
Re: GS450h Transmission. What engine mounts.
Posted: Tue Dec 12, 2023 7:36 pm
by ggeter
Sorry late to the part on this one. My trans is bolted straight to my frame using angle iron with 1/8" rubber pad where the iron matches to the frame. Not elegant, but it's lasted over a year:
viewtopic.php?p=32724#p32724
Re: GS450h Transmission. What engine mounts.
Posted: Tue Dec 12, 2023 8:04 pm
by acollins22
Thank you everyone.
I have gone for the Land Rover mounts and they look just the job. I am still a way from being able to test anything but so far, so good.
Cheers,
Andy.
Re: GS450h Transmission. What engine mounts.
Posted: Sat Feb 03, 2024 12:58 pm
by nino500
acollins22 wrote: ↑Sun Jun 11, 2023 6:34 pm
This is for a Scimitar so it's a ladder chassis.
Oh, snap! I didn't think anyone else would be thinking of a Scimitar for conversion, let alone with a GS450h.
I don't have even the project car yet but going to view an SE5a tomorrow.
I see you have engine mounts coming so you must be quite far along. Following with interest.